Model 405C Sect. IV Page 1
SECTION IV
4-1 INTRODUCTION 5) Ohmmeter. Recommended Q equipment: 410B
Vacuum Tube Voltmeter or 412A DC Vacuum Tube
This section contains maintenance and servicing Voltmeter.
information for the 405C with the exception of
its decade counter units. Information covering
these units is contained in the AC-4 Decade Coun- 6) Variable power transformer to vary line voltage
ter Manual. between 103, 115 and 127 volts. The transformer
should have a current capacity of at least 3 amps,
and its output voltage should be monitored by a
Included in this section is a performance check to voltmeter accurate within * 1 volt.
verify instrument operation. The check can be
made with the instrument in its cabinet and is a
good test as part of preventive maintenance and
incoming quality control inspection.
4-3 PERFORMANCE CHECK
The stepping switch used for ranging requires
periodic cleaning and lubrication. It is important A. TRACKING AND RANGING CHECK
to service it when due. See paragraph 4-9. 1) Turn instrument on, set line voltage to 115 volts,
8 and allow 5-minutes warm up.
2) Set RANGE switch to AUTOand SAMPLING con-
4-2 TEST EQUIPMENT
trol to maximum (clockwise) but not to EXT.
The following is a list of recommended test equip
ment for servicing and trouble shooting your 405 C : 3) Connect calibration generator to 405C INPUT
connector and adjust generator output to +0.8 volt.
1) A dc voltmeter having an input resistance of at Adjust 40.5'2 CALIBRATE control to produce read-
least 100 megohms. Recommended @ equipment: Out of + .800.
410B Vacuum Tube Voltmeter or 412A DC Vacuum
Tube Voltmeter. 4) Check 405C readout against calibration gener-
ator output voltages listed below: 405A indication
2) Trigger generator to provide a 20-volt positive should be within 0.2% *1 count of generator output
pulse for triggering the 405C externally. Re- at all voltages.
commended !@ equipment: 202A Low Frequency
Function Generator. 000 + .1 + .8 + 20
+ . 001 + .2 + .9 + 30
3) Calibration generator to check calibration and + .002 + .3 +1 + 50
tracking of the 405C. Generator output should be + .003 + .4 +2 + 100
adjustable in steps of millivolts, tenths of volts, + .010 + .5 +3 + 200
and volts, and should be accurate within 0.1%. Re- + .02 + .6 +5 + 300
commended @ equipment: Model 738AR Volt- + .03 + .7 + 10
meter Calibrator.
4) Oscilloscope to check circuit waveforms. The 5) Repeat step 4 for negative voltages.
oscilloscope should have an upper frequency limit
of at least 200 kc. Recommended @ equipment: 6) Repeat step 4 and 5 at line voltages of 103 and
120A Oscilloscope. 127 volts.
005 18- 2 |
ACEC
