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1990-10-14
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SB-802
RM-76 Microprocessor Failure 2-8-80
When servicing an RM-76 for IC5 failure, also check pin 39 vdd voltage,
which should be approximately 6vdc. Higher voltage will lead to premature
second failure. An incidental symptom for this problem would be such
reports as all "8's" before total failure.
Replace IC5 and IC2, NJM78L06A, the 6v regulator for the microprocessor.
Also check IC1, FS7806M, which supplies regulated 6v for all other
sections. Failure of this regulator (at about 10v dc) will give all logic
hi's.
JEB/yn
(c) 2880TKC