27 A/D Converter Diagram. _--___-_________--_______________
28 Identification af Se~,ent.s and Mulriplex lines. -------29 Tap and Bottom Cover Assembly. ------------------------30 Locarion of Calibration Ad,ustmenfs. -----------------31 Location of Test mints.
32 Location of Chassis Connections. ---------------------33 Location of Fuses. ------------------------------------34 case Outline - Integrated CirCUitS. -------------------35 case Outline - Integrated circuits. _---_______________36 Case Outline - Integraeed Circuits. _--____--_____--__37 case Outline - Inregrated circuits. -------------------38 case ourline - Transistors.
39 Case Outline - Thick Film Networks. _---__-_____-_______
40 Case Outline - Thick Film Networks. -------------------41 Case O"tline - Custom LSI. ---_----_---_-_------------42 Component Layout* pc-349. --_-_--______________________
43 component Layout,
digital multimeter capable of measuring voltage, cur-
rent, and resistance. me Model 1608 offers SeYen
ranges of voltage from lrn" to 1000 volts, nine ranges
of current from 1O"A to 1ooomA, and ten ranges Of resistance from 1n to lOOOM12. The Model 1608 display
is 3 digifs plus 100% overrange.
1-2. FEATURES.
a. Voltage sensitivity to 1 micravole per digit.
current .se"Giti"ity to O.OlnA per digit.
b.
Resistance sensitivity to 0.001n per digit.
C.
Floating capabilify LO _+1*00 "OlC.5 above case.
d.
e. Built-in analog output.
Optional Made1 1602R Digital Output
f.
Optional Model1688ARrchargeable "attery Pack.
s.
The Model 1608 is a wide-range
GENERAL INFORMATION
HANDLE AND
TILT BAIL
I
BAT TEST A
BAT TEST B
S
~
I
CONDENSED OPERATING INSTRUCTIONS
LINE
COW
STORAGE
S
S = SCREW
LOOSEN FOR
DISASSEMBLY
2
1174
MODEL 1608
INITIAL PREPARATION
5112 J113 !
520
I
ANALOG OUTPUT
SWITCHES SHOWN FOR
OPERATION FROM 105-125V LINE
DiGi
:TAL
'UT
OUTF
J302
3
L‘IG”RE 7.
Exploded view Of Model 1600,16881\
4
0976
I
I
I
BATTERi FUSES
F203, F204
I
SPACER
(4 PLACES)
MODEL 1608 CHASSIS
CAUTION
DISCONNECT LINE CORD BEFORE OPENING
THE TOP AND BOTTDM COVER,
LINE VOLTAGE ON THE CHASSIS
REPRESENTS A SHOCK HAZARD.
FIGURE 8.
Installation "f Battery Pack.
\\
0976 5
INITIAL PREPARATION
MODEL 160B
SECTION 2.
GENERAL.
2-l.
needed for incoming inspecrian and preparation for
use.
INSPECTION. The Model 1603 was carefully in-
2-2.
spected both mechanically and electrically before
shipment. "pm receiving the instrument, check for
any obvious damage which may have occurred during
f*El"Sit.
TO verify the electrical specifications, follow the
procedures given in Section 6.
PREPAR**ION FOR "SE.
2-3.
ready-to-use.
line voltage or from rechargeable nickel-cadmium batteries (when the oprional Model 1688A Rechargeable
Battery Pack is installed).
How to operate From IdlIe Power.
a.
provides a three-wire cord which mates with third-wire
;rounded receptacles (see Figure 4 for ~1% configura--
tion,.
by wrapping the card around the base of the i"str"-
ment as shown in Figure 4.
the permanently installed line cord is stored
wow to Set Line Switches. The Made1 1608 has
1.
two rear panel Line Switches which enable selection
of line voltages over ranges from x0-llO", 105125v,
195-235", or 210-250". TO operate from line power.
determine the appropriate line voltage range to be
used and set the Line Swirches as fallows:
I
This section provides information
Report any damages to tne shipping agent.
The instrument can be powered from
TABLE 2-1.
Summary of Line Switch Settings.
‘Jo-110” I
The Model 160~ is shipped
The Model 16OB
LOW. 117
105-125” NORM, 117
I
For example, if the line voltage ea be used is
approximately 115 volts, select NORM and 117 which
permits B range of operarion from 105 to 125v.
hfter line Switches are set, connect the line cord
and set the Power Switch to LINE.
210-250"
195-235”
1
LO", 234
NORM. 234
INITIAL PREPARATION
b. Row to operate From Battery Power. TO operate
the Model 16OB from batteries, the Model 1688A Rechargeable battery Pack must be installed. The Model
1688A can be either field or factory installed.
batteries in the Model 1688A may need recharging be-
fare their first usage to power the Model 1600.)
The Model 1688A Rechargeable Battery Pack can
be insralled within the Model 1608 chassis at
any time.
Output is already installed, the Model 1688A
cannot be used simultaneously.
1. HOW to Install Model 168% Rechargeable Battery Pack.
1688A come already installed in the battery pack.
the battery pack includes 7 rechargeable "C" cells
(1.2", 3 AMP HR) and 1 rechargeable pack (16.8V).
If baeeeries need to be replaced or re-installed,
be certain to observe the proper polarity of individual cells as shown in Figure 6. To install the
Model 1688A Battery Pack, turn the instrument over
so that the bottom cover faces up. Loosen four
slotted screws on the batrom cover as shown in
Figure 4. (A chisel-blade screwdriver is requires'
to loosen the slotted screws.) Turn over the instrument with tap cover facing up, taking care to
hold the top and bottom covers together. Carefully
remove the top cover to gain access fo the printed
circuit board. (Two "ires that connect to the
Analog Oufput must be disconnected at the PC board
before the top cover can be set aside.) Check to
I
I
see that the four insulating spacers are in yasi-
tion on the printed circuit board. Place the Model
1688A Battery Pack in position an the spacers with
the cable oriented as sham in Figure 8.
4-wire Conneceor (5205) into the mating receptacle
(P205) taking care to orient the connector as
shown in Figure 8. After the Battery Pack is installed. replace the top cover. Turn over the instrumen; wiih bottom co&r facing up and tighten
down the four slotted-head screws.
Sumnary of nateerie Used in Model 1688A
However, if the Model 16028 Digital
The batteries furnished with the Model
(The
NOTE
Plug the
TABLE 2-2.
,.ine Fuse Requirements. The Model 1608 uses
2.
~VO line fuses to protect the line-operated power
SWPlY.
blow.
3. How to Replace Fuses in Model 1688A. The
!Jodel, 1688H uses 1 ampere fuses to protect the
power supply regulators in case of malfunction.
Fuses F203 and F204 are plug-in types and are located on pc board PC-349 as shown in Figure 8.
Keplace with 1 ampere, 3AB, slo-blo, Keithley Part
NO. FU-28.
6
ne fuse types are l/8 ampere, MB, slow-
Replace with Keithley Part No. F"-20.
Rechargeable "C" cell,
1.2". 2 AMP-FIR
Rechargeable battery
pack, 16.8V, .225
Am-m
1
TM-32
0976
The instrument must he operated in the BAT
mode in order t” obtain a valid battery condition at test points A and 8. This3 Will
enstire that tile batteries are supplying
power to the instrument. If the voltages
are measured when the Model 1608 is opera-
ted in the LINE mode a different reading
may be observed since the batteries are not
connected and rherefore do not supply power
to the instrumenr.
0976
OPERATING INSTR”CTIONS
MODEL 160B
SECTION 3.
GENERAL.
3-l.
needed to operate the Model 160B for measU*eme"f Of
voltage, cuirent, and resistance.
HOW TO SELECT POWER.
3-2.
powered from line voltage or rechargeable nickel-cadmium batteries ("hen the Model 1688A is installed).
The Model XOB has a built-in line-voltage power sup-
ply and line cord.
chargeable Battery Set is ordered and installed, then
the user has the oprion of selecting line or bateery
operation via the front panel rotary power switch.
The accessory Model 1688A Rechargeable Battery See may be ordered at ebe time of purchase of the Model 160B or may be purchased
and field installed at a later time if so
desired.
Wi*i"g. As a result, no modifications need
to be made to the Model 160B chassis.
a. "m, to Operate from Line Power. The Model 160B
can be powered from Line voltage over four ranges
from a minimum of 90" to a maximum of 25OV.
Table 2-1.
1. Set rear panel Line Switches to appropriate
positions as show" in Figure 5.
This sec~ian provides information
The Model 160B may be
If the accessory Model 1604 Re-
NOTE
me Model 1688A features plug-in
OPERATING INSTRUCTIONS
see
HOW TO MAKE INPUT CONNECTIONS.
3-3.
has two front panel terminals identified as "HI"
(red) and '3.0" (black). These terminals accomodate
banana plugs. alligator clips, spade lugs, bare
wirea, and other similar input connections. Leads
may be fabricated using a good quality capper wire
terminated by single banana plugs such as Keichley
Part No. K-5 or dual banana plug such as Keithley
Part NO. m-7. Ready-made test leads are also avail-
able from Keithley. Accessory Model 1681 Clip-o"
Test Lead Set includes two 40 inch long leads terminated by a banana plug and spring-loaded clip which
easily attaches co wires and terminals on pc boards,
Model 1683 Universal Test Lead Kit features in-
etc.
terchangeable probe tips for various applications.
