Keithley 6512 Instruction Manual page 125

Maintenance
Table 7-13
Ranging amplifier checks
Step Item/component
1 Range
2 Apply 190V DC to input
3 Range
4 Apply 19V DC to input
5 Range
6 Apply 1.9V DC to input
7 Range
8 Apply 190mV DC to input
Table 7-14
Digital circuitry checks
Step Item/component
1 Range
2 U109, pin 40
3 U109, pin 2
4 U109, pin 3
5 U109, pin 4
6 U109, pin 6
7 U109, pin 37
8 U102, pin 6
9 U102, pin 3
Table 7-15
Display board checks
Step Item/component
1 Power
2 U201, pin 9
3 U201,U202 pins 11-18
4 U204, pins 11-18, U205,
pins 15-18
5 U209, pins 10-15
6 P1016, pin 14
7 P1016, pin 15
8 P1016, pin 16
7-16
Required condition
Power-on, 200V DC range, zero check off
1.9V
Select 20V DC range
1.9V
Select 2V DC range
1.9V
Select 200mV DC range
1.9V
Required condition
Power-on, 200V DC range
+5V, ±5%
500µsec negative pulse every 1.6msec
Stays low <1sec on power-on, then goes
high (≈ 4V)
655kHz clock
655kHz clock
Variable pulse train
Variable pulse train
Negative-going pulse every 350msec
Required condition
Power-on, 200V DC range, zero check on
+5V, ±5%
Variable pulses
Variable pulses
1msec negative-going pulses every 10msec
Press COUL, ZERO CHECK, TRIG, or
DATA ON button
Press AMPS, SHIFT, RECALL, or SUP-
PRESS
Press VOLTS, OHMS, AUTO, ZERO COR-
RECT, or PROGRAM button
Remarks
Measure between 2V ANALOG
OUTPUT and COM.
Check X0.01 gain.
Check X0.1 gain.
Check X1 gain.
Check X10 gain.
Remarks
All voltages referenced to digital
common.
+5V digital supply.
Interrupt clock.
MPU reset.
Data strobe.
Address strobe.
A/D data.
A/D control.
Meter complete pulse
Remarks
All voltages referenced to digital
common.
+5V digital supply.
Segment drivers.
Digit drivers.
Pulse present when key is pressed.
Pulse present when key is pressed.
Pulse present when key is pressed.