The 
WARNING 
heading used in this manual explain dangers 
that could result in personal injury 
or 
death. 
The 
CAUTION 
heading used in this manual explain hazards 
that could damage the instrument. 
1.6 SPECIFICATIONS 
Detailed  Model  197 specifications  may be  found  preceding 
the table of  contents of  this manual. 
1.7 UNPACKING AND INSPECTION 
The Model 197 Autoranging Microvolt DMM was carefully 
inspected,  both  electrically  and  mechanically  before  ship- 
ment.  Upon  receiving  the  instrument,  carefully  unpack  all 
items  from  the  shipping  carton and check  for any obvious 
signs of  physical damage that may have occurred during tran- 
sit. Report any damage to the shipping agent. Retain and use 
the original packing materials in case reshipment is necessary. 
The following items are shipped with every Model 197 order: 
Model 197 Autoranging DMM 
Model 197 Instruction  Manual 
Model 1751 Safety Shrouded Test Leads 
Additional  accessories as ordered. 
If 
an  additional  instruction  manual  is  required,  order  the 
manual  package  (Keithley  Part  Number  197-901-00). The 
manual package includes an instruction  manual and any ap- 
plicable addenda. 
1.8 USING THE MODEL 197 MANUAL 
This  manual  contains  information  necessary  for  operating 
and  servicing  the  Model  197 Autoranging Microvolt  DMM 
and the Model 1978 Rechargeable Battery Pack. The informa- 
tion is divided into the following sections. 
1. 
Section  2 contains detailed bench  operation  information 
for the Model 197. 
2.  Section 
3 
contains the information needed to verify the ac- 
curacy of  the Model 197. Performance verification can be 
done upon  receipt  of  the  unit 
or 
whenever  the basic  ac- 
curacy of  the instrument  is in question. 
3. 
Information concerning theory of  operation, maintenance 
and servicing is contained  in Sections 4 through 
6. 
NOTE 
The Models  1973 and 1972 IEEE-488  interfaces 
come  supplied  with  their  own  instruction 
manual. 
1.9 INITIAL OPERATION 
Perform the following steps in sequence to acquaint yourself 
with  the basic operation  of  the Model 197. 
Verify that the instrument was not damaged in transit, (see 
paragraph  1.7). 
Carefully  read  over  all safety  information  (see Section 
2 
Basic Operation). 
Refer to paragraph 2.3 (Line Power) and set the line voltage 
switch.  Plug  the  power  cord  into  a  properly  grounded 
receptacle. If  the Model 1978 is installed the charging circuit 
is activated. 
Acquaint yourself with the front panel controls as follows: 
1. 
Turn on the instrument using the ON/OFF button. All of 
the zeroes are briefly displayed. 
2.  Connect the supplied test leads to the HI and 
LO 
input ter- 
minals.  Connect  the red  test  lead  to the  HI  terminal  and 
the black test lead to the 
LO 
terminal. Short the test leads 
together. 
3.  Select  AC  volts  and  autoranging  by  pressing  in  the 
AC/DC, V and AUTO buttons. The AC, AUTO and mV 
annunciators  are displayed.  Pressing  in  any of  the  other 
range buttons activates manual ranging. This is indicated 
by the absence of  the AUTO annunciator. 
4.  Select DC volts  by  releasing  (out position) the  AC/DC 
button. 
V 
is still selected. The AC annunciator  turns off. 
5. 
Select the autoranging OHMS by pressing in  the AUTO, 
and 
3 
buttons. DC must still be selected. The 
3 
(omega) 
symbol is displayed. Press  the  AC/DC button  in  (means 
select AC) and note that  the  "Err"  message is displayed. 
This indicates an invalid mode. 
6. 
Select AC or DC current by setting the AC/DC button ac- 
cordingly and pressing  in  the A button. The annunciator 
that reflects the selected mode 
is 
displayed. Note that cur- 
rent will not  autorange. The 10A and 
LO 
terminals must 
be used on the 10A range. 
7.  Select dB by selecting AC 
or 
DC volts and pressing the dB 
button. The dB annunciator is now displayed. Press the dB 
button to take the instrument  out of  the dB  mode. 
8. 
The REL  (relative) feature can be used with any measure- 
ment  function: Volts, Amps,  Ohms 
or 
dB. For example, 
select the ohms function and autorange. The display reads 
approximately 000.1403,  which is  the test lead resistance. 
Press  the REL  button. The REL  annunciator  is  turned  on 
and  the  display  reads  000.0003.  The  relative  level  of 
000.143  will  be  subtracted  from  all  subsequent 
measurements.  Press  the  REL  button  a  second  time  to 
cancel the REL  level. 
1-2 
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