Keithley 615 Service manual

CONTENTS

02738

SPECIFICATIONS

MODEL 615

SPECIFICATIONS

AS A VOLTMETER:
RANGE:

ACCURACY: +0.290 of reading +1 digit on all ranges exclu.

ZERO DRIFT: Less than 1 millivolt in the first hour or subse-

NOISE: * 1 digit with input shorted on most sensitive range.

INPUT IMPEDANCE: Greater the” 10” phms shunted by

NMRR: Greater than 60 d8 on the most sensitive range de.

AS AN AMMETER:
RANGE: lo-‘2 ampere full scale (1O-L5 ampere, least sig.

ACCURACY: b-0.5% of reading,

NOISE: f-4 digits with input open and shielded on most
OFFSET CURRENT: Less than 5 x IO-l5 ampere

AS AN OHMMETER:
RANGE:

ACCURACY: &0.5% of reading.

AS A COULOMEMETER:
RANGE:

ACCURACY: +5% of reading 3~2 digits on all ranges. Drift

100

nificant digit) to 100 volts in four decade ranires.

sive of noise and drift.

quent 24.hour periods

150 mliCrOYOlt* pm “C.

35 picofarads. Input resistance may aIs0 be selected in

decade steps from 10 to 10” ohms.

creasing to 40 dB on the

nificant digit) to 0.1 ampere in 12 decade ranges.

ampere ranges using optimum sensitivity control setting;
*2% of reading *I digit 0n l@a and lo-3 ampere ranges
and 14% of reading *1 digit on
ranges exclusive of noise and zer0 drift.

sewitive range.

digit) to

ranges using optimum sensitivity control setting; *4% of
reading + 1 digit from
and zero drift.

millivolts full scale

10,000

ohms full scale

10” ohms

in

eleven

109 to 10’”

(100

microvolts.

least sig

after l.hour warmup. Less than

lOOwIt range at

-tl

line frequency.

digit

on 0.1 to l@’

1O-Lo to lo.‘1 ampere

(10

ohms. least significant

decade ranges.

hl

digit on
ohms exclusive pf noise

10’ to lOa ohm

10.” coulomb full sca1e (lo-” coulomb. least

significant digit) to 10’5coulomb in seven decade ranges.
due ta offset c”rrent does not exceed 5 x lO-‘I coulambs,

secpnd.

GENERAL:
DISPLAY: 4

sensftlwty
tivity setting.

POLARfTV SELECTION & OVERLOAD INDICATION: Auto-

matic.

OVERRANGING: lOO%overrangingon all ranges exceptwhen

“Sing Se”sltl”lty setting of 100.0.

DISPLAY RATE: 24 readings per second maximum (20 per

second on 50 Hz models); adjustable to tw, readings
per minute.

PRfNTER OUTPUTS AND OUTPUT CONTROLS: Model 4401

accessory provides BCD output and external cpntmls.

ISOLATION: Circuit ground to chassis ground: Greater than

IO6 ohms Shunted by 0.2 microfarad. Circuit ground may

be floated up to

CMRR: For high open-circuit CMRR. residual unshielded

capmtance between input high and chassis ground is less
than 0.1 picofarad.

ANALOG OUTPUTS:

Unity gain: At dc. Output is equal to input within 100 ppm.
exclusive of noise and zero drift. for Output currents of

100

1 mA: fl milliampere at up to 1 volt for full scale input,

100%

setting.

1 V: *l volt at

100% pverfange capability except M 100.0 sensitivity
setting.

CONNECTORS: Input: Tefkxvinsulated triaxial. Analog wt.

puts: Unity Gain: Binding Ppsts. 1 mA; Switchcraft Nl13B.
1V; Amphenol 80 PC 2F. Printer output &controls: 50.pin

Amphenol Micro-Ribbon.

DIMENSIONS, WEIGHT: 5%” high x

(132 x 433 x 280 mm); net weight. 20 pounds (9.1 kg).

POWER: 105.125 or 210.250 volts (switch selected), 60 HZ:

50 Hz models available. 35 watts.

ACCESSORIES SUPPLIED:

Made1 6011 Input Cable: 30” triaxiel cable with triaxial
connector and 3 alligator clips.

digits from 0000 to

settings; from 0000

100 volts

microamperes or fess.

overrange capability except on

up to 0.1 microampere for full scale input.

1999 on 0.1, 1.0,

to 999 on the 100.0 sensi-

with respect to chassis ground.

100.0

19”

wide Y 10” deep

and 10.0

sensitivity

ii

0372R

MODEL 615 ELECTROMETEX

SECTION 1.

l-l.

GENERAL.

a. The Keittlley Model 615 Digital Eleceromeeer is a

fast, accurate and sensitive Electrometer with digital
display.
instrument which measures a wide range of d-c voltage,
current, resistance and charge. Thy4Electrometer’s
input resistance of greater than 10 ohms is the re­sult of extensive instrument development with high in­put impedance transistors. The Model 615 has all the
capabilities of conventional VTVMs, but it can also

make many more measurements without circuit loading.

b. The Electrometer has four decade voltage ranges
from 0.100 volt full scale to 100 volts, 12-decade
CUrrent ranges from 10-12 ampere full scale tcl 0.1 am­pere, 11 decade linear resistance ranges from lo4 ohms
full scale to 1OL4 ohms, and seven decade charge rang-

es from lo-11 coulomb full scale to 1O-5 coulomb.

C. The Model 615 employs matched insulated-gate
field-effect ~ransiseors followed by a transistor dif­ferential amplifier and complimentary outpue stage.

A large amount of negative feedback is used for sta­biliey and accuracy.

1-2. FEATURES.

a. Unique input circuit provides overload profec-

tion up eo 500 volts on most ranges without damage.

b. Time stability is better than 1 millivolt/day
after l-hour warmup. Less than 150 microvolts per ‘=C
zero drift with temperature.

C. Offset current less than 5 x 1O-L5 amperes min-

It is a versatile, comp’letely solid-state

GENERAL DESCRIPTION

imizes zero offset with high source resistance.

d. A front panel ZERO CHECK Switch permits check-

ing zero-offset without disturbing the tneasurement

CiX”iC.

e. Operarion up to *lOO voles above case ground is

possible without affecting the reading. Isolatio”~

from csrcuit low to case ground is greaeec than 106

ohms shunted by 0.2 microfarad.

f. Analog output provided for 1 mA full scale re­corders such as the Keiehley Model 370 Recorder or
other floating instrument.

g. Digital display enables voltage’measurements to

l O.Z% of reading *I digit.

h. Polarity is automatically indicated on the dis-

Pk+,

i. Display rate 1s adjustable from 24 readings per
second to two readings per minute LO acconmadate the
mode of data retrieval.

j. Analog-to-digital converter is a dual slope in­tearaeing type circuit to pro”ide inaounity to line
power frequency pickup.

k. Model 4401 Printer Output.Cards are available

for factory or user installation. This option pro­vides BCD outputs far significant digits, range, pol­arity, sensitivity and overrange. Various remaee
control lines are also provided. The Output Buffer
cards are easily inserted into prewired, premouneed
card-edge connectors an the Model 615 chassis.

04728

OPERATION

WDEL 615 ELECTROMETER

Model 615 Front Panel Controls and Terminals (Figures 1 & 3).

TABLE 2.

contra1 F”“ctio”*l Description

SENSITIVITY Switch

Selects full-ecsle voltage sensitivity; slso used to mulriply
current, resietance and charge ranges on the Range Switch.

Automatically eelecrs the proper decimal point position.

RANGE Switch

Selects the mode which ia to be measured: voltage, current,

resistance or cherge.
FEEDBACK Switch
POWER Switch

Selects either NORMAL or FAST modes of operation.

Controls e-c line power to instrument (an/off).

DISPLAY RATE Control Determines number of analog-to-digital conversions per second.
ZERO caner01 Provides fine zero control adJuseme”e.

ZERO CHECK Switch Provides zero offset check without disturbing the source circuit.
INPUT Receptacle

Connefts wurce to input. ~ecepeacle is a Teflon insulneed

triaxia1 connector.

LO

TERMINAL

*Display Lights

Numerical Readout

Provides connection to input low.
Indicates polarity of input signal.
Indicates magnitude of input signal.

Par.

2-2,2-3

Z-2,2-3

2-2,2-4,2-5

2-2
2-3
2-2
2-2

2-l

2-l
2-3
2-3

Control

COARSE ZERO Switch

1 MA OuTPuT Receptacle

PRINTER/CONTROL
CO”“eCtOC

SPARE Receptacle

Xl OUTPm and
G”m.tl Terminals

CASE

GROUND Terminal

LO Terminal
1 VOLT OWPIPI
Line Cord

F”M

Model 615 Rear Panel Controls end Terminals (Figure 2).

TABLE 3.

Functional Description

Provides extended adfustment cepabflity of the front panel
ZERO Control.

Connect[i analog output to monitoring device.
50 pin connector for BCII digital output: provldea printer

control and remote control when Model 4401 printer ootput

cards ere installed.

Blank hole with cover plate for mounting edditional 50 pi”
CO”“BCtOC.

Provides extremely linear unity gsi” operation. Also used
for guerded reeFstance a.easureme”te.

Connected to Model 615 cabinet and outside shell of input
Connector.

Pravidea connection to input low end front panel LO connection.
Provides l’volt output for calibration purposes.
connecta line power to inatroment.
3

AD

Slow Blov.

117 volt - 314 A.
234 volt - 3/g A.

Psr.

2-2

2-9

2-10

__-

2-9

2-6

2-6
2-9
2-2
2-2

117-234V Switch Sets lnatrument for either 117 or 234 volt a-c power operation.

2-2

2 0470

MODEL 615 ELECTROMETER

GENERAL DESCRIPTION

SENSITIVITY Switch

POWER DISFLAY

ZERO
Switch PATE CONTROL
(S102)

CONTROL (R1222)

(R1201)

FIGURE 1. Model 615 Front Panel Controls and Terminals.

(S1203)

FEEDBACK LD

Switch (S1204)

RANGE Switch

(51201)

BINDING

POST

(51202)

ZERO CHECK

(S1202)

INPUI

RECEPTACLE

(51209)

COARSE ZERO

switcn (S1205)

Xl ouepur

(51203)

1 VOLT ODTPW

Transistor

FIGURE 2. Model 615 Rear Panel Controls and Terminals.

(9102)

Transformer

0570

3

OPERATION

MODEL 615 ELECTROMETER

SECTION 2.

2-l.

INPLPI CONNECTIONS.

8. The INPUT Receptacle of the,Model 615 is a Tef­lon insulated triaxial connector. The center termi­nal is the high impedance terminal: the inner shield
is the low impedance terminal; the outer shield is
case ground.

b. The front panel LO Terminal is connected to

the inner shield or low impedance terminal. The LO

Terminal is connected to the rear panel LO Terminal.
When the shorting link o” the rear panel is connected,

the LO is connected to case ground.

(See Figure 3).

INPUT

OPERATION

d. Carefully shield the input connection and the
source being meaaured, since power line frequencies
are well within the pass band of the Electrometer o”
a11 ranges.

may cause definite readout

“se high resistance, low-loss materials - such

e.

as polyethylene, polystyrene or Teflon - for insula-

tion. The insulation resistance of test leads and
fixtures should be several orders of magnitude higher
than the source resistance. Excessive leakage will
reduce accuracy.

employs a graphite coating between the dielectric and

the surrounding shield braid.

f. Any change in the capacitance of the measuring

circuit to ground will cause disturbances in the read-

ing, especially on the more sensitive ranges. fake
the measuring setup a.s rigid as possible, and tie

down connecting cables to prevent their movement. If
a continuous vibration is present, it may appear at

the output as a sinusoidal signal and other precau­tions may be necessary to isolate the instrument and
the connecting cable from the vibration.

Unless the shielding is thorough, pickup

disturbances.

“se a law-noise type cable which

NOTE

FIGIRE 3. Model 615 Triaxial Input Receptacle.

c. The Model 6011 Input Cable (provided) is a 30”
triaxial cable with triaxial connector and 3 alligator
clips. See Table 4 far color coding of the alligator
clips.

The high impedance terminal is shielded by the

inner braid of the eriaxfal cable up to the miniature

alligator clip.

Color Coding of Alligator Clips for Model 6011 Input

TABLE 4.

Cable.

Lead

heavy wire with

Input

high

C*llt*r

red clip cover

thin wire with

Input low

Inner Shield

black clip cover

thin wire with Case Ground

Outer Shield

green clip cO”er

Clean, dry connections and cables are very

important to maintain the value of all in­sulation materials. Eve” the best insula­tion will be compromised by dirt, dust,
solder flux, films of ail or water vapor.

A good cleaning agent is methyl alcohol,
which dissolves most common dirvwithout

chemically attacking the insulation.

D=Y

the cables or connections after washing

with alcohol or dry nitrogen if available.

If available, Freon is a” excellent clean­ing agent.

The

g.

accessories described in Section 7 are de­signed to increase the accuracy and convenience of
input connections. “se them to gain maximum

capabil-

ity of the Model 615.

h. Far low impedance measurements - below lo*

ohms or above 10-S ampere - unshielded leads may be

used.

i. When the Model 615 is used on the most sensi­tive ~“rrent range with the FEEDBACK Switch at FAST,
same insulators - such as Teflon - may produce ran­dom signals which show up as erratic readout deflec-

tions. Insulation used in the Model 615 is carefully

selected to minimize these spurious signals.

It is advantageous to connect the Model 615 in-

j.

put to the source only when a reading is to

be made.

“se a high impedance transfer switch and well shield­ed chamber if available.

4

04728

MODEL 615 ELECTROMETER

OPERATION

NOTE

In some cases, the offset current can charge
the external test circuitry. One example of
this occurs when measuring a capacitor’s
leakage resistance by observing the decay of
the Germinal voltage. If the leakage current
is less than the offset c”rrent (less than 5

x lo-l5 ampere), there may be no decay of the

terminal voltage when the Electrometer is
left connected across the capacitor’s termi-

nals.

k. The Model 6012 Triaxial-to-Coaxial Adapter en­ables using coaxial cables and accessories with the
Model 615 by adapting the triaxial INPUT connector to
the UHF coaxial type,

CAUTION

The Adapter connect? circuit law to case
ground. The Model 615 cannot be used off­ground when using the Adapter. The instru­ment cabinet will be at the same potential
as the input law.

NOTE

Keep the shield cap (provided) on the INPUT
Receptacle when the Electrometer is not in
use co prevent overloads due to external
noise pickup.

2-2.

PKECMINARY

OPERATING

PROCEDURES.

f. The Model 615 may have excessive drift or zero

offset after long periods of storage or after an over-

load. This my be corrected with the zero controls

although drifting may continue for several hours.

NOTE

If the Model 615 has been stared for a long
time, the offset current may exceed the
specification when first
decrease to below the specified amo”nt
after one or two hours of “se.
inherent characteristic of the input tran­sistors; the instrument is not faulty.

g. Although the offset current of the Electrometer

is much below that found in conventional voltmeters,

it cm be observed on the readout since the offset
currene charges the input capacitance, the Electrome­ter appears to drift when the input is open. Use the
ZERO CHECK Button to discharge the charge build-up,

h.

Follow the particular procedures in paragraphs
2-3 co 2-7 for measuring voltage, current, resistance,
and charge.

2-3. DIGITAL READOUT OPERATION.

a. Valtmecer Digital Readout.

1. When the RANGE Switch is placed in the VOLTS
position, ehe Electrometer digital readout desig­nates the actual voltage measured using four numer­ical digit readouts.

used,

but should

This is an

a. Check the 117-234V Switch for the proper AC line

voltage.

b. Check for proper rated fuse.

See the front panel controls as follows:

C.

ZERO CHECK Button
RANGE Switch
SF.NSItI”ITY Switch

FEEDBACK Switch NORMAL

POWER Switch OFF

d. Connect the power cord. Place POWER Switch to
ON position.
ZERO Conerol if necessary. Zero is indicated by con­tinuously flashing * polaricy lights.

The rear panel COARSE ZERO Control may be
adjusted if a large zero offset is indicated.

e. After a few moments increase the voltage sensi­tivity by advancing the Switch to one position CLIUIIC­erclockwiae.
Control.

After one-half hour warm-up, adjust the

NOTK

Continua zeroing with the FINE ZERO

wise- Position

2. The SENSITIVITY Switch has four positions
which control the lighted decimal point location
and therefore the full scale voltage range. The

full scale voltage range far each

position is shown in Table 5.

TABLE 5.

SENSITIVITY Switch

Position

I -~-

0.1 Positicm 1 (full”
1 1 Position Position

10 10 Position Position

100 100 PosFtFon PosFtFon

I I

3. The fourth (left most digit) readout permits
a.* averrange display. The largest reading that can
be displayed “sing all four digit readouts is 1999.

If there is’an overload condition, then all read­outs will blank (none of the digital readout tubes
will be lighted).

counterclockwise) counterclockwise)

2 2 x.xXx x.xXx
3 3 xX.xX xX.xX
4 4 (fully (fully xXx.x xXx.x

clockwise) clockwise)

The polarity (*) display indica-

SENSITIVITY

Decimal Point

msi.cion

.xXxX

Switch

0570

5

OPERATION

MODEL 615 ELECTROMETER

tars remain lighted during an overload condition
indicating the correct polarity. Thus the Electrom­eter display will indicate correctly within specifi­cations with no ambFguous overload display.

4. To remove the overload condition, change the
SENSITIVITY Switch setting or decrease the input
signal magnitude.

b. Ammeter Digital Readout

1. When the RANGE Switch is placed in the AMMETER
position, the Electrometer digital readout desig-

nates the voltage across an accurately known self­contained resistor. The RANGE Switch selects the

calibrated range resistor for current measurements
from 10-l to lo-11 amperes. The range resistor is
the reciprocal value of the Range setting. The
readout indicates the voltage across the Range re­sismr.

2. The full scale current range is determined by

multiplying the Range setting times the digital

readout display.

The SENSITIVITY Switch operates

in the same fashion aa for voltmeter measurements.

(Refer to preceding paragraph 2-3, a).

3. The full scale current range far various front
panel control settings is shown in Table 6.

TABLE 6.

ac~rately knovn capacitor since the Electrometer

is sensitive to the integral of the current applied

from the external unknown source.

2. The coulomb measurement is determined by mul-

tiplying the RANGE Switch setting times the digital

readout display.

e. DISPLAY RATE Control. (This control is a con­tinuously variable control that permits the user to
select the rate of analog-to-digital conversion).
That is, the control determines the number of times
a new reading will be recomputed per unit of time.
Thts is useful for sampling a continuously varying in­pllt current as well as for controlling slower external

devices such as paper tape punches and printers. With

the DISPIAY Control in the MAX Position the display
rate is 24 times per second (20 for 50 HZ models).

When the control is varied clockwise, the rate de-

creases to a minimum of about 2 per minute in the ex­treme clockwise position. The front panel DISPLAY

SATE Control applies to the digital circuitry only.

VOLTAGE MEASUREMENTS.

2-4.

a. The Model 615 can meas,,re an unknown voltage

when the low impedance terminal is up to 100 volts

off case ground. Safe operation of the Electrometer
is insured by grounding the case. To use the Model
615 for off ground voltage measurements, disconnect
the shorting link between LO and CASE GND Terminals
on rhe rear panel. (Refer t.3 Figure 2).

Full Scale RANGE SENSITIVITY I

Switch

C. Ohmmeter Readout.

1. When the RANGE Switch is placed in the OHMS
position, the Electromerer digital readout desig­nates the actual voltage across the unknown resis­tor as an accurately known current (internal to the
Electrometer) is applied to the unknown.

2. The RANGE Switch selects the current for Olw
lll~ClS”C~lU~“t~.

The current is the reciprocal value
of the OHMS range setting from 105 to lo12 ohms.
The SENSITIVITY Switch operates in the same fashion
aa for voltmeter measurements.

3, The actual resistance measurement is deter-

mined by multiplying the RANGE Switch setting tFmes

the digital readout display.

d. Coulombmeter Readout.

1. When the RANGE Switch is placed in the CO”­LO”BS position, the Electrometer digital readout
designates the actual voltage across a self-contained

CAUTION

Operating the Model 615 at more than 100
volts off ground may permanently damage

the instrument. The isolation between
circuit low and ground could break dawn
making the instrument unusable far safe

off ground measurements.

Refer to Paragraph 2-6 far complete instructions for
making off ground measurements.

b. The Model 615 has been designed to meas”re valt-

ages up to 100 volts from very high resistance sources.
However, the Model 615 can also be used for meaaure­ments from low sr,urce resistance and voltages up to 30
kilovolts with high voltage divider probe.

1, The input resistance can be decreased in or-

der to reduce the effects of stray pickup with low

sou*ce resistances.

Refer to Paragraph 2-4, f for

complete instructions.

2. ear measurements of voltage up to 30 kilovolts

refer to Paragraph 2-4, g which describes various

divider probes available from Keithley.
c. The Model 615 can measure voltages in two modes:

Normal Mode and Fast Mode.

