Do a forum search on "feathering", and you'll see a few discussions on this about JVC models. This also happened to me with a JVC I acquired, but resolved it by adjusting my alignment of the video head drum. I cannot recall if adjusting the A/C head alignment was necessary. It's been too long. But that may have some impact as well. I was fortunate, in that the edge of the tape that got feathered did not have any information on it that prevented clean video and audio playback. It still played just fine in other machines and also in my JVC with fixed alignment.
Where in the tape path this happens is on the last guide that the tape travels across before going into the take up reel (on the right side when facing unit from front). For JVC, the top of this guide has a "bulge" (for lack of a better term that escapes me), which many other manufacturers don't have. When the tape rides too high, the top edge of the tape will roll up over this "bulge", which is not what the design intended. This causes the "feathering". After I got my alignment fixed with proper studio released tapes, it still took me a while to put the lid back on until I trusted the tapes would not be feathered any more. A bit of anxiety to overcome, of course.
Adjusting alignment is something that is normally not encouraged to do. Naturally, there are very few that would likely be able to do this for you. And it could cost quite a bit. But this is very likely a symptom of poor alignment and you don't have much choice in getting it resolved, I would venture to say. Wait for more replies and do some research before attempting though. lordsmurf has posted a thread on here about how to carefully go about this on your own.
http://www.digitalfaq.com/forum/vcr-...c-vhs-vcr.html
I managed to do this, and it was my first time, but I did some research and was careful. JVC's are easier to adjust video head alignment on, which is the good news. You can find some JVC Service Manuals online, or even on this forum. Even if it's not the exact model, if it has the same screw setup on the A/C head (which I would probably not start with, the video head alignment is more likely) it can tell you about what each screw does. The manual will talk about an alignment tape, which are pretty rare these days, and not absolutely necessary. The video head alignment is pretty universal. Finding the right tool to adjust the posts by the video drum may be an issue there though. If you don't have a screwdriver with a notch cut out of the center or an actual VCR drum alignment tool (basically same thing), if you are careful you may be able to just rotate it with a tiny screwdriver in one of the four notches on top of the post, going very slowly and gently. Alignment can be done with an oscilloscope for most certain results. Youtubers have some DIY videos on this topic of vcr alignment. 12voltvids is one channel that is at least from someone who was in the business for most of his career. Others may be less experienced. But this requires hooking up a scope to test points. I think the test points may be pretty easy to find on a JVC compared to others manufacturers, but still may be beyond your comfort zone, which is fine.
However, many say you can do it good enough without any electrical probing. You need to use a tape that is known to have good alignment to begin with, i.e. A VHS released by a major studio in SP mode. Start by aligning picture and HiFi sound so that it's optimal on SP tapes. Read lordsmurf's guide. But I think the left post adjusts the top of the picture and the right post adjusts the bottom of the picture. And adjusting one does effect the other, so it may require a bit of back and forth. Most important is to take a picture or remember where you started and don't go too far from that point without seeing improvement. Then, try to find an EP tape that was released by a major studio. I happened to have a TV series release from a major studio that had to compress a whole season onto 3 tapes. That may be a good bet for where to find such a tape. The EP tape will have a much narrower tolerance than the SP, so that's why you start with SP. EP may be helpful for fine tuning after optimized for SP. The more tapes you have on hand the better. Not sure if they are necessarily all so well aligned. But they should be trusted over homemade tapes from a random uncalibrated VCR.
Best of luck to you!