'I%e Kit includes regular probes, alligator clips,
banana plugs. spade lugs, and phone tips. All-cow==
leads and teminarions are best for measurements on
the lm" and ln ranges.
3-4. HO" TO SELECT FUNCTION. Function is selected
by means of a single front panel Range Switch. llie
Range dial is marked in "en&wring" units for meas-
"remenf Of voltage (rn", V), C"r*e"t ("‘4, LL4, n!A), and
resistance (‘2, kn, M0).
the knob clockwise causes the Model 160B to switch
to a less sensitive range.
For each function, rotating
The Model 1608
3. Set front panel Power Switch to LINE.
b. "cm to Operate from Battery Power.
Install Mode11688ARechargeable Battery Pack.
I .
2. Check battery voltages at Teat Points A and
B to ensure thaL batteries are charged sufficiently.
1. If necessary, plug line cord info ac power
and set Power Switch to CHG to bring battery "altage up to useable levels.
4. When bartery level is sufficient, disconnect
line cord and set Power Swifch LO BAT.
switch
POSition
OFF
LINE
CHG
BAT
Line Connected
1688A not installed
OFF
ON
OFF
OFF
a. DC “catage. The voltage sectors of the Range
Switch are designated in millivolts ("IV) and volts
I", for full ranees from lm" to 1000". A full stop
it'the 1000 "&range prevents inadverranr switching to the nanoampere ranges by clockwise rotation.
b, Resistance.
Lange Switch are designared in ohms (n), kilohms
(kn), and megohms (MO) for full ranges from 1 ohm
to 1000 megohms.
CU**e"t. The current sectors of the Range
C.
Switch are designafed in nanoamperes ("A), microamperes (,,A), and milliamperes (mA) for full ranges
franI 10 nanoamperes to 1000 milliamperes.
Condition of Instrument
Line connected
16888 installed
OFF
ON
ON
ON
The resistance sectors of the
Line not connected
1688~ installed
8
0976
POWER
S203
-ZERO
R114
- RANGE
SlOl
FIGURE 10. Front Panel Controls.
3-5. HO” TO ME‘“LS”RE “OLTIICE.
ures dc “aleage in seven ranges:
lV, lOV, LOO”, and 1ooov. Maximum dc input is 1200”
dc + peak ac.
a. How to Select Ra”E,e.
selected by rotating the Range Switch to the appropriate position.
in millivolts CmV); four positions are direct-reading in voles (VI. Decimal point is selected by the
Kan,qe Switch. Polarity is automatically displayed.
If the input signal exceeds twice full range, the
display blanks (3 least significant digits) to indicate an “overran& condition.
Range
SeCti”
1000 v
100 v
10 v
,
100 mv
10 mv
*Maximum allowable input is 1200” dc plus
peak ac even though display can be read
beyond 1.200”.
Three positions are direct-reading
“01
1 v
1 In”
TABLE 3-2.
1tage Ranges Displ;
Max. Display
1999 *
199.9
19.99
1.999
199.9
19.99
1.999
The Model 1608 meas-
Im”, lOnl”, loom”,
Function and range is
d
b. How to Determine Accuracy. The xodel 16011 nccuracy is iO.I% of readina f 1 dirit.
a display reading of 1.005 volt dc will have a” ,a,,certainty of 10.1% f 1 digit or r.002 volts.
put resisrance in the dc m”de is 10 o,c~“,,cs. !,eaiurements from relatively high source resistnnccs
could cause an additional reading error.
of error due to loading can bc determined by rhc
following relatiansbip:
% error = 100 x RS i (R, + 10’)
where R, = Source resistance in ohms
For example, a so”rcc resistance “f 10,000 ohms Viii
result in a loading error of approximately 0.1% ai
reading.
The input current of the 1608 Cal” also cause
reading errors on the nlOSL sensitive vo1cage
ranges when high source resistances are present. For example, an input CUrrent of lOpA
and a so”rce resistvnce of MI! produce a”
error voltage of loll”.
c. Maximum Allowable Input. The maximum L”P”L to
the Model 1608 is 1200” dc + peak ac. On lrn”, lOn,V,
and lOOn,” ranges,
6OOV (12OOV momentary) dc + peak ac. ‘,‘hc ?,odel ,,SO”
can display dc voltages greater tba” r120O” but dnmage to the input is possible.
the maximum conti”uox,s input is
For enarno1e.
The in-
The dln”“,:i
1174
0
OPERATING INSTR”CTIONS
MODEL L6OB
IMPORTANT
The Model 1608 provides ac rejection (NMRR)
of greater than 60 dB on the highesf range.
However, a large ac signal superimposed on
a dc level could cause damage if the input
CO the Model 160" exceeds 1200 volts dc +
peak UC.
d. How to Zero the Display. To accurately zero
the instrument, place a low-thermal short (such as a
piece Of clean copper wire) across the input rerminals, set Lhe Range Switch to the lm" range, and adjust the front panel Zero conerol for a flashing "i"
sign at the display.
The display should then read
t.OOO, with some flicker of the least significant
digit due to noise and A-D converter uncertainfy.
Once the zero has been set accurately, there should
be little reason to rezero the instrumenf again soon
when making measurements on the 10~1" through 1000"
ranges. The time stability of rhe zero setring is
excellent, and in applications requiring continuous
operation of the Model 160B, the zero setting will
hold for months. The front panel Zero control is
convenienf when making measurements on fhe 11"" Range.
A test set-up and cables when connected to the 160B
may cause offset voltages because of thermoelectric
effects (see section 3-9). These offset voltages
might be only a few microvolts or several tens of
microvolts. In such situations, the Zero control
can be used to buck out any initial offsefs.
I.""
thermal cabling and connections should be used whenever possible. The instrument zero can also be check
ed, and adjusted, by shorring the input on any range
(voltage, current, or resistance).
me zero c**t*01
will have varying effects on the differenr ranges
depending on the sensitivity of the input amplifier,
but the zero control can be used in this manner.
Again, it should be emphasized, that for most meas-
"remene~ with the Model 160B, the Zero control can
be set once and then left untouched. (See also ?ec-
tion 3-6c "LO" Ohms Zeroing").
NOTE
With the input open 0" the lm" Range, the
Model 160~3 display may show a reading as
high as i.100. This 19 equ*va1ent to an
offset currene of lo.opA.
If the display
shows a reading grearer than t.100, then
the internal potentiometer, R121, should
be readjusted. Typically, ehe offset current will be less than 5p~.
HOW TO MEASURE RESISTANCE. The Model 1608
1-6.
measures resistance in 10 ranges: lsr, 1on, 10011,
Ikn, IOk&?, lOOk0, IM,,, lOMn, lOOK,, and 100011!2.
a. HO" to Select Range.
Function and range is
selected by rotafinf: the Ranae Swifch LO rhe BPPTOpriate position. Three posi;ions are direct-reading
in ohms (n): three positions are direct-reading in
kilohms (kn); four positions are direct-reading in
megohms (MQ) Decimal point is selected by Range
Switch. If the input signal exceeds twice full range,
the display blanks to indicate an "overra"& condl-
ti**.
TABLE 3-3.
Resistance current Ranges
Range Max. Impressed
setting LIiF3play units current
1. n 1.999 ii I InA
10 n 19.99 n lti
1 MI1 1.999 Mn 100 “A
10 Mn 19.99 MO 10 "A
100 Mr! 199.9 Mn I"‘4
1000 M* 1999 MO 0.1 "A
b. How to Determine Accuracy. The accuracy of cbe
Model 1608 is specified in terms of a nercen~ of
reading and a p¢ of range. For example, a display of 1.000 kilohID (kn.1 will haw an uncertainty
of ~0.004kQ.
C. HO” to Measure “LOW” ohms. when making measurements on the ln, lOn, and 1OOn ranges, rhe Model
160B is to be zeroed on the IQ range. The zeroing
is accomplished by shorting the test leads together.
and adjusting the display for a flashing + and -
.ooon. By zeroing the instrument in this manner,
lead resistance of 200 mill.iohms (minimum) can be
compensated for. The instrument must be rezeroed on
the lil range each time a different set of iese leads
is used. Before making meaS"reme"tS right *t the input rerminals (no test leads used), rhe instrumene
should be zeroed on the iii Range after placing a
short, such as a piece of copper wire, across the
binding posts. Copper leads and clips are best for
making measurements on the ln Range, because the
voltage drop across a In resistor is only Im".
CAUTION
e. 80" to "se Model 1601 AC/DC Probe.
measuremenfs, connect the Model 1601 accessory K/DC
Probe to the Model 1608 inpur terminals.
Range to desired voltage range.
to AC.
"se the probe tip plus ground clip to make
Set switch on probe
connections to circuit under eesc.
complete specifications.
f.
How to "se Model 1682 RF Probe.
measurements, connect the Model 1682 Probe to the
Model 160B input terminals.
Set the Range to desired
TO make ac
Set the
see section 5 for
To make rf ac
voltage range. Maximum allowable input is 30" *Ins
ac, 200” dc.
10
Care should be taken when making resistance
measurements in circuits which may have voltages on capacitors, etc. or "here line voltage is present. Although the Model 1608 is
fully protected against accidental voltages
up to 250" rms in resistance function, if
higher voltages are applied, damage may occur.
1174
-FUSE SHOWN FUSE SHOWN
TWICE ACTUAL SI
Range Max.
setting IDisplay Units
I,0 nA 19.99
100 nA 199.9
LO
100
1
1.