1. Normal Mode.

In the Normal Mode - FEEDBACK

Switch at NOWAL - the unknown voltage is connected

to the INPW Receptacle. Input impedance with th

RANGE Switch in VOLTS position is greater than 10

84

ohms shunted by 35 picofarsds,

0570

2. Fast Mode.

1" the fast Mude - FEEDBACK

Switch at FAST - the effects of inp"t cable capaci-

tance may be reduced for measurements fcum very high
source resistances. Guarded valtage measuremenr~

may aiso be made.
d. normal lode voltage Measurements

ZERO CHECK ButtOn LOCK

RANGE Switch

SENSITIVITY Switch

VOLTS
Fully Cluckwise

FEEDBACK Switch NORMAL

TO make aff graund measureme"zs, refer 'CO

Paragraph 2-6.

2. connect the Modei 6011 Trianial Input Cable

eo the unknown voltage as fallows:

a) the heavy wire with red clip cover should

be connected to the source high potential.

c) The thin wire wirhgrceaclip cover should
not be connecred when the shorting link between
LO end CASE Terminals on the rear panel is con­nected.

NOTE

To make off ground measurements. refer to

Paragraph 2-6.

3. ""lock the ZERO CHECK Button eo make a mea-

surement

4. Adjusr the SENSITIVITY Switch c~unrercL~ckwie.e

LO increase the Model 615 sensitivity. Readjust rhe

ZERO control as necessary after each change in sen-

sitivity.

5. The voltage measured is indicated directly 0"
the digital display with the decimal poinr automat­ically indicated. The poiarity is auLomatical,y
indicated corresponding CO Lhe potential of the

Electr~merer input high with respect to input low.

NOTE

The Model 615 has 100% overranging on all

ranges except for rhe 100 volt full range
sensitivity. An overload on any range is
indicated by a blanked digital display, a

feature which averts erroneous readings

when 200% of full range Is exceeded. The

digital display is Lighted when the over-

load is removed.

e. ~aat Mode voltage Measurements

1. set the frant panel controls as follows:
ZERO CHECK Butfc'n LOCK

RANGE Switch
SENSITIVITY SWitCh
FEEDBACK Switch

VOLTS
Fully Clockwise

FAST

0470

OPERATION

2.

Model 6103A Divider Probe for measurements up

to 30

kilovolts. This probe permits meas”rements

with overall accuracy of Cg%.

1012

ohms maximum. The actual voltage is obtained

Input r**i*t**c* is

by multiplying the Electrometer digital display

times the divider ratio.

NOTE

The Model 6012 Triaxial-to-Coaxial Adapter

must be

used

with Models 6102A and 6103A
sF”ce tile probes are termFnated with a LW
connector. When using the Model 6012, the
case ground is connected to inp”t law so
that the Electrometer may not be used for

off ground measurements. -

2-5. CURRENT

MEASUREMENTS.

a. The Model 615 can measure an unknown current
when the low impedance terminal is up to 100 volts off
case ground. Safe operation of the Electrometer is
insured by grounding the case. To “se the Model 615
far off ground current measurements, disconnect the
shorting link between LO and CASE GND Terminals on the
rear panel. (Refer co Figure 2).

CAUTION

Operating the Model 615 at more than 100
volts off ground may permanently damage

the instrument. The isolation between
circuit low and ground could break down
making the instrument unusable for safe
off ground meawrements.

Refer to Paragraph 2-6 for complete instructions for
making off ground meas”eements.

b. The Model 615 can meas”re currents in two modes:

Normal Mode and Fat Mode.

1. Normal Mode.

eny renge

- the cwrent is determined by measuring

In the Normal Mode - used on

the voltage drop across a self-contained reeistor
shunting the electrometer amplifier input. This
method permits a minimum noise m~as”rement when re-

sponse speed is not.critical.

2. Fwt Mode.

I” the F.ast Mode - for “se only

MODEL 615 ELECTROMETER

below 10-S ampere range - a self contained resistor
is connected between the electrometer amplifier in­put and output (in the feedback loop). This method
permits faster response speed since the effect of

input capacitance is minimized. The input volcsge
drop is reduced to less than 100 microvolts on any
range. Refer to Table 7 for typical Response and
Noise performance for various values of input capac­itance.

C. Normal Mode Current Measurements.

1. Set the front panel controls as follows:
ZERO CHECK nutron

LOCK
RANGE Switch 10-l AMPERES
SENSITIVITY Switch Fully Counterclock-

wise

FEEDBACK Switch NORMAL

NOTE

To

make off

ground measurements, refer to

Paragraph 2-6.

2. Connect the

Model 6011 Triaxial Input Cable

for meeauring s,, unknown current as follows.

a) The heavy wire with red clip cover should

be connected to the source high potential.

b) The thin wire with black clip cover should

be connected so as to place the Electrometer in

series with the c”rrent to be measured.

c) The thin wire with green

clip cover should
not be connected when the shorting link between
LO and CASE GND Terminals an the rear panel is
connected.

3.

Unlock the ZERO CHECK Button to make B mea-

surement.

4. Adjust the RANGE Switch to increase the Slec-

emmeter sa”siti”ity for CUrrent measurements.

5. The full range c”rrent for the Electrometer
is determined by multiplying the digital display
times the RANGE Switch setting. The best accuracy
for current meas”rements is obtained by “sing a

Typical Effects of External Inp”t Capacitance on Response Speed and Noise Performance in C”rre,,t Measurements

TABLE 7.

with the Model 615.

i-l****

$;to -

$"

10-S
10-7
10-6

s

Rise Time (seconds)

No C

2.0 2.0
.07 .45 .45 .07
,015 ,015

,003 .003
.003 ,003

2eE

5000pF

2.0 6 x lo-l5 1.5 x 10-14
.45' .07
,015 ;.i ;,m;l3 ;.":

,003
,003 3.3

No C

- x

8.5 x 10-14

Output

Noise

(Peak-Co-Peak)

$5;

s’x 10-11

x 10-10

5000pF

7 x 10-13
i.2 ;,!p;"
2

x 10-10

MODEL 615

SENSITIVITY Switch seeting which permits the use of
the smallest value rage resistor. The rsnge resis­tor value is equivalent CO the reciprocal of the
RANGE Switch setting. The input voltage drop across

the shunt resistor is indicated directly on the

Electrometer digital display.

ELECTROMETER

NOTE

OPERATION

The ZEN, CHECK Sutt~” provides a short
across the feedback of the Electrometer
Amplifier to enable zero adjustment.
Do not apply a short circuit ecross the
Electrometer input terminals since this
will creete ““stable amplifier operation

The SENSITIVITY Switch settings permit sn

input voltage drop af O.i, 1, 10, and 100

volts for current measuremenfs in the

mrmsl Mode. on the LO-9 to 10-l’ AMPERES

settings of the RAN E Switch, the resistors

(109, 1010, and 101
age coefficient uf .O*% per vale (naminal).
1f the SENSITIVITY Switch is adjusted far a

100 v”lt input drop, then a” additional
error of 2% occurs for the current messure-

lS**t.

the smallest input drop possible to minimize
voltage coefficient errors.

d.

low 10-5 amperes).

1. Set the front panel controls es follows:

ZERO CHECK Button

RANGE Switch
SENSITIVITY Switch

FEEDBACK Switch

TO make aff graund measurements refer ta

Psragraph 2-6.

2.

for measuring an unknow” current ae in 2-5, c-2.

3. unlock the ZERO CHECK Sutton t” make e mee-

surement

‘rherefore ie is reconrmended t” select

Fast mde Current Weasurements (for current be-

Connect the Model 6011 Triaxial 1”put Cable

E

ohms) used have a volt-

LOCK

10-6 AMPERES

Fully Councerclock-

wise

FAST

NOTE

4. Adjust the RANGE Switch to increase the Slec-

tr”meCer seneitivity for current measurements.

5. The full range current for the Electrometer
is determined by multiplying the digital readout
times the RANGE Switch setting. The best accuracy
for current measurements is Obtained by using a
SENSITIVITY switch setting which permits the use of
the smallest value range resistor. The range cesis­t”r value is equivalent to the reciprocal of the
RANGE Switch settine. The input voltane drop, across
ehe shunt resistor Is indicated directly on the
EiectromeLer digital display.

NOTE

The source resistance of the circuit eo be

measured should not be Less than 0.1 rimes

the range resistar used since adequate
feedback voltage cannot be developed at the
input and zero stability is adversely af­fected. The range resistor is the recip­rocal of the AMPERES range in ohms.

CAUTION

Foe measurement of capacitor leakage cur-

rents using the Pest Mode, a very

voltage supply must

pacitor connected across the input, the
electrometer is exCrem*ly sensitive to
voltage transients with a resultant in-

crease in readout noise.

be

used. With a ~a-

stable

I
I

I-

a-7

I 1
I

SOURCE I

L--------l L------------l

FIGURE 4.

0470 9

I I
I

: ME)WJ&NG I

I

1 = ’ readout

‘f

X

R+Ri”

Error Due to Ammeter Resistsnce.

I
I

I

1 readout

__ _ _ _

I

R

AMMETER

I

I

OPERATION MODEL 615 ELECTROMETER

e. Galvanometric current Measurement Method.

I. operate the Electrometer in the Fast Mode as

described in Paragraph 2-5, d.

3. Adjust the Current Source co obtain a null on

the Electrometer digital readout. Increase the
Electrometer sensitivity as needed. The value of
the current which is suppressed is indicated o” the
current source setting.

NOTE

The connections for the Galvanometric Method

require the following accessories.

1 - Model 261 Current Source
1 - Model 6012 Adapter
1 - UHF tee fitting, Part No. cs-171
1 - Low noise coaxial cable, Model 2611
1 - Low noise coaxial cable, Part No. 19072C.

2-6.

OFF GROUND MEASUREMENTS.

a. ‘fhe Model 615

can be used for measurements when
the low impedance rerminal is up to IO0 volts off case
ground.

Safe operation of the Electrometer is insured
by grounding the case. To use the Model 615 for off
ground measurements, disconnect the shorting link be­tween LO and CASE GNC Terminals a” the rear panel.
(Refer co Figure 2).

CAUTION

Operating the Model 615 at more than 100

volts off ground may permanently damage

the instrument. The isolation between
circuit low and ground could break down
making the instrument unusable for safe
off ground measurements.

b. Normal Mode Measurements. D‘sconnect the short­ing link between LO and CASE GND Terminals on the rear
panel.

Connect the Model 615 case securely to earth
ground for maximum operator safety. Operate the Alec­trometer 8s described in Paragraphs 2-4 or 2-5.

c. Fast Mode Measurements. Disconnect the shorting
link between LO and CASE CND Terminals on the rear
panel. Connect the Model 615 case securely eo earth
ground for maximum operator safety. Operate the Alec­trometer as described in Paragraphs 2-4 or 2-5.

WARNING

The 1X4 analog outp”f can only be

used with
a recorder which will operate off ground
such as the Keithley Model 370.

NOTE

The

Model 615 ca”““t be operated off ground

if the Model 6012 Adapter is used since the

input Low and chassis ground are connected.

2-7. RESISTANCE MEASUREMENTS.

a. The Model 615 ca” be used to measure resistance

since the Electrometer permits accurate voltage or

current measurements from high resistance sources.

ResFstance can be

measured F” the following three ways.

1. Normal constant CurrenL Technique.

2.

Fast Constsne Current Technique.

3. Volt-Ammeter Method.

b. Normal Constant C”rre”t Resistance Measurement.

1. I” the constant current method, the Electrom-

eter meas”res the voltage drop across the unknown

resistance when a constant current is applied. The
voltage drop is the” proportional to the resistance
of the unknown.

2.

The Normal mode is recommended f r measure-

ments from 100 to 1O’l ohms. Above 10

Pl

ohms use

the Fast constant current technique.

10

0470

MODEL 615 ELECTROMETER

OPERATION

3. Set the front panel controis as fallows:
ZERO CHECK SULLO” LOCK

RANGE Switch
SENSITI”ITY Switch

FEEDBACK switch NORMAL

1011 OHMS

Fully Counterclock-

wxse

4. Connect the unknown resistance between the

electrometer input high and low as for normal Mode
Voltage Measurements.

5. Unlock the ZERO CHECK Hutton to make a mea-

S”Tellle”t.

NOTE

Do nae open circuir the Electromeeer on the
OHMS ranges; the input will de”elop a large
voltage due to its constant currene charac-

teristic. Keep the input shorted or the

ZERO CHECK Button locked.

6. the unknown resistance is determined by multi­plying the digital display times the RANGE twitch
setting. “se the smallest RANGE Swiech setting for
beBe possible accuracy.

7. The applied test voltage is indicated directly

on the digital display in volts.

8. The test current is the reciprocal of the OHMS
Range setting.

NOTE

2. set the front panel controls as follows:
ZERO CHECK Button LOCK

RANGE Switch 1011 OHMS

SENSITI”ICY SWFtch Fully Counterclock-

wise

FEEDBACK Switch FAST

3. connect the unknown resistance between the

Electrometer input high and GUARD Terminal as for

Fast Mode Voltage Measurements.

4. ““Lock the ZERO CHECK Button to make a mea-

SuremenL.

5. the unknown rcsisrance is determined by multi-

plying the digital display times the RANGE switch
setting.

6. The low terminal of the INPUT Receptacle is

now a driven guard.

It may be used t” minimize the
effects of capacity berween hi&h end low and errors
due to leakage reSiSta”ce between big,, and low.

7. The Model 6oLl Input Cable. supplied with the
Model 615, provides a convenient means of making
guarded reeistance meesurements. connect the shart-

in&t link between the CASE GRO”ND and GUARD Terminals
“n the rear panel. This allows the CASE GROUND ur
blue test lead terminal to be connected CO the Luw

impedance side of the unknown resistance.

me inner

shield or the black test clip is the GUARD Terminal.
d.

Volt-Ammeter Resistance Measurement (to 10’6

ohms).

Shield the input if the resistance sample
exceeds 108 ohms.

Fast COnSLant current Resistance Measurement.

(&ommended for 10” to 1ol4 ohms measurements).

1. The Fast Mode permits faster response speed

when measuring very high resistances.

FIGURE 6. Volt-Ameter Resistance ,.,easuremenc.

1.

In the Volt-Ammeter method the voltage applied
to the sample is arbitrarily set at any cO”“enir”t
uoltage. The current through the resistance sa,“ple
is measured by the Electrometer. ‘rhe resistance of
the unknown is calculated in terms of the known
voltage impressed and the resultant measured current

2. This method requires the use of the folluwing

0470

11

OPEP.ATION

MODEL 615 ELECTROMETER

instr”me”ts and *cc***0ri**.

1 - Voltage Source, such as Keithley Models

240A or 241.

1 - Shielded switch, such as Keithley Models

6104, 3011 or 4194.

1 - Test Cable, such as Model 6108
1 - Model 6012, “XF to Triax Adapter.

3. Connect the voltage source, switch, and uo­known resistance as shown in Figure 6. since the
~lecrrometer is used for the measuremene of current,

refer to Paragraph 2-5 for complete instructions.

NOTE

Refer to Paragraph 2-6 for complete instruc­tions for meking off ground measurements.

4.

To make a eesistame measurement, place Switch

s in the “OFF” position 8s shown in Figure 6. Ad-

,,st the voltage source for a predetermined voltage.

Place Switch S in the “ON” position to

apply the

voltage ecross the unknown resistance. Allow a

iod of time for the current through the unknown re-

sistance to stabilize.

Unlock the ZERO CHECK Sutton

to take a current reading. Adjust the RANGE Switch

and SENSITIVITY Switch to obtain a satisfactory

reading.

5. After a reading is made. place the ZERO CHECK

Sutton to LOCK poeition and place Switch s to “OFF”
pOSiti”“.

Rem”“* the unknown resista”Ce and replace

with a second sample if necessary.

NOTE

If the voltage applied to the sample is not

100 times the Electrometer input drop, the”
the unknown resistance ia calculated es
follows:

R x = Vsource

- “Input oroe

lMeeasured

where Rx = ““known resistance,

VSource - Applied voltage,
“Input Drop

= Electrometer input voltage

drop

and l”easured = Current measured by Electrom-

eter.

2-8. CHARGE mASuP.EMmTS.

per-

Eq. 1

b. Set the front

ZERO CHECK Button

KANCE Switch
SENSITIVITY Switch

FEEDS.4CK switch

panel controls as

LOCK

10-7 COULOMBS

Fully Counterclock.

wise

FAST

follows:

c. Connect the Electrometer to the current eource

to be measured as described in Paragraph 2-5.

d. Unlock the ZERO CHECK Sutton to make B measure-

ment. Adjust the SENSITIVITY Switch to obtain a see-

isfactory reading.

changing the SENSITIVITY Switch
setting doea not affect the transfer of charge from
the source to Electrometer.

e. The coulombmeter reading is determined by mulci­plying the digital display times the RANGE Switch
CO”LOMBS setting.

If the RANGE Switch must be changed
to obtain a satisfactory reading, repeat steps b, c.
and d above.

NOTE

The input offset current of the Electrometer
contributes a charge of 5 x IO-l5 coulomb

per second and should be subtracted from the
actual reading.

f. After a coulombmeter reading is made, discharge

the integrating capacitor in the Electrometer by

placing tile ZERO CHECK BUteon to I.OCK position.

Dis­charge capacitor for at lease 20 seconds on the IO-’
COULOMB range before making another measurement.

NOTE

For informeti”” concerning Static Charge
measurements, request the Product Note

entitled “Electrometer Stetic Charge
Measurements”. The Model 615 should be
used with Keithley Models 2501 end 2503

Static detector Probes for

Static

Charge
Meas”rements. 0” not sttempe to use the
Model 615 in the COULDMBS mode for Static
Charge meesuremeots since the Electrometer

is very sensitive to charge trensients.

2-9,

RECORDER OUTPUTS.
The Modal 615 provides several outputs for

1toring an a”al”g or dIgital signal. me “ario”

outputs are

summarized as follows.

~~.

a. Charge measurement or current integration can be

accomplished using the Model 615 in the coulombmeter

mode,
very accurate self-contained

eter output is

The electrometer indicates the voltage across a

capacitor. The Electrom-

therefore a voltage which is

propor-

tional to the integral of the applied curreot.

NOTE

For a more complete discussion of current

integration, request the Keithley Product
Note entitled “Using the Electrometer Volt­meter es a Current Integrating or Charge

Meas”ring I”sCr”ment.”

12

1. 1MA OUTPUT. This ““tpot provides a 1 milli-

ampere analog outpoe corresponding to a full range

itlP”C .

NOTE

The Keithley Model.370 may be conveniently
used to obtain a chart record with 1% Ii”­earity. The Model 370 haa 10 speeds, re-

quires no preamp, and permits operation up
to *lOO volts off ground when used with
the Model 615.

A special

phone plug such

as Switchcraft S-290 must be used with the

Model 615.

0470

OPERATION

2. 1 VOLT OlJTPLn.
analog output corresponding to a full range input.
The 1 VOLT OOTPW is useful for monitoring by oscil-

loscopes or voltmeters which will not load the ELec­trometer output to exceed 0.1 microamperes. This

output is also used for calibration of the analag-

to-digital converter.

3. X1 OUTPUT (unity Cain). This output provides
a unity gain signal for applications requiring very
accurate measurements from high impedance sources.
The output is equal to input within 100 ppm at dc,
exclusive of noise and zero drift, for output cur--

rents of 100 microamperes or lees.

4. DIGITAL OuTPLm.
a complete description of the PRINTER/CONTROL con­nector and external controls.

b. Use of the Xl Output (Unity Gain)

1. normal “ode ?.,eaeureme,,ts.

a) Connect the Electrometer to the unknown volc­age source as described in Paragraph 2-4, d for
normal Mode voltage measuremeots.

b) Connect an *ccuraLe voltmeter such as a

0.01% differeneial voltmeter between the X1 Output buffer output cards and a mating Amphenol connec­and the GUARD Terminal as shown in Figure 7.

This output provides a I vole

refer to Paragraph 2-10 for

a. General

1. The Model 615 has provision for the installa­tion of output buffer printed circuit boards co ob­tein Sinary Coded Decimal (RCD) outputs. Two !+!a­pin card-edge connectors are installed and complece­ly wired on the main PC board.

2. A factory-wired 50-pin PRINTER/CONTROL cannec­tar is also provided on the rear panel.

nector is wired to provide signals as described in
Table 8. This Amphenol (RLue Ribbon Series) connec-

tar can be ordered with special wiring configure-

tions.

3. Output buffer cards available from Keithley

as Model 4401 Printer Output Cards. may be ordered

factory installed or ordered at a later date for

user installation, since no soldering or rewiring

is required. These Output Cards are available with
other codes (Standard Code is l-2-4-8) on a CIISC~I
design basis.

4. Accessories
a) Model 4401 Printer Output Cards. include two

tor.

Thik con-

c) Adjust the Model 615 ZERO Control to obtain

a null reading on the differential voltmeter with

the ZERO CHECK Switch in LOCK position.

2. Fast Mode MeasuremenLs b. Output Codes and Levels.
a) Connecr the Electrometer to the unknown volt-

age source ee described in Paragraph 2-4, e for
Fast Mode voltage measucements.

b) Connect a recorder or oscilloscope between

the x1 Output and the GUARD Terminal. In the FAST

Mode, the XI Output Terminal is connected to input

low. The GUARD Terminal provides an output for
recording purposes.

b) A fifty line cable for hook-up to external

devices (printers, computers, etc.) is avaiLable.

