Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Default Panasonic PVM2767 Combo tv/vcr fix - flashing timer light - no tv action

Hi. Have in hand 1 Panasonic PVM2767 tv/vcr combo. Timer lamp flashing, no
tv action, no high voltage, etc, but tape drive responding normally.

Tried factory method of clearing this error, no go there.

Digging in -- Shorted C-E of relay drive transistor. Made tv part come up.
Looked good, showed playing tape long as I held transistor shorted. Scoped
base of this transistor -- off = 0 volts, on = .4 volts. On-Off comes from
pin 29 of IC6001. At that point it goes from 0 to 5 volts, but was low past
surface mount 2700 ohm resistor. Followed to tv board - went to relay switch
transistor and to Child Board. Disconnected line to Child Board and set ran,
with relay acting normally. High Voltage running 29.6 KV, well within spec.
Reconnected line to Child Board. No workie.

Pulled Child Board. Found Q505 shorted. Replaced. Set would then click on
then right back off. There are 5 small transistors on this board. I went
ahead and changed all, they are cheap. Set works perfectly.

Child Board is the HV overcurrent protect circuit. Check HV reading, make
sure it isn't too high. In this case, the overcurrent circuit was faulty,
which I fixed.

Hope this helps someone in the future and saves them some troubleshooting
time.

Danny


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