LB.4
,lh
UA
InA
1.999 II‘4 1040
19.99
199.9
1.999 n!A 10 il
Il.4
IL4
irA
UA
s,,une R*
10 rnA 19.99 In.4 I. 0
100
1000
lx.4
mi\
199.9 mA 0.1 !1
1.999
ti
1060
10%
10311
10%
0.1 G
OPERATING INSTR”CTIONS
MODEL 160B
d. HOW to "se the Model 1651 Current Shunt (for
meaS"remenfS to SOA). current measuremenf capability
Of the Model 160B may be extended to 50 amperes
through ctle use Of accessory Model 1651 SO-Ampere
shunt.
The Model 1651 permits 4-terminal connections
to minimize meaeuremene error.ciue to lead resistance.
To use the Model 1651, connect the voltage sensing
leads eo the Model 160B input terminals. Connect
separate current leads (not furnished) beuveen xhe
source and the large hex-head bolts on the Model 1651.
The current leads should be rated for currents up to
50 amperes. me Shunt resistance is 0.001 ohm, vhich
produces a sensitivity of lmV/Amp. As examples, 10
amps current results in a lOIn" drop on 1Oln" RANGE,
and 30 amps yields a voltage drop Of 3Oln" which can
be read on the loom" RANGE. Power diss*paCed in the
shunt is 2.5 watts at 50 amperes.
3-8. NOISE CONSIDERATIONS.
The 1imic of resolution
in voltage and current measurements is determined
largely by rhe noise generated in the source. stray
low-level noise is present in some form in nearly al1
electrical circuits. The instrument does not distin-
guish between stray and signal voltages since it measures the net "olfage.
when using the lnl" and 1omv
ranges, consider the presence of low-level e1ectrical phenomena such as thermocouples (thermoelectric
effect), flexing of coaxial cables (triboelectric
effect), apparent residual charges on capacitors
(dielectric absorption), and battery action Of t"O
terminals (galvanic action).
3-11. AC ELECTRIC FIELDS. The presence of electric
fields generated by power lines or other sources can
have an effect on instrument operation. AC voltages
which are very large with respect to the full-range
sensitivity could drive the input amplifier into saturarion, thus producing an errOneo"S DC OUtpUt. At
line frequency or twice line frequency, the insLrument is capable of rejecting AC voltages whose peak-
to-peak amplitude is equal to the full-range DC sell-
sftivity on the loom" through 1OOOV ranges. This
level of interfering AC signal will produce no more
than 1 digit error.
On the lm" and 1OmV Ranges, the
instrumenf can reject line frequency and twice line
frequency signals whose p-p amplitude is equal CD 10
eimes the full-range sensitivity. Far example, on
rhe ID," Range, a 1OmV p-p, 50 Hz signal will produce
no more than 1~" (1 digit) DC erroi-.
Peak-to-peak AC
voltages greater than 1x the full-range sensitivity
o,, the 1OOm" through 1000" ranges, the 10X the fullrange sensitivity on the lln" and 1omv ranges will
cause clipping in the AC section of the Model 160B
input amplifier.
For this reason, shielding is re-
com,,,ended when making sensieive DC voltage measure-
menrs, or when making measurements from high so"rce
impedances.
(See Shielding, Section 3-12.) The inserunlent is also capable of rejecting frequencies
other than power line frequencies.
There is one problem to consider; however, the input amplifier of the
Model l6OB uses a modulator to convert DC signals LO
AC signals before amplification. The drive frequency
of this modulator is 220 HZ nominally, f approx. 5%.
Interfering AC signals with frequencies equal to the
modulator drive frequency, or mu1tipl.e~ fhereof, will
appear 8.3 modulated DC, and produce large DC errors.
3-9.
THERMAL EMFS.
Thermal emfs (thermoelectric
potentials) are generated by thermal differences between two junctions of dissimilar metals. To minimize the drift caused by thermal emfs, "se copper
leads to connect the circuie to the instrument. The
front panel ZERO control can be used to buck out a
cmstant thermal offset "aleage if necessary. The
Keithley accessory Model 1483 La" Thermal. Connecrio"
Kit contains all necessary materials for making very
low thermal copper crimp connections far minimizing
thermal effects.
3-10.
MAGNETIC FIELDS.
The presence of strong magnetic fields can be a potential sw.,rce of ac noise.
Magnetic flux lines which CUt a conductor can produce
large a-c noise especially at power line frequencies.
The voltage induced due to magnetic flux is propor-
tional fO the area enclosed by the circuit as well
as the rate of change of magnetic flux. For example,
the motion of a 3-inch diameter loop in the earth's
magnetic field Will induce a signal of several tenths
of a microvolt.
one way to minimize magnetic pickup
is to arrange all wiring so that rhe loop area enclosed is as small as possible (such as twisting inpur leads). A second way co minimize magnetic pickup
is to use shielding as described in Section 3-12.
3-12. SHIELDING.
a. Electric Fields. Shielding is usually necea8arv when the insrrument is in the eresence of verv
l&e a-c fields or when very sensi;ive measuremen;s
are being made. The shields of rhe measurement circuit and leads should be connecee* together to ground
at only one point.
This provides a "tree" configura-
tion, which minimizes ground loops.
b. Magnetic Fields. Magnetic shielding 19 useful
where very large magnetic fields are present. Shield-
ing, which is available in ehe form of plates, foil
or cables, can be used to shield the measuring circuit, the lead wires, or the instrument itself.
C. Other Considerations.
1. Voltmeter Measurements. Use shielded input
leads when source resiseances are greater than 1
kilohm or when long input cables are used.
2. Current Measurements. On the mA and PA current ranges, no special shielding precautions need
be taken. However, an the 100 and 10 nanoampcre
ranges, shielded input leads are recommended.
3. llesiatance Measurements. Shielding of input
leads and source are recommended for measurements
on the 10 megohm through 1000 megohm ranges to prevent errOneO"S readings.
12
1174
FIGURE 12.
Voltage Measurements Using Model 1601 AC/DC Probe.
CURRENT TERMINALS
VOLTAGE TERMINALS
1
1174
;*
VOLTAGE LEADS
FURNISHED
OPERATING lNSTR"CTlONS
I
i+
--~ EXTERNAL
MODEL 1608
MODEL 1608
E%'
DC
FIGURE 14.
3-13. HOW TO USE THE ANALOC
has an analog output of il volt at full-range (non-
inverting) at up to 1 milliampere (2mA at 2 volts)
for recording or monitoring purposes.
analog output enables the Model 1608 to be used as
a la"-noise, low drift DC amplifier.
TABLE 3-5.
hi" at liNALOG OUTPUT
Range
1 In"
1.0 rn"
100 In"
For off-ground operarim, the analog output should
be connected only to equipment capable of operating
off-ground also.
is at the same poeential as the "LO" input terminal
of the Model 160".
3-14. HOW TO USE MODEL 1608 OFF-GROUND. The "LO"
terminal can be operated off ground at potentials
Of up tLl 11200".
to power line ground is specified at lOOOMn, or 10'0
(shunted by 300@).
tance from I.0 to GNE is two decades greater than
log!? (lO"O).
operating the Model 1608 off ground results in very
1.itr1e loading (from LO to GNU) of a floating source.
AC 1000" above ground, the Model 1608 will require,
typically, only 1Onh from the source.
i.solation also accounts for the high common-mode re-
x1000
x100
x10
The low side of the analog output
Isolation franI ehe "LO" terminal
Ty,,ically, the isolation resis-
Because of this excellent isolation,
Gain
OUTPUT.
Full Range
The Model 16OB
Also, the
OUtpUt
1"
1"
1"
The
excellent
CASE 8'
GROUND
Floating Operation
"across lk
The "isolation" capacitance from LO to GNC is impor-
tant when AC common-mode signals are present. in
the Model 1608, rhis capacitance is specified at 300
pF maximum.
has a reactance of approximately 10Mli. With the HI
terminal driven and a source impedance of lkll, R
1OOOV p-p, 60 Hz, common-mode signal will produce a
voltage of only loom" p-p across the Model 1608 in-
put terminals. This lOOmV p-p signal will be lurtbcr
rejected by the input amplifier and A-1) converrer SC
that the total rejection at the digital display is
at 1easL 140 LIB. At lower levels of *C common-mode
signals, the total rejection at the display is even
greater.
should produce only about 1 digit errur on the lh"
Range for a total rejection of approx. 160 dR. (IiT
driven, IkQ source impedance.1 WiCh both AC and IDC
common-mode signals, rejecti,, is lnuch greater than
specified when the Model 160B LO terminal is driven,
rather than the HI rerminal. Where there is a need
for even greater isolation from LO (0 power Line
ground, or where there is a need fo float at porcn-
tials greater than UOO volts above power Line ground
the Model 1688A Battery Pack should bc used.
TYPICAL
>lO"n ISOLATION
I
At a frequency of 60 HZ, 300 picofarads
For example, a 60 Hz, 100" p-p signal
RESISTANCE
= I x lkn = 10-a x 103 = lOll"DC
14
MODEL 160B
OPERATINC INSTRUCTIONS
out&t IO& “0” s &Sure f0 0~tp~f LO.
OUtput Device: 2N5089 or equivalent (greater than
25volt breakdown, less than 0.5 volt while sinking f15 milliamperes).
REMOTE CONTROLS:
Strobe: 6 lines for serializing in multiples Of 4
bits. Logic "1" inhibits controlled OUtpUt lines.
i’
O"t"UC Hold:
ing af DigitLOutput.
