Part of tape only displays properly on fast forward?
 

Strange issue I'm having with a VHS-C tape. I know it's the tape's fault because the same thing happens with two different players. There is about ~15 minutes of footage on it, recorded on three different days. The first day's footage plays back normally. The rest of the tape has a jumbled signal/vertical hold, although the audio is still normal. However fast forwarding through these parts shows a normal picture. What would be the fix for such an issue?

Confirm the tape is only NTSC, or only PAL, not mixed.

If mixed, that's the issue.
If not, then more troubleshooting is needed.

The tape is a Maxwell TC-30. As far as I know, it was purchased in the US and should be NTSC

https://ez647.sk/video/maxell_hgx_c.html

Assuming there is no physical damage to the tape itself (open the tape's door and look to be sure there's no physical damage or malformed tape).

Something I've experienced with a tape having multiple recordings from different times or possibly machines is one of the recordings has no audio or video during normal playback. When paused or Rew/FF while playing, a picture is visible. Sometimes the counter on the VCR won't move when rewinding or fast forwarding the tape from stop.

These are all symptoms of the control track on the tape being out of alignment with the player, which means the machine that made the recording had a misaligned A/C (linear audio and control track) head. Perhaps there are varying degrees of this condition, and a slightly less misaligned track can still have the audio track play, but the control track is still off enough that it cannot maintain stable frame sync on the video track.

If this were the case, the A/C head of the VCR could be changed to match the alignment of the tape. The head would be adjusted until the playback of the video and audio is optimal. However, BEWARE! ATTEMPT THIS ONLY AT YOUR OWN RISK, AND BE FULLY AWARE OF THE RISKS OF WHAT YOU ARE DOING! Big warning, aside, if you learn enough about the A/C head alignment and do attempt this, you'll have to then get your machine back into proper alignment. Either by somehow being able to undo what adjustments you did do, or by perhaps using a tape that has good alignment to help you get your A/C head back in alignment. Alignment tapes exist, but are not easy to find. An alternative could be to use a commercially released tape that one would hope has been generated from properly aligned equipment. Of course, there is alignment for SP speed tapes, and then there's alignment for EP speed tapes. SP is a bit more forgiving. But EP is much more delicate due to how much more is compressed on to the tape in that speed. If you are a technically inclined person, you could try using an oscilloscope output from an audio test point to help get the maximum audio signal strength, and assume that equates to best alignment.

Anyway, just an idea to consider that is entirely at your own risk to pursue depending on your level of experience/comfort. And this is purely a guess, since there's no way for me to physically observe things. Perhaps if you have a machine that you don't care about screwing up to test that theory, and if you are willing to accept that this machine may not otherwise be optimal for best playback quality.

Another thought to possibly try, which may help determine whether it is a misaligned control track, is to take the cover off the machine and apply a bit of pressure to the top of the A/C head in such a way that the head moves down a bit with respect to the tape, trying to simulate what would happen if the tape and head alignment were altered. Of course, this is also a do at your own risk type of thing, depending on your level of comfort. Doing this could have the risk of altering the machine's default alignment, or possibly effect the tape's travel over guides that could cause harm to the tape (i.e. feathering the edge of the tape). Again, just ideas here. No official endorsements or guarantees.

Unless a video sample is posted there is no way to guess what really is the problem, Tape problems cannot be described by words. Sure I can guess it's a miss alignment and requires mis-aligning the camcorder but what if the problem is entirely something else.

Misalignment is one possible issue, but so is simple misrecording by the camcorder (and it was never good footage).

Interesting that the first clip plays OK but the next two do not, yet audio is OK. That may mean the control track (and audio) were recorded OK, but the video on the second two clips was not. It might be something prevented one record head from recording normally while the other recorded OK. The FFWD play may look sort of OK because it only sees the signal laid down by the good record head.

If the video is important you might be able to recover something by capturing the FFWD image and the normal playback sound, and then time stretching the captured video to match the notional good sound. I will not be a great picture but perhaps better than nothing.

I'll upload a sample when I'm able. I don't currently have a full capture of that tape, as I've since moved on to others.

If it is misalignment, is there a guide here for re-aliging the A/C head? And yes, a misrecording is possible. I wouldn't know because this tape hasn't been played back in some time.

This is probably what I'll end up doing. It's possible I could smooth it out to a proper framerate with some interpolation script, but that would require a bit of further research.

By chance do you have any other tapes recorded with the same camcorder immediately after the problematic tape? Do you have the camcorder?

FWIW I've used the "respeed" video capabilities in a NLE to sync video with sound. Easier than tweaking scripts.

Best of luck with the project.

The camera is likely still around, but somewhere in storage. Would require some digging.

The tape right after that one chronologically doesn't have that issue, and it was recorded on the same camcorder. As I mention in this thread, I get plenty of tracking issues a few tapes after then, but none as severe as this particular tape. The ones immediately before/and after don't have any issues as far as I see.

I would open the flap of the cassette and look for any physical tape damage. including stretching at the edges.

I have another VHS-C with similar problems. Thankfully, I've gone through all 40+ tapes and these two are the only ones with such issues. This one has 13 thin horizontal lines running through the picture, and each part of the video the lines section off are delayed by slight increments which creates this wavy water ripple effect across the whole thing.

If I were to change the alignment on a VCR to match the misalignment of these tapes, would it be hard to do that for two separate cases of misalignment?

I can confirm it is an alignment issue. I used a secondary VCR (so as not to mess up my primary JVC one) to fiddle with the alignment under the hood, and I can get an unobstructed clear picture. The problem now is that it's inconsistent; an alignment that works for one part may start jittering again five seconds later. It also only displays the image proper when both aligment heads are extremely loose; And believe me, I started out the proper way using only 1/16ths of turns w/ a Flathead. Because of this, simply rewinding the tape back to the relevant part will pull on the alignment just so that it has to be re-calibrated all over again. My current solution is to re-calibrate/capture ad infinitum and then stitch all the good parts together in Premiere. but I still haven't gotten perfect captures for certain bits such that I can make one perfect compilation yet.

Not a solution but I wonder if the problem is in part due to the 4-head head arrangement used to record a VHS compatible signal on the tape with the smaller VHS-C head drum that requires 270 degree contact with tape?

I'm also wondering if this is more difficult than it should be because I don't know enough about alignment and I'm doing it wrong?