Bottom field issue on Panasonic NV-FS200?
 

Hi,

I don't know the correct term, but I'm getting these weird zig zag lines in every bottom field on my Panasonic NV-FS200. These were captured through a DataVideo TBC3000 into an ATI 600 USB card, on Windows 7 with VirtualDub2:
Attachment 18349
Attachment 18350
Attachment 18351
Attachment 18352
Attachment 18353

Can somebody explain where this could come from? What part inside my VCR could be the culprit?
I probably won't be able to repair it myself, but I know of one company in Belgium that service VCR's. Also Branko from vcrshop.nl could be an option.

Hopefully there is a way to fix this. Besides the Panasonic I also have a JVC HR-S7600, which I prefer for the picture quality, but in my opinion the Panasonic has much better audio, which is a must because I mainly have music videos on VHS.

Thanks for the help (I've attached the fields in lossless quality in a zip file)
Karel

One of the heads could be dirty, Have you tried cleaning the video heads?

Yes, I believe I have cleaned the heads after I bought it. When I look back at my captures from then I see the same problem.
But I will try doing a fresh clean.
What is the reasoning behind this? I thought each head is involved in lines from both fields?

First order of business would probably be narrowing it down to which device in the chain is causing it.

I presume the same chain with your 7600 in place of the FS200 does not produce this issue? If that's true, then the issue is narrowed down to the FS200 itself. If the 7600 produces the same issue, then issue is probably elsewhere in the chain or could also be that specific tape, but I presume that all tapes come out this way on the FS200?

Also, what's the history on the FS200? Has it ever been recapped? I'm not sure what sort of cap issue would selectively affect every other field though.

You might also want to make sure it is in normal mode and not "edit". I've heard edit can cause some odd issues and is really only meant for tape dubbing and may contain some signal irregularities that is meant to be interpreted by the recording VCR and not actually encoded onto the dubbed tape.

Hi, thanks for the reply
Yes no such issue with the 7600. I've tried different tapes, the screenshots in the OP are from 4 different VHS cassettes. I've also tried the ES10 as passtrough instead of the TBC3000, and similar results (not identical, since no line TBC for example, but certainly something going on in the bottom field). I've also tried the TBC3000 with the 7600, no such problem, so can't be the DataVideo TBC.

I bought the FS200 secondhand from the son of the owner, an amateur videomaker I believe. But I don't know much more about its history. There has been no recapping since I've owned it. But I'm also hoping that a "simple recapping" might solve the problem.

I've tried both EDIT and NORMAL mode, there seems to be no difference.

When you switch the TBC off on the FS200, do the extra lines go away? How about when you set it to black and white?

Each head reads a field and the frame has two fields, Odd scan lines field and even scan lines field, So yes each head reads a set of scan lines, Look at the heads with a microscope, it could be that one head has something stuck on it, the bad news is that one head could be worn more than the other therefore protruding less than the other, If so you need some technical skills and special tools to perform this kind of troubleshooting procedures and alignments. After the heads every field is processed by the same electronic components starting from the RF board itself all the way to the video output socket, so it makes no sense that you have noise in one filed and not the other.

Ah yes of course! I was confused with the interlacing... since tracks on the VHS store top and bottom field alternately, each head basically only reads one type of field. So that points to there definitely being something wrong with one of the heads. I have no microscope, but I hope cleaning will help. Otherwise, head replacement?

I cleaned the video heads, and I believe the problem is solved. The heads were VERY dirty. But while testing new problems popped up, like a low frequency wave going either up or down when using the DataVideo TBC-3000, even when the tape isn't playing and the output from my Panasonic is black. I'm suspecting a bad S-Video cable. Coicidentally I was also testing on a VHS where the bottom field was indeed heavily distorted (top field fine)! So I will post and confirm later if the problem is really solved.
Thanks for the advice!