Display Hold:
reading (escept far polarity and decimal) at
“igital output and Display.
0976
I.oeic "0" retains data from last read-
Logic “0” retains data from last
15
CwmATING INSTR”CTIONS
MODEL 160B
3-15.
HOW TO USE MODEL 16028 DIGITAL OUTPUT.
a. General.
FIGURE 16.
The Model 16028 Digital Output provides
Exploded View of Model 1608/1602B
binary-coded decimal (BCD) ouepufs and several control
inputs.
installed" or "field-i"srallable".
2his accessory is available either
The Model 1602B
"fsctary-
consists of a single printed circuit baard (K-352)
with input and integrally mounted "u~pue ca""ecfar,
and an ouf,,"t mating cm,ne~tc,r with hoad.
b. Installation of Model 1602B.
The Model 16028
ia installed inrernal to the Model 160B and is DOW~Ied by the Model 1608 line operated power supply:
NOTE
It is not ineended
used simulta"eously with the Model
that the Model 16028 be
1688A
Battery Pack. To use the Model 1602B. the
Model 1688A muse be remaved and set aside.
It is possible, however, for the u8er eo
make his own wiring modifications 8" that
the
Model 1688.4 Battery Pack can power rhe
Model 160B while lacated outside the Made1
160B.
DISCONNECT LINE COBB BEFORE OPENING
THE TOP AND BOTTOM CO"ER.
LINE VOLTAGE ON THE CHASSIS
REPRESENTS A SHOCK HAZARD.
CAUTION
To install the Model 16028. turn the Model 160B "ver
so mar: me DOttOm cover races up. Locate and loose”
.
four slotred scre"s as shown in Figure 4. The 8cre"B
are "captive" and should "at be completely removed.
Once the screws are loosened,
covers ragether and turn Wodel 1608
CO"Br- is up.
Carefully lift off rhe top c"ver and
disconnect the wires to the Analog Output.
hold
top and bott"m
so chat the top
Locate 16-
pin receptacle 5201 o" the ma,." circuit board W-349).
Plug the mating c""necLor (P301) from the Model 1602B
into 5201, after checking that pin numbers are corresponding. Locate Spin plug P208 on the main circuit
b"ard (PC-349).
P208.
Be sure that the
"A" af 5303.
Connect 5303
from the Model 1602B to
“A”
of PZOE lines up with the
Place Model 1602B board o" four spacers
with cables positioned as shown in Figure 17. Rem"ve
digital-output c"ver plate fram Model 160B fop c"ver.
Place t"p c"ver back on instrument, after reconnecting
Amlog output wires. Turn instrument 0"e-L and tighten
four slotted screws.
C.
Pi" Idenrif*cae*on of FleaI? Panel Digital OutpUt
connector.
(5302)
external equipment.
The Model 1602B uses a 37-pin connector
Co provide all input and output connections to
Pins are identified as shown in
Table 3-7.
16
0976
A DE
PZO8
(PC-3491
DIGITAL OUTPUT
CONNECTOR 5302
,J303
FROM PC-352
5303
1174
P301
(FROM ~~-352)
FIGURE 17.
Installatian of Model 1602B.
17
OPERATING 1NSTR”CTIONS
MODEL 1608
19
OUtpUt Data Lines.
d.
FIGmw. 18.
BCD (l-2-4-8) open-collector
Rear Panel Digital OUtpUt Connector.
positive logic represents each of 3 dv&a, OVerrange
digit, ""erload, decimal position, and polarity.
1.
open-collector output.
The output data buffers
of the Model 1602B consist of CMOS NOR gates driving
individual "open-callector" transistors. A main
fearure of open-collector outputs is the ability to
interface with a variety of data processing equip-
ment types including printers and campucers. The
open-collector output operates in eirher a saturated
(low-impedance) state or an open (high-impedance)
state.
including TTL, DTL, RTL, and CMOS.
It is compaCible with many Lypes of lagic
The Model 16028
OUtpUt lines can operate at voltage levels up to
+ZOV, and hence can interface directly with CMOS
circuits operating with +15V supplies.
I" most cases,
a pull-up resist"= is needed to define the "open"
or logic "1" state.
The value will depend on the
capacitive caupling among wires in the cable and to
other circuitry external to the Model 160B/1602B.
For operation with S-volt power supplies, a value
of Sk to 1Okn is usually sufficient, and the minim"!" value is about 3OOn. The Model 1602~ printed
circuit board is designed so that pull-up resisto=8 can be mounted on the board itself (rather
than added externally). One end of the pull-up
resistors can then be connected to an excerna,.
power supply at pin 18 of the 37-pin output conneceor (5302).
The PC board spacing is designed
for l/4 watt carbon resistors.
1
The open-collector configurafian can be
4.
used to connect multiple "utputs to one input of
a data-processing system. For example, if the
16028 is ineerfaced to a 16-bit compute=, ehe 3
BCD digits may be presented to a lh-bit data =e@seer in the computer by setting lines 25, 5,
and 24 t" logic "0" at a given time.
If the DP,
overload, polarity, and 1 x lo3 outputs are wired
Model 1602B Connector Pin Ideneification.
TABLE 3-7.
1 Not Used
2
Not Used
3 DISPLAY HOLD
4 STROBE, ST-6
5 STROBE,
6
STROBE,
ST-2
ST-5
7 LO
8 DP-3 (100.0~
9
10
11
m-1 coooj
FLAG
OVERLOAD
12 DATA. 8 x 10'
13 DATA; 2 x 10'
14 DATA, 8 x lOI
15 DATA, 2 Y 10'
16 DATA. 8 x 10'
17
DATA; 2 x 10'
18 EXT VOLTS
19 Not Used
20 Not USed
21
22
Not Used
FLAG RESET
23 BCD HOLD
24
STROBE.
ST-3
25 STROBE; ST-l
26
27 w-2 (10.00)
28 m
29 POLARITY
30
STROBE, ST-4
DATA, 1 x LO3
31 DATA, 4 x LO2
32 DATA, 1 x lo2
33
34
35 DATA, 4 x 10'
36 DATA, 1 x lOa
37 Not USed
_- __-__-_--___
DATA, 4 x 10'
DATA,
1 x IO'
18
1174
MODEL 1608
"PERATINC INSTRUCTIONS
25
36
I-
STROBE 1
I x in0
17 2 x 100
35 4 x 100
16 8 x 100
5
34
15
33
14
24
32
13
31
12
I
18
STROBE 2
1 x 101
2 x 101
4 x 101
8 x 101
STROBE 3
1 x 102
2 x 102
4 x 102
8 x 102
EXT. VOLTS
b). When a particular 16”B/16028 is being op-
eraied, line 6 may be set to logic “O”, enabling
FLAG and FLZG. when the data from this particu-
lar 160BI1602R is not of interest, line 6 may be
set to Logic “1”. which disables FLAG ant, FnE.
men, ametIer device may use the same line for
interrupt or polling.
Pi” NO.
26
30
11
!
STROBE 4
1 Y 103 (““ERRANCE)
OVERLOAD
29 POLAKI'TY
6
10
28 Fix
!
1
STROBE 5
FLAC
Name
i
Since the dafa is in 4-bLr or smaller
cl.
groups, all output dafa from the 1602B may be
sequentially connected to a 4-bit bus using the
same technique described above. This is useful
when interfacing to progralmnable calculators and
logic systems where bit-parallel, character-serial data tranSmiSSi0” is used.
3. nverrange Digit, Overload, and Polarity.
These three lines are controlled by the same strobe.
me presence of the overrange digit is indicated by
a “high” output. An overload condition is hdiC.9
ted by a “low” output. For polarity, “+” is repre-
DIGITAL OUTPUT DIGITAL OUTPUT
LATCHES UPDATED LATCHES UPDATED
I
/
I
I
-f----
~~I.-
2”
EXPLANATION OF EVENTS*
Conversion cycle #1 complete.
1).
2). Digital Output latches updated with data from conversion #l. "Flag" line goes
from "0" to "1".
"BCD Hold" goes low (after "Flag" line has gone high).
31.
"Flag" line goes high.
4).
sion #2, because "BCD Hold" line is low.
"BCD Hold" released (after "Flag" line has gone high).
5).
"Flag" line goes high.
61.
Flag Reset" goes from "1" to "0". causing the "Flag" to go from "1" to "0".
"Flog" line goes high even though "Flag Reset" line is still low. Digital Out-
latches contain data from conversion #5.
put
FIGURE 19. Timing Diagram for Model 1602B.
Digital Output latches still contain data from cower-
Digital Output latches now contain data from conversion
Latches in LSI circuit (in Model 1608) updated.
MODEL 1608
f. Output Control Lines. The Model 16028 has six
Strobe lines, a Flag Reset line, a BCD Hold, and a
Display Hold.
1. Strobe Lines. All data outputs are grouped
into 3- and 4-line groups. .Eachgroup is controlled
by a "Strobe" line.
Flag and Flag are also controlled by a Strobe line. Logic "1" on a Strobe line
turns all the transistor "open-collector" outputs
off in a particular group. A logic "0" o" a Strobe
line enables the data to determine the logic states
Of the group.
3-s.
Section d (above) gives additional information
'rhe groupings are indicated in Table
on open-collector outputs.
Flag Reset Line. Flag may be reset at any
2.
time by setting Flag Reset to logic "0". The Flag
is reset by the transition of the Flag Reset line
from logic "1" to logic "0". The signal at the
Flag Reset line may be either a pulse or a level.
