JVC HR-J692U issues after playing old tapes?
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I have a JVC HR-J692U that I've been using to capture old tapes. One tape seems to have damaged the VCR. I previously had to take this tape apart, to fix it after the clip that holds the leader on the spool popped off after running it through a rewinder. While I was capturing it, the VCR ground to a halt several times. When I ejected the tape after a halt, it'd be scratched. When I'd reinsert it, it still wouldn't play, but I could get it to go if I fast forwarded it a bit in a rewinder.
It appears the source of these issues is some damage the tape caused to the VCR. They're all showing up on a test tape that used to play perfectly. The VCR also squeaks now when playing, the video is blurry and distorted (e.g. the edge of my test tape is wavy when it used to be straight), and it will now grind to a halt and scratch the test tape. I've attached some images of the tape scratching and video distortion. I have a few questions:
Scratching on tape after halt: Attachment 14221 Playback distortion (with whatever deinterlace VLC used). This tape used to play with straight edges on the picture, now the edges and picture are wavy. Attachment 14219 Playback distortion (without deinterlacing) Attachment 14220 |
In a way it doesnt matter what caused the problem with the VCR. It now needs repairing or replacement. When they're not working properly VCR's can scratch, stretch, mangle, tapes. The damage to picture and sound is probably permanent. Sometimes tapes can damage the VCR. It's wise not to play any important tape on a VCR unless both are in top working condition.
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Do you have a picture of the insides of the VCR maybe? It seems like something in the tape path is not acting as it should but hard to say what without seeing it.
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If the tape is scratched chances are one of the heads is chipped, you should stop putting tapes in it immediately.
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So to give an update, I brought the VCR in question to a local TV/VCR repair place to have it checked out, and the owner said he could find no problems with the VCR, except that it was one of the dirtiest he's ever seen. He said he have it a thorough cleaning. I've now gotten around to testing it, and it appears to be working fine. The picture is much better and I don't hear any more squeaking.
I've included some captures below from the same test tape as above (but a later section that wasn't played when the VCR was having problems). I'd been running a lot of really old tapes through this VCR, and some of them seem to have problems in the rewinder (maybe sticky shed?). Could a really dirty, gummed up tape path explain the kinds of problems I was having (including the scratching)? I'd been using a cleaning tape when I had video problems (Insignia brand from Best Buy, it has a kind of tyvek like tape that's used with a wet cleaning solution), but I'm guessing that wasn't adequate. postclean-interlaced.jpg Attachment 14537 postclean-deinterlaced.jpg Attachment 14538 PS: Sorry for taking so long with the follow up. I had to tear down my setup to move to a different room, and I was only just able to put everything back together. |
You have massive dot crawl around the black lines in red and blue areas, Are you using composite or S-Video? If S-Video you may want to check the design of the cable if it is coaxial or just side by side wires from Chinese knock-offs. Get Monster brand, they are cheap now since there is little demand for them, I remember when they were selling for like $120.
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By specification, though it needs a 75Ω impedance characteristic: Rₛ(75Ω) = Rₗ(75Ω) = Z₀(75Ω) which should transfer without reflection and at the Rₗ node be -3dB on the source. All good. there's a lot of things that can go wrong at the nodes if there's a mismatch, namely things like dot-crawl, reflection and if the universe really conspires against you, equipment damage, however unlikely with the tiny amounts of power we're talking about here. It's a very deep and complex topic and I've skimmed over a lot of detail here. Mild issues are most likely to be seen in the areas of greatest intensity change in the signal, for example, black/white fast transitions in Y, and why plenty of old tapes have very, very 'ghosty' white text on black backgrounds, it's simply the signal 'bouncing around' in the transmission line in most instances. On off-air recordings, the ghosts tend to be more widely spaced if it's an antenna-> VCR mismatch due to the physical length (say 30 metres) and round-trip propagation delay of the cable. Properly designed RF cables are lossy, they should be dropping 50% of the voltage of the signal as Z, irrespective of length. Anyway, yes, there's plenty of junk S-Video cables that generate precisely the issue you've spotted. |
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Rewinders can be brutal on tapes. Unlike many VCR's they dont slow the tape down when approaching the beginning or end of the tape, and neither do they stop the tape before it reaches the physical end. For a tape to become broken off at the hub should normally be rare. A leader to tape splice break is more common as the adhesive eventually fails. Quote:
I'm increasingly convinced Peter Brothers is right in recommending professional tape cleaning (as well as thorough cleaning of the VCR's tape path) for best playback. Once an important tape is damaged it may need a good professional clean to gently remove the now dislodged tape particles without damaging the surface of the tape that is still intact. |
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