Specify part number SC-51 and length desired.

1. me PRINTER/CONTROL outputs are i3inary Coded

Oecimsl (SCO) signals with l-2-4-8 Standard code.

2. The Standard signsl levels are as follows:
Logic “0” < co.4 volt
Logic “1” > *lO volts at up to 1 milliampere.

-

0470

FIcUwi 7. Use of xl Output for Measurement from a High Resistance Source.

I 3

OPERATION

MODEL 615 ELECTROMETER

PRINTER/CONTROL Connector Pin Identification.

.n NO.

1
2

,........................................................ . . . . . . . . . * . . . . . . . . . . . . . . . .

3
4

,...................................................................................

5 1 x
6

,................................ * . . . . . . . . . . . . . . . . . . . . . . . . . . . . e . . . . . . . . . . . . . . . . . . . . . II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . m . . . . . . . . . . . . .

7

8

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

9

10 2 x 100

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

11 1 x 101

!.f . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

13
14

. . . . . . . . . . . . . . . . . . . . . . . . T!.?Y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

15
16

, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

17
18 +3.6V

, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

19 Blank

20 Blank

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

21 Blank
22

. . . . . . . . . . . . . . . ..*............-....................................................

23 114” Pulse

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . * . . . . . . . . . . . . ..*...........................

24 +BV
25 +2v

omput Function

1 x 100

2 x 100
1 x 101

2 x 101

102

2 x 102
1 x 103

COllllllO”

1 x 100

oata
“ata

“ata 28 4 x 101
mea

oaca 30
oata

oata

__-

Range 34
Range 35 8 x 100

Range

COlllUlO”

1 x 100

1 x 100

2 x 100
t15v

---

m*arity 38

___

sensitivity
Se”Siti”ity 41

__-

--­___

_-_

Blank

___

Print Command

Hi Reference
LOW Reference 50

I

. . . . . . . . . ‘.” . . . . . . . . . . . . . . . . . . . . . . :.I...? . . . . . . . . . . . . . . . . . . . . “.“..r.” . . . . . . .

. . . . . . . . . 2 . . . . . . . . . . . . . . . . . . . . . .8..x.!.? . . . . . . . . . . . . . . . . . . . . D.2.” . . . . . .

. . . . . . . . . . . . . . ..*...................... * . . . . . . . . . . . . . . . . . . . . . . . . ..........

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . ..,

. . . . . . . . . i.:. . . . . . . . . . . . . . . . . . . ..~~~.! . . . . . . . . . . . . . . . . ...... :.I .......,

. . . . . . . . . 3: . . . . . . . . . . . . . . . . . . . . . t!” . . . . . . . . . . . . . . . . ......... :.:.-. ......,

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . e . . . . . . . . . . . . . . . . . . . . . .................................

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... .

(Refer also to Figure 8).

Pi” NO. *UtD”t F”“Cei”n

27

8 x 10 oata

OBCB

4 x 102

31
32

8 x 102

COlll!llO”

33 8 x 103

4x 100

oata
oata

___

Overload
Range

Range

COUXllO”

40

common
COllllllO”

42

-15v

43 cammon
44 Grounded

45 Grounded
46 Grounded

47

Blank

48 Blank

49

Blank
Blank

d

___

-_-

-__

--­___

Hold i/l

“old $2

‘Trigger

---

-__

--_
___

TABLE 8.

14

FIGURE 8.

PRINTER/CONTROL Connector

Terminal

Identification

0470

MODEL 615 ELECTROMETER

OPERATION

C. output Information.

TABLE 9.

Model 4401 minter outpue Cards.

Model 4401 Printer Output Cards:

Provide BC,, out­put and external Control of Model 615; may be
purchased installed or separately for field in­stallation (no wiring required).
minter outputs: BC” positive output represents
each of the four digits, exponene, sensieivity,
polarity and overrange. Standard code is l-2-4-

“0” < co.4 volt; “1” z 110 volts at up to

8.
one milliampere: o=oooo.
Print Commnd: Positive pulse of 14 volts from
a zzoo-ohm source with 1 volt per microsecond
rise time, 100 microseconds minimum pulse width.
print co,,ms”d give” after each A LO D conversion.
Renwte Controls:
Hold iii: Closure to ground inhibits A to D co”­version, ac that instant.
Hold ,12: Closure to ground inhibits A to D co”­version after reading has bee” completed.
trigger: Closure to ground initiates one conver­sion when in Hold 02. Integraeion period stares

8.3 ms (10 ma on 50-Hz models) after “Trigger”
or release of Hold 82.
connector: 50-p<* Amphenol Micro-Ribbon mou”Led

an Model 615. O”fp”t macing connector supplied
with 4401.

2. Overrange Indication.

The fourth (from the

right) Numerical Readout Indicatar represmts the
overrange or m”se significant digit. A” overload
candieia” is shown by a blanked readout with “nly

the polarity indicared. The Model 615 uses one RCD

line to identify ehe overrange digit and overload
condicio” as sham in Table 11.

‘TABLE 11

I

33 32

8 7

Overload C”olm”” Comma”

1 x 103

(2 (4 (8 x x x 103) 103) 103)

O,l

0 0 8

3. mlarity IndicaLio”. The poiaricy is indicat­ed automatically by the Polarity Iadicator Lighfs
and corresponding BCD output as show” in Table i?.

TABLE 12

OUtoUt

oecima1 Digits

Generated I

NOTE

The term “Closure to Ground” or “Grounded

control line” means a shore to common di­rectly or through a saturated NPN eransis­tar (VcE < c0.N). Only the “COMMON” as
supplied at the PRINTER/CONTROL co”“ector
should be used for claaures to ground.

1. Full Scale Magnitude. The full scale magni-

tude for the ~“del 615 is indicated by three front

panel Numerical Readout indicamr lights with cor­responding RCD outputs as show” in Table 10.

TABLE 10.

3 1 x 101

4 2 x 101
28 4 x 101
29 8 x 101

5 1 x 102

6 2 x 102
30 4 Y 102
31 8 x 102

O,l

2,3

4,5x6,7

8.9

0.1
2,3
4>5,6,7
829

I

38 14

13

39 +15v common

Polarity

+15v (2 (8 (4 x x

(1

x 100) 100) x W)

100) 0,1

0 2 8

Four pins may be used to obcai” BCD polarity codes

*or external printers, where 1010 = + and 1011 =

- printer characters.

4. 8ensiei”ity Indication (mcimal Point coca-

Lion). The

SENSITI”ITY

Switch has four positions

which automarically control the locaeio” of the

lighted Decimal Point Indicator. The decimal point
location is also represented by a BCD outpue as
sham i” Table 13.

TABLE 13

Decimal Digits

OutpUt

Position 1.2

Position 3,4
COIIEW”
C~lmM”

5. Range Indication (Exponent). The Model 615
provides BCD outputs corresponding LO ehe exponent
of the RANGE Switch 88 show” in Table 14.

Generated

I

I

0470

15

OPERATION

I

0470

TABLE 14

MODEL 615 ELECTROMETER

b) A” external device ca” also be used for

mester control such 8s a high speed printer.

Connector

Pin NO. Output

I

9

10
34
35
11
12
36
37

The print-out of the RANGE switch expanent uses 2
coluums to represent information far exponents from
00 thru 12. The exponent must be interpreted as
positive or negative depending on the parameter (am­peres, coulombs, or ohms).

6. The ““de1 615 with Model 4401 Printer Output

Cards also provides ee,,wte control commanda for ex-

ternal devices. These commands are described fully
in Paragraph 2-10, d.

7. Examples of e typical printer output for vari­ous Model 615 readings are show” t” Table 15. In
the examples the p=<ntl”S davice 1s assumad to co”-

tain fonts of digits 0

columns ere needed to print all date.

1 x 100
2 v Exponent
4 x 100

8 x

1 x Exponent 031

COUSIIO”
COUSUO”
Common

Exponent 021

100

Exponent

100

Exponent 899

101

to

9.

Decimal Digits

Generated

223
495,637

In this case, eight

c) A completely independent “master clack” can

I

be used for system control for maximum flexibility.

3. Description Of external controls.
a) “HOLD 1”. This control inhibits A to D co”-

version at the instant a closure to Sraund is
made. The conversion cycle will =esume inmediate-

ly when the “HOLD 1” line is opened.

“HOLD 2”. This control inhibits A ta D con-

b)

version after a complete reading cycle. Further
conversions are inhibited as long as a closure to
ground is made. The c”“ve=slo” cycle will resume
immediately when the “HOLD 2” line is opened.

c) “TRIGGER”. This control initiates one com-

plete conversion when “HOLD 2” line is grounded.
Closure to ground may be momentsry or any longer

duration to initiate a conversion.

d)

“PRINT

positi”* going pulse of 14 volts after a complete

A to D conversion is made end all data line out-

puts are final readings.

Power Supply Voltages. The PRINTER/CONTROL

4.

Connector also provides p”we= supply u”ltaSes of

+15, -15, and ~3.6 valta as shown in Table 16.

COMMAND”. This control provides a

d. External Control.

1. To obtain optimum system performance, it is
often desirable to operate the Model 615 synchron­““sly with other digital equipment, such a8 printers,
paper tape punches, computers and other data handling
devices. The Model 615 with 4401 Printer Cards in­stalled provides several printer control commands for

the purpose of synchronizing external equipment to
schieva maximum conversion rates.

Several alternate approaches may be used in de-

2.

signing the overall system control scheme.

a) The Model 615 can be used to provide maste=

control of external devices so that the maximum

possible conversion rates ca” be obtained.

Front Panel

Diaital Readout

+0.275

+1.347

-086.4

-(blank)
+(hla”kj

+oo.oo

-.1632
+19.99

Range Switch

setting Polarity E Digit 6. Overlosd I

1O-5 AMPERES +
109 OHMS
VOLTS 0

lo-l1 AMPERES

VOLTS

VOLTS 1 632 0 00 -. 1632 volts

10-7 AMPF,RBS

+

+

+ 1

Significant ;

i
i

!

TABLE 16

Maximum

VOltaRe ‘aed Current

I

+3.6V
+15v

-15V

r

5. High and Low Reference. The PRINTER/CONTROL
Connector provides tw” Reference Voltages, High
(+SV) and Low (c2V). These levels may be used to
define the “HIGH” and “LOW” digital output states

for‘ external printing or computer devices.

TABLE 15.

Msg. i sells. i mp. I”t*CpC*t~tiLW

0 ! !

1 i 347 1 09 +1.347 x lo9 amp ohms

0

275 1 05 +.2?5 x 10-5

F 864

: 000 - . 11 averlaad 10-7 COULOMBS .i : negstive +

: 000

i
:
f

1
i

;

000 1 2

i

999 j 2 E 07 +19.99 x 10-7 amp

+50 In4
Cl0 mA 14,17,39

-10 IsA

i Renge

I

3

- 07

00 -R6.4 volts

positive overload

00 +oo.oo volts

I

Pin
18
42

No.

I

I

16

MODEL 615

ELECTROMETER

OPERATION

a. Summary of oigital Outputs and Controls.

1. Standard Output Codes and Levels.

The stend-

ard output code for Model 4401 Printer Output Cards

is 1-2-4-S binary Coded Decimsl (&Xl). A binary

coded decimal digit is represented by a four-bit

binary code as shown in Table 17.

a) The “ON” state is defined as en output grear­er then +10 voles into a resistance load of 10 kil­ohms or greater.

b) The “OFF” stete is defined a9 en outPut less
than co.4 volts.

TABLE 17.

Decimal

Number 4 bit

0 0

1 0

? 0

3
4
5
6
7
8
9

0 0
0
0
0
0

1
1 0 0

3 bit 2 bit

0
0 0
0 1

0

1
1
1
I
1

0

0

0

1

1

0

1 bit

L

c) Refer to Figure 19 for e circuit diagram of

the Model 4401 Standard Printer Output buffer

stage.

the “TRIGGER” command inLtiac*s one complete

conversion cycle. A second conversion will fol-

law only if the TRIGGER cormwind is removed and
re-applied a second time. The maximum conver­sion rate uslng.an external trigger is 24 read­ings per second.

b) Conversion Cycle Timing. The Conversion
Cycle is composed of three timing periods, namely,
Integrator Zero, Integrator Sampling, and A-D
mounting period.

9.

P

1.

integrator Zero Period (ZERO). When a

Refer fo Timing Diagram Figure

trigger pulse initiates a new conversion cycle,

the Integrator circuit is zeroed for e period
not to exceed 8.33 miilisecands for 60 SC oper­ation. (The Integrator Zero Period is 10.00
milliseconds for 50 Hz operation).

2. Integrator Sampling Period (INTEGIUTE).

0
1

0

1

0

1

0

1

0

1

The Integrator Sampling Period follows automac-

ically the Integrator Zero Period and lasts for
a duration of 16.67 milliseconds for 60 HZ op­eration. The Integrator Sampling Period Lasts

for a duration of 20.00 milliseconds for 50 ilz

0 pa L ;,ioyil.

*..

3. ‘A-D Counting Period (COUNT). The A-D

Counting Period is initiated immediately follow-

ing the Incegraeor Sampling Period. The actual
counting time duration will depend on the actual

integrator voltage up to a maximum of 2000 clock
pulses or 16.67 milliseconds.

Following the
counting period a Buffer/Storage command is
auromefically generated in order to store the
new reading in the output registers.

2. PRINTER/CONTROL Connector. The PRINTER/CONTROL

Connector used an the Model 615 provides for connec-

tions to 50 pins es Shown in

Table

8. The mating

connector supplied with Model 4401 is an Amphenol

Part Number 57-30500 or Keithley Part Number CS-220,

available on specie1 order.

3. Analog-to-Digital Conversion Cycle.
a) The analog-to-digital conversion cycle can

be initiated in any one of three ways.

1. DISPLAY RATE Control Set at MAX. With the
DISPLAY RATE Control set at MAX, cbe end of one
complete conversion triggers e second conversion

to obtain the maximum conversion rate of 24 read­ings per second.

2. DISPLAY RATE Control Set at Other Than MAX.

With the DISPLAY RATE Control set et some posi-

tion other than MAX, (uncalibrated control set-

ting) the end of one complete conversion triggers

a second conversion which is delayed by a speci-

fic time interval (DELAY). The time delay is a

function of the position of a continuously’vari­able control to provide a conversion rate from
24 readings per second to 2 readings per minute.

3.

‘71OI.D 2” With TRIGGER Control. With the

“HOLD 2” command grounded, a closure to~ground of

4. PRINT COMMAND. The PRINT COMMAND signal
is used to trigger external printers or paper
tape punches. The PRINT COMMAND signal is de­layed 10 microseconds to allow the storage leg­isters to settle.

The PRINT COMMAND pulse width

is approximately 100 microseconds with e 1 voltl

microsecond rise time into a 1 kilohm load. The

pulse amplitude is approximated by the following

equation:

e, = 14~/(~+2200).

Eq. 2
where R ia the outpat load resistor.
The “OFF” state is less then +0.4 volt with ap-

proximately 1 milliampere sink current.

NOTE

The date stared in the Output Registers will
not change for et least 25 milliseconds for
60 HZ operation.

If the front panel con­trols are changed, the Sensitivity or Range
SCD output may be effected.

2-11. 117-234V LINE POWER OPERATION.

The Model 615

is shipped for use with 117” e-c line power unless

ordered for 234V operation. To convert eny instrument

for either 117” or 234V operation, use a screwdriver
to set the 117-234” Switch an the reer panel. The

0470

17

OPERATION

MODEL 615 ELECTROMETER

INTEGRATOR

ZERO
CROSSING
DETECTOR

SUFFER
STORE

PULSE

41.67 ms

INTEGRATE

16.67 mS

COUNT

16.67 Ins

:-I--

bi

ei

l

PRINT
COMMAND

CLOCK PULSES

slide switch is identified for either 117 or 234V co
avoid an incorrect sectinS. The proper fuse must be
used far 117 or 234V and can be changed by

the fuse holder cap on the rear panel. Refer to Table
3 for proper type of fuse require*.

Z-12.
615

unless ordered for 50 Hz operation. The Model 615 will

operate at either 50 or 60

reJection will be degraded. Field conversion from 60

Hz eo 50 Hz is not recommended since the A to D con-

50 HZ LINE

is shipped for use with 60 Hz line power frequency

POWER FREQUENCY OPERATION. The Model

2000

FIGURE

Hz but line frequency noise

3000

9.

Timing Diagram for Model 615.

removing

.^

5000 (~OOU)

verter would require recalibration. TO co”“erc the
line frequency operation. replace the oscillator ccys­tal Y501 as shown in Table 18.

2000

18

0470

XODEL 615 ELECTROMETER

CIRCUIT DESCRIPTION

SECTION 3.

3-l. GENE&U..

a. The Keithley Model 615 Digital Electrometer con-

SiSe.3 of t&m separate sections (except for the power
supplies) packaged rogeeber in one chassis for optimum
performance and convenience:
analog-to-digital converter.

b. The Electrometer is basically an extremely sta­ble and linear DC voltmeter with a full-scale sensi­tir;‘y of 100 millivolts and an input impedance of

10 ohms shunted by 35 picafarads. sy using the
frone panel controls, shunr resiseors and capacitors
are selected to make measurements over a total of 120

voltage, current, resistance, and coulomb rariges.
Current and resistance are measured using precision

resistance standards, from 10 ohm wirewound resistors
to 1011 ohm glass-sealed, deposited carbon resistors.

Coulombs are measured using close tolerance polysty-

rene film capacitor standards.

the analog-to-digital converter is a dual slope

c.
integrating type converter with medium conversion
rate, cold cathode readout tubes, BCD outpue options
and external control.

3-2. ELECTF.omTER A!4PLIFIER OeEP.ATION.

a. The Model 615 electrometer amplifier employs

matched insulated-gate field-effect transistor8 fol-

lowed by a transis;or differential amplifier with a

high-voltage complementary output stage. Refer to

an Electrometer and an

CIRCUIT DESCRIPTION

Figure 10 which shows a block diagram of the Electrom­eter.

b. The Electrometer amplifier is connected as a
unity-gain, voltage-to-current converter configura­tion. Refer to Figure 11 for a simplified diagram of
the unity-gain amplifier in the Normal Mode. The
sensitivity selection circuitry is arranged such that
a full-scale input voltage (ei) results in a 1 rnilli­ampere output current through the Sensitivity resis­tor represented by Rs.
(es) is determined as follows:

The unity-gain voltage output

e, = ei .&

where K is the amplifier loop gain.

3-3. AMPLIFIER CIRCUIT

a. The amplifier input stage is a pair of insulated­gate field-effect rzr~nsistors (IGFET) designated 01201
and ~1202 connected in B differential configuration.
The “gate” terminal of transistor Q1202 is connected
eo the unity-gain output.

b. The input stage is followed by a Cransistor dif­ferential amplifier composed of transistors Q1203 and

Q1204. Transistors 01207 and 01212 make UP a bizh

&in stage which pre;ents “fold-we+ and ;‘lock-;p”

with positive input overloads. Diode D1214 between

0472R

19

CIRC”IT DESCRIPTION

INPUT- , 4x1

,

A

ei

(P-Q!

MODEL 615 ELECTROMETER

\

f

is

FIGURE II.

base and emitter of transistor Q1209 prevents “fold-

over”

and

“lock-up” under negative input overloada.

NOTE

Amplifier “fold-over” is defined 88 a co”-

dieion where the i”sfrumenL erroneously

Indicates an on scale reading with a large
overload.
an amplifier stage saturates.

c. Frequency compensation is provided by capacitors
Cl213 and C1214, resistors R1240 and R1241, and cepac­ieor c1215.
trolled frequency response characteristic to insure
stability under all condicians of input end output ca­pncieance loading.

d. The complementary-output stage composed of tran­sisters Q1210 and Ql211 is connected co the unity-gain
output to complete the unity-gain amplifier clrcult.

e. The power supplies which provide *120 volts dc

for the output transistor atsge are floating with re­spect to chassis ground. The *9v power auppliea for
the amplifier gain stages are referred to the unity­gain output.

“Lock-up” is a condition where

The compensation networks provide a con-

""lty-Gain Amplifier

g. The analog output signal for recorder outputs is

derived from a resistor divider network represented by

resistor RD in Figure 10.

1. 1 VOLT OUTPUT (51207). This output is derived
from the 1 milliampere current (for full scale in­puts) which flows through a,resistor network of

1010.1 ohms. This output has been designed co pro­vide a reference voltage for the analog-to-digital
converter. The 1 VOLT OUTPUT Terminal may be used

for monitoring purpose where loading ca” be 0.1 mi-

croampere maximum.

2. 1 MA OUTPUT (51206). This output provides a
one milliampere dc current for a full scale input
voltage of 100 millivolts, 1 volt, 10 volts, or 100
volts depending on the SENSITIVITY Switch setting.
The output cannectar used is a Witchcraft N113S fe­male phone jack which connects ehe output in series
with the reference voleege divider RD.

