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Panasonic PV-4760 Erratic Display Problem

Can anybody help me fix the following problem with my venerable Panasonic PV-4760 VCR?

All tape and tuner functions work perfectly when the dispaly stays on. The tape path, heads, and drive belts are clean.

When the VCR is first plugged in, the display comes on and the VCR functions perfectly. However, after typically a minute or so, the display begins to flicker and eventually goes out --the VCR goes dead.

After the above problem occurs, the VCR can turn itself on or off by itself, erratically.

Can anybody, please, help me fix this problem? I have basic technical knowledge, but I am not an electronics expert, so, please, do not get too technical. This VCR has almost everything well labeled inside, so if you refer to a particular item number and tell me approximately where it is located (I do not have a service manual), I should be able to find it.

I read somewhere that the cause of this problem may be a "transistor C4130 (NTE 2312) 330 uf caps, 22uf cap", but I do not have a clue of what any of these numbers/letters mean or where to find that part in the VCR. I trust that somebody in this forum can help.

Thank you in advance for your kind assistance in this matter.

Telly

Reply to
Telly
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"Telly" ha scritto nel messaggio news: snipped-for-privacy@g49g2000cwa.googlegroups.com...

They are the famous failing electrolytic caps in the Panasonic VTR PSUs. Change all electrolytic capacitors in the power supply, this will fix your problem !!!

I.

Reply to
Inty

Dear Inty,

What a speedy reply! Thank you very much. I'll try that.

May I bother you with one more question? Does an online manual for this VCR or equivalent exist anywhere? The power supply of the PV-4760 seems hard to get to, and I do not want to damage something while trying to fix the erratic display problem.

Thank you again, Telly

Reply to
Telly

"Telly" ha scritto nel messaggio news: snipped-for-privacy@g47g2000cwa.googlegroups.com...

Do not change the whole psu. Change only electrolyitic caps in the secondary part !

I.

Reply to
Inty

And the 4.7uF (10 uF on some models) in the primary side.

Mark Z.

Reply to
Mark D. Zacharias

Dear Inty and Mark,

Thank you both.

Please, forgive my ignorance, but don't I need to remove the black plastic cage that surrounds the power supply in order to get to the capacitors? I have removed the top and bottom covers and the front panel, but I do not see an easy way to expose the parts of the power supply. That is why I thought of asking for the possible existence of an online service manual or equivalent --to avoid bothering other people with my questions.

Thank you again, Telly

Reply to
Telly

If the power supply is not plainly seen to be removable, it must be an older one with much more difficult access. Probably not a doit-yourself type repair for most people. On the older ones. the front panel must be removed, and a fairly complicated disassembly done just to gain access. Not a big problem for a technician ( that's why we make the big money after all - NOT), but unless you've done this sort of thing before, perhaps better left to a professional.

Mark Z.

Reply to
Mark D. Zacharias

Dear Mark,

Yes, my VCR is of the older type, with very hard to reach power supply. The technicians deserve every penny they charge, after all!

Having said that, and although I am not by any means an electronics expert, I did build a PC from scratch and worked the first time I turned it on, and I did manage to fix a troublesome cassette carriage (basket) on a Sony SLV-760HF VCR. I believe that, if I had a service manual or instructions on how to get to the capacitors of the power supply of my PV-4760, I would be able to replace them. It's a spare-time challenge, rather than desire to save $$. I was thrilled to discover this forum and see how helpful other people can be.

Thank you again.

Telly

Reply to
Telly

Well, remove the plastic front panel, remove the screws holding the main board to the bottom of the unit, swing the board out, and start trying to worm the power supply out of there. The capacitors involved are mainly in the secondary circuit of the power supply, with just a 4.7 or a 10 uf in the primary also needing to be replaced. They'll mostly be either 1000 uF, or 330 uF, rated either 6.3, 10, or 18 volts. There will also be one or more 33 or 47 uF caps that should also be replaced, and maybe a 1 or 2.2 uF also to be replaced. Being of the electrolytic type, pay attention to polarity, and be sure to put the new ones in there the same way.

There is a small-value electrolytic on the +44 volt line which tends to hold voltage, and you'll probably get a spark and a snap! when you find it. Not a biggie really, but it WILL get your attention.

Post back for additional help.

Mark Z.

Reply to
Mark D. Zacharias

Dear Mark,

Thank you very much.

I have ordered the power-supply rebuild kit. As soon as I get it, I'll go to work and see how far I'll go without bothering you again. I'll report back as to what happened.

Appreciative, Telly

Reply to
Telly

You can e-mail me direct when the time comes. A picture of the unit might help jog my memory.

mail to: snipped-for-privacy@labolgcbs.net

and reverse the domain name.

later.

mz

Reply to
Mark D. Zacharias

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