When a pulse is used, the pulse width should be at
least l"&C.
If a level is used, a logic "0" on
the Flag Reset line will not prevent the Flag from
going high when the next "good data" is available.
BCD Hold. If this line is set to logic "0".
3.
the data at the Digital Output will "at be updated
as conversions are completed. Flag will operate
normally.
When BCD Hold is returned to logic "1".
the Digital Output will be updated normally. New
data will be available beginning with the next
logic "0" to logic "1" transition of the Flag.
1
me BCD Hold is not synchronized with a particular
point in the conversion cycle. when the BCD Hold
line is set to logic "O", the "updating" pulses
to the Digital Output latches are blocked. If
the BCD Hold is activated during the time when
Flag is normally low, either "one of or some of
the Di@tal Output latches will be updated. If
the BCD Hold is released during the time when
slag is normally Low, only some of the Digital
Output latches may be updated at the next Flag
high.
For these reasons. the SCD Hold should
be acrivated and released only during the time
when the Flag is normally high (this is approx-
imately 200mS regardless of whether Flag Reset
is used). The BCD Hold should be activated after
Flag has gone from low to high; the BCD hold
should be released after the Flag has gone first
from high to law and then from low to high.
NOTE
The SCD Hold has no control over the "DP"
(decimal point) lines.
The logic states
of the data on these lines is determined
by the setting of the Model 160~ ~a"Se
Switch.
The Range Switch setting should
not be changed while the Digital OUtpUt
is in a "Hold mode".
4.
Display Hold.
This "Hold" line affects the
Model 160B LSI circuit directly. When this ""aid"
is applied, the numerical data present at the Model
160~. display and at the Digital Output is "at updated as conversi~na are completed. Tne Display
Hold line is activated by a logic "0". When Display Hold is returned to logic "I", numerical
data at the display and Digital Output will be
updated normally.
The Display Hold is not synchronized with a par-
ticular point in
the conversion cycle.
If the
Display Hold is activated during the time that
the Flag is normally low, numerical data from
either the moot recent conversion or the co"ver-
sion previous to it may be retained. A similar
situation can occur if the Display Hold is re-
leased during the time when Flag is normally law.
The Display "old should be activated after Flag
has gone from low to
high:
the Display Hold
should be released after the Flag has gone first
from high co law and the" from low to high.
like the SCD
Hold,
it is very unlikely that ac-
Lln-
tivating or releasing the Display Hold during
Flag low time would produce mixed data at Cbe
display and Digital Output. If it does not
matter whether the retained data is from the
most recent Conversion or the co""ersio" immediately preceeding it, the Display Hold can be
applied arbitrarily. I" any operating system
however. the Display Hold should be synchronized
in some way "ith the Flag.
1174
FIGURE 20.
tick Mounting af Model 160B
3-16.
now TO RACK MOUNT THE MODEL 160B. The Model
1010 Rack Mounting Kit adapts the Model 1608 for
standard S-114 in x 19 in. rack mounting, with 11 in.
depth behind the front panel.
a. “sing two Phillips screws (Item 7) attach sup-
port Plate (Item 2) to Front Panel (Item 1).
b. “sing four Phillips screws (Item 7). attact,
left and right side Brackets (Items 3 and 4) to Front
Panel (Item 1).
d. Assembly of rack hardware ia complete except
for mounting of IrlStrune”t.
22
0875
MODEL 1608
T,,E”RY OF OPEKnTI”N
SECTION 4.
THEORY OF OPERATION
1174
CURRENT
SHUNT
RESISTORS
OPTIONAL
DIGITAL
OUTPUT
IlV OUTPUT
.‘i
MODEL 160B
summary of Voltage sensitivity.
TABLE 4-1.
Attenuator Amplifier Full-Range
Range setting SenSitiYity Gain
lrn" --- 1 m" Xl000
1" In"
100 m"
1 ”
l/l"0
__-
1" In" Xl""
1"" lnv Xl"
1" In" X10"
10 v l/l"" 100 In" x10 1 volt
100 " 1/10,0"" 1" mV
1000 " 1/1",""0 100 mv x10 1 volt
3. Filfer Network. Basically, the filter is a
l-section RC low-pass filter made up of R116, R117,
and C104.
Rl16 and R117 in series have a nominal
resistance value of 112kn. At 5" Hz, Cl04 (.S$F)
has a reactance of approx. 6k0, and with the 112kn
produces an attenuation of apprax. 20 co 1. This
attenuation gives the Model 160B a normal-mode rejection spec of 60 dB above 1 digit on the 1OOmV
range, as an example. "6" dB above 1 digit" means
that the Model 16"B can re,ect a 1OOm" p-p, 50 Hz
signal an the 1O"mV range with no more than a 1
digit error. 1""mV p-p at 5" Hz would be reduced
to 5mV p-p at the output of the filter.
This 5mv
p-p, after "chopping" and amplifying is enough to
cause amplifier "104 to reach its maximum allowed
OUtpUt level.
A signal greater than 5m" at the
oUtpUt of the filter causes "104 to saturate. when
Saturation 0cc"r-s) significant DC error signals can
he produced at the output af ehe overall amplifier.
4. Modulator Circuit. This circuit converts an
input dc signal to an ac signal with a fundamental
frequency component of approx. 22" HZ. The fre-
quency of 220 Hz was chosen because this frequency
is not harmonically related to either 50 Hz or 60
HZ. The circuit utilizes a dual MOS-FET (Ql"2A
and Ql"2B) connected in a series-shunt configura-
tion. This type of eeries-shunt modulator maintains high input impedance.
5. AC Amplifier. The ac amplifier uses a lownoise integrated circuit, "104. The amplifier feedback network provides a gain of approx. 2000 at the
modulating frequency of 220 Hz, while maintaining
a gain of 1 far amplifier ("104) dc offset voltages.
6. Demodularor Circuit. The demodulator is synchronized with the input modulator. A JFET, 4103,
with low on-resistance is used to alrernately atten-
uate or pass ehe signal present at the output of ac
amplifier "104. The negaeive portions of the 22"
Hz ac signal are allowed to pass which produces a
"half-wave-rectified" negative dc signal at the input to dc amplifier, "105.
7.
DC Amplifier. This amplifier is composed of
resistors R128 and R129, capacieors Cl13 and Cl14,
and integrated circuit "105. The integrated cir-
cuit provides sufficient gain to bring the foral
open-loop dc gain of the overall amplifier to a
minimum of about 20 million. The feedback capaci-
tor. Cl13 and Cl14 in series, was selected to give
a noise bandwidth of apprax. 0.5 Hz fo rhe overall
amplifier when it is used at a closed-loop gain of
10"".
The integrated circuit, UlOS, must be capa-
Amplifier F"ll-Ra"ge
DC output
1 Volt
1 volt
1 volt
1 volt
X10"
1 Volt
ble of driving the feedback network (R160.4, B, C,
and D),
ehe A-to-D convereer, and ehe Analog Output
to t2 VDC.
8. Modulator-DemodulaCar "rive Circuit. CMOS
inverters, U103A and "1038, provide oppoatte phase
square .,,aves used to drive MS-PET modulator tran-
siseors Ql"2A and QlOZB. Inverter U103B also provides a drive signal for demodulator JFET Ql"3.
Resistors Rl21, P.122, and R123, and capacitors Cl08
and Cl"9 effect the rise and fall times of the
square-wave drive signals. R121 adjusts the rise
and fall time of Ql"2A only, 80 that the total
charge, both posifiva and negative, transferred to
the input can be minimized. Any net charge at the
input creates a current, which in the Model 160B
is specified to be less than il"pA.
The frequency
of the drive signal is determined by the clock cir-
cuit and LSI "201. Circuitry in LSI "201 divides
down a nominal clock frequency of 9680 Hz to produce 22" Hz.
9. OffseE Current Zero Circuit.
See section
4-Z&.
1". Front Panel Zero. The voltages across potentiometer R114 are set-up by a seable zener reference diode, VRl"1. and an IC op-amp. "102.
These voltages are approximately +2 "DC, which give
RI14 an adjustment range of approximately 45"uVolcs.
A typical Model 1608 has an internal offset of about
-l""uValts in the chopper amplifier. Hence. adjuscing the Front Panel Zero from end to end "ill typi-
cally produce aboue +lZS,,"olrs and -325v"olts.
This
"extra" adjustment a~ ehe negative end of the range
allows sizeable positive offsets to be compensated
for, as is the case when the Zero is used for tese
lead compensation on the law-ohms Ranges. 200~ of
test lead resistance will produce +ZOO,,"oles of zero
offset, which can be "bucked o"t" by the Zero con-
ti-"1.
(See also Section 3-5d). Zeroing of the
chopper amplifier output is actually accomplished
by having the "Zero" circuit either source or sink
whatever current is present in feedback resistor
R160". For example, an Offset voltage of -1llu" on
the feedback line produces a c"rrenf of -1,A in resiseor R16"" (111.135n). A voltage of -1u"olt at
the wiper of Zero poteneiometer RI14 will produce
an equal current Of -1uA in resistor R115 (M").
With fhts zeroing scheme. for the chopper amplifier
output to be at zero, the voltage at the feedback
line will always be offset from the voltage at the
input by a constant, say for example. -1llu"olts.
(The feedback line connects to the junction of R16"C
and R160D).
