INSTRUCTION MANUAL
MODEL 605
NEGATIVE CAPACITANCE
ELECTROMETER
WARRANTY
We warrant each of our products to be free
from defects in material and workmanship. Our
obligation under this warranty is to repair or
replace any instrument or part thereof (except
tubes and batteries) which, within a year after
shipment, proves defective upon examination.
We will pay domestic surface freight costs.
To exercise this warranty, call your local
field representative or the Cleveland factory,
DDD 216-248-0400. You will be given assist-
ance and shipping instructions.
REPAIRS AND RECALIBRATION
Keithley Instruments maintains a complete repair service and standards laboratory in Cleveland, and has an authorized field repair facility
in Los Angeles.
0 1967
To insure prompt repair or recalibration serv-
ice, please contact your local field representa-
tive or the plant directly before returning the
instrument.
Estimates for repairs, normal recalibrations,
and calibrations traceable to the National Bureau of Standards are available upon request.
KEITHLEY INSTRUMENTS. INC.
MODEL 605 NEGATIVE CAPACITANCE ELECTROMETER
TABLE OF CONTENTS
TABLE OF CONTENTS
Section
MODEL 605 SPECIFICATIONS . . . . . .
1. GENERAL DESCRIPTION. . . . . . .
l-l. General. . . , . . . .
l-2. Features . . . . . . . .
2.
OPERATION. . . . . . . . . . .
2-l. Input Head . . . . . . ,
2-2. Power Module . . . . . .
2-3. Operating Procedure. . .
2-4~. Line Frequency Noise and
Minimum Response Speed .
2-5. Capacitance Tuning . .
2-6. Microelectrode Resistance
Measurement. . . . . . .
2-7.
3. CTRCUIT DESCKIPTION. . . . . . . . 9
3-l. General. . . . . . . . . . 9
3-2. Input Head , . . . . . 9
3-3. Power Module . . . . . .lO
Drift, Grid Current and
Ringing. . . . . . . . .
Page
.ii
.l
.l
.l
.3
.3
.3
.3
.5
. 6
.7
. 7
Section
4. MAINTENANCE. . . . . . . . . . . . 11
4.-l.
4,-2. Parts Replacement. , . . . . 11
4,-3.
4,-4.. Troubleshooting. . . , . . . 13
4.-s.
4,-b.
5. ACCESSORIES. . . . . . . . , . . . 19
5-l. Model 6051 Mounting
5-2. Model 6052 Integrator. . . . 19
5-3. Model 6053 Cable . . . . . . 19
6. REPLACEABLE PARTS. . . . . . . . . 21
6-1.
6-2.
General. . . . . . . . . , . 11
Spec'ial Maintenance
Precautions. . . . . . . . . 11
Procedures to Guide
Troubleshooting. . . . . . . 14,
Calibration. . . . . . . . . 14,
Bracket. . . . . . . . . . . 19
Replaceable Parts List . . . 21
How to Order Parts . . . . . 21
Model 605 Replaceable
Parts List . . . . . . . . . 22
Schematic Diagram
20387~ . . . . . . . . . . . 27
Green Repair and
Calibration Forms . . . . . . 29
Page
0168~
gr Change Notice
9~ Yellow Change Notice sheet is included
only for instrument modifications
affecting the Instruction Manual.
Last Page
GENERAL DESCRIPTION
MODEL 605 NEGATIVE CAPACITANCE ELECTROMETER
TABLE 1. Model 605
INPUT RESISTANCE: Greater than
INPUT CAPACITANCE NEUTRALIZATION: Up to 100 picofarads.
GRID CURRENT: Less than 10-L3 ampere without compensation.
RESPONSE AND NOlSE CHARACTERISTICS:
source Max. Rise Time,
Resistor, Min. f.ldb
megohms kilocycles
”
li
22 15 20
GAIN: 2 +5%.
VOLTAGE SUPPRESSION: Zero may be offset with IO-turn zero
control approximately flOO millivolts with respect to the input.
DRIFT: Less than 1 millivolt per hour after l-hour warmup;
DYNAMIC RANGE: iI volt at input.
MAXIMUM INPUT OVERLOAD: 3~100 volts.*’
OUTPUT RESISTANCE: Less than 1000 ohms.
CALIBRATION: Ramp required, may be Senerated by a triangle
CONNECTORS: Input, Output and Calibrate: BNC. Indifferent
BATTERIES: Five TR286, one E12. 200 hours battery life.
DIMENSIONS, WEIGHT:
ACCESSORIES SUPPLIED:
~.~,__
-*Ma” reclwre *eVeral minutes to recover 10 soecified drift.
less than 1 millivolt per “C;
less than lo-l4 ampere per day;
18s.~ than 10.” ampere per “C.
wave (ramp) generator. An oscilloscope square wave calibrator
output may be used when integrated by Keithley Model 6052.
Electrode: Spring-loaded clip.
Input Head: 1%” high x 3%” wide x 2%” deep;
net weiSht. 9 ounces (3.foot power cable attached).
Power Module: 2” high x IO” wide x 5%” deep;
“et weight. 3 pounds.
Model 6051 Mounting Bracket: Permits head to be supported by
ring stand and rod clamp.
BNC to Binding Post adapter, mating input co”“ector.
*Noise measured between 10 cp* and ml KC with Amplifier tuned for
rated rise t,me.
nnn
,~”
20
(63%) (lo-90%)
Specifications.
W
ohms.
microseconds Max. Input Noise,”
1 26
15
26 3;;
27 450
microvolts rms
FIGUW 1.
ii
Kci~thley Model 605 Negative Capacitance Elect:rometer.
0267
MODEL 605 NEGATIVE CAPACITANCE ELECTROMETER
GENERAL DESCRIP'TION
SECTION 1.
l-l.
1-2.
introducing extraneous power line noise.
meter which compensates for resting potentials and other dc offsets up to 100 millivolts;
a control on the input head for preliminary capacitance adjustment; and a fine capacitance
adjustment on the power module.
zero potentiometer allows adjustment without disturbing the experiment.
GENERAL.
a. What is a negative capacitance electrometer?
When a signal from a high impedance source is amplified, the capacitance of the
1.
amplifier input and the connecting cable greatly degrades the signal rise time.
example,
a 4,00-microsecond rise time.