3. Xl OUTPUT (51203). This output is the unity­gain output as shown in Figure 11. The ~1 Output
provides a voltage es which is equal to ehe input
according Co the following ratio.

f. The SENSITIVITY Switch S1203 selects a resistor
network (represented by resistor Rs) to provide full
scale input ranges from 100 millivolts to 100 “Olts in
four steps. The output voltage to current conve’rsio”
is determined as follows:

sq. 4

20

where K is the amplifier loop gain.

3-4. AMMETER OPERATION.

a. Normal Mode. With the FEEDBACK Switch in the

0470

CIRCUIT DESCRIPTION

NORMAL position, a* accurately known RANGE Swirch re­~istor (CURRENT Range only) RI202 through R1212 is
connected in shunt across the Electrometer amplifier

input

Refer eo Figure 10 for a block diagram of the
Electrometer. The amplifier measures rhe voltage drop
across he Range resistor to determine the input cur­rent. The digital readout display and analog outputs
are calibrated to indicate the magnitude and polarity

of the voltage. The actual current is obtained by mul-

tiplying the readout times the current range selected.

b. Fast Node. With the FEEDBACK Switch in the

FAST position, an accurately known RANGE Switch resis-

tor (CURRENT Range only) R1202 through RI212 is con-

nected across the amplifier feedback Loop as shown in
Figure 12. The unity-gain output (Xl) is connected to

Input LO.
be used for monitoring purposes.

In this mode the GUARD and X1 Terminals may

The Fast Mode con-

ciguration minimizes the slowing effects Of input ca­pacitance. The input voltage drop is maintained at
less than 100 micravalcs.

sistore are R1202 through F.1212.

c. Normal Mode Operation. When the FEEDBACK Switch

is in rhe NORMAL position, the unknown resistor is

connected between the INPUT high and low as described

in the OPERATTON section of this manual. The actual
resistance is determined by multiplying the digital
readour display times the OHMS Range selected.

The analog-to-digital converter circuit des-

cription can be found in paragraph 3-7.
This circuitry is separate from the analog

circuitry and is located on individual

printed circuit boards.

0470

CIRCUIT DESCRIPTION

1VOLT OUTPUT

INPUT ,

22

> I

I

C

+ ,,

I\

I
I

I

0

Y

m

0

+

::RO

<GUARD

vo

FIGURE 14. Coulombmeter Fast Made.

0470

MODEL 615 CIRCUIT DESCRIPTION

I

*II’1
. ! ! ! !

I I I I I I I
I I I I

I I I

I

0671

FIGURE 15.

Block Diagram ot

AID Converter.

23

a. General (refer to Figure 15 for a detailed block

i------------------L--,

diagram of the A-to-D cO”“erter). The analog-to-dig-

ital converter operates using a dual slope integration
technique which has inherent line frequency noise re­jection. The *“*log sign*1 is applied t” the integra­tor for one complete line frequency cycle, therefore
integrating the line frequency noise. me analog sig­nal is the” remove* from the integrator input. The
voltage on the integraeor is then driven to zero to
complete the voltage-to-time conversion. The time in­terval to reach a “zero crossing” is counted and dis­played on the “Readaut” in praportio” e” the origi”al
analog sign*,. The sequence is then repeated for a
second reading. (Refer to the Timing Diagram shown

in Figure 9).

b. The A-m-D converter is composed of nine major
circuits which perform the analog-to-digital conver­sions an* provide Various control commands.

1. Oscillator or clock

2. BCD counter

3. Delay Hold
b. Program/Decoder

5. I”tegr*tOr

6. Nero Crossing Detector

7. Buffer/Storage Register

8. Decoder/Driver

9. Numerical Readouf.

C. Oscillator or Clock.

pulses at a rate of 120 kilohertz for Electrometer

using 60 HZ line power. (The 50 HZ units have B pulse

race of 100 kilohertz).

The Oscillator produces

or “ntil Trigger is shorted to ground. After con­“ersio”, ehe instrument will again be inhibited at

the beginning af ehe period (2).

3. If both Switches s1 an* s2 are clased, rile

conversion cycle works in the foliuwing manner.

a) After the previous converSion ihas been cm-

pleted, etle leading edge of the program comma**

(2) resets the flip-flop. I” this new con*icim
q is high and, therefore. the clock gives 110 out­put.

b) At that rime,

its cycle and, after the appropriate time. pro­duces a pulse LhaL sets the flip-flap. This
changes g to a law state and a new C”n”erSio,l
cycle begins. After the reading has bee” corn-

pleted, the (2) camman* again resets the Elip-

flop and the timer again issues a “ew pulse co
set the flip-flop.

the ““ijunction timer begins

i.EW

H -

I I

d. BCD Counter. The BCD COULI~BT‘ counts the Clock
pulses with a total range of 5000 co”“cs. The Counter
ia composed of 4 i”di”idual counters designated 1, 10,
100, and 1000.

1. The “I”, “IO”, and “100” counters have a ca-

pacity of ten co”“ts each.

3. The tot*1 capacity of all four co”“ters is

5000 counts.

e, Delay Hold. The Delay Hold circuit controls the
DISPLAY RATE function and external Hold and Trigger
colmnan*a (refer eo Figure 16).

1t determines the length of time between A-ta-

1.
D conversions when the front panel DISPLAY RATE Con­trol is Bet to any position other charI MAX. me
clock is stopped ac the beginning of the ZERO (2)
period for a time
DISPLAY RATE Control.

It ensures chat when the Hold 2 is grounded

2.

the conversion in process will be cornpIeced and new
data will be stored in the m,t,,ut storage register.
Then the clack will be inhibited at the beginning of

the ZERO period (2). The instrument will remain in

this condition indefinitely until Hold 2 is released

determined

by the rotation of the

Program/Decoder. The Program/Decoder circuit

e.

produces evenr commands to cantrol the overall se-

quence of events for a complete A-to-D conversian.

Integrator. The 1ntegraeor circuit operation is

8.

composed of three periods (refer to Figure 9).

I. zero Period. luring this period the intcgra-

tar amplifier is zeroed by ehe closure of s~itcll Sb.

Switches S,, s,, an* s* *IYe open to prevent integru-

tar charging (refer eo Figure 17).

2.

Integration Period. During this period,
switch Sb, SC, and Sd are open. Switch s, is closed
to permit charging by the analog voleage for a per-

24

0410

FIGURE 17. rntegrator Block Diagram

h. zeru crossing Detector. me zero crossing De-

tector circuit provides a “High” or “Low” level output

depending on the polarity of the detected input. me-

Eer to Table 19 for a description of voitage outputs

of Lhe Zero Crossing detector (refer co figure 18).

Zero Crossing Detector Outpur Levels.
M N
0” -0.5” i1.5”

I

0”

I

i.

Buffer/Storage register. The ~ufferl~torage

Register is composed of “flip-flops” arranged to copy

the states of the various BCD counters.

Storage Register requires a Buffer Store command be-

fore any information can be transferred. The “flip­flop” circuits provide coded information for Decoder/

Driver and the BCD outputs.

~j. Decoder/Dri.ver. The Decoder/Driver circuit de-

0470

TABLE 19.

13.5”

B

0”

c
ov

~1.5”

The BUf fer/

I

MODEL 615 ELECTROMETER

CIRCUIT DESCRIPTION

TABLE 20.

I

comnan*

I

Function

ZERO

324

I

tor is charged by the analog signal for a period “f
1 line cycle or 16.67 milliseconds.

signal is remove* an* the integrator output is

driven co zero by e reference current. The Zero
Crossing Detector senses a zero crossing of the In-

eegreeor output an* remOweS the refeeence current.

The

The +1.5 vole levels are provided for control of the

Integrator an* Polarity storage Register. A pu1ae
command is also produced to initiate a Buffer/Store

and print Command output.

Suffer/Storage Register copies the SCD Counterstatea
et that instant of time.

in the Register is then available for the Decoder/

Driver an* external printout.

output and drives the numerical Readout for a digit­al display.

Model 4401 Buffer Card “utput~ in the form of posi-

cive (+lO volt) true logic (1-2-4-S BCD Code).

10.
Counter reaches 2000 counts and the Program/Decoder
provides a “2” commend to initiate a new conversion

cycle.

11. The Unijunction Timing Circuit will initiate

the ZERO period after a preset time delay controlled

by the front panel DISPLAY RATE Control.

3-S. AN.4Loc-TO-DIGrt*L CONVERTER CIRCD~TRY.

a. General. The circuits described in this eecti””

at-e located on the various Sub-Assemblies listed below
end in Table 22 of Section 4.

b. Oscillator Board.
portions of three circuits:
circuit, the Delay/Hold circuit, and the Discharge­Voltage current source CirCUlt.

0:1

5. When the “3,4” comnlan* is given, the integra-

6. When the “O,l” command is given, the analog

detector provides outputs as shown in Table 19.

7. When the Buffer/Store command is given, the

8. The Decoder/Driver decodee the Buffer/Storage

9. The BCD output information is available at the

The conversion cycle is completed when the SCD

1. Oscillator Board, PC-217.

2. Integrator Board, PC-246.

3. Display/overload Board, PC-241

4. Readout Board, X-229
Polarity Board, PC-207

5.

6. output Buffer Board, PC-2L8

7. output Buffer Board, PC-209

1. Oscillator Cic’cuit. Trensi~tor Q501, crystal

I

The SCD coded information

The Oscillaeor Board codtains

INTEGRATE

COUNT

the Oscillator (clock)

~501, and phase shift capacitors C501, and C502 form
a “colpitts” type oscillator. Capacitors ~503 and
~504 are used for trimming the oscillator frequency.

I

I

The ““Cput is taken from the collector of transistor
Q510 which is a comnon emitter gain stage used for

squaring ee ““tpllt. Transistor Q507 serves as an
emitter-follower to reduce output impedance.

2. Delay/Hold Circuit. There ace three major

components in the Delay/Hold circuit: en “RS” type

flip-flop circuit, a ‘Wnijunction” timing circuit

an* a “ROld” gate circuit.

“RS” Type Flip-Flop

=)

gates the output of the clock depending on the
inputs at pins R and S. The RS flip-flop is coo­strucced of gates QA5OlB and QA5OlC. The pins
are identified as shown in Figure 16.

“Unijunction” Timing Circuit. The unijunc-

b)

tion timing circuit determines the time delay

tween conversion cycles to obtain the

version rate 88 determined by the front panel DIS­PLAY RATE Control. The circuit is composed of
tran9isCors Q513 and Q514, timing capacitor C507,
and timing resistors ~532 end R1269 (DISPLAY RATE
Caner01 potentiometer located on the front panel).

c) “HOLD” Gate Circuit. (Refer to Figure 16
for identification of switches S1 and S2). The
“HOLD” gate circuit is composed of gates QASOlA.

QA501D, and QA502 (A, 8, C, and D). Switch S1 is
gate QA501A and is controlled by either the “HOLD

2” exrernal line or the “MAX” position on the

DISPLAY RATE Control.
Q513 which is controlled by either ebe “Q” output
of the flip-flop or the “HOLD 2” external line.
The “HOLD I” circuit is composed of gates QASOZS
and QA502C.

3. Discharge-Voltage Current Source Circuit.
The positive current source composed of tran~ierors
Q502 and Q506 delivers a constant current of +7.5
milliamperes tb drive a g-volt zener diode D602

(located on the Integrator Board, PC-246) when +REF
Terminal (Pin 13) is greater than co.7 volt. The
negative current ~““rce composed of erensistors Q508

and Q509 delivers a constant current of -7.5 milli-

amperes to drive a 9-volt zener diode 0601 (also

located on the Integrator Board, ~-246).

Integrator Board. The Integrator Board consists

c.

“f two ma,or circuits:
Zero Crossing Detector circuit.

1. Integrator Circuit. (Refer to Figure 17 for

identification of switches Sa, Sb, S,, and Sd). The
operation of the Integrator is controlled by ehe
poSitionS of switches So, Sb, S,, and Sd. switch
S, is transistor Q605. Switch Sb is transistor
Q606. Transistors Q601 through Q604 are control
circuits arranged e” turn off the proper FET Switchee
depending on the signals at pins 11 and 12. The in-

tegrator smplifier conslets of transistors Q607 and
~608 and ineegraced circuit QA601. The feedback ca-

pacitor is C603. Switches SC and Sd (located on the
Oscillator Board, PC-217) control the current for

‘)-volt zener diodes 0601 an* 0602.

Circuit.

Switch S2 is transistor

the Integrator circuit and the

The flip-flop

be-

desired coo-

~e~iseors ~602

26

0470

CIRCUIT DESCRIPTION

MODEL 615 ELECTROMETER

through P.611 are full-scale calibration resistors.

2. Zero Crossing Detector Circuit.

(Refer to
Figure 18). The high gain amplifier is composed of
cascaded amplifiers Q~602 and qA603.

justment network consists of resistors

R648, R649,

and ~650. and diodes D6ii and 0612.

The zero ad-

~645, Rb46,

Transistor ~609 and other components form a 6-volt

supply for QA603 and the zero circuit. The Level-

splitter circuit consists of diodes D613 and D614,

resistors

~65L, ~652,

and R653 and gatee QA604 (A,

USC).
d. Display/Overload Board. The Display/Overload

Board conrains a BCD Counter (“1000” counter), a Pro­gram Decoder circuit, a”d a” Overload Control circuit.

1. The BCD Counter is composed of “J-K” flip-flop

circuits QA301 and

2.

The Program Decoder circuit is composed of

gates

QA303C

QA3048, QA304C, QA304D, QA305A, QA3058, QA305C.

QA305D, QA303E, QA306A, QA3068,

2

Commands).

3.

The Overload Control circuit provides a” over-

QA302.

and QA303D (3.4 Command) and QA304A,

and QA306C (0,L. &

load signal if a zero crossing does “ot occur in the
Discharge Period (0,L). 1t controls the Numerical
Blanking circuit end provides a” Overload Print sig­*al.

e. Readout Board. The Readout Board contains Dec-

ade Counter circuits, Buffer Storage circuits, and me-

coder Driver and Di.splay circuits.

1. Decade Counter Circuits. Each decade counter

is composed af four J-K flip-flops. Circuits QA401
through ~A406 are Dual J-K FLip-Flop integrated cir­cuits.

gate QA204A.

The -REF Control signal is determined

by QA202A, QA203A, QA2038, QA2028, OA202C, QA2”3C,

QA203D,

and QA2048.

4. Buffer Store

Command

Circuit. me Buffer
Store command is provided by J-K flip QA20111 and
gates

QA204C

and QA207A.

5. Overload Blanking Circuit. A portion of the

Overload

Blanking circuit QA204D. QA206R, and QA207B

is located on the Polarity Board. The remainder of

the circuit is Located a” the Display/Overload Board.

E-241.

g. output Buffer Board. PC-2LS. This board con-

tains

L5

buffer circuits to provide BCD Data and Over­load and Polarity Print signals. Buffer circuits “A”
through “P” consist of transistor buffer stages PS

shown in Figure

19.

h. Output Suffer Board, R-209. ‘This board contains
six buffer circuits and various gate circuirs to pro­vide Prinf Command and Range Signal PrinL signals.

1. Suffer Circuits.

Buffer circuits “*” through

“E” provide SC0 Range information.

2.

Print Command Circuits.

Suffer circuits com-

posed of transistors QllOi, Q1102, Q1104, Q1105.

41106,

and Q1107 provide Print Command signals as

determined by gaeee QAllOl (A,B,C, and D) and QALLO~

(A,t.C, and D).

3. Range signal Circuit. Transistors QllOS,

~21109, and QlllO comprise a Range Signal Buffer

stage controlled by the Lange Signal.

-

2.

Buffer Storage Circuits. The Buffer Storage

register is composed of Dual J-K Flip-Flop integrated

circuits QA409 through QA41k.

3.

Decoder Driver Circuits. QA415, QA416, and

QA417 ere Decimal Decoder Driver integrated cfrcuits.

4. Display CFrcuFts.

V4OL, “402, end “403 are

Readout Tubes for Units, Tens, and Hundreds respec­tively.

f. Polarity Board. The Polarity Board conteins

various circuits which are controlled by signals “6”

end “C” from the Zero Crossing Detector signal as
shown in Figure 18.

1. Polarity Indicator Control Cixc”it. This cir­cuit drives the Polarity Indicator DS201 LO provide
a Polarity display. QAZOIA and QA206A are J-K Flip-

Flop circuits which conrroi transistors Q201 and 4202

2.

Polarity PrinC Signal Circuit. The Polarity

Print signal is determined by the q output of J-K

flip-flop QA206A.

3.

Discharge voltage Polerity Control Circuit.

The +REF Control signel is determined by QAZOlA and

0470

FIGURE 19.

Model 4401 Suffer Stage.

27

CIRCUIT DESCRIPTION

MODEL 615 ELECTROMETER

4. Reference Voltages. A High and LOW Reference

voltage is provided by resistor divider R1114, R1115,

and R1116. The voltages are +8 volts (High) and +2

volts (Low).

POWER SUPPLIES (refer ea Schematic Diagram

3-9.
24044E).

a. *15 vole Supply.

1. The 115 volt supplies tap a-c power from a

secondary of transformer T101. Diodes 0103, D105,

0107

and

0108 and capacitors CL04 and Cl05 compose

a full-wave rectifier with filtering.

2. Transistors Q114 and Q115 form a differential
amplifier which compares the voltage at R115 with
the voltage of zener diode 0110. The difference

voltage is amplified by transistor Q109 and fed to

Darlington transistor pair, Q106 and Q107, which
series regulate the oueput voltage.

3. Transistors Q116 and 4117 form a differential
amplifier which compares the voltage ae R123 with
respect to la. The difference voltage is amplified

‘by transistor Q113 and fed to Darlington transistor

pair, QllO and Qlll, which series regulate the -15

volt aueput.

4. Transismrs Q108 and Q112 limit rhe output

current to about 200 milliamperes.
b. t3.6 Volt Supply.

1. The ~3.6 volt supply taps a-c power from a
secondary of transformer TlOl.. Diodes DlOl and D102
2nd capacitor Cl01 form a full-wave rectifier with

filtering.

2. Transismr 4105 amplifies the difference be­tween the ~3.6 volt output and a reference voltage

derived from the ~15 vole supply and determined by

resistors R103 and R104. The difference voltage is

amplified by rraneistor Q104 which drives a Darling-

ton tmnsistor pair, QlOl and Q102. The Darlingto”
pair series regulares the +3.6 volt output.

3. Transismr 4103 limits the output current to

about 3 amperes.

C.

+170 Volt Supply.

1. The +170” supply taps a-c power from a second-

ary of transformer T101.

Diode Dill and capacitor

Cl12 farm a half-wave rectifier with filtering.

2. Transistor Ql19 amplifies the voltage devel­aped by the resistor divider RUE and R129. The
output of Q119 controls the series regulator cran­sistar Q118 to maintain the +170 volt output.

3. When the electrometer is overloaded, and over­load signal drives transistor Q120 which in turn
controls the voltage at the base of transistor Q119.

The circuit composed of diode D112, transistor Q120,

and resistors R130, R131 and RI32 reduces the +I70
volt output to +80 voles when overloading occurs.

Grounding the overload input turns off transistor
Q120 causing diode 0112 to conduct and drive Q119.

4. The reduced +80 volt output causes blanking an
all Numerical Readout Tubes connected co the +170

volt supply.

t210 volt output. The t210 volt supply is an

d.

unregulated voltage supply using the, half-wave fil-

tered voltage at diode Dlll and capacitor C112.

e. “9

Volt

Supplies (shown an Schematic 24267E)

1. The *9 “olt supplies tap a-c power from a sac­ondary of transformer T1201 or T101. Diodes 01201
to D1204 and capacitors Cl216 and Cl217 for a full-

wave rectifier with filtering.

2. Zener diodes 01205 to 01208 provide regulated
*9 volt outputs.

f. 1120 “0lC Supplies.

I. The 1120 volt supplies cap a-c power from a

secondary of transformer T1201.

Diodes D1211 and
D1212 and capacitors Cl218 and Cl219 form a half­we.ve rectifier with filtering.

2. Zener diodes 01209 and 01210 provide regulated

-rl20 vole outputs.

28

0470

MODEL 615 ELECTROMETER REPLACEABLE PARTS

SECTION 4. REPLACEABLE PARTS

4-1. REPLACEABLE PARTS LIST. This section contains (Code Number), Manufacturer Part Number, and the
a list of components used in the Model 615 Digital

Electrometer for user reference. The Replaceable erence Number where applicable. The complete name and

Parts List describes the individual parts giving Cir- address of the Manufacturers is listed in Table 24.

cuit Designation, Description, Suggested Manufacturer (Refer also to Table 21 for Abbreviations and Symbols).

Keithley Part Number. Alsa included is a Figure Ref-

Abbreviations and Svmbols
A
Cb”aC

CerD
Cer Trimmer
CO”lP

DCb
Desig.

EAl
ET8
ETT

ELECTRICAL SCHEMATICS AND DUCRA”S. Schematics

4-2.
and diagrams are included to describe the electrical
circuits as described in Section 3.

which identifies all schematic part numbers included.