24
1174
ANALOG AMPLIFIER
INPUT HI
INPUT LO
?I7
INPUT HI
INPUT LO
AC AMPLIFIER
ATTENUATOR - MODULATOR - A,
FIGURE 22. DC Voltage operation.
- DEMODULATOR
RANGE
SWITCHING
DC AMPLIFIER
w
I ',
OUTPUT
INPUT HI
INPUT LO
0
f-i+7
'I
FUSE
ox0
1
OVERLOAD
PROTECTION
FIGURE 23. Resistance operation.
Lr
RANGE SWITCHING
I
I
I
ANALOG
AMPLIFIER
1174
C.
“hnmlecer circuitry. This circuitry provides a
number Of fixed currents by using a Stable voltage re-
ference, a differential voltage amplifier, and a ser-
ies resistor.
voltage overloads Of 25” volts at the Model 1608 input terminals.
1. “oltane Reference. An adjustable divider made
up of resistors R1.05, 11106, and RI’“7 provides an
output of approximately -1”“nl” from a stable zener
reference, “Rl”1.
inverting input of the differential voltage ampli-
fier.
amplifier ourput is 311 accurate +l”“m” when the input terminals of the Model 1608 are shorted.)
resistors and 1C op-amp are connected as a unity
gain differential amplifier; resistor ~11” adjusts
the gain accuracy.
cuit is connected to a reference voltage.
inverting input is connected to the feedback volt-
age of the analog amplifier.
voltage is esual to the innur voltaee of the analoe
The circuit is also proLecte* against
This divider is cannected tcl the
(The divider is actually adjusted so that the
This ampli-
l‘he inverting input of the cir-
me *cl”-
Because the feedback
4. OverLoad Protection. when a positiw overload voltage up CO f25O “DC is applied to the Model
1608 input terminals, CR101 is reverse biased and
prevents damays to IC amplifier, “101.
from the +250 “DC source is ttmxgh a current setting resistor and R102.
which prevents excessive currents in the low-value
current-setting resistors.
load voltage up to -250 VDC is applied to the input
terminals, Ql.O1 is biased to limit the current to
appvaximate1y 2mA. Maximum current possible from
“101 and Rl”2 at -250 “DC is approximately Z.Sti,
which is low enough to protecf the low-value current
seccing resistors.
positive overloads, and an approximate -6V zener
drop for negative overloads.
of U1”l.
4-3. ANALOG-TO-DIGITAL CONVERTER.
digital converter includes the following circuits:
an “absolute-value” circuit, a polarity detector, an
integrator and threshold detector, a,, ISI circuit, a
clock, an LED display, and display drive circuitry.
a. Absolute-value Circuit.
a positive DC output voltage regardless of the polarity of the input voltage.
by:
“0”f = k lhnl
K102 has a value of 49wn
when a negative over-
Q106 has a normal diode drop for
It protects the input
‘This circuit produces
The relationship is defined
where k = +1
current flow
me analog-co-
1
26
1174
ANALOG SIGNAL
1V = FULL RANGE
R16ZA,R134
TO POLARITY INDICATOR
LOGIC
1
R162F,G
Actual operation is as follows: A positive dc voltage
at p*n 12 of K162 produces an equal dc voltage at the
output of Ul”7, and also causes the output of U106 to
go negative. When this happens, CR105 is reverse
biased, and “107 is effectively isolated from the ac-
tion of “106. A negative dc voltage at pin 12 of RI62
causes the autput of “106 to 80 positive; the output
of U106 must go sufficiently posirive to forward bias
CR105 and drive the input of “107. In this situation,
U107 and Ul”6 together function as a two-stage invert-
ing amplifier. The gain of this inverting amplifier
is accurately set to -1 by internal adfustmenf R134
(“-DC CAL”) and rcsisrors R162A, R, and H. K135 (“RECT
ZERO”) sets the zero offset voltage of “106 equal f0
-l/Z the zero Offset voltage Of “107. rfhus, the zexo
offset is the same for hot-h positive and negative dc
signals, and this zero offset can be compensated far
with the “DISPLAY ZERO”,
C117, and cl18 provide filtering of AC components pre-
sent in the input signal.
R136.1 capacitors ~115, C116.
J
1
TO A/D CONVERTER
b. Polaricy Defector.
cuit uses TWO transistors, “108C and U1”8D, of an IC
rransistor array. These transi~rors are used as a
simple differential-voltage amplifier with one,output
connected LO y~~wer supply common. A positive-going
output “f “106 callses the collector of transistor
“1081~ to go negative. When this happens, Q206 is
shut off, and the “+” segments of display DS201 ~r’e
aha shut off.
:he base of transistor u108D to be clamped at appraximately -0.7”. which shuts off the collector current
of “108D. AS a result, the voltage at the collector
of 11108” gaes to a level of approximately +“.,“, which
is sufficient to drive Q206 into saturation and turn
on the “+” segments of “S201.
0976
A negative-going OUCPUC of U206 CRUSTS
The polarity detection cir-
CS
TH
7 SEGMENT
DECODER
I 1
DISPLAY
OUTPUTS
i
TO
DISPLAY
Cl 20
28
LSI CIRCUITRY
DETECTOR
OCLOCK
1174
a
1 +TL;f.;./y i
IDENTIFICATION OF MULTIPLEX LINES
PIGURE 28.
curacy. Once the reference current is set, a” input
of 250m" is represented as 250 counts out of 2016,
and 1.999" is represented as 1999 counts out of 2016.
An input of 2v or greater causes the 3 least-signi-
ficant digits to blank.
NOTI:
one comp1ere con"ersio" cycle is 2048 CO"rLfS.
The six counter is able to count to 2016 be-
fore it is stopped.
CO"*ltS, the information in the BDC counter is
transferred into latches, and then the "CD
counter is reset to Zl?TO. 2048 CO""tS at a
clock frequency of 9680 Hz results in a total
conversion time of approximately 0.21 seconds
(which is equivalent to about 5 readingslsec.).
d. Clock.
timer, Ll202, hooked up far astable operation. Rexis-
t,,rs ,I205 and R206, together with capacitor C201, set
up a non-symmetrical square-wave with a nominal frequency of 9680 HZ and a duty cycle of about 5%. 4201,
along with R202, R203, and R204 is used to invert the
output of uzm.
"isplay. The Model 1608 digital readout is
e.
,nade up of three LED seven segment displays (DS202,
~203, and uS204) and one LED "21" display (DS201).
1. Display Multiplexing. The LED displays are
znultiplexed to minimize the number of interconnec-
tions, simplify the drive circuitry, and reduce
power consumption. The timing for the multiplexing
The clock circuit makes use Of an IC
During the remaining 32
Identification of segments and Multiplex Lines.
f
,,I
e
dp .
IDENTIFICATION OF SEGMENTS
is determined by the LSI circuit, L201. and is see
up such that each mu1cip1ex line is hi& for 8
clock pulses (;~pproximately 825uSec.1 and low for
24 clock pulses.
signated as TO, Tl, T2, and T3, and each line cun-
trols an LED display (See Figure 28). Circuit opera-
tion during a particular multiplexing interval. say
TO, is as follows: when TO is high, the oucpuc Of
"20% is 10". This produces a CUrrelIt in R218B Of
approximately lOmA which is sufficient to drive
Q202 into saturation, and effectively c"nnect 1~5201
to the f5" power line. Simultaneously, the LSI
circuit supplies the correct digital information
for DS201 to the display segment ciriuers.
circuit action the" occurs during the oe,,er multiplexing intervals --- 'i‘l, T2, and T3.
2. Display Drive.
signed to handle a variety of LED common-anode displays. Because 't~~nstant--current" drivers are used.
displays with different voltage drops per sewent
can be drive" without changing the circuit power
conaumptian. The driver* take the same current
from ehe C5" power supply regardless of whether
the display segment drop is 1" or 3.5". Actam
operarion of a particular segment, segment h for
example, is as follows: when the "A" 1inc of LSI
circuit "201 is high. the" the open-collector DUtput of buffer U204A is shut off.
voltage at pin 5 of resistor network R211 is spproximarely 11.3". which is also the voltage at pin 9
of transistor array "205. nssuming a base-to-emitter voltage of 0.7". Lhen the voltage at pin 10
Of "205 is approximately i4.6"; this voltage generates a 15,nA c,,rrent in the 400 emitter resistor.
I I
d
The four mulriplex lines are de-
b
c
The aan,e
The display drivers are de-
AS a result, LhC
0976
29
THEORY OF OPERATION
MODEL 1608
When the “A” line of U201 is low, then the output
of "204,, is also low, and the transistor current
source (pins 9, 10, and 11 of 11205) controlled by
"204A is shut off.
Transistor 4207, and ifs associaCed circuitry duplicates the operation of the other
six transisror current sourcgs.
The “decimal point”
lines of 115202, DS203, and OS204 are controlled by
the Range Switch, and the currents for the decimal
points are determined by R209, R210, and R211.
4-4. POWER SUPPLY.
the Model 1608 uses either line
power or battery power (when the Model 1668A is installed).
a. Line Power.
Transformer I’201 has two tapped
primary windings which are connected in series or in
parallel depending on the position of line switches
5201 and 5202.
4-5-6 for all settings.
Fuse F201 is in series with winding
Fuse ~202 is connected only
when winding l-2-3 is connected in parallel with wind-
ing 4-5-6. The secondary of I’201 has two tapped windings. T,,C lower caps (11 and LO; 8 and 7) are used
in line mode. 'The upper taps (12 and 10; 9 and 7) are
used in charge mode.