A negative capacitance electrometer is useful for improving the rise time of signals
2.
from high impedance sources. This is accomplished by applying in-phase feedback from
the output of a fixed gain amplifier to the input through a properly chosen capacitor.
Reducing the effective capacitance in the example to 1 picofarad, possible with the
Model 605, improves rise time to 20 microseconds.
FEATURES.
Battery operation allows the Model 605 to operate inside shielded areas without
a.
"Only three operating controls and a power switch are used:
b.
The Keithley Model 605 is a negative capacitance electrometer
with only ZO-picofarad shunt capacitance, a signal from a ZO-megohm source has
The remote location of the fine capacitance control and
GENERAL DESCRIPTION
For
a lo-turn zero potentio-
10!i4
current minimizes the possibility of polarizing the cell under study.
lof5
and short circuit noise less than 35 microvolts rms. The rise time of less than 20 micro-
seconds with a 22-megohm source permits faithful reproduction of pulse.
testing and optimum neutralization adjustment without disturbing the test preparation.
The Model 605 has grid current less than lo-l3 ampere and current drift less than
ampere per day or per % without requiring a compensating adjustment. The low grid
1n addition to low grid current,
ohms,
e. The power module has an input for a ramp calibrating s~ignal, allowing microelectrode
shunt capacitance adjustable to less than 1 picofarad with a 22 megohm source,
the Model 605 offers input resistance greater than
04,67R
OPERATION
MODEL 605 NEGATIVE CAPACITANCE ELECTROMETER
TABLE 2.
The table briefly describes each control and terminal,
Input Head Controls and Terminals.
and indicates the paragraph which
contains instructions on the use of the control or terminal.
:ontrol or Terminal
:ord
Input Receptacle
Connects the Input Head to the Power Module
Bnc connector for signal input from microelectrode
Functional Description Par.
2-3
2-3, 2
and indifferent electrode
Spring Lock Terminal
Ground post for easy connection of indifferent
2-3
electrode
:apacitance Adjust
:ontro1
For preliminary adjustments for neutralizing
strav caDacitances on the inout circuitrv
TABLE 3.
Power Module Controls and Connectors.
2-3, 2
The table briefly describes each control and connector, and indicates the paragraph which
contains instructions on the use of the control or connector.
3ntrol or connector Functional Description
3WER Switch
ERO Control
Turns the power supply on and off 2-3
Zeroes the output voltage.
Also compensates for
resting potentials and other dc offsets.
INE CAP ADJ Control
Used for neutralizing small changes of input capa-
citance
ROBE Receptacle
Nine terminal mating connector for the Cord from
the Input Head
UTPUT Receptacle
AL Receptacle
Bnc connector for output signal
Bnc connector to receive ramp calibration signal,
allowing microelectrode testing and optimum capacitance neutralization adjustment
Par.
2-3
2-3 2-t
2-3
2-3
2-3
0767R
MODEL 605 NEGATIVE CAPACITANCE ELECTROMETER
OPERATION
SECTION 2.
2-l.
amplifier,
mental system.
the supplied mounting bracket.
caused by salt solutions,
solutions.
2-2. POWER MODULE.
teries to operate the amplifier. Battery power allows the Model 605 to operate inside
shielded areas without introducing extraneous power line noise.
2-3. OPERATING PROCEDURE.
from the Input Head to the PROBE Receptacle on the Power Module.
Cord in place by rotating the outer jacket clockwise.
amplifier, potentiometric recorder, or some other suitable monitoring device. The OUTPUT
Receptacle is a bnc connector.
INPUT HEAD.
enabling the Model 605 to be placed conveniently anywhere in a crowded experi-
Connect the Input Head to the Power Module by connecting the nine-lead,shielded Cord
a.
Connect the OUTPUT Receptacle on the Power Module to the input of an oscilloscope,
b.
The Input Head is a small nine-ounce remote head that contains the
The Head may be easily mounted in a standard rod and clamp system, using
The Input Head is chrome plated to minimize corrosion
and its tight fitting cover protects the amplifier from spilled
The Power Module contains the operating controls and six mercury bat-
OPERATION
Lock the plug on the
c. Apply a triangular wave to the CAL Receptacle on the Power Module.
Apply this signal with either a triangular wave generator, or, as shown in Figure 3,
1.
with an oscilloscope square-wave calibrator output integrated by the Keithley Model 6052
Integrator. Turn the generator signal to off.
The CAL Receptacle is an input for a ramp calibrating signal, allowing microelectrode
2.
testing and optimum neutralization adjustment without disturbing the test preparation.
(See paragraphs 2-5 and Z-6).
Spring Lock
Terminal (5102)
Receptacle
(X01)
Control (C101)
The triangular signal is applied at the CAL Receptacle.
OUTPUT
Receptacle
(5106)
CAL
Receptacle
PROBE
Receptacle
(5103)
FINE CAP ADJ
Control (R131)
POWER Switch
(5101)
FIGURE 2.
Parts List and schematic diagram.
0367R
Model 605 Controls and Terminals. Circuit designations refer to Replaceable
3
OPERATION MODEL 605 NEGATIVE CAPACITANCE ELECTROMETER
This signal is differentiated by the RC combination of a 5 picofarad capacitor in the
Input Head, C103,
the indifferent electrode through the bath.
the input of the amplifier.
and the resistance of the microelectrode connected from the Input to
Thus, a current square wave is applied to
Since, however,
neither electrode has yet been connected,
an appropriate resistor, approximately 22 megohms, can be connected across the Input
to simulate the source resistance of a microelectrode.
Mount the Input Head with a standard rod and clamp system using the supplied mount-
d.
ing bracket or just place the Head on the bench top.
Connect the Input Receptacle on the Input Head to the microelectrode or the calomel
e.
cell.
mating bnc connector.
Shielded or unshielded cable may be used. For shielded connections, use the
For unshielded connections, insert a bare wire into the center ter-
minal of the Input Receptacle or use the banana jack adapter.
Connect the indifferent electrode to the bath or dish. The indifferent electrode
f.
may be connected either to the shield of the mating bnc connector or to the Auxiliary
Spring Lock Terminal.
Short the tip of the microelectrode to the indifferent electrode by dipping the end
g.
of the microelectrode into the salt bath.
FIGURE 3.
The Power Module on the Model 605 has an Input for a Ramp Calibrating Signal,
Allowing Microelectrode Testing and Optimum Neutralization Adjustment Without Disturbing
any Test Preparation. The ramp signal may be obtained from a ramp generator, or, as
shown above, from an oscilloscope square-wave calibrator output integrated by the accessory Keithley Model 6052 Integrator.