4-3. WOW TO “SE THE REPLACEABLE PARTS LIST. This
Parts List is arranged such that ehe individual types
of components are listed in alphabetical order.
perts for the instrument’s Main Chassis are listed

fallowed by printed circuit boards and other subassem-

blies. Refer to Table 23 for listing of circuit des-

ignacion series assigned to each major sub-assembly.

4-4. HOW TO ORDER PARTS.

a. Replaceable parts may be ordered through the

Sales Service Department, Keithley Instruments, Inc.

ampere
Carbon Variable

Ceramic Disc
Ceramic Trimmer
Camposition

Deposited Carbon
Designation

Electrolytic, Aluminum
Electralytic, tubular
Electrolytic, tantalum

Refer co Table 22

TABLE 21.

F farad
Fig.

GCb Glass enclased Carbon

k
u

M
Mfg.

MU
MY

NO.

The

Figure

kilo (103)

micro (10-6)
Meg (106)

Manufacturer
Metal Film
MYhC

Number

or your nearest Keithley representaeive.

b. When ordering parts, include the following in-

formation.

1. Instrument Part Number

2. Instrument Serial Number
Part Description

3.

4. Schematic Circuit Designation

5. Keiehley Part Number.

C. All parts listed are maintained in Keiehley
Spare Parts Stack. Any part not listed can be made
available upan request. Parts identified by the

Keithley Manufacturing Code Number 80164 should be

ordered directly from Keithley Instruments, Inc.

0.
P

PC
POly

Ref.

V

w
ww
W&V*=

OhIn

pico (to-121

Printed Circuit
Polystyrene

Reference
Tinner Capperweld
volt
watt

Wirewound
Wirewound Variable

Description

Electrometer Board
Electrometer Board
Power Supply
Polarity Board
O-1 Display/Overload Board

I

Readout-Board

Oscillator Saard

Integraror Board
ouepu? Buffer Bw.rd

o”tp”t Suffer BOard

I

0472R

Circuit Designation

Main Chassis, 112
Main Chassis. #I
Main Chassis; 83 240443

PC-207 234490
PC-241 24031D
PC-229
PC-217 23452D
PC-246 24042E
PC-218 23457D
PC-209 23481E

Schematic Pert Number

24267E
24151E

234513

REPLACEABLE PARTS MODEL 615 ELECTROMETER

TABLE 23.

DeSigX+tiO"
Power supply
PC-207
PC-241
PC-229

PC-217
PC-246
PC-218
PC-209

Power supply sub-assembly shown on Schematics 24267E and 24151,~.

Polarity P.C. Board. Plugs into connector 51214.
O-1 Display/Overload P.C. Board. Plugs into connector 51215.
Readout P.C. Board. Plugs into connectors 51216 and 51217.
Oscillator P.C. Board.
Integrator P.C. Board. Plugs into connector 51219.
OUtput Buffer P.C. Board.
Output Buffer P.C. Board. Plugs into connector 51213.

circuit
tIesi*.

Value Rating

Cl201 .Ol UF
Cl202
Cl203
Cl204

150 pF

5 PF

10 DF

Cl205 22 ;F

Description

Plugs illto connector 51218.

Plugs ineo connector 51212.

MAIN CHASSIS REPLACEABLE PARTS LIST

(Refer to Schemetic Diagram 242673 for circuit designations)

CAPACITORS

Mfg. Mfg.

CWh Pare NO. Part NO.

600" CelCD
600V

Certl
200" Poly
500" POly
5oov

P0ly

72982
72982 ED-150
00686
71590 CPR-22J
71590

ED-.01
E1013-1
CPR-22J

series

Nunbe r
100 34
200 36
300 37

Page

400

500

38
39

600 41
1000 43
1100

Keithley

43

Fig.
Ref.

C22-.OlM 22
C22-150P 21

C31-5P

30
C138-1OP 30
C138-22P 30

Cl206 47 pF
Cl207
Cl208

Cl209

100 DF
.OOl' @F

lrrF

Cl210 :01 WF
Cl211 ,001 p

Cl212 100 pF
Cl213 .033 UF
Cl214 .033 PI
Cl215 150 pF

Cl216
Cl217
Cl218
Cl219
Cl220

100 UF

100 GF
40 L@
40 P

.Ol fl

Cl221 .0047 UF
Cl222 .OO47 1*F
Cl223 .0047 p.F
Cl224 .0047 p
Cl225

5 PF

5oov
zoov
200" P&
zoov
2oov Poly

2oov Poly
2oov
2oov
2oov
600V cerll

5ov

POly
P01"

Poly

POly

MY
MY

EAl

71590
84171
84171
84171
84171

84171
84171
13050
13050
72982

90201
5ov EAI 90201
350v ETB 56289
350v ET8
600V &L-II

600" CS%tTD
600V Gel-D
600" &t-D
600"
600V

cem
CerD

56289

72982

72982

72982

72982

72982

72982

CPR-47J

C138-47P 30

ZPJ-101G c108-100P 30
2PJ-102G Clog-.OOlM 30
2PJ-104G
ZPJ-103G

ZPJ-102G

C108-.lM 30

ClOB-.OlM 30

ClO&.OOlM

30
ZPJ-101G clog-1OOP 30
SM2A

C143-.033M
SM2A C143-.033M
ED-150 C22-15OP

MTV 1OON 50 PDN C186-1OOM
Mm 1OON 50 Pm C186-1OOM
TVA 1611 C23-40M
TVA 1611 C23-40M
ED-.01 C22-.OlM

ED-.0047 C22-.0047M
ED-.0047 C22-.0047M
ED-.0047 C22-.0047M
ED-.0047

C22-.0047N
ED-5 C22-5P

22
22
22

22
22
22
22
22

22
22
22
22
22

30

0671R

MODEL 615 ELECTROMETER

REPLACEABLE PARTS

CONNECTORS

circuit
tIesiR. Deb-criptioll

51215

51216
51217
51218
51219

51201
P1201
51202

51203
51204

51205

51206
51207

51208
51209

_-_

.I1210
51211

Receptacle, 15 Pi",

Display/Overload Board

Receptacle, 15 Pin,

Readout Board

Receptacle, 6 Pin,

Readout Board

Receptacle, 15 Pill,

Oscillator Board

Receptacle, 15 Pill,

Integrator Board

Receptacle, Printed circuit
contacts, Printed circuit

Binding Post Terminal,

Green (Case GND)
Binding Pose Terminal, Red (Xl)
Binding Post Terminal,

Blue (Guard)
BkLdiwg Post Terminal, Black (LO)

Receptacle, Phone Type
Receptacle, Microphone Type
NOC "Led
Receptacle, Triaxial, Input

Plug, Triaxial Mate of 51209
cap, Input
Binding Post Terminal, Black (ID)
Receptacle, 50 Pi",

Printer/control

Plug, 50 Pin, Mate of 51211

Mfg. Mfg.

Code
09922
73690
73690
09922

09922

91662 02-005-113-6-200
91662 02-006-113-6-200

58474 DFZlGC

58474
58474

58474
82389
02660

95712 33050-Z-NT34 cs-181
95712

02660 31-007 CAP-18
58474 DPZlBC BP-11 (Black)
02660 47-40500-I

02660 57-30500-I

Part No. Part NO. Ref.

PSC-4SS15-2
02-015-113-6-200
02-006-113-6-200

PSC-4SS15-12

PSC-4SS15-12

DF21RC
DF21BC

DF21BC
N113B

EO-PCZF

2743-l-NT34 cs-141

Keithley Fig.

CS-175
B-226
B-225

CS-175

CS-175

B-199
cs-200

BP-11 (Green)
BP-11 (Red)

BP-11 (Blue)

BP-11 (Slack)
CS-231
CS-32

CS-221
CS-220

22
22
22

22
22

22
22

2

2
2

2
2
2

1

1

2

51212
51213
J1214

-__

circllit

tk2si.e.
i31201*

01202*
D1203*
D1204*
01205

01206
D1207
D1208
01209
01210

01211
D1212
D1213
01214

Receptacle, 44 Pi",

output Buffer Card

Receptacle, 44 Pill,

Output Buffer Card

Receptacle, 15 Pi",

Polarity Board

Plug, Phone Type, Mates with

51206

Type

Silicon

*(4-Diode Full-Wave Bridge Module)
zener "R-20
zener IN936

zener "R-20

7.ener

7.ener VR-120A

7.ener VR-120A
SiliCOlI

Silicon
SiliCOll
SilkOIl

09922 PSC4DD22-12

09922
09922 PSC4SS15-12

82389

DIODES

NUUltl~~

PD-10 83701

113936

lN3256
lN3256
lN645
lN645

PSC4DD22-12 CS-205

267

Mfg.

Code Pal-t No.

84970 ix-31 22
04713 ix-5 22

84970 DZ-31 22
04713 DZ-5 22
84970 DZ-32 22
84970 DZ-32 22

02735 RF-22 22
02735 RF-22 22
01295 RF-14 22
01295 RF-14 22

c-205

CS-175

CS-244

Keithley Fig.

RF-36

22

22
22

Ref.
22

0273B

31

REPLACEABLE PARTS

MODEL 615 ELECTROMETER

PRINTED CIRCUITS AND SUB-ASSEMBLIES

circuit Schematic

Lksig. Description Part Number

Power supply Mother Board
PC-207 Polarify P.C. Board.
PC-241
PC-229
PC-217 Oscillator P.C. Board.
PC-246
PC-218 Model 4401 Output Buffer P.C. Board. 23457D

PC-209 Model 4401 Output Buffer P.C. Board. 23481B

Ci?X"it

Desig.

R1201

R1202

R1203

R1204

RI205

R1206

RI207

R1208

RI209

Rl210

Value

10 Mn
10 a
100 n
1 Kn

10 Kn

100 KO
1 Mr2

10 MO
108 n
109 n

O-1 Display/Overload P.C. Board.
Readout P.C. Board.

Integrator P.C. Board.

RESISTORS

Rating Type Code Part No.
10%. l/2 W

.25%, 10 W

.25%, 10 W
l/4%, l/2 "
l/4%, l/2 w

l/4%, l/2 w
l/4%, l/Z "
l%, l/2 "
l%, 2 W
+3 -0% L/R w

Comp 01121 EB RI-1OM 21
ww
ww
MtF 07716 CEC-TO R127-1K
Mm

MtF 07716 CEC-TO
MtP 07716 CEC-TO
DCb 91637
DCb 91637 DC-2
GCb 63060 Rx-1

Mfg. Mfg. Keithley

02985 TS-10 R163-10
02985 TS-10 Rl63-100

07716 CEC-TO R127-10K 30

DCF-l/2

24044E
234490
240310
234518
234520
240423

Part No. Ref.

R127-100K
R127-1M
RlZ-IOM
R14-108
RZO-10g

Fig.
Ref.

22

23

24
25
26
27
28
29

Fig.

30
30
30

30
30
30
30
30

R1211
P.1212
R1213
R1214
R1215

R1216
RI217
R1218
R1219
RI220

R1221
R1222
R1223
K1224
R1225

R1226
R1227
Rl228
R1229
RI230

RI231
R1232
R1233
R1234
R1235

1010 n
1011 D

100 n
900 0
10 n

2 KR

7.15 Khl

10 Mn

2.2 MO
100 Ko.

68 Kfl

10 K&I
68 K0
226 0
226 n

226 fi
226 fl

226 Cl
226 0
226 S,

226 n
226 n

226 $7

34.8 RR
200 Kfl

+3 -0% l/R W
+3 -0% L/R w

.5%. l/2 w
.5%, l/2 w

L-L, l/2 w
20%, 2W

I%, l/2 w
l%, l/2 w
l%, l/2 W
IO%, L/4 "

l%, l/8 w
5%

l%, l/S w
I%, l/2 w

l%, l/2 w

l%, l/2 w
l%, l/2 w
l%, l/2 W
l%, l/2 w
l%, l/2 w

l%, l/2 W
I%, l/2 W
l%, l/2 W
l%, l/2 w
l%, l/2 w

GCb 63060 Rx-1
GCb 63060 RX-1
MtF 07716
MtF 07716
DCb 91637 DCF-1/Z

ww 71450 lNS-115
MU 07716 CEC
DCb
DCb
camp

MtF

_--

MtF
Mm
Mm

MCF
MtF
MCF
MtF
PKF

MCF
MtF
MtF

DCb

91637 DCF-l/2
91637 DCF-l/2
44655

07716 CEA RSB-68K
07716 8400 RP84-10K
07716
07716
07716 CEC R94-226

07716 CEC R94-226
07716
07716 CEC R94-226
07716 CEC R94-226
07716 CEC R94-226

07716 CEC
07716 CEC
07716 CEC
07716 CEC
91637 DCF-l/2

CBC
CBC

RCO7

CEA
CEC

CEC

R20-101'
RZO-lOI1
R61-100
R61-900
RIZ-10

RP50-2K
R94-7.15K
RlZ-1OM
RlZ-2.2M
R76-LOOK

RSE-68K
R94-226

R94-226

R94-226
R94-226
R94-226
R94-34.8K
R12-200K

30
30
22
22
22

22
22
31
31
22

22

22

22
32
32

32
32
32
32
32

32
32
32

'2

? ?

32

0671R

07716
07716
"7716

')I637

01121

RY4-36.5K
KY4-36.5K
R94-11.m
R12-?OOK
RI-2.2K

22
22
22
22
22

K1251
R1252
R1253
K1254

RI255

R1256
RI257

R1258

RI259

R1260

I?1261
R1262
Kl'263
RI264
RI265

X1266
R1267
131268
K1269
R1270

1.0101 m

90.000 m

9.000 Kn

909.09 $7

101.01 iz

1” K.2
Not. USed
Not USed

Not USed
Not USed

2K n
500K n

220 n

l%, l/2 w
IO'%, l/2 w

101, 112 w
10%. l/2 w
l%, l/2 w
Lo%, 1,4 w
IO%, L/4 w

.Ol% .33w
.05% .33w

.05% .33w
.05% .33w

.O5% .33w
I%, l/2 w

2%, 2w

*20%, 1/4w

10%. 114"

01121 ER RI-2.2K
07716 ccc

K94-28.X
07716 CEC K94-21.5K
07716 CEC 1194-7.15K
"1121 EL+ I?-27OK

0,121 EB RI-100K
01121
07716 CEC
44655

E8 iti-4.x

RY4-15K

RCO7

R76-47
44655 RC07 R76-47

01121 EL7 KI-680
01121 ER Rl-1.m
01121 E8
01121 es

RI-680

RI-1.8K
11637 k-5 R4A-20K

91637 KS-5
0,716 cut

17870 1250
1,870

1250

17870 1250

17870

17870

07716

71450
71450

44655

1250
1250
CEC

INS 115

GC45

RCO,

R4&2"K

Ml-100K

R166-1.0101K

RL65-9O.OOOK

RL65-9.00OK

R165-909.09
k165-101.01
R94- LOK

KP5”-2K
KP75-500K

K76-220

22
22
22
22
22

22
22
22

22
22

22
22
22
22

22
22

31
22
11
31

31
?I
31

22
22

22

RI271
RI272
K1273

220 .1
220 a
220 n

lo%, l/4 w
lo%, l/4 w
lO%, l/4 w

circuit
Iksig.

DeSCripLiCA” Code Part NO.

S12Ol Rotary Switch less components, RANGE

--_
___

s1202 Limit Switch, ZERO CHECK

-__

SIZO3

---

Rotary Switch with components, Range Switch 80164

Dial Assembly, Range Switch

Knob Assembly, zero Check Switch 80164

Rotary Switch less components, SENSITIYITY 80164 SW-307
Rotary Switch with componenes, sensieivity Switch

Knob Assembly, Sensitivity Switch

0671K

44655

44655

44655

KC07
RCO,
RC07

R76-220
K76-220
K76-220

Mfg.

80164 SW-287
80164
04426

24026.4
SW-94

15461A

80164
80164 21384‘4

22
22
22

Fig.
Ref.

I

1

L

33

REPIACFABLE PARTS

MODEL 615 ELECTROMETER

Ci?X"it
Desig.

S1204

---

-__

s1205

___

---

51206

-__

Rotary Switch less components, FEEDBACK 80164 SW-308
k.tary SWifCh with components, Feedback SWitCh
Knob Assembly, Feedback Switch 80164

Rotary Switch less components, COARSE ZERO 80164
RoCary Switch with components, COQZW Zero Switch 80164

Knob Assembly, Coarse Zero Switch 80164
Rotary Switch, DISPLAY RATE (See also R1269) 71450

Knob Assembly, Display Rate Control 80164

Number

*01201

. ~~~

q1202

41203 NPN, Case TO-92
91204 NPN, Case TO-92
Q1205 NPN, Case TO-92

Q1206 NPN, Case TO-92
Q1207 NPN, Case TO-106
Q1208 NPN, Case TO-92

Q1209 PNP, Case TO-92

* These transistors should be replaced by ordering replacement FET Input Board No. 23733.

2N3903 04713
2N3903
2N3903 04713

2N3903
2N3565

2N3903
2N3905

Q1210 NPN, Case TO-39 MN3003

LkSCriptiO"

SWITCHES

AND CONTROLS (Cont'd.)

Mfg. Keichley
Code

80164

TRANSISTORS

Mfg.
Code Part NO.

04713

04713
07263

04713

04713
04713

Part NO. Ref.

Fig.

___

21384A
SW-286

--_

163738

RP75-500K
21384A

Keithley

Fig.

Ref.

22
22

TG-49 22

TG-49 22

TG-49 22
TG-49 22

TG-39 22
TG-49 22

TG-53

22

W-58 22

1

2

1

QlZll PNP, Case TO-39
Q1212 PNP, Case TO-92

MM4003

2N3905

04713
04713

POWER SUPPLY PARTS

LIST

TG-59 22

TG-53

22

(Refer to Schematic Diagram 24044E for circuit designations).

CAPACITORS

Mfg. Mfg. Keithley

Fig.

2000 p.F 15v EAL 29309 3675020015c C93-ZOOOM 22
220 pF 1ooov Cm-D 71590 DD-221-10% c22-22OP 22

150 pF 1000v &b-D 71590 DD-151-109: C22-15OP 22

200 pF 35v EAL 90201 MTVZOON35PDti C177-ZOOM 22

200 pF 35v EAL 90201 MTV200N35PDN C177-ZOOM 22

Cl06 200 pF 35v EAL 90201

MTVZOON35PDN

C177-ZOOM 22
Cl07 200 llF 35v EAL 90201 MTVZOON35PDN C177-ZOOM 22
Cl06 1.2 !.lF 2ov ETT 17554 TSD120125 C179-1.2M 22
Cl09 5 PF 1ooov &.tTl 71590 DD-050-10% c22-5P 22
Cl10 125 WF 15v ETB 73445 C426 C3-125M 22

Cl11 125 @ 15v ETB 73445 C426 C3-125M 22
Cl12 15 llF 300" EAL 90201 PTCOlSM300P3E c173-15M 22
Cl13 Not "sed
Cl14

68 pi

5oov Mica 84171 DM15-680J CZl-68PF 22

34

027X?

REPLKEABLE PARTS

circuit

oesig.

0104 SiliCO” lN645 01295
0105 Silicon IN645 01295

0106 SiliCO" 1N645 01295
0107 Silicon 18645 017.95
0108 SiliCO" IN645 01295
D109 Silicon lN645 01295
0110 Zener lN936 04713

0111
D112

Cit-C”it

oesig.

FlOl (117")

FlOl (234V)

--­PlOl
Slcll

s102

Type Number
SiliCO” 13327

Silicon
Silicon

oescri.FJtion Code Part NO.

Fuse, slow blow, 314 A, 250"
Fuse, slow blow, 318 A, 250V 71400
Fuse Holder 75915 342012

Cord Set, 6 feet 93656 4638-13
Slide Switch, 117-234V 80164 SW-151

Toggle Switch, F’OWER

Mfg. Mfg. Keithley Fig.

71400 Type MDL F"-19

80164 SW-265 SW-265

Mfg.

Code Part No.

13327
01295

Keichley

Part NO. Ref.

Type MDL FU-18

FH-3

co-5 2
SW-151

Fig.
Ref.

2

2
2

2

1

TlOl

RlOl
R102
R103 10 kfi
R104 1.1 kS,

R105 1 kR
Rl06

R107
R108
RlO9
RllO

Rlll
R112 4.7 k0
RI13
R114 4.75 kil
R115

R116 8.06 kn
R117
R118
R119
RI20

6.8 k0

0.2 n

100 n

150 n
33 kR
3n
680 0

3.3 kfi

3.3 kfl

2 kfl

18.2K

7.5 kff

33 kfi

3R

Power Transformer 80164 TR-126 TX-126

RESISMRS

Keithley Fig.
PBrt NO. Ref.

