Audio tracking / Cleaning VCR Hi-Fi audio heads?

[kingbean]

I've been working through a lot of VHS tapes of late, and last week noticed some of my recent transfers has audio problems.

I've since deleted the files, but it sounded like it was losing tracking on the Hi-Fi audio track - sound would go from crisp and clear, to dull and muddy, then back, and so on. It also had some crackle present. The picture looked fine.

I pulled out the VCR, cleaned the video heads (also responsible for the Hi-Fi audio?) and packed it all up again. I re-captured the tape, and although it was much better, it still seemed to drop out a bit, and the crackle still came back on occasion. I've since captured some other tapes and the crackle is still present.

So, bit of a two part question:

1. Is there a particular spot I should be focussing on when cleaning the video head? Here a photo of the insides of my VCR (JVC HR-S5500AM). The red circle is what I've cleaned (with printer paper and 100% isopropyl alcohol). Do I need to pay any attention to the green circles? Is that linear audio?
   
   VCR_Inside.jpg
   
   
2. Is the hi-fi dropping/crackling a tracking issue? I haven't had any issues with it in the past, but now it's popping up on several tapes, and not present when played back on another VCR. Is it possible a bad tape messed up my VCR's tracking? Is it something I can fix myself?
   
   I've attached two samples: Audio_Crackles is the crackling sound (not always as obvious as it in this this clip) and Audio_Muffled which is a short clip going from 'lo-fi' to hi-fi audio. Previously it would cycle like this through the whole tape - it's now only present a little bit here and there.

Any advice would be greatly appreciated!

[latreche34]

Your VCR is switching between HiFi stereo audio track and mono linear audio track when HiFi is unstable, It could be a tracking issue or a bad tape. If you have a calibration tape and the know how you can re-align the VCR.

[kingbean]

Unfortunately I have neither a calibration tape nor the know how. The HiFi/linear thing is happening on some tapes, but not all. The crackling is more persistent across tapes, but again not all of them and not always. Are the two related? i.e. is crackling indicative of an unstable HiFi track which in turn leads to switching to linear?

[latreche34]

Yes, Get a different VCR to see if the tapes are faulty.

[kingbean]

I had tried that previously and didn't notice any crackle, but tested it again now and, listening closely, the crackle is still there but it's not as present nor frequent. So likely a tape issue, which one VCR handles better than the other?

Is there any benefit to extra head cleaning, or is that nothing to do with this issue?

[keaton]

Regarding the initial post, yes, you can clean the areas circled in green with isopropyl alcohol and a Q-tip. The green head on the right is the Audio and Control (A/C) head for linear (non-HiFi) audio track and control track. The video head is usually the most prone to collecting dirt, and you should clean it (not with a Q-tip, as you are aware) until there's little to no dirt showing up on what you clean it with. Maybe there's a chance of some stray and stubborn piece of debris on a video head that doesn't come off so easy after a dirty tape was played. But I also wouldn't recommend overcleaning the heads, as you don't want to reduce their lifespan. Only clean it if you suspect there's a stubborn "clog" type issue or when you suspect dirt is causing playback issues. If you deal with a lot of dirty tapes, you may have to clean often. But all I'm trying to say is don't clean it when not necessary.

As others pointed out, it is wise to try another machine to see if you can determine if it's "baked in" to the tape (i.e. a bad spot or recording), or if it is a combination of the tape's and the machine's alignments. It's not fun, but if you find a machine that handles the audio better, you could merge the video from one capture with the audio of another. This only works if you aren't dropping frames during video capture. Otherwise, video and audio may drift a bit when combined like that. A TBC should prevent that problem.

When HiFi audio fails, VCR switches to linear audio track. Although, HiFi is preferred, if you cannot resolve the issue of alternating audio, there should be a control for your player to force playback of the linear track for the entire playback.

Tracking can be a reason for HiFi to crackle or dropout. When I have a rough spot on a tape, I try to recapture those portions with tracking adjusted until the audio plays without crackle or dropout to linear audio. Doesn't always work, but if it's an occasional problem, you might be able to edit the recaptures together with the original capture. Of course, this is when you cannot find a better solution. Also, sometimes when this is done, the audio is good, but the video is not due to the change in tracking settings. This also requires similar editing to get the good audio spliced with the good video.

A bad tape should not mess up your player's alignment. It can certainly make heads dirty. If a tape's alignment is so bad that even tracking adjustments don't resolve the issue on multiple machines, some resort to deliberately changing the alignment of a player to get the tape to play. This is something reserved for a deck you don't mind messing with and a tape you really want to capture and you've exhausted all other options. Only for the advanced who can get the machine back to proper alignment after done with the tape.

[timtape]

Just to add, the HiFi track sample you uploaded was recorded in stereo but the linear track we hear is in mono. That makes the linear track sound inferior. (Some VHS decks have the ability to record and play back stereo linear audio). The linear audio track is also misaligned, making it sound duller than the linear audio on your tape.

When the linear track is played back optimally, the sometimes unavoidable switching from HiFi to Linear (and back again) doesnt sound as jarring and can even be unnoticeable.