4,
0767R
m
MODEL 605 NEGATIVE CAPACITANCE ELECTROMETER OPERATION
h. Turn POWER Switch on the Power Module to "on".
supply on and off.
Zero the oscilloscope and observe the output of the Model 605 on the oscilloscope.
1.
Zero the output 01 the Model 605 with the ZERO Control on the Power Module. Besides
i.
zeroing the output,
The Supply is on when the red dot is visible through the switch knob.
the ZERO Control also compensates for resting potentials and other dc
The POWEK Switch turns the power
offsets within a span of approximately 100 millivolts.
NOTE
There is no output overload protection on the Model 605.‘ A brief output short
circuit will not damage the Model 605,
but will cause excessive drain on the
batteries.
k. Apply a triangular signal with the signal generator to the CAL Receptacle on the
Power Module and note the output on the oscilloscope.
Compensate for stray capacitance
on the input by adjusting the Capacitance Adjust Control on the Input Head and the FINE
CAP ADJ Control on the Power Module.
The Capacitance Adjust Control on the Input Head,
which is a 55-turn stable glass piston trinnner, because of its fine resolution and wide
range,
is for preliminary adjustments. The FINE CAP ADJ Control is used for neutralizing
small changes of input capacitance, and, since it is on the Power Module, can be used
without disturbing the Input Head or the microelectrode.
Start with the FINE CAP ADJ Control at MAX (completely clockwise) and the
1.
CapBcitance Adjust Control on the Input Head in the completely counter-clockwise
position.
Turn the Capacitance Adjust Control on the Input Head until the square wave rise
2.
time on the oscilloscope decreases. When maximum tolerable overshoot is reached, the
input capacitance is nulled.
If fine
3.
Turn off the triangular signal to the CAL Receptacle. Do not disconnect the cable
1.
between the signal generator and the CAL Receptacle.
capacitance
adjustment is also necessary, use the FINE CAP ADJ Control.
If the cable is disconnected, the
input capacitances will change and the Model 605 will no longer be tuned.
m. Insert the microelectrode into the cell and observe the resting potential, pulses
and the response to external stimulae.
The microelectrode resistance can be checked
periodically by applying a triangular signal with the signal generator and observing the
magnitude of the output square wave (see paragraph 2-6).
NOTE
The Model 605 has a voltage gain of 2.
Therefore, be sure to divide the output
signal by a factor of 2 when using an oscilloscope, recorder, etc.
Z-4,. LINE FREQUENCY NOISE AND MINIMUM RESPONSE SPEED.
problem in many measurement setups.
There are several ways in which this noise can be
Line frequency noise may be a
eliminated or minimized.
a. Using shielded cable at the Input Receptacle on the Input Head of the Model 605 re-
duces the noise pickup. However,
mum obtainable rise time because of the distributed
use of a shielded cable at the input increases the mini-
capacitance
of the cable.
0767~
5
OPERATION
A shielded room can also reduce line frequency noise.
b.
MODEL 605 NEGATIVE CAPACITANCE ELECTROMETER
The shielded room is an impro-
vement over the shielded input cable because the rise time is not degenerated. However,
there still is line frequency pickup from the electronic equipment used in the experimental
setup. To reduce line pickup within a shielded room, a shielded cable can be used.
As be-
fore, however, the rise time will increase.
c. A wire screen cage and an unshielded input cable is generally the best setup.
this setup almost all the line frequency noise can be excluded.
The unshielded inpuzith
cable minimizes the distributed input capacitance and yields optimum rise time.
Mount the Input Head of the Model 605 as close to the preparation as possible. The
d.
longer the lead the greater the capacitance to ground and, therefore, the greater the rise
time.
Longer leads will produce more electrostatic ac pickup too:
also, increased cable
length between Input Head and Power Module will increase rise time, and over 3 feet of
cable between the Model 605 OUTPUT and the oscilloscope may increase rise time.
2-5.
CAPACITANCE TUNING. Rise time can be easily checked and optimized with the Model 605.
To tune for the desired rise time,
a.
connect the microelectrode to the indifferent elec-
trode by immersing the tip of the microelectrode into the bath, but not into the cell.
Apply a triangular voltage wave to the CAL Input on the Power Module (about 1000 cps
b.
is good).
Adjust the amplitude of this wave to read between 100 and 200 millivolts at the
Model 605 Output (one or two hundred millivolts is representative of the signal to be mea-
sured). A 5 picofarad capacitor in the Input Head,
C103, and the resistance of the microelectrode form a differentiator to produce a square current pulse at the input of the
Input Head.
Tune for optimum rise time by making capacitance adjustments using the Capacitance
C.
Adjust Controls.
There are two copsiderations to be taken into account before determining what
1.
optimum tuning is.
a) Decreasing the rise time of the amplifier by tuning necessarily increases the
amplifier noise.
The acceptable noise level can only be determined by the magnitude
of the signal being measured.
b) Rise time can be decreased by further neutralization but eventually overshoot and
oscillation result. Excessive overshoot causes :an erroneous reading for a fast impulse.
The Model 605 specified rise time (see Specifications, Table 1) can be achieved
2.
only under the following conditions.
Set the FINE,CAP ADJ Control in the MAX Position (completely clockwise).
a)
b) Achieve minimum distributed capacitance at the input by connecting a 10 or 22
megohm resistor with short leads from the input to the indifferent electrode.
Adjust the Capacitance Control on the Input Head for minimum rise time.
Cl
6
0767R
MODEL 605 NEGATIVE CAPACITANCE ELECTROMETER
To make intracellular potential measurements after tuning for the optimum rise
d.
time,
and take readings.
the
turn off the signal generator,* insert the tip of the microelectrode into the cell
In like manner,
tip
of the microelectrode out of the cell while leaving it immersed in the bath,
tuning can be achieved after a measurement by taking
applying the calibration signal and tuning.
2-6. MICROELECTRODE RESISTANCE MEASUREMENT.
OPERATION
To determine the resistance of the microelectrode,
a.
of approximately 10 megohms between the input and the indifferent electrode.
first connect a known resistor
APPLY e
triangular wave to the CAL Receptacle. Choose a convenient wave amplitude and do not
change it.
Model 605.
