Can these VHS dropouts be fixed?

[PizzaTime]

Hello,

I have a problem tape (Fuji T-160) that has these consistent, frequent dropouts. I figured I'd just have to clean the video heads, but that didn't change anything. I initially played it in my JVC HR-DVS3U and SR-VS30, but it was mostly blue/blank. I then played it in my AG-1970P, and that outputted more video results than the other two (I should note, the results didn't seem to vary if I flipped the switch from T120 to T160). The AG-1970P is the sample that I have attached to this thread.

[aramkolt]

What is interesting about that clip is just how regular the interval is for the static coming and going. Is that near the beginning of the tape and is the tape itself have any visible damage in those areas when you flip up and look at the tape door?

I take it that only this tape does it?

I haven't seen this before, but I could see a magnet at some point in the past being placed over the radius of the tape and each time the video reads from that clock position of the reel, it's static and then goes back to normal video once the tape is back out of the magnet exposed area maybe?

[PizzaTime]

Quote:

Originally Posted by aramkolt

What is interesting about that clip is just how regular the interval is for the static coming and going. Is that near the beginning of the tape and is the tape itself have any visible damage in those areas when you flip up and look at the tape door?

I thought that was very strange as well. This is about 3 minutes into the tape (SP mode). There is a whole different scene or two in the first 3 minutes that play completely fine. There does not appear to be any visible damage on the tape.

Quote:

Originally Posted by aramkolt

I take it that only this tape does it?

Correct.

[timtape]

Cleaning the video heads wont fix it as they are obviously reading the picture fine in other parts of the sample.

That cyclic loss of RF is the same symptom as when a tape is played back with no sync between its video signal and its control track.

Before playing this tape have you tried cleaning the audio/control track head, specifically the lower part?

Perhaps the control track was recorded a little weakly, or perhaps the tape is damaged, perhaps creased or frilled/stretched on the bottom edge where the control track is. I'd inspect that bottom edge. Perhaps the cold weather at time of recording was a factor.

[PizzaTime]

Oh! I forgot to mention that the time counter does not change during this sequence. Don't know if that helps with the problem solving at all.

[timtape]

Quote:

Originally Posted by PizzaTime

Oh! I forgot to mention that the time counter does not change during this sequence. Don't know if that helps with the problem solving at all.

It sure seems to because the time counter gets its "time" from the control track! The control track tells the VCR where the video tracks are and how to lock onto them, moment by moment, and right through the tape playback. That's why I mentioned the control track and asked you to inspect the bottom edge of the tape for damage, for the control track is recorded on that bottom edge.

This Wiki diagram shows the audio track on the bottom edge and the control track on the top edge (I thought it was the other way around). But it will be either the top or bottom edge of the tape that I would inspect carefully.

[PizzaTime]

Quote:

Originally Posted by timtape

It sure seems to because the time counter gets its "time" from the control track! The control track tells the VCR where the video tracks are and how to lock onto them, moment by moment, and right through the tape playback. That's why I mentioned the control track and asked you to inspect the bottom edge of the tape for damage, for the control track is recorded on that bottom edge.

This Wiki diagram shows the audio track on the bottom edge and the control track on the top edge (I thought it was the other way around). But it will be either the top or bottom edge of the tape that I would inspect carefully.

Here is an examination of it while playing the bad segment. Nothing on the tape is sticking out to me. Thoughts?

[timtape]

If there's no tape damage and it's confined to one scene or one camera, perhaps the camera was faulty at time of that shooting such as having a dirty A/C head. If so, probably difficult to fix I guess.

[keaton]

Certainly agree with the control track on the tape being the contributing factor to why the video drops out intermittently. The time counter stopping confirms the control track not aligning between tape and video player. If the tape doesn't show damage, one possibility could be the control track is fluctuating in it's position along the tape and contributing to the fluctuating in and out of alignment with the control track head on the player.

I've seen tapes with "loss of lock" type tracking problems before. Sometimes I've had some luck playing back the tape on a different tracking setting that might look bad on the normally good parts of the tape, but may look better when playing over the normally bad spots. Of course, if you did get some better results on the "bad" parts, then it becomes a tedious exercise of combining the different lossless captures (i.e. Huffyuv, Lagarith, or whatever you're using) together using the best frames from each capture. Of course, it's rather time intensive doing multiple captures and trying to stitch them together. I only bother with that when it's something I really want to preserve as best I can.

I have one tape where the control track is so misaligned that it seemed blank (no time counting) until I paused or went to FF or REW from play. Changing the alignment of the control track head on the VCR would be the only way to try playing back such a tape. Of course, I don't recommend messing with a tape player's alignment unless you really know your stuff. If I can't get results with making a large tracking control adjustment during playback, I let it go. It's not worth messing up a good machine for one tape, no matter how valuable it might be.

[timtape]

Starting play/capture at multiple different starting points in the faulty tape may capture more or all parts of the tape but as Keaton says it may still require a lot of editing.

[dpalomaki]

Does the linear track audio drop out as well or still play normally at the problematic places?

If the tape is losing contact with the control head very gentle pressure on the tape at the head to ensure contact (similar to the pressure pads found on old analog audio tape recorders) might help

[qwertz73]

Could the problematic part of the tape have been demagnetized ?

[PizzaTime]

Quote:

Originally Posted by dpalomaki

Does the linear track audio drop out as well or still play normally at the problematic places?

Depends on the deck. My JVC deck picked up the sound but not video, while my Panasonic deck did not pick up on the audio but it captured (most of) the video.

[Dougmc]

were your tapes placed on top of a crt tv which has a degausing coil or near speakers with magnets?

[dpalomaki]

Maybe capture the audio and video separately then combine them in post.

[timtape]

Quote:

Originally Posted by PizzaTime

Depends on the deck. My JVC deck picked up the sound but not video, while my Panasonic deck did not pick up on the audio but it captured (most of) the video.

I think some decks will mute video and audio whenever a control track is not picked up. They assume that with no control track, no audio or video was recorded either.

A good tech could tap into the control track signal after its preamp and both listen to it and view it on a CRO. Without that information we're sort of flying blind.

[PizzaTime]

Quote:

Originally Posted by Dougmc

were your tapes placed on top of a crt tv which has a degausing coil or near speakers with magnets?

I don't know. I was digitizing them for a friend.

[PizzaTime]

Quote:

Originally Posted by dpalomaki

Maybe capture the audio and video separately then combine them in post.

This is what I ended up doing. The result is not the worst thing ever. I don't know if I'll ever get that info back. I even took a "junk" VCR and experimented with the alignment. Nothing changed.

Edit: I also ran it through a Videonics MX1, or else Vdub would stop capturing after about 2 minutes (the segment is 5min long). Again, it's not the worst thing ever, but it's better than 5 minutes of a blue screen.