Panasonic AG-1980 TBC bright, shaky VHS image?

history1 · #1 07-14-2016, 04:56 PM

Hello. I've got a couple issues with my Panasonic AG-1980. Both have to do with the internal TBC.

The first problem, When the TBC is turned on, the video is a little bit shaky (In defective tapes only maybe). When it's off, it's not shaky. Is this a normal thing for the TBC?, a side effect when it's turned on?

The second problem involves some of the videos on the tapes starting off as being too bright when they start. I discovered that turning the TBC off fixes the problem.

Is there something I can do do fix these problems?, or do I have to send in the VCR for repair? Thanks in advance.

lordsmurf · #2 07-14-2016, 08:30 PM

I need to see a sample of "shaky". Attach a small clip.

Brightness is most often a caps issue. There are also values on the board that should be tweaked after a caps repair. This is probably the most common tell-tale sign of a caps-related problem on this deck. I'm not sure what the tweaks are. The caps replacement is intensive, and best done by pros (ie, TGrant Photo).

history1 · #3 07-15-2016, 12:23 PM

Here are two clips. One is what it looks like when a tape is playing with the TBC off, the other is when it's turned on. This is a slightly defective tape, you can tell. I haven't noticed any issues with good tapes. I suppose this may be normal, I know that you often have to change configurations when playing certain videos. With the VCR TBC off, my AVT-8710 usually takes care of the rest, even some things the line TBC can fix.

lordsmurf · #4 07-15-2016, 04:10 PM

Okay, I see. That's not "shaky". That's vertical bouncing of the image. It's not quite non-technical 'jitter', as it's a single bounce. (Non-technical jitter is up/down bouncing with repetition.)

What you're seeing is a known side-effect of S-VHS line/field TBCs. The tape is too damaged for correction. Correcting one error creates another. You can see removal of horizontal jitter, and removal of most chroma noise happening with the TBC engaged. The reason it's happening here is due to errors at the top of image. Correction (TBC) is not starting from the first line, but a subsequent line.

The ES10 may or may not help.

The cause is the tape was either (a) very low grade, (b) re-recorded, (c) nth gen copy of copy.

This happens. Sometimes (but not often) TBC doesn't help on some tapes.

Now I'm wondering about your brightness issue. Better post a sample of that, too!

history1 · #5 07-16-2016, 01:21 AM

I have an ES15, recommended by Sanlyn a couple years ago. Would that work instead? I've tried it before and it makes dark scenes look bad. Can't I just turn the TBC off and use my AVT-8710 instead? That time/base corrector fixes many problems and even acts like a line TBC sometimes. It does look good with it turned off. The tape IS preety low quality (LDK brand, who's heard of that?) and it is a re-recording. I have the same issue on another tape, but that is Sony brand.

Attached is a preview of my brightness problem. I decided to upload a video, because that will better show you my issue. First you see the video starting very bright (with TBC turned on), then I rewind it. I stopped the tape and pressed play again. The video starts again (With TBC turned off), this time at normal brightness. Pressing stop then play again in the middle of the video also fixes the problem. I've seen it in another one of my videos as well on another tape. It doesn't happen with every video.

msgohan · #6 07-16-2016, 06:06 PM

Quote:

Originally Posted by history1

I have an ES15 ... I've tried it before and it makes dark scenes look bad.

Did you disable the per-input NR? The setting isn't where you would expect it to be. There's also the bright/dark in/out settings.

history1 · #7 07-17-2016, 05:18 PM

The noise reduction was turned off already, but I fiddled around with the bright/dark in/out settings and I managed to make the video look as good as without using the ES15. Problem solved, thank you.

I also experimented with adjusting the brightness in ATI MMC without adjusting those settings and it works the same.

I've heard that these pass-thru devices actually make the picture look worse. Is it because some people don't adjust these settings? I did a picture comparison of one with ES15 and one without and both virtually look the same quality. I've got many tapes that the picture bounces with the VCR TBC turned on, should I use the ES15 for those? Should I use it for everything?

history1 · #8 07-17-2016, 05:18 PM

The noise reduction was turned off already, but I fiddled around with the bright/dark in/out settings and I managed to make the video look as good as without using the ES15. Problem solved, thank you.

I also experimented with adjusting the brightness in ATI MMC without adjusting those settings and it works the same.

I've heard that these pass-thru devices actually make the picture look worse. Is it because some people don't adjust these settings? I did a picture comparison of one with ES15 and one without and both virtually look the same quality. I've got many tapes that the picture bounces with the VCR TBC turned on, should I use the ES15 for those? Should I use it for everything?