Maintenance
7-16
Table 7-13
Ranging amplifier checks
Step
Item/component
Required condition
Remarks
1
2
3
4
5
6
7
8
Range
Apply 190V DC to input
Range
Apply 19V DC to input
Range
Apply 1.9V DC to input
Range
Apply 190mV DC to input
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
Measure between 2V ANALOG
OUTPUT and COM.
Check X0.01 gain.
Check X0.1 gain.
Check X1 gain.
Check X10 gain.
Table 7-14
Digital circuitry checks
Step
Item/component
Required condition
Remarks
1
2
3
4
5
6
7
8
9
Range
U109, pin 40
U109, pin 2
U109, pin 3
U109, pin 4
U109, pin 6
U109, pin 37
U102, pin 6
U102, pin 3
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
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
Table 7-15
Display board checks
Step
Item/component
Required condition
Remarks
1
2
3
4
5
6
7
8
Power
U201, pin 9
U201,U202 pins 11-18
U204, pins 11-18, U205,
pins 15-18
U209, pins 10-15
P1016, pin 14
P1016, pin 15
P1016, pin 16
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
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.
Summary of Contents for 6512
Page 119: ...Maintenance 7 10 Figure 7 5 Exploded view...
Page 131: ......