Playing VHS tapes shows horizontal black bar?
 

Hello.

I am trying to play several old pre-recorded videos from 1981. They are commercial VHS movies. When I play them in my VHS player the video has a black color horizontal bar (blanking??) that very slowly rolls up the screen. The picture itself is good and stable but this bar moves up the screen and then starts over. Does anyone have a solution for this problem?

Attach a sample clip and/or sample image.

Here are a few photos of what I see. I cannot figure out why several years ago I could play these tapes and now suddenly there is a problem with the horizontal line.

Try adjusting your tracking and see if that solves the problem.

Hi. Tracking does not affect the bar.

Does this happen with all your tapes...? Could be a misalignment problem too... but I'm not a repair technician. A small sample would definitely help. A few seconds would be enough.

If there are tracking issues, there will normally be noise somewhere. It looks like something is giving the TV a hard time locking to the vertical sync signal that tells it where the frame start. Does the same thing happen on other TVs or capture devices?

I have a PAL home video tape exhibiting the same behavior that worked perfectly 5 years ago (rolling frames and in most cases half frame that moves slowly up or down randomly), VHS tapes do go bad if not stored correctly and that's why the sooner you digitize them the better. I digitized my tape already, the only problem is it was digitized with a normal VHS VCR via composite in DV using the Edirol VMC-1, yah I know.

I've tried to diagnose the problem but I couldn't come to a definitive conclusion, However I found some interesting results:

1- First I though it was the pulse track since it was slightly curly at the bottom edge of the tape, so I forwarded the tape to a spot where there is no tape damage and the rolling frame issue is still there.
2- I searched for a spot where the video plays fine with no rolling frames, and disconnected the pulse head ribbon cable, the miss tracking resulted in a noise stripe completely different than the rolling frames, So this rules out a miss tracking theory.
3- And yes I tried two different VCR's and they showed the same tape behavior at the exact same spots, So two VCR's cannot be miss aligned the same way, This should rule out mechanism miss alignment.
4- When played in -1/2x, -3x, 1/2x 3x or any frame by frame fractional speed forward or reverse as well as -1x (reverse play) the video plays perfectly with a dynamic drum equipped system, this rules out any damage to the active video fields recorded on tape.

So the only items left to check are the horizontal sync pulses, vertical sync pulses and the head switch pulses (A/B) recorded within the scan lines, Obviously this is not a horizontal timing problem, So that points out to the last two items which are the vertical sync pulses and the head switch pulses recorded at the beginning of each field.

Why those pulses go bad, One thing I can think off is probably because they are recorded close to the edge of the tape right next to the pulse track, But since they are hellically scanned as opposed to the pulse track which is read linearly with a fixed head they are susceptible to any tape wear even when it is not visible to the human eye. Another possible cause to that wear is tape stretching due to heat which is not reversible, My tape was stored in a very hot room for the last few years.

Does a good external TBC fix those missing or corrupted pulses? that's a million dollar question. I've already tried the AVTtool TBC and it didn't change anything I don't have the green box though.

As I mentioned above the DD system was able to read the fields just fine since it ignores all sync pulses and rely only on the maximum RF signal by adjusting the head tilt and capstan speed, the caveat is that the DD system is not active when in normal playback.

A little more detail.

1. I first tried a JVC VCR. The machine is 10+ years old but in great shape. The tape played but the entire picture itself was rolling slowly up the screen. Tracking did not impact it. I was using the composite video out.
2. Thinking I may have a VCR problem I tried a 2nd Toshiba VCR. This machine is about 8 years old and in good shape. In that machine the picture was steady and only the black bar was slowly moving up the screen. These are the photos I shared previously. No change due to tracking. I was using the composite video out.
3. I then repeated both JVC and Toshiba VCR using different monitors. One was an older Sony Trinitron and the other was a current Samsung flat screen. With both monitors I witnessed the scenarios 1 and 2 above.
4. I then purchased a Vidicraft IVC-100 to add in line between the VCR and the TV. No difference.
5. I then tried a Grex and no change.

I read the post regarding the vertical sync pulse being burnt in near the edge of the tape. This may explain by 2 different VCR has 2 different things occurring: slow rolling picture and slow rolling horizontal bar with stable picture.

A. I did clean both VCR heads first using a cleaning tape but maybe I did not do it correctly or with the right process. Maybe one the the experts can advise on the best cleaning process to use.
B. Could it be that the tape is damaged? Going Ape circa 1981 is one of the VHS I am having issues with. If someone has a clean copy available for purchase I would be interested.

The last time I viewed the tape was about 10 years ago. I do not remember what VCR I had at that time but I know I used a 36 inch Mitsubishi TV with a vertical hold control. So maybe there was a VCR I used at that time that was more tolerant of the vertical sync issue and how to process it internal to the VCR. If anyone has one of these older VCR let me know.

In any event there must be others like me who have old VCR tapes to view on latest technology TV's.

That looks like a PAL/NTSC issue.
If just PAL or NTSC, then a timing error, one that may require JVC stabilizer.

Better VCR is probably required, specially a recommended JVC S-VHS deck. Look in marketplace subforum, and I have some for sure.

- Cleaning heads does nothing, and almsot always a bad idea.
- Cleaning tapes do nothing.
- The Grex is a pathetic device, does nothing for analog tapes. (Ironically, works well for digital > DVD recorder.)
- Vidicraft does nothing.

Not surprised by any of that.

The CRT was probably more lenient, not just a VCR. But this is digital capture, different needs.

Also remember that no matter what you try, some tapes are just screwed. It doesn't happen often, but it happens. Just don't assume that's the case until you've trued known remedies.

Thanks. I tried a Toshiba S VHS and the tape looks ok. I do still see part of the bar at the bottom of the screen0

The bar at the very bottom bottom (if not moving) is the overscan head-switching noise. This was often masked by CRTs. It was always there, you just never saw it.

My HDTV does not crop out the overscan, thus all my decks show it even when viewing tapes normally, but my CRT in the bedroom does not.

In the recent years of flat panels they introduced an option called "just scan" which displays the entire resolution pixel by pixel, My LG OLED has it but my LG LCD TV from 2004 (720p only model) don't have it and the picture is way over scanned. I believe they introduced it with the arrival of 1080p panels.

If that bar keeps rolling up and down the screen it looks like "NO COPY" copy protection they used to put on tapes before macrovision but it should only do that if the tape was copied.....

I have some tapes that have that also and if I try to copy,I see just that.....