Observe the magnitude of the square wave at the OUTPUT Receptacle of the
Repeat this procedure with a few other resistors with values of approximately
20, 50 or perhaps 100 megohms.
b. Next, connect the microelectrode to the Input Receptacle on the Input Head and short
the microelectrode to the indifferent electrode by immersing the tip of the microelectrode
into the bath, but not into the cell.
Do not change the amplitude of the applied triangular wave. Observe the magnitude
c.
of the square wave at the OUTPUT Receptacle of the Model 605 and compare the amplitude of
this output with the amplitudes of the outputs of the known resistors.
Determine the re-
sistance of the microelectrode by interpolation.
To make intracellular potential measurements upon determining the resistance of the
d.
microelectrode,
turn off the signal generator,+ ihsert the tip of the microelectrode into
the cell and take readings.
2-7. DRIFT, GRID CURRENT AND RINGING.
Drift is an inherent property of all electrometer tubes. The Model 605 uses an
a.
electrometer tube, VlOl, at the input and has the expected drift characteristic.
The Model 605, however,
cation can be met.
warm-up,
and becomes moderately constant and quite predictable. HOWeVer, a severe over-
load at the input,
must be warmed-up for at least one hour before the drift specifi-
The drift of the Electrometer is cumulative, after the proper
in the range of 20 to 100 volts,
will cause increased drift for several
minutes.
The Model 605 must be warmed-up for a short period,much less then an hour, before
b.
grid current specification is realized.
put will temporarily increase the grid current.
An overload between 20 and 400 volts at the in-
The grid current after an overload or
just when the instrument is turned on will generally be about lo-l2 ampere.
Ringing at about 5 kc at up to 5 mv will occur in the electrometer tube when it is
c.
shocked.
This ringing will subside after one or two minutes. However, the normal intra-
cellular setup should be shock free because of the delicate microelectrode. Therefore,
there should be no shock induced upon the Model 605 under normal conditions.
yc Do not disconnect the CAL Cable from the Power Module.
-- -----
capacitance.
Cable from the generator and short that end.
If it isnecessary to remove the signal generator, then disconnect the CAL
This will preserve the capacitance adjust-
This will change the input
ment.
0467~
7
MODEL 605 NEGATIVE CAPACITANCE ELECTROMETER
CIRCUIT DESCRIPTION
SECTION 3.
3-1. GENERAL.
capacitor is applied from the output of the amplifier to the input to neutralize the inpur
capacitance and improve the signal rise time. The Input Head of the Model 605 contains a
th'ree-stage amplifier and the capacitive feedback networks. Within the Power Module is
the power supply of the instrument,
The Keithley Model 605 is a negative capacitance eLectrometer.
CIRCUIT DESCRIPTION
A variable
the zero control network and the output divider rc-
1~130
CAP ADJ (CIOI)
3-2. INPUT HEAD.
The amplifier is a three-stage amplifier that employs positive feedback to achieve
B .
optimum signal rise time and negative feedback to obtain +2 gain stability,
A fraction of the output stage of the amplifier drives the cathode of the input
b.
stage, electrometer tube VlOL.
The output of Tube VlOl drives the differential amplifier stage, transistors QlOl
c.
and 4102,
04,67R
for amplification.
K131
9
CIRCUIT DESCRIPTION
MODEL 605 NEGATIVE CAPACITANCE ELECTROMETER
The output of the differential amplifier, in turn,
d.
put stage which is a bridge network composed of transistor Q103 and a floating power
supply, Bl04., B105 and B106.
Positive capacitive feedback, used to neutralize input capacitance, is fed through
e.
the variable piston trimmer,
is connected to a variable output divider,
CAPACITANCE ADJUSTMENT.
The potentiometer, RlO3, adjusts the frequency characteristics of the amplifier.
f.
3-3. POWER MODULE.
The output divider resistors Rl28 and Rl29, which are 6 kilohm resistors, fix the
a.
gain of the amplifier at +2.
"out
Where Vout is the output voltage in volts;
Vin is the input voltage in volts;
and R128 and R129 are the divider resistors in ohms.
Since resistors Rl28 and R129 are both 6 kilohms, the equation becomes:
= Vin
ClOl, to the input of tube VlOl. The other end of the trimmer
resistors R130 and Rl31, to achieve a FINE
The gain of the amplifier is determined by the equation:
R128 + R129
(
Rl29 )
drives the emmitter-follower out-
equation 1
"out
and the gain is +2.
The ZERO Adjust Potentiometer, Rll4, and the Coarse Zero Adjust, P102, adjust the
b.
dc voltage of the screen grid for tube VlOl.
Batteries Bl02 and B103 supply the power to the Coarse Zero Control PlO2, which, in
tu',,, determines the voltage at the screen grid of tube "101.
filament power to VlOl.
= Vin
6 kJl + 6 kR
(
6 kR
) = 2Vin,
This control fixes the tube operating points.
Battery BlOl supplies
10
04,67R
MODEL 605 NEGATIVE CAPACITANCE ELECTROMETER
MAINTENANCE
SECTION 4.
4,-l.
the Model 605 Negative Capacitance Electrometer.
be followed as close as possible to maintain the accuracy of the instrument.
high-quality electronic equipment.
4.-2.
Model 605.
meet the specifications.
Instruments, Inc.
operation.
an emergency, but the drift, noise and grid current specifications may not be met. When
replacing the electrometer tube, do not touch the glass base where the leads emerge. ItIcreased leakage will result from any contamination.
GENERAL.
Section 4 contains the maintenance,
a.
The Model 605 requires no periodic maintenance beyond the normal care required of
b.
PARTS REPLACEMENT.
The Replaceable Parts List in Section 6 describes the electrical components of the
a.
Replace components only as necessary.
The electrometer tube, VlOl, is specially selected and aged; order only from Keithley
b.
In normal use, it should not need replacement pefore 10,000 hours of
It can be checked only by replacement.
MAINTENANCE
troubleshooting and calibration procedures for
It is recommended that these procedures
Use only reliable replacements which
A standard 5886 tube can be used in
c. Transistors QlOl and Q102 are matched for low noise; order only in pairs from Keithley
Instruments, Inc.
4~-3. SPECIAL MAINTENANCE PRECAUTIONS.
Salt Solution Handling.
a.
Special care should be taken in handling the salt solutions so that they will not
1.
contaminate the Electrometer.