1. +5v Supply.
In LINE operation, the ac “oltage between transformer leads 10 and 11 is full-wave
rectified by CK203. The filtered full-wave dc volt-
age (approximately 10”) is regulated by integrated
circuit u207.
The outpur regulated voltage is 5”
15%.
2.. -12” Supply. I” LINE operation, the voltage
between transformer leads 7 and 8 is full-wave rec-
tified by CR204.
The filtered full-wave dc voltqe
(approximately 18") is regulated by integrated cir-
cuit U208.
The regulated output voltage is -12”
i5%.
b.
Battery Power. When “ATTERY mode is selected,
the Mode11668ABattery Pack is connected into the inputs of u207 and U208 while the line voltage is disconnected at the secondary.
vide input power for the l 5” supply.
tales provide input power for the -12” supply.
The 8.4” batteries pro-
The 16.8" bat-
Bat-
tery test point h provides a measurement of the 16.8”
battery supply with respecr to power supply low.
Therefore, the voltage measured is the difference bc-
tween the battery supply and the -12 vole uurput which
is approximately +4.8 volts. nartery LCSC point R
provides a measurement of the 8.4” battery supply.
Battery Char&q. In the Charge mode, rbe 8.4”
ba;;er*eS are connected between the output of CR203
and the input of U207.
‘TO accommodate the barteries
in series with the regulator (U2071, one AC input oI
CR203 is switched to a higher voltage rap (pin 121 on
eransformer T201.
‘The 16.8” batteries are connected
between CR204 and “208. and CR204 is switched to pin
9 af T201.
Actual charging of the 8.4” batteries is
accomplished by the current pulses in filter capaci-
ior C203; charging of ehe 16.8” batteries is by cur-
rent pulses in C206.
Pin Identification for LSI.
TABLE 4-4.
Pi”
NO.
“Wig. FU”CLiO”
/
1 f I Segment drive
2 8
) Segment drive
“altape l.C”ClS
l 5” = ON, 0” = OFF 15 dp 1 Decimal point ~ +5v - ON, 0” = OFF
+5v = ON, 0” = OFF
3 iT1 ~ Multiplex line f5” = ON, 0” = OFF
Pi”
lie. Ilesig.
16
17
:44 I
‘TO ~ Multiplex line +5v -
I
4 , T3 Multiplex Line
5 : HOLD i
6 MR
7 TH
Not "se*
1 Threshold input +5” or -12”
8 1 CM Clock
+5v = ON, 0" = OFF
,
____ ____
Approx. lOk”Z, +5v LO -12” 22 C”M ~ common or “LO” 0”
18 Fl
19 i F4
20 1 +5v Power, f5"
21 I -12" ,~ Power, -12"
9 b : Se,,q”ent drive +5v = ON, 0" = OFF 23 ~ CN ~
10 a
11 d
12 e
13 c Segment drive
Se,qent drive
Segment drive .+5” = ON, 0” = OFF
+5v = ON, 0" = OFF 24 i ~2
25 IR4 i
Se~tnent drive +5v = ON, 0” = OFF 26 8.1
f5" = ON, 0" = OFF 27
/ R2
14 cs Current Switch I+5” = integrate mode
I
FunCtion
I
I
Not Used
) Not Used
~ ?utip1ex line
Nat Used
Not Used
Not Used
Not “SCd
Voltage Le”els
ON, 0” = OFF
! ---: +5v
-12"
i +5v = ON, 0" = OFF
_---
_---
30
0976
a. SeVerI segmell-to-BCD canvercer. ‘This converter
uses one Hex Inverter n!301).
three "uad 2-InnuT NOR
C. OUtpUt Data Buffers.
The dara buffers consist
basically of five Quad 2sInput NOR gates (U314 thraugb
SECTION 5.
MODEL 1601 AC-DC PROBE
GENERAL. The Model 1601 is a combination ac-dc probe
that enables the user fo measure "oltqes from 45 Hz
to 45kHz when used with the Model 160B. The slide
switch (SlOl) can be used to select either AC mode
or straight-through DC Mode.
SPECIFICATIONS:
DC: straight-through probe does not alter any
Model 1608 specifications except:
farads input capacitance 2) 0.5 atqere maximum
current 3) 0.3 ohms resistive offset 4) i20 microvolts rhermal offset.
Since the probe assembly should provide goad service
with normal handling "o maintenance is usually "ecWSClry.
rogether at the factory using a special salvent.
Therefore ebe probe should not be disassembled. If
repair is necessary, contact the Keiebley Represen-
tative in your area.
ELECTRICAL PARTS LIST: (See schemaeic 24669C)
JlOl
SlOl
Cl01
Cl02
DlOl
0102
D103
RlOL
R102
KL03
8104
Shielded Banana Plug.
6 in. long x 314 in. diameters
3 ft. (1 m) cable, "et weight l/4
The probe body (Items 2 and 3) is fastened
Banana Plug (2 req'd)
Switch, AC-DC RI
capacitor, 0.047pF STAND
3. Verify that the Model 160B reading is within
the tolerance stated in Table 6-4 for 10, IOP, and
loon ranges.
4. With Resistance Source (E) connected and set
to On, select the 1mV range and adjust the Model
16OB zero for a ~.OOOmV reading.
Accuracv Check for DC "oltaee
1.000000 ” 0.001
1.000000 " 0.01
10.00000 v 0.01
1.000000 " _-
10.00000 " __
100.0000 " __
1000.0000 " -_
1 mv 20.03% 1.000 In”
10 In" ?0.015% 10.00 mv i2 digits
100 In" ?0.015% 100.0 In" t2 digits
I " 10.005% 1.000 " 12 digits
10 " ?0.005% 10.00 " i2 digits
100 " F0.005% 100.0 " F2 digits
1000 " ?0.005% 1000 " ~2 digits
TABLE 6-3.
e.
Current Accuracy Check.
Fuse Check.
1.
Select lOOOn!A range.
a).
b). Measure resistance between input terminals,
using ohmmeter (F).
t2 digits
36 1174
1.01
”
1.01 v 1 MO 1
1.01 v 100 ul 10 "A iO.,O25% 10.00 UA
1.01 v 10 KG 100 !A 10.025% 100.0 UA
SO”rce (D)
settinp
10 MO
100 n.4 iO.O25% 100.0 XIA
UA
?0.025% 1.000 u*
1mA lrl!A
10 InA 10 mA ?0.02% 10.00 mA
100 mA 100 * ?0.02% 100.0 InA
1000 mA 1000 mA ?0.02% 1000 ti
**see Specifications for temperature coefficient for *c currelIt.
2. Accuracy Verification.
connect Resismnce source (E) in series
a).
wirh Voltage source (B) to farm a current Bo”r’c‘3
(for lO”A, loo”*, l&4, lO!lA, an* 100u. ranges).
b). set Voltage source (8) to 0.000000” and
Resistance source (E) to on.
Connect "Current Source" to Model 160B
c).
input.
d). Select Im" range on rhe Model 160B.
e). Adjust zero on the Model 160B for a i.OOOm"
display.
Select lOti range on the Model 160B.
f).
6). Verify the lOllA, lOOnA, lpA, lO"A, and
lOO"A ranges using tile source settings given in
Table 6-5.
NOTE
Voltage source (8) must be set lam" high to
compensaee for the Model 1608 "input drop"
at full-range.
?0.02%
6-4.
ing adjustments should be performed when any specification has been determined to be out of tolcrancc.
For checking the Model 1608 to its maximum publislied
specificaclms, the Performance Verification pracrdures given in Section 6-3 should he used.
taining the Model 160B on a six-month recalibration
cycle, Tables 6-8, 6-9, and 6-K should be used. The
"Tolerance an Reading" given in Tables 6-8, 6-9, and
6-10 is adjusted to allow for time drift- of critical
components, and also fhe effects of humidiry.
6-8, 6-9, and 6-10 also give the probable component
to be investigated if a range does not meet spccifications after the Adjustment Procedure has been con>pleted.
The Model 16OB factory-calibration is at a
level that will aSSUre all specifications are
met for a period of 12 months after shipment
from the factory.
tion, a six-month re-cd cycle is recommended
since component tolerance drift may prevent recalibration to stringent factory-cnlibraci""
levels witbut component replacement.
lawfng calibrarion procedure uses levels that
will .¶ssure that the instrument meets puhlishcd
specifications for a six month period wichouc
requiring componenC changes.
should be performed under laboratory candi-
cions of approximately 25-C and lees than 50%
relative humidity.
1.000 mA
.4D.NSmENT/CALIBRATION PR”CE”“KE. The follow-
For main-
Tables
IMPORTANT
For subsequent recalibrn-
me fal-
Adjusrmenrs
Verify that the ImA, lomA, lOOmA, and 1000
1).
m&t ranges are within the eokxances given in Table
6-5.
0875
a. HO" to open Instrument.
over so that the bottom cover is facing up. Loose"
Turn the Hodcl l6OB
METALCAL
MC-212 -
METALCAL
MC-213 -
INSERT 26090A
2 REQUIRED
TOP COVER
26545C
FRONT PANEL
262WC
MOOIF;;KE;OTTOM
24446
as717
38
FIGURE 29.
HAiDLE
257290
Top and Boccam Cover Assembly.