R76-6.8K
RlSl-0.2
RSS-10K
R88-1.X

R76-1K

RSS-100

R88-150
R76-33K
R12-3 22

R76-680

R76-3.3K

R76-4.7K 22

R76-3.3K

R&L4.75K 22

RP50-2K 22

R88-8.06K 22

R&3-18.2K 22

R&3-7.5K 22

R76-33K 22

R12-3 22

10%. l/Ii w Camp
*lo%, 4.25 W
I%, 1/a w
l%, l/8 w
lO%, l/4 w

1%. l/S w
l%, l/8 w
lO%, l/k w
1%. II2 w
IO%, l/4 w

lO%, l/4 w
lO%, l/4 w

lo%, l/4 w

l%, l/8 w

20%, 2 w

1%. l/S w

TC"
MtF
MtF

MCF
MCF

DCb’

cmp
Comp 44655

camp 44655 CB-472
camp 44655 CB-332
MtF 07716 XEA-4.75KO
wwvar 71450 1NS 115-2K.G

Mm 07716
Comp
MeF
Camp 44655 a-333
OCb 91637

Mfg.
code cart No.

44655
91637
07716

07716

44655
07716

07716
44655
91637 DCP-l/2-3SI
44655

07716

07716

Mfg.

CB-682

cu-2
CEA-1oKn
CEA-l.lM

C&102

CF.&100”

CFA-1500

C&333

CB-681

CB-332

C!LA-8.06KsI

CEA-18.2Kn

CEA-7.5Kn
DCF-l/2-3n

2

22
22
22
22
22

22
22
22

22
22
22

R121

R122

R123

0273R

33 kn

33 kn

7.5 kfl

44655 CB-333
44655 CB-333
07716

CEA-7.5Kn

R76-33K
R76-33K
R88-7.5K

22

22

22

35

REPLACEABLE PARTS

MODEL 615 ELECTROMETER

RESISTORS (Cont’d.)

R124

Rl25
R126

R127 56
R128

R129

R130

100 kn

!4

80.6 k*

7.32

1.5 kR

R131 1 ho

R132 12

kn

R133 10 k&l

QlOl

4102
6103
QlO4
Q105

QlO6
Q107

QlO8

Q109

QllO

kn

Rating
lO%, l/2 w

Type

Comp 01121 ES

lO%, l/4 w camp
lo%,

l/4

lo%,

l/4

w
I%, l/2 w
l%, l/S w
lo%, l/4 w

w

LO%,

l/4

w
lO%, l/4 w
lO%, l/4 w

camp

Camp
MtF
MtF

Comp

COmp

camp
Comp

TRANSISTORS

Mfg.
Code

Mfg.

Code

44655
44655

44655 RCO7

Mfg.
Part NO.

RCO,
RC07

07716 CEC

07716
44655

44655 RC07 R76-1K
44655
44655

lx.4

KC07

RC07

RCO,

Keithley

Pale No.

RI-82

R76-1M

R76-100K
R76-56K

R94-8D.6K

R88-7.3x
R76-1.5K

R76-12K
R76-IOK

Keiehley
Pat-f NO.

TG-68
TG-54

l-G-39
x-39

x-33
TG-39

w-43
TG-39

TG-39

TG-33

Fig.
Ref.

22
22

22
22

22

22

22

22

Fig.

Ref.

22

22
22

22

22
22

22
22
22
22

Qlll

Q112 S17638
Q113 517638 07263 TG-33
Q114 2N3565
Q115

Q116 S17638
Q117 517638 07263 TG-33

QllE
Q119

9120 2N3565 07263 TG-39

40319 02734 TG-50

2N3565

40346 02735 w-44
40346 02735 TG-44

07263
07263 TG-39

07263 TG-39

07263 TG-33

c-33

POLARITY BOARD (P.C.-207) REPLACEABLE PARTS LIST

(Refer to Schematic Diagram 234490 for circuit designations).

CAP.4CITOR

CiL-C”it
msig.

c201

Value

150

pF

Rati”g
600V

Type
CerD

Mfg.

Code

72982

Mfg.

Part NO.

ED-150

INTEGRATED CIRCUITS

circuit
Desig.

QA201
QA202

QA203

Description

Dual J-K Flip-Flop
Quad 2 Input Gate
Quad 2 Input Gate

Mfg.
Code

04713
04713
04713

Mfg.

Part NO.

MC890P
MC824P
MC824P

Keithley

Pare Ii”.

C22-150P

22
22

22

22
22

22

22

22

22

22

Fig.
Ref.

23

Keithley
Pare NO.

lC-8
1c-5

1C-5

36

MODEL 615 ELECTROMETER

REPLACEABLE PHRTS

INTEGRATED CIRC”lTS (Cant’d.)

Circuit
Desig.

QAZ”4

QA205
QA206

QA2O7

*Polarity Pilot Light

Circ”it

Desig.

R201 270 n
R202
R2O3

K204

2.2 kn

1.5 k0

1.5 kfl

DeSCZiptiO”

Quad 2 Input Gate
Quad 2 Input Gate

Dual J-K Flip-Flop
Dual 3 Input Buffer,

non-inverting

Descripeion

Paring

lo%, l/2 w
10%. 1/G w
lo%, l/4 w
LO%, l/4 w

N”mber

Mfg. Mfg.

Code Part NO. Part NO.

04713

MC824P

04713 MC824P IC-5
04713 MC890P IC-8

Mfg.
Code

91802

04713

Mfg.

Part NO.
2330 series

MC888P

Keithiey

Part NO.
PL-43

P.ESISTORS

COU’P

Mfg.
Code

44655 RC07 R76-270

Mfg.

Part No.

Keithley

Part NO.

camp 44655 RC07 R76-2.2K
Camp 44655 RC07 R76-1.5K
camp 44655 RC07 R76-1.5K

TRANSISTORS

Mfg. Keiehley
Code

Part NO.

Keithky

IC-5

IC-6

Fig.
Ref.

23

Fig.
Ref.

23
23
23
23

Fig.
Ref.

Q201
Q202

Circuit
uesig.

VA301
QA302
QA303

QA304

QA305
QA306

2N5184 02735
2N5184 02735

O-1 DISPLAYIOVERLOAD BOARD (PC-2411 REPLACEABLE PARTS LIST

(Refer ?o Schematic Diagram 240310 for circuit designations).

INTEGRATED CIRCUITS

LJeSCriptiO”

Dual J-K Flip-Flop
Dual J-K Flip-Flap

Hex InverCer
Quad 2 Input Gate
Quad 2 Input Gate

Quad 2 Inp”t Gaee

LAMP

Description Code Part No. Part NO.

Pilot Light, frone panel thousands tube

RESISTORS

Racing Type

W-67
TG-67

Mfg. Mfg.

Code Part No.

Keithley

Part iia.

23
23

Fig.
Ref.

04713 MC89OP IC-8 24
04713 MC890P IC-8 24
04713 MC889P IC-7
04713

MC824P IC-5

04713 MC824P IC-5
04713

MC824P IC-5

Mfg. Mfg. Keirhley

24
24
24

24

Fig.

Ref.

80164

Mfg.
Code

a-42 w-42

Mfg.

Part NO.

Keiehley

Part NO.

24

Fig.
Ref.

0671R

IO%, 114 w camp 44655 RC07
I%, l/2 w

MtF 07716 CEC

iR,b-1.5x
R94-1OK

2 4
24

37

REPLACEABLE

PARTS

MODEL 615 ELECTROMETER

RESISTORS (Cont'd.)

circuit
De&?.

R303

X304

circuit
oeei*.

4301

Q302

circuit

Desig.
P401

P402

CirE"le

lIeaiR.

Mfg. Mfg. Keithley

Value

1.5 kn

820 n

RatinK

lO%, l/4 w
lO%, l/4 w

Type
CO¶!JP 44655 KC07 R76-1.5K

camp 44655 RCO7 R76-820

Code

Part No. Part No. Ref.

TRANSISTORS

Mfg.

Number
2N5184

2N5184

Code
02735 TG-67 24

02735 TG-67

READOUT BOARD (P.C.-229) REPLACEABLE PARTS LIST

(Refer to Schematic Diagram 23451E for circuit designations).

Mfg. Mfg.

Description

Code

Part No.

Plug, 6 pins, connect* to 51206 73690 02-006-105-6-200
Plug, 22 pins, connects to 31207 73690 02-015-105-6-200

INTEGRATED CIRCUITS

Mfg. Mfg. Ksithley

DeBCriDtion

Code Pert NO. Part No. Ref.

Fig.

24
24

Keithley Fig.

Part No. Ref.

24

Keithley Fig.

Part No. Ref.
w-223 25

cs-222

25

Fig.

QA401
QA402
OA403

Dual J-K Flip-Flop
Dual J-K Flip-Flop
Dual J-K Fliv-Flop
Dual J-K Pli&Flo; 04713
Dual J-K Flip-Flop 04713 MCS9OP

QA406 Dual J-K Flip-Flop
QA407 Quad 2 Input Gate

QA408

QA409

QA410
QA411

QA412
QA413

QA414

Quad 2 Input Gate
Dual J-K Flip-Flop

Dual J-K Flip-Flop

Dual J-K Flip-Flop
Dual J-K Flip-Flop
Dual J-K Flip-Flop

Dual J-K Flip-Flop

QA415 Decimal Decoder/Driver

QA416
QA417

Decimal Decoder/Driver
Decimal DscodertDciver

circuit
DWiR.

v401
V402
v403

"nits Readout Tube
Tens Readout Tube
Hundreds Readout

Tube

04713
04713
04713

MCS9lP IC-9
MC891P IC-9 25
MC89lP IC-9 25
MC89OP IC-8

IC-8

04713
04713
04713
04713
04713

04713
04713
04713
04713
07263

07263
07263

MC89lP

IC-8
MC824P x-5 25
MCS24P X-5 25
MC890P

MC89OP

MC89OP

IC-8 25

IC-8 25

IC-8

MC89OP IC-8 25

MC89OP IC-8 25

MC89OP IC-8

U6B996079X IC-3 25
U65996079X IC-3 25

U6B996079X IC-3 25

READOUT TUBES

Mfg.

Coda

Mfg. Keithley Fig.
Part

No.

Part No. Ref.

83594 85750 EV-5750 25
83594 85750 w-5750 25
83594 B5750 EV-5750

25

25

25

25

25

38

0671R

MODEL 615 ELECTROMETER

RSPMCEABLE PARTS

RESISTORS

Circuit
Desig.

R401
R402
R403

CirC”it

Desip.

C501
cl02
c503
c504
c505

C506
c507
c5og

Circuit
neaix.

Ratiw,
5%. l/2 w

5%, l/2 w
5%,, l/2 w

OSCILLATOR BOARD (P.C.-217) REPLACEABLE PARTS LIST

(Refer to Schematic Diagram 234520 for circuit designations).

Value

.OO22 &F
.OOl @

Rating
1oov

1oov

4.5-25 pF 5oov
22 pF 5oov
470 pF 600V

220 pP 600V
56 w

15v

10 VP 2ov

Description Code Parr No. Part No.

*we
camp

camp
camp

CAPACITORS

Code

01121

01121
01121

Mfg. Mfg.

Type Code

Mfg. Mfg.

Poly
P0ly

13934 am-222-1-C

13934 E3FR-222-1-C
Cer Trimmer 71590
Mica
CerD

CerD
ETT
ETT

84171 DM15-220.J

72902 ED-470 C22-470P

72982 ED-220 c22-22OP

17554

17554 TSDZ-20-106

CRYSTAL

Mfg. Mfg. Keithley

Part NO.

EB-LOU7 R19-1OK
EB-1Olw
EB-1Ou2 R19-10K

Keiehley

Part NO.

ClSZ-.0022M
C152-.DOlM

SOZAZ

C76-4.5-25P
CZl-22P

cc201556610

C234-56M 26

C179-10M

Keithley

Fig.

Part No. Ref.

25

R19-10K

25

7.5

Fig.

Pert NO. Ref.

26
26
26
26
26

26
26

Y501

CitYlliC
Deaig.

D501
D502
0503

CFtxUFC
Desi*.

QA501
QA502

R501
R502
R503
R504
R505

Crystal for 60 Hz operation 80164
crysea for 50 HZ operation 80164

DIODES

Type

Silicon
Silicon
Silicon

Number Code

lN645 01295
lN645 01295
lN914 01295

INTEGRATED CIRCUITS

Description Coda Part No.

Quad 2 Input NOR Gate, 14-pin DIP
Quad 2 Input NOR Gate. 14-pin DIP

RESISTORS

Value

3.3 k0 LO%, l/4 w
33 k0 lO%, l/4 w

68.1 0 l%, l/S w

4.99 kil l%, l/S w
1 kn lO%, l/4 w

Rating TYDB

C0mp 44655 m-332
Camp 44655 CB-333
MU 07716 CEA-68.10

MtF 07716 CBA-4.99M

COtUp 44655 CB-102

Mfg.

Mfg.

04713

CR-1
CR-2

Mfg.

MCS24P

Keithley

Part No.

RF-14

RF-14
RF-28

Ketthley
Part

No.

IC-5

CR-1
CR-2

Fig.

Ref.

26
26
26

Fbg.

ref.

26

04713 MCg24P IC-5 26

Mfg.
Code

Mfg.

Part No.

Fig.
Ref.

R76-3.3K 26
R76-33K 26
RSS-68.1 26
RSS-4.99K 26
R76-1K 26

R506
R507
Ii508

0273R

1 kR lo%, l/4 w
1 ksl l%, 1/g w
470 n lO%, l/4 w

cmlp 44655 CB-102

Me 07716

CEA-XC

CO@2 44655 m-471

R76-1K 26
RSS-1K 26
R76-470 26

39

REPLACEABLE PARTS

RESISTORS (Cant'd.)

MODEL 615

ELECTROMETER

circuit
Desig.

R509

R510
R511

R512
R513
R514
R515

R516

R517
RSla
R519

R520

R521
R522
R523

R524

R525

R526
R527
R528

R529
R530

R531

8532

R533
p534
R535

Value Rating Type

4.7 kR lO%, l/4 w

56 k0 LO%, l/4 w

4.7 kn lO%, l/4 "
470 n lO%, l/4 w
680 n

lO%, l/4 w
470 n lo%, l/4 w
237 Cl l%, l/8 w

1 kn l%, l/S "

4.99 kn

l%, 1/a w
56 ki, lO%, l/4 "
237 0

l%, 1/a w

3.3 k0 LO%, l/4 w

Used

on Model 445 only

camp
COIIIP

COW
COCV
COmp
camp
MtF

MtF

MtF
COlllP

MtF

COl!W

Used on Model 445 only
Used on Model 445 only
1 kn lO%, l/4 w

10 ka lO%, l/4 w

1 kfi lO%, l/4 w

3.9 kO lO%, l/4 w

3.9 kn

lob, l/4"
330 n lO%, l/4 w

1.5 kR lo%, l/4"

5.6 kfl lO%, l/4 w
10 k!l LO%, l/4 w

10 0 LO%, l/4"

1.5 kO

1 k0

lO%, l/4 w

l%, l/8 w

camp

camp
camp

camp
camp
camp
ComP

camp
camp
camp
camp
MtF

Mfg. Mfg. Keithley
Code

44655
44655

44655

44655

44655
44655
07716

07716
07716
44655
07716
44655

44655

44655

44655
44655
44655

44655

44655

44655

44655

44655

44655

07716

Pare No. Part No.
CB-472

CB-563

R76-4.7K
R76-56K

m-472 R76-4.7K
m-471
CS-681
m-471
CPA-237n

CEA-X.0

cm-4.99m
CB-563
CEA-2370
CL?-332

m-102
m-103

m-102
m-392
m-392

m-331

C&152

C&562
CB-103

CE100

CS-152

CPA-1Kn

R76-470
R76-680
R76-470
R&3-237

RSS-LK

RSS-4.99K

R76-56K

Raa-237
R76-3.3K

R76-1K

R76-LOK

R76-1K

R76-3.9K

R76-3.9K

R76-330

R76-1.5K

R76-5.6K

R76-10K

R76-10

R76-1.5K

Raa-1K

Fig.
Ref.

26

26

26
26
26
26
26

26
26
26
26
26

26

26

26

26
26
26
26

26
26

26
26
26

R536
R537
R538

Q501

NPN, Case TO-106

47 n lO%, l/4"
33 n lO%, l/4 w
Not Used

Q502 NPN, Case TO-106
Q503
Q504
Q505

4506

NPN, Case TO-106

PNP, Case TO-106
NPN, Case TO-106

PNP, Case TO-106
9507 NPN, Case TO-106
Q508

qsos
Q510

PNP, Case TO-106

NPN, Case TO-106

NPN, Case TO-106

Q511
Q512
Q513
Q514

NPN, Case TO-106
unijunction,

Case TO-72

---

2N5134
2N5134
2N5134
2N5139
2135134

2N5139
2N5134
2N5139
2N5134
2N5134

Used on Model 445 only
Used on Model 445 only

2N5134

2N2646

camp
camp

--

44655
44655

--

TRANSISTORS

0m.e
07263

07263
07263

07263

07263
07263

07263
07263
07263
07263

07263 TG-65
03508

m-470
m-330

R76-47
R76-33

Keithley
Part No. Ref.

TG-65 26
TG-65 26
TG-65 26
TG-66 26
TG-65 26

TG-66 26
TG-65 26
TG-66 26
TG-65 26
TG-65 26

TG-52

26

26

.26

Fig.

26
26

40

027313

MODEL 615 ELECTROMCTER

INTEGRATOR BOARD (P.C.-246) REPLACEABLE PARTS LIST

(Refer to Schematic Diagram 24042E far circuit designations)

CAPACITORS

Circuit Mfg.

LJesig.

C601
C602

C603
C604
C605

C606
C607
C6Oa
C609
C610

C611 20"
C612
C613
C614
C615
C616
C617

C618 500" 72982

circuit
txsig.

0601

D605 Silicon IN645 01295 RF-14 27

“&llX

100 pF
10 DF

0.082 LLF
10 irF

1000 pF

220 PF

.0047 WI

0.1 ,rF

Type
Zener IN916

Rating Type
6OOV ce m

500" F%ly

100"
20" ETT
600"

600"
600"
250V
20"

1ooov

20"
20"

LO"
500"
500"
25V

POlY
ce ru
CerD

cercl
ETT

CerD
ETT 17554 x02-20-106 C179-10M

N”lllhe r

lN936
2N3565
2N3565

Code

72982
71590
13934
17554
72982

72982
72982
73445
17554

56289

17554
17554

17554
00656
72982
56289

Mfg. Keiehley
COdt- Part NO. Ref.

0‘713 "Z-5 27

Mfg.
Part NO. Part NO. Ref.

ED-100 C22-1OOP 27
CPR-1OJ C138-1OP 27
E3FR-22-1-C
TSD2-20-106 C179-lOM
ED-1000 C22-,001 27

ED-220
ED-.0047
C280AEiPlOOK
TSD2-20-106
XAQ390

TXJZ-20-106
TSDZ-20-106
TSD2-10-226
cc22 c77-1.5P
ED-10 C22-LOP
5c13
ED-10 C22-lOP 27

Keithley

C152-,082M 27

c22-22OP
c**-.0047M
C178-.LM
C179-1034
C72-390P

C179-10M
C179-10M
ClaO-22M

C85-lM

ix-5
x-39
x-39

Fig.

27

27
27
27

27

27
27

27
27

27
27
27
27

Fig.

27
27
27

0606 Silicon lN645 01295 RF-14 27
0607 Silicon lN914 01295 w-28 27
0608 Silicon 1N91k 01295 w-28 27
0609 Silicon lN645 01295 w-14 27
0610 SiiiCCXl lN645 01295 RF-14 27

D611 Silicon 1~645 01295 RF-14 27
0612 Silicon lN645 01295 RF-14 27
0613
"614

D615

Mfg. Mfg. Keithley Fig.

Code

QA601 Integrated circuit 07263 U5B770939X IC-1 27
QA602 Integrated Circuir 07263 U5B770939X IC-1 27
QA603 High Speed Differential comparator
Qh604 Quad 2 1npue Gate 04713 ~Ca24~ IC-5 27

RESISTORS

07263 "58771039X IC-4

Mfg. Mfg. Keithley Fig.
Code Part NO. Part NO. Ref.

44655 RC07 R76-10K
91637

Part NO. Part NO. Ref.

MFF-l/8 R177"

w-28
RF-28

RF-14

27
27

27

27

27
27

0671R

41

RESISTORS (Cont'd.)

RBeing

R603
R604 7.5 kfl 1-k 118 w
R605 7.5 kR I%, l/a w

R606 10 !a *20%, 3/4 w
R607

R6oa

R609
R610

R611
R612
R613
K614
R615

P.616
R617
R618
R.619

R620

R621 4.7 k0 lo%, l/4 w
Rb22 4.1 k0

R623 4.7 kR
R624 49.9 kIl

R625

7.5 kn

*

7.5 kn

7.5 kfl

7.5 k0
10 kii

10 kCi
100 kn

Not Used

49.9 kfl

680 a

680 n

33 kn

4.7 k0
33 k0

100 kn lO%, l/4 w

l%, l/8 W

ix, i/a w
1%, 1/a w

ix, l/a w
l%, l/8 W

*20%, 3/4 w

lO%, l/4 w
lo%, l/4 w

LX, ua w
LO%, l/4 w

lo%, l/4 w
lO%, l/4 w
lo%, l/4 w
lO%, l/L w

lo%, l/4 w
lO%, l/L w
l%, l/8 W

MtF'
CDIQP

Mfg.