The Model 605 has a tight-fitting chrome plated Input Head that should preserve
2.
its beauty for years to come. Spilling salt solutions on the Input Head should not be
harmful to the circuitry inside, However, the Head is not water proof, and immersing
it in a solution may ruin the circuitry.
Equipment Recommended for Model 605 Troubleshooting and Calibration.
ments or their equivalents.
dc voltmeter, with minimum lOO-megohm
input resistance, 10% accuracy, range from
1 volt to 300 volts
When ordering, QlOl is supplied with an identifying paint dot.
TABLE 4,.
Instrument
Troubleshooting and Calibrating Equipment.
Use these instru-
Use
Circuit checking
t
Tektronix Type 502A OscilLoscope
0767R
Calibration
11
MAINTENANCE
The Power Module is not sealed or chrome plated but since it can be removed from
3.
the proximity of the experiment,
contamination from the salt solutions.
splashes that it does receive.
Input Circuitry.
b.
The high impedance input circuitry should receive special care.
1.
MODEL 605 NEGATIVE CAPACITANCE ELECTROMETER
it should not receive a large dose of splashing and
It should, however,
survive the spills and
Do not touch or contaminate the Teflon insulation,
2.
the glass piston capacitor (ClOl),
tamination will destroy the offset current specification.
If a component becomes contaminated it may be cleaned with a cotton swab and
3.
alcohol. However,
contaminated from the salt solution,
Batteries.
c.
Maintain the batteries in good
1.
condition.
To check the batteries, turn the
2.
POWER Switch to off (red dot not visible)
and check the voltage across each battery
with a voltmeter.
The mercury batteries, as used in
3.
the Model 605, have a very discernible
aging characteristic (See Figure 5). DUr-
ing the useful life of the battery a steady
voltage exists between the terminals of the
battery.
life has been reached a very rapid voltage
drop occurs, and the battery must be replaced.
When the end of the cells useful
if a component or the Teflon insulation of a connector becomes badly
or the electrometer tube (VlOl) in any way. Con-
replacement may be necessary.
I
FIGURE 5.
the polystyrene capacitor (ClO3),
Battery Life for Model 605.
Low battery voltage is characferized by excessive output drift, inability to zero
4.
the output, erratic spikes .in the output of the Model 605, poor rise time of the amplifier, or less than f2 volts dynamic range at the output.
Coarse Zero Control.
d.
If the zero drifts out of range of the ZERO Control on the front panel, it can be
1.
brought back into range of the ZERO Control by adjusting the Coarse Zero Divider inside
the Power Module.
To adjust the Coarse Zero Divider, move the two connectors, P10'2 (Figure 6), up
2.
or down one position.
a greater zero suppression range with less zero resolution is desired.
number of spaces between the connectors 1'102,
er the number of spaces between the connectors PLOZ, the wider the zero range.
ing the spaces, however, decreases the life of batteries B102 and B103.
1. 2
Maintain one position between the connectors at all times unless
The lesser the
the finer the zero resolution.
The great-
Increas-
0767R
MODEL 605 NEGATIVE CAPACITANCE ELECTROMETEK MAINTENANCE
Model 605 Troubleshooting
Probable Cause
Solution
Check per paragraph 4-3 and
Difficulty
Output will not zero
TABLE 5.
Batteries failing
replace faulty batteries
Coarse Zero Divider is not Adjust per paragraph 4-6
properly positioned
Excessive zero drift Batteries failing
Check per paragraph 4&3 and
replace faulty batteries
Defective electrometer tube Check VlOl and replace if
faulty
Excessive grid current Excessive humidityor Check VlOl and replace if
defective electrometer tube faulty
Contaminated insulation Clean with cotton swab and
alcohol
Excessive microphonics
Defective electrometer tube
Check VlOl and replace if
(morel than 10 m" at the faulty
input)
Slow rise time Maladjusted roll-off network
Adjust per paragraph 4,-6
Excessive distributed capa- See paragraph 2-5
citance on the input lead
Batteries failing Check per paragraph 4,-3 and
replace faulty batteries
4,-4,. TROUBLESHOOTING.
a. The procedures which follow give instructions for repairing troubles which might
occur in the Model 605. Use the procedures outlined and use only specified replacement
parts. Table 4, lists equipment recommended for troubleshooting.
be readily Located or repaired, Keithley Instruments, Inc.,
can service the instrument
If the trouble cannot
at its complete service facilities. Contact your nearest representative.
Table 5 contains the more canm~n troubles which might occur. If the repairs indi-
b.
cated in the table do not clear up the trouble, find the difficulty through a circuit-bycircuit check as given in paragraph 4-5. Refer to the circuit description in Section 3
to find the more critical components and to determine their function in the circuit. The
complete circuit schematic, 20387C, is found in Section 6.
03671:
13
MAINTENANCE
MODEL 605 NEGATIVE CAPACITANCE ELECTROMETER
4,-5.
(p:;agraph 4,-3).
PROCEDURES TO GUIDE TROUBLESHOOTING.
If the instrument will not work properly,
If these are found to be satisfactory,
check the condition of the batteries
use the following procedures to
isolate the trouble.
Disconnect all wires and cables from the Input Head and the Power Module. connect
b.
the Input Head to the Power Module with the supplied nine-lead, shielded cord.
Disconnect resistor R128 and short out resistor R129. This removes the negative
c.
feedback, which stabilizes the fixed gain of 2,
a gain around 2000.
The point between batteries B105 and 13106 (point A, Figure 6) is now ground.
d.
Short the input to ground, point A, by running a wire from the Input on the Input
e.
Head to the OUTPUT on the Power Module.
Zero the output.
f.
Such a system enables the user to better check the circuit voltages.
Point A, ground,
The output is taken from the emitter of transistor Q103 (which is
and produces an open loop amplifier with
is connected to the OUTPUT.
connected to the chassis) to point A, which is ground and is connected to the OUTPUT.
Monitor the output signal with a dc voltmeter that has a minimum input resistance
1.
of 100 megohms.
Connect the ground of the voltmeter to the OUTPUT of the Model 605 and
connect the high side of the voltmeter to the case of the Model 605.
Zero the output with the ZERO Control.
2.
If the output can be zeroed,
g.
the dc voltmeter.
shown on the schematic.
If the output cannot be zeroed,
h.
