12
NATURE OF FAULT PROBABLE CAUSES
Unit not switching 'ON' Check fuses, Power On Switch,
Connections to Rear Panel Terminal Block
OK. Check Mains transformer and DC
voltages as per Table 1. If faulty replace
Main PCB.
UV indication permanently 'ON' Check PT supply, PT Fuse and Sense
transformer. If all are OK, check DC O/P
voltage @ TP9 on Main PCB. If faulty replace
Main PCB. If OK replace Display PCB
Display reads '000' in all position A to D convertor is faulty. Replace Main
of selector switch. PCB or else Display PCB.
Or
No variation in display reading by
varying R,L set controls
L or R or UV/OV indications not coming IC3 on Display PCB is faulty. Replace
after varying P.T. input beyond dead Display PCB.
band settings.
Or
L or R indication remains
permanently 'ON'
LR or RR not coming after varying Digital circuitary on Main PCB faulty.
PT I/P voltage after the set time Replace Main PCB.
delay.
Or
Time delay LED on Main PCB
remains 'ON' permanently
Time delay is not as per set value Time Delay dial might have shifted. Adjust
the setting of T.D. as follows. Slightly loosen
the Knob and rotate T.D. control fully
anticlockwise to match the dot with the
starting dot marked below. Tighten & check
the T.D. value for 30 secs. Readjust slightly if
necessary.
LR & RR commands coming but Check contacts on Rear Panel Terminal
OLTC not operating Block. If OK, check control panel wiring.
If contacts are not OK, replace Main
PCB.
'LR' or 'RR' commands remain IC4 on Main PCB faulty. Replace Main
"ON" permanently PCB.
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