Code Pare No. Pare No. Ref.
07716

07716
07716

73138 77PRlOK RP64-1OK
91637 MTF-L/B u77*
07716 CEA RBB-7.5K 27
07716 CEA Raa-7.5K
07716

73138 77PRlOK RP64-10K 27
44655
44655 RC07 R76-100K

91637 w-i/a
44655 RC07 R76-680 27

44655
44655
44655 RC07

44655
44655 RC07 R76-4.7K

44655 RCO7 R76-4.7K 27

44655
91637 m-l/a R177-49.9K 27
44655 RC07

Mfg.

CEA
CEA

CE4 Raa-7.5K

RC07 R76-10K

RC07 R76-680 27
RCO7 R76-33K

RC07 R76-33K 27

RCO7 R76-4.7K 27

Keithley Fig.

Raa-7.5K 27
Raa-7.5K
Raa-7.5K

R177-49.9K 27

R76-4.7K

R76-1OOK

27
27

27
27

27
27

27
27

27
27

27

27

R626
R627
R628
R629
R630

R631
R632
R633
R634
R635

R.636
R637
R638
R639
R640

R641

R642
R643
R644
R645

R646
R647
R648

R649

R650

R651
R652
R653
R654
R655

100 kn
301 kfl
47 n

49.9 kfl
100 k0

1 k0
15 k0
301 kfl

1.5 kfl
47 n

2.2 k0
47 0
47 n

1.5 kn

1.5 kn
100 R

10 n

3.01 kn
1 kR

2.7 k0
10 kR

10 n
100 kn

1 kfi

100 kn

3.3 kR
a20 n

2.2 ktl
220 R
10 kfl

lO%, l/4 w
i%, l/a w

lO%, l/4 w
ix, i/a w
IO%, l/4 w

lO%, l/4 w

lO%, l/4 w
i%, i/a w

lO%, l/4 w

lO%, l/4 w
LO%, l/4 w

lO%, l/4 w

LO%, l/4 w

LO%, l/4 w

LO%, l/4 w

lO%, l/4 w

lo%, l/4 w

l%, 1/a w

m, l/a w

LO%, l/4 w

10%. l/4 w
lo%, l/4 w
lO%, l/4 w
lO%, l/4 w
IO%, l/4 w

lO%, l/4 w
10%. l/4 w
lO%, l/4 w
lo%, l/4 w
lO%, l/4 w

44655 RCO7

07716 CEA R88-301K

44655
07716 CEA Raa-49.9K
44655

44655
44655

07716

44655
44655

44655 RC07
44655 RCO7 R76-47
44655 RC07
44655
44655

44655

44655 RC07
07716 CEA Rae-3.01K
07716 CEA

44655

44655

44655 RC07

44655 RC07

44655

44655

44655

44655

44655

44655 RC07 R76-220

44655

RC07 R76-47
RC07 R76-100K
RC07 R76-1K

RC07 R76-15K

CRA R88-301K

RC07 R76-l.SK
RC07 R76-47

RCO7 R76-1.5K
RC07 R76-1.5K

RC07 R76-100

RCO7 R76-2.7K

RC07 R76-10K

RC07
RC07

RC07 R76-3.3K
RC07

RC07 R76-2.2K

RC07 R76-10K 27

R76-100K

R76-2.2K

R76-47

R76-10
R88-1K

R76-10

R76-100K
R76-1K
R76-100K

R76-a20

27
27

27
27
27

27
27
27
27
27

27
27
27
27
27

27

27
27
27
27

27
27
27
27
27

27
27
27
27

*NOTE:

42

rhis part selected in final test.

04728

MODEL 615 ELECTROMETER

KEPLACEHBLE PAKTS

RESISTORS (Cont’d.)

Circ”it

CJesig.

R656

Type

MZF
R657 6.04 kfi I%, l/B w Pie 07716 CEA
R658
R659

circuie
Desig.

9601
Q602
Q603
Q604
Q605

Q606
Q607
0608

Not USed
47 kll

10%, l/4 w Camp 44655 KC07

Mfg. Keithley

Number
%I5139

2N5139
2N5134

2N5134

2N4220
2N4220

T1570
T1570

Code Part NO. Ref.
07263 Z-66 27

07263 W-66 27

07263 W-65 27
07263 X-65 27

04713 TG-42 27

04713 X-42 27

cllZ95 TG-71 27

01295 x-71 27

Mfg.
Code

07716

Keithley

Part NO.

R88-6.9%
R88-6.04K

Fig.
Ref.

27
27

R76-47K 27

Fig.

6609 S17638 07263 lx-33 27
Q610 2N422cl 04713 TG-42 27

Q611 2N5139 07263 W-66 27
Q612 2N4220 04713 TG-42 27

MODEL 4401 OwrP"T BUFFER BOARD (P.C.-218) REPLACEABLE PARTS LIST

(Refer to schematic Diagram 234570 for circuit designations)

NOTE

On Schematic Diagram 234571) there are 15 buffers labeled

‘A’

through 'P' not including 'I'. Each

buffer is composed of 4 resistors and 3 transistors. A sample buffer circuit is given in the lower

lefchand corner of the Schematic. Following is a ty,,ical replaceable pares list for each buffer.

BUFFER RESISTORS (A fhr" P)

circuit
b8i.e.

RlOOl

8.1002
R1003
RIO04

"ahe

180 k0

3.9 kR
120 kc7
10 k*

Rating

Type Code Part NO. Part NO. Ref.

IO%, l/4 w camp
lO%, 114 w camp
lo%, l/4 w camp 44655 RC07 R76-120K
lo%, l/4 w camp

Mfg. Mfg. Keirhley Fig.

44655

44655

44655

RCO7 R76-180K 28
KC07 R76-3.9K

RC07 R76-1OK

BUFFER TRANSISTORS (A thru P)

91001
Q1002
Q1003

Mfg.
Code

MODEL 4401 OLTLT'UT BUFFER BOARD (P.C.-209)

REPLACEABLE PARTS LIST

Keithley

Part NO.

TG-39
x-39

TC-39

(Refer to schematic Diagram 2348X for circuie desi@,ations).

circuit
Desig.

Value

Rating

Mfg.

Code

Mfg.

Part NO.

Keirhley

Part NO.

28
28
28

Fig.
Ref.

28
28

28

Fig.

Ref.

Cl101
Cl102

.OOl LlF
.0033 UF

6OOV

600"

72982

72982

ED-.001
ED-.0033

CZZ-.OOlM

CZZ-.0033M

29

29

Cl103 ,001 pi 6OOV CerD 72983 ED-.001 C22-.OOLM 29
Cl104 0.1 pF 250" 73445 C280AE/P10OK C178-O.lM 29
Cl105 100 pF 6OOV C‘2rD 72982 ED-100 c22-1OOP 29

0472R

43

REPLACEABLE PARTS

067111

MODEL 615 ELECTROMETEl

CAPACITORS (Cone'd.)

Cl106
Cl107
Cl108
Cl109
Cl110

Circuit
DWiR.

QAllOl
QA1102

RllOl
It1102

R1103
R1104
RlL05

R1106
R1107
R1108

R1109
a110

Value Rating
100

pF

470

pF

470 pF

22

WF

10 w

600"
600V

600V
1ov
2ov

Description

Quad 2 Input Gate
Quad 2 Inpue Gate

Rating

1 kn

3.3 kn
1 kfi

3.3 kR
120 kcl

10 kfl
180 kR

2.2 !cn
1 kR
10 kn

lo%, l/4 w

10%. l/4 w

10x; li4 N
IO%, l/4 w
Lo%, l/4 w

lo%, l/4 w
10%. l/4 w
10%; l/4 w

lO%, l/4 w

lO%, l/4 w

Mfg.

Code
72982

72982
72982
17554
17554

Mfg.
Code

Mfg.

Part NO.

ED-100
ED-470

ED-470
TSD2-lo-226
TSDZ-20-106

Mfg.

Part NO. Part No.

04713 MC724P
04713

MC724P IC-5

RESISTORS

Mfg.
Code

Mfg.

Part No.

Comp 44655 RC07
Comp 44655 RC07
Camp 44655 RC07
CNllp 44655 RC07
Camp 44655 RCO7

C0Ulp 44655 RCO7
camp 44655 RC07
Camp 44655 RC07
conlp 44655 RC07
CO¶fp 44655 RC07

KeithLey

Pare NO.
c22-1OOP

C22-47OP

C22-47OP
Cl80-22M
C179-10M

Keichley

IC-5

Keithley

Part NO.
R76-1K

R76-3.3K
k76-1K
R76-3.3K

R76-L20K 29
R76-10K 29

R76-180K 29
R76-2.2K 29
R76-1K 29
R76-10K 29

Pig.
Ref.

29
29
29
29
29

Fig.
Ref.

29
29

Fig.
Ref.

29
29
29
29

Rllll 120 kn
a112 180 kfi
R1113 2.2 kfl
R1114 6.98 k0
R1115

~1116
R1117
R1118
Rll19
R1120

circuie

6.04 k.0
2 k0

120 kn
10 kR
180 kfl

3.9 k0

CJesig.
QllOl

Q1102
Q1103

Q1104

Q1105

10%. l/4 w

lO%, l/4 w
lO%, l/4 w
l%, l/8 w
l%, 1/a w

1%. l/8 w
lO%, l/4 w
lO%, l/4 w
lO%, l/4 w
lO%, l/4 w

Number

2N3565
2133565

Nat Used

2N3565
2N3565

C0ltlp 44655 RC07
Comp 44655 RC07
C0lllp 44655 RC07

MtF 07716

CEA

MCF 07716 CEA

Mm 07716 CEA
C0lUp 44655 RC07
COTUp 44655 RC07
Camp 44655 RCO7
Camp 44655 RC07

Mfg.

Code
07263

07263
07263

07263

Keithley

Pare No.

TG-39 29

TG-39

x-39 29
TG-39 29

R76-120K 29
R76-180K 29
R76-2.2K 29
R&3-6.98K 29
RR&6.04K 29

R88-2K 29
R76-120K 29
R76-10K 29
R76-180K 29
R76-3.9K 29

Fig.
Ref.

29

29
29
29

7.9

29

44

KEPL4CEA”LE PARTS

Value

10 kn
120 k0

10 kR

180 kfi

3.9 k*

lo%, l/4 w
lo%, l/4 w

lo%, l/4 w
lo%, l/4 w

2N3565
2N356.5
2133565

Type
Como

Code

44655
camp 44655
camp 44655

Mfg.

Camp

44655
Camp 44655

07263 E-39
07263
07263

Mfg.

Keiehley

Part NO. Part NO.
RCO,

RC07
RC07
RC07
RC07

K76-10K
R76-120K
R76-10K 29
R76-180K 29
R76-3.9K 29

TG-39
m-39

Fig.
Ref.

29
29

29
29
29

45

REPLACEABLE PARTS

MODEL 615 ELECTROMETER

Code u.lt Of Sueeested Ma”“facturers. iLlsed on Federal Sll”“l” Code for Elanllfarr!,rers. cata1oeine Handbook “4

TABLE 24.

1121 Allen-Bradley Corp.

1201 South 2nd Street

Milwaukee, wis.

53204

1295 Texas I”stc”me”ts, 1°C.

Semic”“d”ct”r-C”mp”“e”t~ Di”.
13500 N, Central Expressway

Dallas, Texas 75231

1686 RCL Electronics, 1°C.

195 McGregor street

Manchester, N.H.

03102

2660 Amphenol Electronics, Corp.

2801 South 25th *venue
Br”ad”iew, Ill. 60153

2734 Radio Corp. of America

Defense Electronic Products
Camden, New Jersey

2735 Radio Corp. of America

Commercial Receiving Tube h
Semic”“d”cr”r Division
Somerville, N.J.

13050

13327

13934

17554

24655

27682

44655

Potter co.
Highway 51 N.

WBSS”“, MfSS. 39191

S”litr”” DeYices, Inc.
256 Oak Tree Road

Tappa”, New York 10983

Midvec Corp.

602 Mai”

Oshkosh, Nebr.

69154

C”mp”“e”ts, 1°C.
Smith street
Biddeford, Maine 04005

General Radio Co.

22 Baker Avenue

West Concord, Mass.

01781

Hathaway Instruments, Inc.

5800 E. Jewel1 *venue
Denver, C”l”rado 80222

Ohmite Mfg. CO.

73138

73445

73690

75915

80164

83594

neckma” I”str”me”ts, 1°C.

Helipot Division
2500 Harbor Blvd.

Fullerton, Calif. 92634

hlperex Electronic co., Di”.
of North American Philips Co.
Hicksville, N.Y.

Ek” Resistor co.

1158 Broadway

New

York, New York

Littlefuse,

1°C.
800 E. Northwest Highway
Des Plaines, Ill. 60016

Keithley Instruments, Inc.

28775 Aurora Road
Cleveland, Ohio 44139

Burroughs Corp.
Electronic Componente Div.
PoSt Office BOX 1226
Plainfield, N.J.

07061

3601 Howard Street

1508 General Electric Company

SemiC”“duCt”r Products Dept.
Electronics Pack
Syracuse, New York 13201

4713 M”t”r”la Semic”“d”eC”r

Products, Inc.
5005 East McDowell Road
Phoenix, Ariz.

85008

5397 Union Carbide Corp.

Electronics Division

562.99

58474

71279

Skokie, Illinois 60076

Sprague Electric co.

North Adams, Mass.

Superior Electric Co., The
383 Middle Street
Bristol, Con*. 06012

Cambridge Thermionic Corp.
430 Concord Avenue

Cambridge, Mass.

84171

84790

90201

Arc” Electronics, Inc.

C”nm”“ity Drive
Great Neck, N.Y.

D”ra Corp.

11022

Implement Div.-P.O. Bdx 231

Zanesville, Ohio 43702
Mallory Capacitor

3029 west W.¶shi*gt0*
Post Office Box 372
Indianapolis, Ind.

46206

270 Park Avenue

New York, New York 10017

7263 Fairchild Camera & Instrument

Corp., Semic”“ducc”c Division
313 Frontage Road

Mountain Vie”, Calif.

71400

71450

B”ssman” Mfg. Di”. “f

McGrev-Edison Co.

2538 W. University Street
St. LOUIS, MO.

cm core.

91637

91662

Dale Electronics, 1°C.
Post Office Box 609
Columbus, Nebr. 68601

Elco Corp.

Willow Grove, Pa.

1142 W. Beardeley Avenue

7716 IRC, 1°C.

2850 Mt. Pleasant
Burlington, Iowa 52601

71590

Elkhart, Ind.

Centralab Division of

91802

Industrial mvicee, Inc.

9.82 River Road
Edgewater, New Jereey 07020

Globe-Union, 1°C.

9922 Burndy Corp.

Richards Avenue
Norwalk, Con”. 06852

72982

2040 National Semiconductor Corp.

C0mecce Drive
Post Office Box 443

932 E. Keefe Avenue

Milwaukee, Wis. 53212

Erie Technological
Products, Inc.
644 W. 12th Street
Erie, Pa. Lb512

93656

95712

Electric Cord Co.

1275 Bloomfield Avenue

Caldwell, N.J.
Dage Electric co., Inc

Hurricane Road
Franklin, Indiana

Danbury, Con”. 06813

.I,

46

0470

MODEL 615

SERVICING

SECTION 5.

5-1. GENERAL. This section contains procedures for
checkout and servicing the instrument. Follow the
step-by-seep procedures for complete servicing.

5-2. SERVICING SCHEDULE.
periodic maintenance beyond the normal care required
for high-quality electronic equipment.

PARTS REPLACEMENT.

5-3.

Parts List, section 4, for information regarding com­ponent specifications and part numbers. Replace com­ponents as indicated using replacement parts which
meet the listed specifications.

Difficulty

No front penel display.

This i*strume*e requires "0

Refer to the Replaceable

Troubleshooting & $orrective Action

Probable Cause
Power failure
21OV Supply failure
120" Supply failure

Line switch set at 234V with
117V line incmt

SERVICING

5-4. TROUBLESHOOTING.

a. Test Equipment. Refer to Table b-l for cecom-

mended teet equipment for servicing and calibrating

this instrument.

b. Troubleshooting Guide. Refer to Table 5-1 for

troubleshooting information and corrective action.

NOTE
If the insrrument problem cannot be readily
located or repaired, contact a Keithley rep-

resentative or the Sales Service Department,
Cleveland, Ohio.

TABLE 5-l.

S”lutt”n

Check fuse. If blown, replace with rated
size efter checking for internal shore.
Check for voltage at capacitor Cl12 for

21ov +zov.

Check for voltage ar R128.

Ser switch LO 117V.

Overload indication when input

is shorted.

Ohms ranges inaccurate.
Current readings inaccurate on

one range.

Overrange "1" not lighted when

it should indicate.
Polarity signs do not light.

Analog amplifier La out of
balance.

FET Board faulty
supply voltage is missing

Overload circuit malfunction.

Transistor Q301.
Readout tube V301

Transistors Q201, Q202
Polarity display OS201.

Check analog output on rear panel.

Check the Coarse zero switch for offset.
If output ie greater than 2 volts, replace

input FET board end recheck output.

Check +9 volt supply; 2120 volt supply.

If voltages ere normal, check transistor

Ql20 for open collector malfunction.
Check t9 volt reference voltage et 01206.
Replace shunt reeistor with accurate value.

Replace transistor if "open" from collecto*

to emitter.

Replace transistor if "open" from collect"*

to emitter.

dieplay OS201.

Otherwise replace tube "301.

Otherwise replace polarity

0372

47

CALIBRATION

c<

037

MODEL 61

SECTION 6.

6-L. GENERAL. me following test and adjustaenr pro­cedures, when completed, will ensure that the inetru-

ment is calibrated to published specifications. If

any portion of the procedure cannot be performed due
LO malfunction of the circuitry, refer to the servicing
section of the manual or contact a Keithley Sales Ser-

vice representative.

TEST CONDITIONS. All measurements should be made

6-2.
in a laboratory environment at approx. 25'C and less
than 50% relative humidity. Unless otherwise speci­fied the instrument should be pawered by 117 volts
mm line at 60 Hz.
designated.)

TEST EQUIPMENT.

6-3.
using test equipment which meets or exceeds the mini­mum specifications given in Table 6-l.

PRELIMINARY PROCEDLW. Set the POWER switch to

6-4.
off before connecting the line cord. Place a shield

cap (Keifhley part no. CAP-18) on triaxial input. Con-

nect the line cord to 117 volts, 60 Hz (use a variable

transformer if necessary to obtain the proper voltage

(50 Hz for those ins'truments so

All measureme,,ts should be made

CALIBRATION

within +1 volt).

plug a" the Line cord is connected to earth ground s
that the instrument chassis is not at B live potent!

Turn the instrument on and allow to warm-up for one
hour.
within the instrument have been stabilized:)

6-5.

as follows:

With the input capped, adjust the front panel zero

trol so that the polarity signs on the digital displ;

(5, light alternately with the @ame time interval fo,
each polarity (adjust 80 that + flashing rate is mar

mum). If the front panel zero control doea not perm,

sufficient zeroing capability, adjust the rear panel
COARSE zero control (S1205) until a polarity change i
noted.

(This will ensure that all thermal variations

ADJUSTMENT PROCEDURE.

a. Zero Adjustment.

Make certain that the third ground

Set the front panel controls

Zero Check Button - Lock

Sensitivity Switch - 0.0000
Range Switch - Volts
Feedback Switch

- Normal

Code

Latter

A

P

G current source

Voltmeter, Digital

Recorder, Analog

Voltmeter, Digital

Voltage source

High "egohm Resistors

TABLE 6-l.

Test Equipment

Specification

+o.l% of reading

l.OOOV to 1000 volts
1 volt full scale

+o.Ol% of reading

1.oooov to 1.9999v

~08 to lolzn

+0.2x

t0.21, 10-Q. 10-gA

3.4X, lo-loA, 10-llA

5.05%. lo-lA to LO-7A Fluke 34lA

Manufacturer

and Model No.
Keithley

Model 163
Keithley

Made1 370

Eldorado

Model 1820A

Fluke

Modal 34l.A

Keithley

Model 5155

Keithley
Model 26L*

and GR1433

48

MODEL 615

CALIBRATION

To verify the accuracy on the 10w8A through 10-11~

NOTE*

ranges a specially calibrated Keithley Model 261
Picoampere source is required. The "three month"

accuracy for the Model 261 is +a.6% on lo-8A to

Lo-11.4. However, a Model 261 may be calibrated
co within 50.4% when used with a Model

515A

Megohm Bridge and B set of 5155 Megohm Standards

(traceable to the N.B.S.). Since the resisrars
exhibit a temperature coefficient of approx. -0.1%
per 'C it may be necessary to compensate for cemp­erature variarions between the calibration area
and the measurement area. To minimize the effects
of drift in the value of the resistors it is im­parcant to recalibrate the Model 261 jusr prior
to making a calibration check on the Model 615.
Where it may not be necessary to verify the Made1
615 current ranges f~ within +4%, a standard

Model 261 Picoampere source may be used. To ver-

ify the accuracy an the lO-lA to LOm6A ranges , a

Made1 34LA should be used with preci&x reeis-

tom having 5.03% accuracy.

b. DC 818s Adjustment.