Theobtained values should be within +lO% of the typical voltages
Replace components as necessary.
this signal through the amplifier.
check voltages at various points in the circuit
adjust the ZERO Control to case a signal and trace
Monitor this signal first at the plate of tube VlOl
with the dc voltmeter connected as above.
occur on the plate of VlOl, then the tube,
If a response to the ZERO Control does not
its biasing resistors or the next transistor,
with
QlOl, is defective and should be replaced.
i. Next, monitor the signal at the collectors of the transistors QlOl and Q102.
signal can be obtained, then the transistors,
tor, Q103,
Finally, monitor the signal at the emitter of transistor Q103. If no signal can be
j.
obtained,
Upon completion of troubleshooting the Model 605,
k.
is faulty and should be replaced.
then this transistor or its biasing resistors are faulty and should be replaced.
their biasing resistors or the next transis-
replace the negative feedback re-
If'no
sistor, ~128, remove the short from resistor Rl29 and remove the short between the input
and point A.
The instrument should now work fine.
4-6. CALIBRATION.
a. The following procedures are recommended for calibrating and adjusting the Model 605.
use the equipment recommended in Table 4.
if difficulty is encountered,
contact Keithley Instruments, Inc., or its representative
If the proper facilities are not available or
to arrange for factory calibration.
14,
0767R
MODEL 605 NEGATIVE CAPACITANCE ELECTROMETER
MAINTENANCE
b. Short the
input to
ground.
c. Zero the output by setting the Coarse Zero Divider, P102 (Figure 8), to the proper
position.
paragraph 4-3d). Always keep one vacant terminal between the two connectors.
The proper position may be found by the method of trial and error (See also
Final ad-
justment should be made with the front panel control.
Apply a triangular wave through the CAL Receptacle on the Power Module (See para-
d.
graph Z-3).
Turn the FINE CAP ADJ Control to the MAX Position (completely clockwise).
e.
Adjust the Coarse Capacitance Adjust Control
f.
Now adjust the roll-off potentiometer, R103, for minimum rise time. By adjusting
g.
both controls, i.e
Connect a 22 megohm resistor with short leads between the Input and ground.
on
the
- -. >
Input
the roll-off potentiometer and the Coarse Capacitance Adjust Control,
Head for minimum rise time.
an optimum rise time is achieved.
NOTE
Replacing the Input Head cover changes the input capacitance and may cause mis-
adjustment. A small metal plate with a hole in it above potentiometer Rl03 is
useful for this adjustment.
h. Upon completion of these adjustments, the Model 605 is calibrated and should meet
all specifications
0767R
15
MAINTENANCE
MODEL 605 NEGATIVE CAPACITANCE ELECTROMETER
e
Fl
MC
L
LGURE 6.
,dule.
J
Battery, Connector, Switch and Terminal Locations Within the power
Resistors are shown in Figure 7.
L
FII
in Figure 6.
16
Resistor Locations Within the Power Module. Other components are shown
0767R
MODEL 605 NEGATIVE CAPACITANCE ELECTROMETER
YAW
(hidden) Cord
MAINTENANCE
FIGURE 8. Capacitor,
Connector, Transistor
and Tube Locations
Within the Input Head.
Resistor Locations
are shown in Figure 9.
FIGURE 9.
Resistor Locations With
in the Input Head.
Other component
locations are show
in Figure 8.
RllO
Kill Rio7 Ri03Ri09 RiOi
R108
.RlOl
.R106
0467R
MODEL 605 NEGATIVE CAPACITANCE ELECTROMETER
ACCESSORIES
SECTION 5.
5-1. MODEL 6051 MOUNTING BRACKET,
The Keithley Model 6051 Mounting
a.
Bracket is a supplied accessory that, when
attached to the base of the Model 605 Input
Head, enables the Head to be supported by a
standard laboratory ring stand and rod clamp.
b. To attach the Input Head to the Mount-
ing Bracket,
bottom of the Input Head.
rubber feet between the Input Head and the
Mounting Bracket.
the four previously removed screws.
to Figure 10.)
5-2.
MODEL 6052 INTEGRATOR,
a. The Keithley Model 6052 Integrator is
used to integrate square waves to supply a
ramp function to the Model 605 CAL Receptacle for calibrating the Model 605 (See para-
graph Z-3).
peak is required at the input of the Model
6052.
It has a male uhf input and a female
uhf output.
remove the four screws on the
Place the four
Fasten together using
(Refer
Approximately 50 volts peak-to-
ACCESSORIES
FIGURE 10.
and Model 6051 Mounting Bracket.
Keithley Model 605 Input Head
b. To use the Model 6052 Integrator with
the Model 605, attach the input of the Integrator to the calibration output of an
oscilloscope or some other generating device.
connector,
If the calibrator output uses a bnc
use a uhf-to-bnc adapter such as
the Keithley part number CS-172 which has a
male bnc and a female uhf. Connect the In-
tegrator to the Model 605 CAL Receptacle.
The CAL Receptacle on the Model 605 is a
bnc receptacle.
I
FIGURE 11.
Keithley Model 6052 Integrator.
5-3. MODEL 6053 CABLE.
The Keithley Model
6053 Cable is a 3-foot coaxial cable with
a male uhf on one end and a male bnc on the
other. The Cable is useful for connecting the female uhf output of the Model 6052 Integra-
tor to the Model 605 CAL Receptacle, which is a bnc receptacle.
The 6053 is also useful
for output as well as calibrate.
0767R
19
MODEL 605 NEGATIVE CAPACITANCE ELECTROMETER REPLACEABLE PARTS
SECTION 6.
6-l. RFPLACEABLE PARTS LIST. The Replaceable Parts List describes the components of
the Model 605 (and its accessories). The list gives the circuit designation, the part
description, a suggested manufacturer, the manufacturer's part number and the Keithley
Part Number. The last column indicates the figure picturing the part. The name and
address of the manufacturers listed in the "Mfg. Code" column are in Table 6.
6-2.
Part Number, the circuit designation and a description of the part. All structual parts
and those parts coded for Keithley manufacture (80164,) must be ordered through Keithley
Instruments, Inc. or its representative.
able Parts List;
Department, Keithley Instruments, Inc.
Cb
Cerd
Comp
I
DCb
ETB
Fig
GPT
k
M or meg Mega (106) or Megohm WWVZli?
HOW TO ORDER PARTS.
