Radio Shack TRS-80 Service Manual page 88

Color Computer 2
TRS-BO ®
Service Manual
POWER SUPPLY CHECK (continued)
Measure voltage at
collector of
a
1 (case)
Replace U1
Recheck supply
Check.cathodes of
CR1 &CR2
for AC voltage
Replace 01
Recheck supply
With 'scope determine
frequency of AC
component
Check Vee pin of
each IC to determine
if IC excessively noisy
Use ' scope' .
Check AC voltage
at anodes of
CR3 & CR4
Replace C2
Recheck supply
Replace CS , C11,
or U1 . Recheck supply
Replace despike
capacitor for that
chip
Replace chip
Recheck supply
Replace chip
Recheck supply
ltad1elhaell---------
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