88 above.

To set the dc bias, monitor the voltage

set the front panel controls

acro8e resistor R1249 (test terminals o and E as shown
in Figure

25 mV +3

22).

Adjust the dc bias control (R1268) for

mV using voltmeter (A).

C. Power Supply Check. Set the Sensitivity con-

trol

(51203) t0 the 100.0 volt range; the range switch
to VOLTS; the Feedback switch to PAST. With the line
voltage set to 117 volts measure the power supply

voltages *e follows:

TABLE 6-2.

Power Suonlv Valtanes

C15"

250 mv

(Adjust the +15V cal poc-

enriomerer R115 as shwn
in Figure 22.)

-15"

+3.6V

+17ov
+12ov

-120"

+9.1v

-9.lV

d. Ohma Calibracian.

+0.4"

Zl.lV
7170 to LSOV)

+12v

+12v

70.3v

3.3v

Measure the voltage across
resistors R1213 + R1214 (test terminals B and D as
sham in Figure 22).

(R1216) fo: 1 vole +L m" using voltmeter

Adjust the OHMS CAL potentiometer

(A).

2.

Amperes Range.
BS shown in Table 6-4.
decade steps from lo-LA ta 10-11~.

See the front panel controls

Apply an input current in

MC¶SUFS
the analag wtput at 51207 for full scale indicaeian
an each range. Ihe 1 volt output should be within

+0.5X

on LO-L, to LU-6~ ranges: +2X on LO-7A and

iO-8.4 ranges;

3.

Coulombs Range. See the front panel cantrols

as shown in Table 6-5

decade steps from LOe8A to.lO-11~ +0.4%.

24%

on lo-9A to 1OqlA ranges.

Apply an input currenf in

Measure
the analog output at 51207 for full scale indication
oxeach range.

The output should integrate to 1

volt within e period of 10 seconds +1/Z second (+5%).

4.

Ohms Ranges. See the front panel controls as

shown in Table 6-6.

Apply resistance values at the

input in decade steps from 1050 to 10120.~ Measure

the analog wtput af 51207 for'full scale indication

an each ran e. s The 1 volt output should be within

5.5% an
ranges.

10 n to 106n ranges; 24% on 107~ to 1012~

f. Offset current. Set the front panel centrals

88 fallara:

Zero Check Button - Lock

Sensitivity Switch - 0.0000

Range Switch - LO-l1 Amperes
Feedback Switch

- Fast

Place B cap on the input receptacle and adjust the

zer‘o control 88 necessary for B zero display. on­Lock the zero check button. The digital display
should indicate less than 0.0005 x LO-11 amperes

(5 x lo-l5A).

g. Drift Check. Set the front panel controls as

follows:

Zero Check Button - Lock
Sensitivity Switch - 0.0000
Range Switch - 10-6 ~mperee
Feedback Switch - Fast

Connect recorder (B) to the analog output (51207)
end set for 1 V full scale sensitivity. Readjust

the zero control as necessary. Cannect a 10 kilahm

resistor (LX talerance; Keifhley R88-10K) ~croes the

input. Unlock the zero check button. Monitor the

1 V autput on the recorder far B 24 hour period at
constant ambient temperature. The recorder output
should not vary more than LOX 0f full scale during

the 24 hour period.

e. Analog Range Calibratian.

(Check zero before

each measurement.)

1. Voltage Range. Set the franc panel centrals

as shown in Table 6-3.

Apply an input voltage in
decade steps from 1V to 1OOV +0.02X. Measure the
analog weput at 51207 for fuiL scale indication on

each range.

The 1 volt output should be within

50.2%.

0372

h. Clock Frequency Adjust. Locate the CLOCK test
point on the oscillator board PC-217 as shown in
Figure 26.

Connect a digital frequency counter be-

Ween the CLOCK test point and 1~. Adjust trimming

capacitor C503 so that the frequency reading is 120 k"z

kl Hz for instrumenta operated at 60 Hz. (The crystal

Y501 should be a Keithley CR-L for 60 Hz; CR-2 for
50 Hz.) The frequency reading should be set to 100 kHz

+L Hz for instrumenfs operated at 50 Hz.

49

CALIBRATION

MODEL 61.

TABLE 6-3.

Voltage Ranges

Range Sensitivity

Switch Switch

Feedback

InpUt Full Scale

Volt*gQ.

Output

volts 0.1000 Narmal 0.1000 to.O2% 1.000 +0.2x
Volts 1.000 Normal 1.000 ?o.ozx 1.000 %.2x
volts 10.00 Norms.1 10.00 %.02x 1.000 ?o.zx
va1t.8 100.0 Normal 100.0 ~.a;?% 1.000 3.2%

TABLE 6-4.

Current Ranges

Range

Switch

lo-IA

10-2A
10-3A
10-4A

10-5A

lo-6A
lo-6A

lo-!A
10-8,
Lo-gA

Sensitivity

switch

1.000

1.000

1.000

1.000

1.000

1.000

0.100

0.100

0.100

0.100

0.100

1.000

Feedback

Normal
Normal
Normal
Normal
Normal
Feet

Feet
FBBt
Feet
Feet
Fast

FBst

Input

Current

LO-lA +0.05X
lo-'A ?O.OSX
10-3A %.05X

lo-4A %.05x

lo-5A 7&.05X

10-6A %.05X
1O-7A
lo-8A 7O.OSX 3.2%
10-gA 3.2%

10-LoAa.4X

lo-LIA %.4X
lo-=A 3.4X

Full Scale

output

1.000 +o.5%

1.000 3.5%

1.000 73.5%

1.000 70.5%

1.000 %.5x

1.000 9.5%

1.000 1.000 73.5% T2%

1.000

1.000 74%

1.000 74%

1.000 54x

T2%

TABLE 6-5.

Coulombs Ranges

wge

Switch
lo-79

10-8Q
10-g

18

lo- Q

I

*The time interval for integration to 1.000 volts should be 10 eece. +5X.

Sensitivity

Switch

1.000

Feedback

Fast 10'8A +0.5X 1.000*

1.000 Fast 10-gA 3.5% 1.000*

1.000

1.000

FBBf 10-lOA %.5X 1.000*

Fast lo-1lA 30.5% 1.000*

Input

Current

Full Scale

Output

TABLE 6-6.
ohms llengas

105n

106i-i
1060
1ok
1060
107n

1ok
109n
1oLOn

1olLn
1012n

100.0

10.00

1.000

1.000

1.000

1.000

0.100

Norm?.1 104n +0.05%
Normel 105n To.osx
Normal
Normal
Normal
Normel

106n To.05~
107n To.OS%
108~1 To.05~
108i-1 T0.4~

Normal 108n %.4x
Normal 1090 TO.4%
Normal 1OLh zJ.4x
Normal 1olLn Ta.42
Normal 1olln 3.4%

1.000 tO.sx

1.000 TO.5%

1.000 3.5%

1.000 9.5%

1.000 3.5%

1.000

T4x

1.000 T4x

1.000 74%

1.000 74%

1.000 74%

1.000 34%

50

03 72

MODEL 615 CALIBRATION

i. Overload Blanking Check. see the sensitivity
switch for 1.0000 (with the Range set to volts).
Apply 1 volt at the input and increase until the read-

ing blanks.

dts.

Apply 90 “olte ae the input and increeee until the

reading blanks.

99.9 volts.

,. A-to-D Comrerter Calibration. Set the front

panel conrro1e 88 follows:

Blanking should occur lust beyond 1.999

Set the Sene~civiry switch to 100.6 volts.

Blanking should occur ,usr beyond

Zero Check Buttm - Lock

Sensitivity Switch - 1.000
Range Switch - VOLTS
Feedback Switch

- Normal

Connect digital voltmeter (B) to the 1 vale analog

output.

+2 volts at input using Voltage Source 0). AdjusC

the input e~urce so that the analog reading is +1.9995

Volts.

rhe display indicates between +1.999 volts and a blank-

ed display (overload). (Meplay should alternate be-

tween readings.) After the +CAL 18 adjusted check
the reading by reducing the input voltage until the

digital display indicates between to.999 valts and
+1.000 volts.

0.999 volts and 1.000 volts. Repeat the above steps

using -1.9995 valta and adjust the -CAL potentiomerer

(R606).

Unlock the set.0 check button. Apply approx.

Adjust the l CAL potentiometer (R611) so that

The analog output should read benreen

0372

51

ACCESSORIES

72

MODEL 615

SECTION 7.

7-1. GENERAL. The following Keithley accessories
can be used with the Model 615 to provide additional
convenience and versatility.

Model 6101A Shielded Probe

The Model 6LOlA is a shielded cable with a needle-point

probe and 30 inches of low noise cable terminated by a

IniF connector.

Model 61018 Shielded Probe
Description:
The Model 61018 is a shielded cable with B “gripping

type” probe and 30 inches of low noise cable terminated

by a UHF connector.

ACCESSORIES

7-2.

OPERATING INSTRUCTIONS. A separate Inseruceion
Manual is supplied with each accessory giving complett
opeeaeing information.

Model 6103A Divider Probe

The Model 6103A is a shielded cable with a needle-point

probe and 30 inches pf Law noise cable terminated by a
UHF cmulector.
divider with a LOL2n input resistance. Accuracy is
26% at 30 kilovolts.

Description:
The “ode, 6LO2A is a shielded cable with a needle-paint

probe and 30 inches of law noise cable terminated by a
UHF connectori The probe includes a LO:1 voltage di­vider with LO 0 input resistance. Accuracy is H+% at
1000 volts.

The probe includes a 1OOO:l voltage

Model 6102A Divider Probe

52

03

MODEL 615

Model 6104 Test Shield

The Model 6104 is 8 shielded test box far two-terminal
or three-terminal connections. The INPUT terminal is
feflon insulated.

Applications:

ACCESSORIES

1. Two Terminal Connections.
ments can be made conveniently using the INPUT and
GROUND terminals an the Test BOX. Connect the elec-

trometer to the SNC output.

NORMAL mode far ohms measurement.

2. Three Terminal Connections. The GUARD ouCput

on the Model 615 electrometer can be used for re­sistance measurements where the effects of cable capac­itance may be significant.
INPUT and EXT terminals.
the GUARD output on the eleceromecer.
trometer in FAST mode far ohms measurement.

The Model 6105 is a guarded test fixture for measure­ment of surface and volume resistivities. The chamber

is designed in accordance with ASTM Standard Method of
Test for Electrical Resistance of Insulating Materials,
0257-66.
electrometer and voltage supply.

Applications:
~esistivity can be determined by measuring the current

through a sample with a known voltage impressed. The

measurement can be made most conveniently when a set

of electrodes are used which can be calibrated in terms
of surface or volume resiscivity. The Keiehley Model
6105 Resistivity Adapter has been designed for use with

a Keithley electrometer and an optional high voltage

supply such as the Model 240A.

The 6105 can be used in conlunction with a”

Connect the UT terminal to

Resistance measure-

Use the electrometer in

Connect the unknown between

be the elec-

Model 6105 Resiseivity Chamber

0372

53

ACCESSORIES

615

30’

car

037

MODEL

Model 6106 Electrometer Connection Kit
Description:
The Model 6106 contains a group of the most useful

leads and adapters for Low current measurements. All

components are housed in a rugged carrying case with

individual compartments.

Models 2501, 2503 Static Detector Probes

The Models 2501 and 2503 are specially designed de-

tectors used to measure static charge on plane surfaces.
Either probe must be used with an electrometer such as
the 615.

Pares List:

Description

Cable, 30”, UHF to clips
Cable, 24”, UHF to UHF

Connector, UHF to UHF
Adaptor, UHF to BNC
Adaptor, UHF to BNC
Adaptor Tee, UHF to UHF
Adaptor, Binding Post

The two cables (Items 1 and 2) are coaxial shielded

leads useful for connections where low noise is ester

tia1.
nece two Instruments having UHF receptacles. The

cable (Item 1) can be used to connect to the circuit

under test through the use of clip leads. A binding

post adapter gives easy access to the electrometer

“high” terminal.
permit cables to be connected together. The UHF “tee
connector simplifies galvanometric current measuremer
when using a current source and electrometer or pica.
ammeter. Adapters (Items 4 and 5) are useful for
version from UHF to BNC terminations.

The 24” cable (Item 2) can be used to intercor

Two UHF femal couplers (Item 3)

Item Keithley

NO. Part NO.

1
2
3
4 cs-115
5 CS-172
6 CS-171

7 190718

19072c
18265C
cs-5

Model 2501:

The 2501 is useful for measurements of charge on flat
surfaces.
Reconmended spacing is ,318” from the surface for

10,OOO:l divider ratio.
that a 1 volt deflection on the electrometer corre­spends to LO kilovolts of static charge.

Model 2503 :

The 2503 consists of a rigid probe L/2 inches in di­meter.
probe.

Description:
The Model 6107 is a test fixture which simplifies con-

nections to the electrometer when making pH measure­ments.

factured by Leeds &Northrup, Coleman and Beckman.

The 6107 can be used far guarded measurements as shown

In the diagram.
supplied with the 6107.

The static head is 3 inches in diameter.

The 2501 is calibrated such

Operation Is similar to the use of the 2501

Model 6107 pH Electrode

The adapter can be used with electrodes manu-

A voltage-to-p8 conversion chart is

h

Xl

p2

-----

APL

UHF

54

NODEI. 615

ACCESSORIES

Model 399 Isolat

Description: The Model 399 is a unity-gain a

that provides input isolation greater than 10

‘f!:

lifier

ohms.

It is useable for conrmon mode input voltages up to 1500

volte peak, dc or ac.

Application: The 399 can be used for “FIFO” operation
where both input and output must be floated. IC can

also be used to break ground loops within a system.

The 399 output will drive recorders up to 1 mA. When

used with the Model 615, the electrometer can be float­ed up to 100 volts while driving a Model 370 recorder
up to 100 volts off ground.

Specifications: (condensed)
CAIN: Xl, adjustable ) 3%.

GAIN ACCURACY: & 0.2%

(as set at factory).
CAIN LINEARITY: Within 3 mV for signal levels below 1”.
FREQURKY RESPONSE:

0.3&z (-3

d* response).

1NP”T RESISTANCE:

Fast: dc co IOOHZ; Slow: dc to

106

ohms.

FULL SCALE INPUT: + 1 volt with 100% overrange.

MAXIMUM INPUT OVERLOAD:

INPUT ISOLATION: Greater than 10

100 vole

720

ohma at 50% relative

humidity and 25 C shunted by less than 100 pF.

MAXIl$M COMMON MODE VOLTAGE:

1500 volts peak, dc or ac.

OUTPUT ISOLATION: Greater than lo8 ohms shunted by

Less than 0.001 microfarad.

POWER:

105-125 or 210-250

50-60 Hz, 5 watts.

volts (switch selected),

:ing Amplifier

~escriprion: The 370 is a compact, paper chart re­corder which is compatible with most Keirhley instru-

ments having a 1 mA output.

Applications: The 370 can be
Model615 up to 100

volts

used

directly with the

off ground. The Model 3701

cable supplied can be used for convenient connections

co the instrument.

0372

Model 370

55

ACCESSORIES

6L.

on

MODEL

Model 3001 Bench Mounting Kit

Assemble:

The Model 3001 is a bench mounting kit f.,r use with

instruments 5-114” high x 17-l/2” wide x 10” deep. All
parts are included for conversion of a rack mounted
instrument to bench mounting complete with top cover,

handle assembly, non-skid feet and tilt bail assembly.
Parts List:

Item

NO. Description

1

Cover Assembly
Screw, Slatted 10-32x1/4 4

:

Bail Support, Right

4 Bail Support, Left 1

5 Foot, plastic

6 Screw, Phillips, g-32x3/8

7 Rubber Fc.oe Insert
8 Screw, Phillips, 6-32x1/4 2
9

Tilt

Bail 1

Qty. Per

Awzmbly

1 17604B
1

::
4

Keithley

Part No.

192068

19205B

FE-5
FE-6

147048

1.

Remove the rack angles attached to the

instrument.

with the instrument should be used to install the
bench-style top cover (item 1).

2.

Remove the bottom cover to facilitate the mountin

of the non-skid feet and tilt bail
a screw driver to turn the pawl-type fastenera
the cover (about one-half turn clockwise).

3.

Install the bail supports

b-32 screw8 (item 8).

4.

Install the plastic feet (item 5) using S-32 scre
(item 6) in four

5.

Install tilt bail (item 9)

6.

Install bottom cover using

The

four IO-32 slotted screws suppli

(items

places.

88 shown.

pavl-type fasteners.

rack mount

assembly.

3 and 4) using

“Se

56

DETAIL-A

BOTTOM COVER
OF INSTRUMENT

ITEM-4

0372

MODEL 615

ACCESSORIES

Model 6011 Input Cable

Description: The 6011 is a low-noise triaxial cable,
30” long, terminated by three color-coded alligator
clips.
input.

This cable mates directly with the triaxial

The cable is fabricated “sing a Keichley part

Application: The 6011 may be used for measurements

which require a triarlal connection, especially when
the input LO is floated above CASE ground. The cable
permits full “se of the Model 615 capabilities.

no. B-141 connector and part no. SC-22 law-noise cable.

Model 6301 Cuardad Probe

Description: The 6301 is a guarded triaxial cable, Application: The 6301 my be used for mewurements

3 ft. long, terminated by a probe for making point-to-

point measuremenrs.

which require a triaxial cable with a guarded pftbt,,,.

having an insulation resistance greater than 10

Model 1531 Gripping Probe

Description: The 1531 is a triaxial cable, 3 ft. long,
terminated by B special gripping-type probe.

insulation resistance is greater than lOlO ohms.

The 1531

The

probe is rated for off ground meas”rements up to 500 Y

Lo Lead

Model 6012 TrIax-to-Coax Adapter

Description:

The 6012 is an adapter for mating the
criaxial inpur and UHF (coax) type connecfors. This
adapter can be used with Models blOlA, 61018, b103A,

blOZA, etc.

Applicarion: The 1531 may be used for measurements

which require a triaxial cable. The probe permits .

convenienr connections to the circuit under test due
to the gripping feature.

CS-64 cs-141

0372

57

ACCESSORIES

Model 4401 Printer Output Cards

Description: The Model 4401 consists of two printer
output cards which q ey be installed at the factory or
in the field since no wiring is required. The output

cards plug into prewired connectors on the chassis.
SCD outputs are provided through the use of a 50-pin
prewired output connector.

MODEL 615

Model 4405

Terminal

Box

Description: The Model 4405 consists of a 50-terminal

box with convenient barrier-strip connections and a

3 ft. cable terminated with a CS-220 connector.

Model SC51 Fifty-Conductor Cable

Description:

The Model SC51 cable is useful for fabri­cating a custovlength cable for use with the Model
4401 Printer Output cards.

The cable is sold in custom PC Card Extender

lengths on special order.

Model 4194 Shielded Input Switch

Description: The Model 4194 is a remotely controlled

reed switch that permits shorting of the input during

The

sample changes, etc.

switch is useful in a"to-

mated testing where it is important to keep the source

input shorted when not being measured.

Model 4406 Extender Cards

Description: The Model 4406 consists of two extender

cards and one extractor for pulling pc cards. The ex­tender cards permit access to test points and cali-

bration controls on cards having either 15 or 22 pina.

parts List:
Description Keithley Part No.
PC Card Extractor

4195

(22

pins) PC-225

PC Card Extender (15 pins) PC-224

58

0372

MODEL 615 REPLACEABLE PARTS

Mechanical Parts List.

Item NO.

1 Top Cover Assembly

Cover
Fastener

2 Bottom Cover Assembly

Cover

Pastener
3
4
5

Angle, Rack Assemble

Screw, Slotted, 10 - 32 Y l/4

Front Panel
b Chassis

Quantity Per Assembly

1

2

Keithley Part No.

1715%
17162C

FA-54

179bOC
17957c

FA-54

146248

2379bD

241818

03 72

FIGURE 20. Mechanical Assembly.

59

COMPONENT LAYOUTS

r

037

I ’

I I

PC209

PC218

M&EL 61:

I

t

PC229

I:
E

;

:

:

k

-

!

I

a
%

I

-

-

r,

60

FIGURE 21.

Chasste - Top View.

-L :.

J

j

MODEL 615

COMPONENT LAYOUT

0372

FIGURE 23.

Component Layout, PC207.

67

COMPONENT LAYOUT

MODEL 615

68

FIGURE 24.

Component

Layout, PC241.

037

r

MODEL 615

COMPONENT LAYOUT

0372

FIGURE 25.

Component

Layout, PC229.

71

COMPONENT LAYOUT

MODEL 615

FIGURE 26.

Component

Layout, PC217.

0372

--

L,

I I I

/

MODEL 615

COMPONENT LAYOUTS

0372

FIGURE 27. Component Layout, PC246.

75

COMPONENT LAYOUT

MODEL 61

76

FIGURE 28.

Component Layout, PC218.

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MODEL 615

COMPONENT LAYOUT

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FIGURE 2iJi

'Component Layout, PC209.

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COMPONENT LAYOUTS

MODEL

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80

FIGURE 30. Switch S1201, RANGE.

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