For parts orders, include the instrument's model and serial number, the Keithley
a.
completely describe the part,
Order parts through your nearest Keithley representative or the Sales Service
b.
TABLE 6.
Carbon
Ceramic Disc
Composition
Deposited Carbon
Electrolytic Tubular
f farad
Figure
Glass Piston Trimmer
kilo (103)
REPLACEABLE PARTS
In ordering a part not listed in the Replace-
its function and its location.
Symbols and Abbreviations
Mfg.
Mil. No. Military Type Number
MtF.
n ohm
P
Poly
Ref
req'd
v
v
w
Manufacturer
Metal Film
pica (10-l')
Polystyrene
Reference
required
micro (10w6)
volt
watt
Wirewound Variable
0467~
21
REPLACEABLE PARTS MODEL 605 NEGATIVE CAPACITANCE ELECTROMETER
MODEL 605 REPLACEABLE PARTS LIST
(Refer to Schematic Diagram 20387C for circuit designations)
BATTERIES
Circuit
Desig.
Description
I3101 1.34 volt Mercury Battery
Bl02 8.4, volt Mercury Battery
B103
8.4. volt Mercury Battery
B104, 8.4. volt Mercury Battery
B105
8.4. volt Mercury Battery
B106 8.4~ volt Mercury Battery
Circuit
Desig. Value
Cl01 l-90 pi
Cl02 .004,7
Cl03 5 pf
Cl04 .0022
Cl05 33 pf
Cl06 125 pi
Rating
1000 "
pf Cerd
600 v
200 v Poly
I*f 100 v Poly
600 v Cerd
15 v ETB
CAPACITORS
TYPO
GPT
Mfg.
Code
Mfg.
Part No. Part No. Ref.
Keithley Fig.
61637 El2 BA-7
72665
TR-286 BA-18
72665 TR-286 BA-18
72665 TR-286 BA-18
72665 TR-286 BA-18
72665 TR-286 BA-18
Mfg.
Mfg.
Keithley
Code Part No. Part No.
16509
72982 ED-.004.7
14.167 ElOl3-1
13934, E3FR-222-1-C
72982 ED-33
734.4.5 C4,26
TM90CE c153-9OP
C22-.004.7M
c31-5P
C152-.0022M
C22-33P
C3-125M
Fig.
Ref.
8, 2
8
8
8
8
6
Circuit
Desig.
--___
--___
___
JlOl
JlO2
5103
3104,
JlO5
J106
MISCELLANEOUS PARTS
Description
Battery holder (Mfg. No. 2139)
Battery holder, 5 req'd (Mfg. No. 2173)
Battery holder retaining clip, 2 req'd
(Mfg. No. 66)
Battery holder retaining clip, 10 req'd
(Mfg. No. 62)
Cable clamp
Input Receptacle, bnc (Mil. No. UG-1094/U)
Spring Lock ground post terminal
PROBE Receptacle (Mfg. No. 126-221)
CAL Receptacle, bnc (Mil. No. UG-1094/U)
Printed circuit contacts, 11 pin
(Mfg. No.
02-011-113-6-200)
OUTPUT Receptacle, bnc (Mil. No. UG-1094,/U)
Mfg. Keithley Fig.
Code Part No. Ref.
94.139
94.139
94.139
94.139
80164,
02660
80164
02660
02660
80164,
02660
BH-16
BH-21
BH-23
BH-22
20354,A
cs-15
TE-30
CS-81
cs-15
CS-184,
cs-15
8, 2
8, 2
‘3, 2
6, 2
632
22 0767R
MODEL 605 NEGATIVE CAPACITANCE ELECTROMETER
MISCELLANEOUS PARTS (Cont'd)
REPLACEABLE PARTS
Circuit
Desig.
Mfg.
Description Code
Keithley
Fig.
Part No. Ref.
PlOl Plug, mate of J103 (Mfg. No. 126-220) 02660 cs-a2 2
P102 Contact for J105, 2 req'd (Mfg. No. 50-8017.0313)
80164,
cs-185
6
SlOl POWER Switch 80164 20313A 6, 2
--- Knob Assembly, Power Switch 80164, 18393A
--- FINE CAP ADJ Control (Mfg. Type 4~5) 714,50 RP54,-1K 2
---
Knob, Fine Cap Adj Control
80164, 1564,4.A
--- ZERO Control (Mfg. No. 62JA) 12697 RP4,2-l0K 2
--- Knob, zero Control 80164 154.61A
--- Coarse Capacitance Adjust (Mfg. No. TMVOCE) 16509 c153-VOP 2
--- Knob, Coarse Capacitance Adjust 80164 KN-32
RESISTORS
Circuit Mfg. Mfg.
Desig.
RlOl
R102
R103
R104,
R105
Value Rating
10 MO
100 kfl
20 kR
y&. 7 kQ
39.2 kR
lO%, l/4 w
ix, lfa w
30%, l/2 w
lO%, l/4 w
l%, l/8 w
TYPO
camp
MtF 07716
cermet 73138
Comp
MtF 07716
Code
01121
01121
Part No. Part No. Ref.
CB
CEA
62P-RZOK
CB
CEA
Keithley
R76-10M
R88-100K
RP55-20K
R76-4.7K
R88-39.2K
Fig.
9
9
9
9
9
R106
R107
R108
RI09
RllO
Rlll
R112
R113
R114
R115
R116
R117
Rl18
R1lV
R120
R121 500 n
R122 500 R
11 kn
39.2 kO
100 kQ
4~9.9 kfl
15 kfl
8.06 kfl
8.06 kQ
1.667 kR
10 kSZ
6.8 kR
4,.3 kR
500 12
500 iz
500 n
500 n
l%, l/8 w
l%, 1/a w
lO%, 114, w
I%, 1/a w
l%, 1/a w
l%, l/8 w
l%, 1/a w
I%, l/2 w
5%, 2 w
l%, l/2 w
l%, l/2 w
l%, l/2 w
l%, 112 w
l%, 112 w
l%, 112 w
l%, l/2 w
l%, 112 w
* Nominal value, factory selected
0467R
MtF
MtF
Comp
MtF
MtF
07716 CEA
07716 CEA
01121
07716
07716 CEA
MtF 07716
MtF
DCb
07716
91637
WWV?llY 12697
DCb
DCb
DCb
DCb
DCb
DCb
DCb
DCb
91637
91637
91637 DCF-l/2
91637
91637
91637
91637
91637 DCF-L/2
CB
CEA
CEA
CEA
DCF-l/2
625A
DCF-l/2
DCF-l/2
DCF-l/2
DCF-l/2
DCF-l/Z
DCF-l/2
R88-1lK
R88-39.2K
R76-100K
R88-4,9.9K
R88-15K
R88-8.06K
R88-8.06K
R12-1.667K
RP4,2-10K
Rl2-6.8K
Rl2-4,.3K
Rl2-500
R12-500
R12-500
R12-500
Rl2-500
RlZ-500
9
9
9
9
9
9
9
7
7, 2
7
7
7
7
7
7
7
23
REPLACEABLE PARTS
MODEL 605 NEGATIVE CAPACITANCE ELECTROMETER
RESISTORS (Cont'd)
Circuit
Desig.