1277
Kecommended Test Equiment for Calibration
Item
I ““ltmrter, oigita1
Description
Minimum Specification
10omv @ 0.015%
1v @ 0.01%
.J
K Voltage Divider
Voltage source 1” @ 0.005%
1O:l @ 0.005% ISI bZLA,lOK
100”:1 @ 0.025%
b. Power Supply Check.
he power supply voltages
can be checked with Voltmeter (I) from Table 6-6.
1. +5” Regulated Supply.
Check the Line Voltage
Switches (at rear of instrument) to see if they are
set correctly.
respect to IDput LO.
Measure the voltage at TP202 with
The voltage should be +5”,
55% ii, the “LINE” mode of operation, and also in
the “CHG” and “B,W modes of operation if batteries
are installed.
2.
-1ZV
Regulated Supply.
Check the Line “olt-
age Switches (at rear Of instrument) eo see if they
are set correctly. Measure the voltage at TP201
“it,, respect to Input LO.
-12”, 25% in the “LINE” mode of
me vo1cage should be
operation, and also
in the “CBG” and “BAT” modes of operation if bat-
teries are installed.
3. Baecery Check.
C.
How To Calibrate the msrrumenr.
See Section 6-3a.
For best ac-
curacy, the Model 1608 should be calibrated with the
Model 1609 Cal. Cover Accessory or an equivalent.
‘The instrument should be allowed to stabilize for
approximately l/2 hour after the Cal. Cover is put
in place.
It is important that the calibration sequence be followed exactly, because the ad,uatments
are interrelated and dependent on prior calibration
SCepS.
Manufacturer
Model
nata Precision 2540Rl
Fluke
345,
NOTE
Apply a +lm” signal to the Node1 lb”13 inpii~.
d).
e). Adjust Display Zero (K136) for a rcadin~ UL
+Ol.” at the Model 1608 display.
f). Apply a -Irn” signal.
Adjust Recrifier Zero CR1351 for ii rending
d,
of -01.0 at the Model 160” display.
NOTE
DC “oitage Calibration.
d.
1. Voltage Zero and Offset Current Zero Adjust-
ment.
Select h” range.
a).
b). Place a dmrr (low-thermal copper) across
the input terminals.
ccmnect “oltmeter (I) to the Model 160B
c:).
Analog Output.
d). Adjust front panel Zero Control (R114) for
a reading of t”.?m” at Voltmeter (I).
e). remove the short acrosis the Model 1608 in-
put terminals.
f). Adjust Offset Current Zero (R121) for a
reading
af A20m” at
Voltmeter (I).
1174
3. +OC Cal. and -DC Cal. AdJustment.
Change Divider (K) setting to 0.1 ratio.
a).
t,pply a +lOOm” signal to the Yodel lb”,,
b).
input.
Adjust CDC Cal. (R137) for a reading of
cl.
+lOO.O at the Yodel 16011 display.
Apply a -1oomv signal.
d).
Adjust -DC Cal. (R134) for a readini: of
e).
-100.0 at the Model 1608 display.
39
MAINTENANCE
RllW
MODEL 1608
R136-
R135-
RlZl-
R137-
40
FIGURE 3". Location of Calibration Adjuetmenrs.
1174
MODEL 1608
MAINTENANCE
-1
JTP
"OHMS"
,+lOOmV
REF
2V-
UT-
I
1174
FIGURE 31.
+5V‘TO
MODEL 16028
Location of
Test
Points.
41
MAINTENANCE
MODEL 1608
e. Ohms Calibration.
lOOmV Reference Adjustment.
1.
a). Leave the Model 1608 set 0" the loom"
Range;;leave Voltage source (3 and DiYider (0
connected to the Model 1608 input.
b). See Voltage Source (J) co 0", and set
"ivider (K) to "0" output.
connect Voltmeter (I) to TPlOl (loom" Rd),
Cl.
Adjust the "1OOmV Adj." trimpot (R105) for
d).
+1oornv, i2OjJ" at Voltmeter (I).
Range
1 In" --
open
_-
+hlv 5%
I"" --
100 In"
2. Ohms Reference Accuracy Adjustment.
Apply a +200m" to the Model 1608 input.
b).
AdJust the "Ohms Ref. Accuracy" trimpot
cl.
(KllO) for +300mV, i6Ou" at Voltmeter (I).
Display Test Equipmene
AdJustment Name and
Reading oesig. Reading circuit Ilesig.
Front Panel zero
(R114)
(R121)
Display Zero (RI361
to1.0
(I)
(1)
__
Analog output
set ea 0 + .h"
Analog outpue Offset current zero
set to 0 i 2om"
-Ill!"
+I~oom"
2.5%
i.Ol%
-LOOWl" i.Ol%
short
-_
fZOOnl” ?.Ol%
100 In"
100 ln"
100 rn"
-01.0
+100.0
-100.0
100 Ill" --
100 rn” --
__ ___
__
(1)
__
TPlOl see to lOOmV adj. (R105)
+loom" k 2011"
(1)
TPlOl set to Ohms Ref. Accuracy
l
3OOm" t 60~" CR1101
Rectifier Zero (RI351
+Ilc Cd. (R137)
-DC Cal. (R134)
42
_. - _ _ _ , . .._.. ___ . . ._..__ “.
Range
1 mv 21-112 digits
LO m” tl-l/2 digits ReSFSCOr Network 11160
100 Ill”
I, ”
10 ” il-l/2 digits Resistor Network R159
10” ”
1000 ”
*This rable is to be considered as an extension of Table 6-3.
modified “Tolerance on Reading” column shown here allows the user
to verify that tire instrument will meet published specs lor il period ai 6 months.
*This table Ls to be considered as an extension of Table 6-4.
modified “Tolerance on Reading” column shown here allows the user to
verify that the instrument will meet published specs for a period oi
6 months.
“This table is to be considered as an extension of Table 6-5. me
modified “Tolerance on Reading” column shown here allows the user to
verify that the insrrumenr will meet published specs for a period of
6 months.
**R163 may or may not be installed. See schematic 26590E.
TABLE 6-lo*.
RI45 (IMn)
K146 (look.21
11139 (IOk<:) and CR108
K140 (1!4)
R141 (1000)
RI42 (100)
Rl43 (0.9970)
R144 (0.0987Q) and R163** (201.)
R144 (0.0987Q2) and R163** (2OU)
‘The
1174
MAINTENANCE
5203
P203
III
1‘5114
e
MODEL 160B
c
44
FIGURE 33.
FlOl
CURRENT
PROTECTION
FUSE
Location Of Fuses.
1174
SECTION 7.
Instrument Model Number
a.
~~strurnenr Serial Number
b.
Part Description
C.
CirC"*t Designation (if applicable)
d.
e. Keirhlev Stock Parf Number.
REPLACEABLE PARTS
C. Model 1602B Digiml "utpuc - (26654E).
schematic describes the digital outp"t for Model
1608. Circuit designation series is "300".
This
1174
45
REPI.ACEABI.E PARTS
i’
Allen-Bradley carp.
Milwaukee, WI. 53204
hperex
Elkgrove Village, II,.
Amp 1°C.
Elizabethtown, PA.
Analog Devices, 1°C.
Cambridge, MA.
Beckman instruments, IIIC.
Fullerton, CA. 92634
Berg Electronics, Inc.
New Cumberland, PA.
Bourns, 1°C.
Riverside, CA.
Eussmann Mfg. Div.
St. Louis, MO.
Ccntralab Division
Milwaukee, WI.
Clarostat Mfg. co., 1°C
Dover, NH.
components, 1°C.
Biddeford, ME. 04005
03820
02142
92507
53201
60007
17022
17070
-
Farichild InStrNmenrS Curp.
Mountain View, CA.
General Electric company
Syracuse, NY. 13201
General Insrrument Corp.
Newark, NJ. 0,104
Hewlett-Packard
Palo Al,ea, CA.
1ntersi1, 1°C.
Cupertino, CA. 95014
IKC Division
Burlington, IA. 52601
ITT cannon ,aeceric
Santa Ana, CA.
Kdthley instruments, ~nc.
Cle"eland, OH. 44139
Littlefuse Inc.
Des Plaines, IL.
M"l‘2X
Ihurlers Grove, I,..
Motorola Semiconductor ProduCLs, Inc
Phoenix, AZ.
ti5008
94040
94304
92701
60016
6051.5
Erie 'Technological Products, Inc.
Erie, PA.
16512
National Serniconductar Corp.
Santa Clara, CA. 95051
NPN, Case TO-92 .
NPN, case To-92 .
NPN, Case TO-92 .
NPN, Case TO-92 .
NPN. Case TO-92 .
NPN, Case TO-92 ,
NPN, Case TO-92 ,
NPN, Case TO-92 ,
NPN, Case TO-92 .
NPN, Case TO-92 ,
NPN, case TO-92 .
NW, Caee TO-92 .
NEW, case TO-92 .
NPN, Case TO-92 .
NPN, Case TO-92
NPN, Case TO-92 .
NPN, Case TO-92 .
NPN, Case TO-92 .
NPN, Case TO-92 .
Net?, case TO-92 .
MOT 2N5087
MOT 2N5087
MOT
MOT 2N5087
MOT 2N5087
MOT 2N5087
MOT 2N5087
MOT 2N5087
MOT 2N5087
MOT 2N5087
MOT
MOT 2N5087
MOT 2N5087
MOT 2N5087
MOT
MOT 2N5087
MOT 2N5087
MOT 2N5087
MOT 2N5087
MOT 2N5087