A member here is having issues with his JVC S-VHS VCR, a suggested high-end model with internal line TBC. It's also a deck he got from me about a year ago. When it left here, it was perfectly aligned, and played both SP and EP like a champ. But gravity affects VCRs, regardless of how much it's been used. Shipping can also cause VCRs to adjust badly; some bad jostles + gravity over time = just enough out-of-spec alignment to start to see problems appear.
It's a simple fix, quick adjustment.
This is a very rough write-up. Honestly just an outline for a guide.
And it assumes that you know the VCR was already capable of having a good alignment.
This is also a rough eyeball method. VCR techs like TGrant would use scopes to measure and correct this with near-perfect precise adjustments. (Of course, you'd ship it to him, have him ship it back, and you may find yourself right where you started. Even if you write "DO NOT DROP" in the VCR shipping box, some shipping/postal workers are illiterate goons. So I'd hesitate to send a VCR back for mere alignment. I'd toy with it first.)
Although this could work for any VCR, not just JVC, it usually does not. Nor does it work for all JVCs. The guides inside the deck must easily move with a flathead screwdriver*
. Otherwise just give up now. Something like the Panasonic AG-1980P can never use this method (though it's partly because the guides lock down better). * Update: You can also Dremel out the center of a flathead, and it will allow more decks to be easily realigned.
Removed the lid of the deck.
You can either do this procedure with a tape that's already getting boogered up (due to the alignment being fubar), or a non-important tape (old retail movie). And if using boogered tape, make sure you're not viewing any already-damaged areas.
When the tape is inserted, and starts to play, you'll see the guides slide up near the heads.
Take a photo now! Get a good clear picture of both guides!
You may need to refer back to this original position. You can quickly forget where you started! And then you'll be in even worse shape.
You'll need a small flathead screwdriver.
Let's orient you. The front of the deck is where the tape gate is, where you slide it in. The back is where the power cord is. And hopefully you know your left from your right -- right?
You'll first adjust the right guide.
The right guide mostly controls tracking.
The left guide affects both timing and tracking.
If the round guide was a pie, a good turn is maybe a 1/16th slice (1/4th of a 4th).
You need to be careful, steady hands required. If you slip, and hit the tape, or something else, you may cause significant damage to the deck and/or tape. I try to rest my hand on the tape cage, and hold the screwdriver with both hands. Seriously, this is like surgery on a live VCR.
Insert the screwdriver in the guide top, and give it a slight twist clockwise (or counter). Go slow. Watch how the image on screen reacts to the turn as you're making it. You'll do this while watching in the VirtualDub
preview. If a screwdriver doesn't fit, or it won't turn, then just stop now. You cannot use this guide. Don't force anything.
If clockwise does nothing, or makes it worse, reset yourself. Now try counter. If a 1/16th is bad, try another 1/16, and another. You'll almost never go more than 1/4th (4 x 1/16).
If no effect, either way, return to start position. The left guide perhaps needs a tweak instead. That guide is never almost never more than 1/8th (2 x 1/16th) turns. But again, this is a sloppy eyeballed non-sciency way.
It'll be obvious when it doesn't like what you did.
If none of this helps, you'll need to seek an expert alignment. It can also be a warning sign the the heads are going out of spec, significant wear from usage.
Do you have all this? Good luck!
I shot some images some months back, with the intention to make a guide, but I'm not ready yet. Other priorities first. And I've misplaced those digital photos at the moment. When I eventually write that guide, I'll be sure to update this post.
Again, good luck.