R123
R124,
K125
R126
R127
R128
R129
R130
R131
Value
500 cl
500 n
500 n
500 n
1.5 kn
6 kR
6 kR
22 kn
1 k0
Mfg.
Rating
Type
Code
l%, 112 w DCb 91637
I%, 112 w DCb 91637
l%, 112 w DCb 91637
l%, 112 w DCb 91637
l%, l/2 w
DCb
91637
I%, 112 w DCb 91637
l%, 112 w DCb 91637
lo%, l/2 w Comp
01121
+20x, l/2 w Cb 714,50
Mfg.
Part No. Part No. Ref.
DCF-l/2
DCF-l/2
DCF-l/2
DCF-l/2
DCF-l/2
DCF-l/2
DCF-l/2
EB
TYPE-4.5
Keithley
R12-500
R12-500
R12-500
R12-500
RlZ-1.5K
R12-6K
R12-6K
Rl-22K
RP54,-1K
Fig.
TRANSISTORS
Circuit
Desig.
QlOl 9w
Number
S17638 80164, 20996A 8
Mfg.
code
Keithley
Part No.
Fig.
Ref.
QlO 2 ?';* S17638 80164, 20996A 8
Q103 2~3565 07263 TG-39 8
VACUUM TUBES
Circuit
Desist.
Number
VlOl 5886-5X 80164,
*-'- QlOl and Q102 are matched for low noise.
Mfg.
Code
Keithley
Part No.
EV-5886-5X
Order only in pairs from Keithley.
Fig.
Ref.
When or-
dering replacement parts, QlOl is supplied with identifying paint dot. Original parts
contain no identifying mark.
a
24
0767R
MODEL 605 NEGATIVE CAPACITANCE ELECTROMETER
REPLACEABLE PARTS
TABLE 7.
Code List of Suggested Manufacturers.
Cataloging Handbook H4-1).
Ill21
Allen-Bradley Corp.
Milwaukee, Wis. New York, N. Y.
12660
Amphenol-Borg Electronics Corp.
Broadview, Chicago, Illinois
17263
Fairchild Camera 6: Instru. Corp. 72699
Semiconductor Division
Mountain View, Cal.
17716
International Resistance Co.
Burlington, Iowa
~14,50
Challenge Machine Co., The Beckman Instruments, Inc.
North Wales, Pa. Fullerton, Calif.
~2697
Clarostat Mfg. Co., Inc. 734,45 Amperex Electronic Co. Division ol
Dover, N. H.
~3934,
Midwec Corp.
600 Main
Oshkosh, Nebr.
Manufacturers
(Based on Federal Supply Code for Manufacturers,
61637
72665
Union Carbide Corp.
Mallory Battery Co.
Cleveland, Ohi~o
General Instrument Corp.
Newark, N. J.
72982
Erie Technological Products, Inc.
Erie, Pa.
73138
Helipot Division of
North American Philips Co., Inc.
Hicksville, N. Y.
80164, Keithley Instruments, Inc.
Cleveland, Ohio
-4.167
-6509
Efcon, Inc.
Garden City, Long Island, N. Y.
Voltronics, Inc.
91637 Dale Electronics, Inc.
Columbus, Nebr.
94,139 Keystone Electronics Co.
7746 W. Addison 67-7th Ave.
Chicago, Ill. Newark, N. J.
0467R
25
I I I
I I
REPAIR AND CALIBRATION FORM
For repair or calibration, please fill out this form and return it with your instrument to:
Sales Service Department
Keithley Instruments, Inc.
28775 Aurora Road
rite in this space.
Cleveland, Ohio 44139
User’s Name
company
DFViSiOll
Date
1.
Reason for Return 2.
0 Repair and Recalibration
0 Recalibration only (No report, except
as specified in item 4 on reverse)*
*If repairs are necessary to meet speci-
fications,
they will be in addition to
the calibration.
3.
To help repair the instrument,
1s the problem - Constant
4.
briefly describe the problem:
Under what conditions does the Droblem occur:
a) Control setting
b) Approx. Temperature
c) Approx. Temperature variation *
d) Approx. Humidity (high, medium, low)
Telephone
Ext.
Address
city
Model No.
state
Serial No.
2iP
Calibration Report Desired
0 Report of Calibration Certified
Traceable to N.B.S.
0 Calibration Report
a Certificate of Compliance
(for 2a:;:: sea reverse side of this form)
- Intermittant
Line voltage
=)
F\
Other (such as line transients,
L,
line variations, etc.)
OF
OF
Please draw a block diagram of the system using the Keithley. List any other perti-
5.
nent data which can help in the repa3.r.
Include charts or other data if available.
Signal source
Source Impedance
Readout Device:
0 Recorder
a Oscilloscope
-Other
0 None
Lengths & Types of Connecting Cables
What repairs or modifications have been made on this instrument which are not on fFle
6.
with the Keithley Repair Department?
Please enclose any other pertinent data and char:.- which you feel might help the
7.
Repair and Calibration Department
signature
Tftle
1267
CALIBRATIONS AVAILABLE AT KEITHLEY INSTRUMENTS.
Listed and defined below are the four types of calibrations and their associated
report formats which are presently available at Keithley Instruments.
They fall into
the following categories:
Report of Calibration Certified Traceable to the National Bureau of
1.
Standards
Calibration Report
2.
Certificate of Compliance
3.
Recalibration
4.
All calibration and certification performed by Keithley Instruments is in accord
with MIL-C-45662A.
Prices shown below are'in addition to repair charges for any work necessary to place
a customer's unit into first class condition prior to the calibration.
Loading...