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Old 16th Jan 2024, 12:19 am   #1
Stuart H
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Default Panasonic NV F77B

Hi. I have a Panasonic NV F77B, owned from new and in excellent cosmetic condition. I haven’t used it for a few years and have recently discovered that the composite output is faulty.
The output is either green or completely black. Can anyone offer any suggestions or point me towards a service manual for this model. Audio output and general tape handling appear to be working perfectly.
It has huge sentimental value and I would love to resurrect it.
Many thanks for any help.
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Old 16th Jan 2024, 2:04 pm   #2
HamishBoxer
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Default Re: Panasonic NV F77B

Welcome Stuart! Are you using a Scart lead? They can cause oddball faults at times as can the power supply secondary caps. Try another lead first and check those caps for leakage and bulging, if you have not got an ESR meter.
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Old 16th Jan 2024, 3:38 pm   #3
Welsh Anorak
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Default Re: Panasonic NV F77B

If you have a TV able to cope, can you check if the RF output is OK?

ISTR some SMD electrolytics giving rise to this sort of fault, but there are quite a few on the video processing circuit and do require a bit of skill and appropriate tools to replace.

Of course do first check the leads as HB has suggested.
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Old 18th Jan 2024, 11:28 am   #4
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Default Re: Panasonic NV F77B

Some very good suggestions made already. But I had a Panasonic of simialar vintage with weak and distorted chroma and that indeed turned out to be corroded surface-mount capacitors on a sub panel. Fingers crossed that's not the case here!
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Old 23rd Jan 2024, 6:47 pm   #5
Scott5591
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Default Re: Panasonic NV F77B

From experience it seems like any late 80’s to early 90’s VCR isn’t worth the headache of fixing IMO. Panasonic were terrible for using surface mount capacitors. And most switching power supplies have problems with leaking caps which eat away at the PCB.

Late 90’s and early 2000’s VCR’s seem to be the most reliable even though the build quality is cheap.
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Old 23rd Jan 2024, 7:32 pm   #6
Maarten
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Default Re: Panasonic NV F77B

Unless you happen to sneeze in the vicinity of any mechnical part (only half kidding, it got really bad when Funai was the only remaining manufacturer).
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Old 23rd Jan 2024, 7:59 pm   #7
Scott5591
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Default Re: Panasonic NV F77B

Quote:
Originally Posted by Maarten View Post
Unless you happen to sneeze in the vicinity of any mechnical part (only half kidding, it got really bad when Funai was the only remaining manufacturer).
I’ll agree the mechanisms are quite flimsy but What they have going for them is their simplicity.

Another good thing is they tend to have not been used much due to VHS dying off and VCR’s getting replaced with DVD players.

The higher end JVC SVHS machines I have from 1999-2003 rarely seem to go wrong.

Not sure about late Panasonic models but JVC’s from 1999-2003 have zero Surface mount capacitors in them.

Last edited by Scott5591; 23rd Jan 2024 at 8:04 pm.
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Old 23rd Jan 2024, 10:39 pm   #8
Maarten
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Default Re: Panasonic NV F77B

I think Panasonic also stopped using as much surface mount stuff as they used in the older models. Probably cheaper to go back to through hole capacitors once the circuits got less complicated (more functions were stuffed into large ICs).
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Old 24th Jan 2024, 7:26 pm   #9
Scott5591
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Default Re: Panasonic NV F77B

Quote:
Originally Posted by Maarten View Post
I think Panasonic also stopped using as much surface mount stuff as they used in the older models. Probably cheaper to go back to through hole capacitors once the circuits got less complicated (more functions were stuffed into large ICs).
Some of those early SVHS machines have a gazillion PCB’s in them!

The S8700EK is a pretty solid machine

I also have a S8965EK which was the EOL SVHS with a TBC from 2003. Shoddy build quality but has great electronics inside it
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