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  #1  
02-15-2022, 03:42 PM
Doohickey Doohickey is offline
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I have a used Panasonic HS960, it has great image quality with the TBC off. With the TBC on, it introduces light and dark rolling horizontal "bars", which also vary and flicker based on rest of the image. Some tapes don't show it at all, on some it's really bad. The tapes are fine in a JVC, and are also fine with the TBC off.

I replaced some of the caps on the TBC sub-board (the ones I had replacements on-hand for), which didn't change anything. Has anyone seen this before? Which caps should I start with?

Video sample attached, it's low-quality MP4/h264, but it shows the problem well.

I'm thinking i'll start with the 1uf non-polarized electrolytic which is on the TBC card, if that doesn't change anything, i'll just replace every cap that looks somewhat related to video output or power... But before I do that, if anyone has some more specific knowledge, that'd be very helpful.

Thanks in advance!


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File Type: mp4 TBC_problem_HS960.mp4 (3.78 MB, 23 downloads)
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  #2  
02-15-2022, 10:57 PM
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Seen this on AG-1980. You can't play caps whack-a-mole on these decks. Replace them all.

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  #3  
06-19-2023, 03:56 PM
Doohickey Doohickey is offline
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An update to this: I replaced about half the caps in the whole machine, then I got bored and stopped. It still had the problem after that.

I bought another unit (same model, HS960), and it had the exact same problem(!).

Based on which tapes seem to have problems and which ones not, at the moment I'm inclined to blame the camera or recording setup at the moment. For background, these are recordings of events, camera video output connected to input of first VCR, the, output of that daisy chained to the next one, 2-3 VCRs recording at the same time in this way (cheap retundancy, multiple "master" copies). All tapes from all different VCRs have the problem on a particular day, but on some days (presumably with a different camera or some other change in the setup), none of the different tapes have the problem. VHS-C camera tapes also seem to be free of this problem. What does very consistently, and strongly, show the problem is new tapes just recorded by the same HS960.

I could be completely wrong though, and I haven't thoroughly checked that the different-camera-setup thing is actually the cause. Maybe since new tapes recorded by the same hs960 show it, it's a problem with my setup, although that's very strange given that it only shows up with TBC on..
Or maybe my capture card doesn't like it, I'll try another one at some point and report back.

For now, vhs-decode does the tapes problem free, and in better quality overall, so I'm using that now, no replacing capacitors needed :-)

Last edited by Doohickey; 06-19-2023 at 04:06 PM.
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  #4  
06-20-2023, 06:57 AM
enois enois is offline
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I have exactly the same problem with my HS960 (PAL). I didn't think it was a capacitor problem, for me is more a design flaw or electronic calibration issue.
I never tried to record with it and see if show the problem, I'll do it as soon as I have time.
Can also confirm that with VHS-C tapes no problems.
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