Help needed - Panasonic F70 video p/supply dead

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I have been given a friends video recorder to fix - fault was that one day
they went to use it and there was no power....nothing like a bang or smoke
or power surge - it just died and wont turn on.

Just wondering if anyone has some good knowledge of known common faults for
a Panasonic F70 power supply and also can help with part numbers for some
blown diodes?.

The video is completely dead - no power at all.

Have checked fuses (OK) and changed most of the common caps (except for the
large 83uF 400V filter cap and 1uF 400V cap, and have found D6 (zenner),D10
and D14(zenner) to be open circuit - anyone know what part numbers these

What's the best way to test the power IC's? Are they usually faulty?

I'm fairly new to this, but someone has told me about a book you can get
that has common faults listed for many different brands of TV/VCRs etc?  If
nothing else, it gives a good starting point and could save some time.

Thanking you for any help you can offer here.....


Re: Help needed - Panasonic F70 video p/supply dead

very good vcr, worth repairing. i have one.

you should get a good service person to do it.the power supply needs to
be rebuilt. will cost ~$90 but as i said, worth it

Re: Help needed - Panasonic F70 video p/supply dead

Replace ALL elecrolitics in power supply.
Main AC filter cap is probably OK, but rest need to be replaced. Watch out
for 300V charge that may still be present on AC filter cap.
When replacing caps, see if any of them leaked onto PCB. If that is the
case, clean the board and repair any damaged tracks.

Normally 1uF/400V in primary causes "dead" symptom, but others are bad as
well and cause all sort of problems from bad tuner reception to generating
noise in capstan motor.


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