CJ'\
I
,,<-'-"-',� ....... �
v
Problem
6. Manual or autoranging only
operates in down-range direction.
7.
Range changing continues with
erratic sequence of digits below
10 range.
8.
Unit does not change ranges
automatically. Manual
ranging is okay.
··•
·,-:.}
Possible Causes
I.
Defective up range comparator IC7-B
or associated comparator defective.
Check voltage at test point D for 0V de
when the manual switch is depressed to
the up position.
I.
Lock out signal from IC5 through
IC 14 missing.
l.
Defective K3 relay contact.
Cure
- 'j
)
T roub I eshoo t and repair.
Troubleshoot and repair.
Replace K3 relay.
6.8 Ion Gauge Process Control (Refer to Fig. 5-7 and Fig. 6-l)
I.
Both process control circuits
inoperative.
2.
One process control circuit
inoperative.
I. Normal operation. Autoranging switch
is in the manual position.
2.
Defective delay circuit component
Ql6, Ql 5, R36, R37 or Cl3. Check
for -23V de on Q 15 collector after
filament is turned on.
3.
Defective pressure amplifier IC8, or
associated component (Refer to
Fig. 5-5). Measure the output at test
point H for the following output:
Place switch in auto position.
Troubleshoot and repair.
Troubleshoot and repair.
IO=� range 0V to - IV de corresponding to the meter reading
IO _6 range -IV de to -2V de corresponding to the meter reading
10 5 range -2V de to -3V de corresponding to the meter reading
10=4 range -3V de to -4V de corresponding to the meter reading
10 range -4V de to -5V de corresponding to the meter reading
I.
Defective circuit component IC6,
RA7, RAB, Ql 3, Ql2, Kl or K2.
Troubleshoot and repair.
