hysteriah, just let us know how this story ends. :)

Well, I can already now tell you how this probably "ends". Unless someone here comes up with a great suggestion to something I can try that might fix this VCR, then I will probably put it away and just save it as "for spare parts" until some of my other JVC VCR's might need some spares ;-)

What's the model of the machine on the bottom of the stack? JVC made a variety of machines with that form factor and color, though were usually higher end machines like DVHS or WVHS. The WVHS ones at least tend to require a lot of work before they're usable in my experience, so good luck with that if it isn't already working.

At the bottom of the stack is the JVC HM-DR10000 DVHS. That one is actually working perfectly... so far :)

So, you don't like the idea of tilting the pinch roller block...
:)

I'm not quite sure what you mean with "the pinch roller block"? ...but I've tried replacing the whole pinch roller assembly (see attached photo) from a VCR that I know for sure works perfectly... so I don't really believe that it has something to do with the pinch roller any longer :hmm:

You mount your assembly on an axle. The idea is to bend it a little bit (almost towards the front) to change the angle of the pinch roller relative to the capstan shaft, to make them coaxial again.

It's hardly as accurate as needed but does the headface look as if it's about 90 deg to the chassis? Can you eye it off to compared it to the capstan shaft or a tape guide? A small mirror can help.

Is there any colored screw sealant on any of the three head screws and the head plate? Sometimes we can tell from the sealant whether a screw has been tampered with. For example it's possible the front screws on the head are set correctly but the back one has been loosened.

I often mark with a fine felt tipped pen the position of a screw or guide before carefully adjusting it. If possible video turning the screw to record the exact number of turns you turned the screw and can return it to that exact original position if needed.

Find the back screw position which stops the tape chewing.

There are no shortcuts. The aim is to fix one problem at a time, the first being to fix tape chewing/damage. If at this point the screw adjustment fixes the tape chewing, be happy, even if audio or picture gets worse. We deal with that in another step.

It wouldn't be wise to adjust something if you're not 100% sure that the specific part is at fault. Until the capstan tape runs smoothly, the problem starts after that. Of course, changing the trajectory before the capstan also changes after. But I wouldn't advice such an ax and crowbar (try and error) adjustment method, it is pointless.

Axe and crowbar?

I suggested he first check, as best he can without special tools, the head face's perpendicularity with the chassis. Also inspect the sealant on each of the three screws for possible clues of tampering from original. He can report back on those things.

It's not a part, it's an adjustment. Remember the adjustment can be completely reversed if he does it right. He can undo it. Also remember his video showed changing A/C head tilt temporarily stopped the tape mistracking and subsequent damage at the capstan and PR.

Changing the tilt may not be the solution or the full solution but it's worth a try because again it's completely reversible. There is no penalty. But if it helps that doesnt finish adjustment of the A/C head. It's just a first step. Assuming everything else seems OK there's still head height to check and if necessary adjust. Then linear audio Azimuth.

But if he doesnt want to go through with this that's his call.

He can do nothing without special tools. If you look video there are clearly visible problem is after capstan. No one should mess with factory settings if they are not clearly out of alignment because someone messed with them before. How to check and repair mechanics is clearly described in SM. If you have not all necessary tools never even start to mess with it. You can replace whole mechanics from cheaper VCR and take only head drum from this.

The machine is useless while it chews tapes.

Head zenith does not have to be exact for a good picture and sound. It's more a long term issue which if incorrect leads over time to keystoning of the head face. I assume you know that from audio tape machine heads? It can also create poor audio pickup or poor control track pickup - but not both at the same time. For testing purposes, obviously we are not concerned with long term keystoning.

And I dont believe at all that he is an expert. That's why my suggestions are very limited and finely focussed so that hopefully he doesnt make things worse.

But of course! Did I say NO? If it skew tape, check mechanics (if you have all tools) and repair, or find working mechanics and replace. That simple. But never mess with factory settings without all necessary alignment tools. That simple. What you offer is vice versa.

Even when the original setting- whether factory setting or not - can be perfectly returned to?

Exactly. Because they can not be perfectly returned no matter what lines you draw with a marker pen and even no point to do it. That's the Papuan method - change something and see what happens.

OK, "Perfectly" was not the right word. Thanks for picking it up. There's always some error. There was a great scientific and engineering advance made when plus and minus tolerances started to be used in specifications and measurements, which implies perfect precision and performance is unattainable with real world equipment.

If we have to return a screw to exactly the same angle we deviated from without even a miniscule margin for error, we could never adequately service a tape machine. For there can be many such adjustments. You dont seem to understand a fumdamental necessity in the real world, the need to make tradeoffs. Who is the unrealistic perfectionist here?

Yes I am a perfectionist but why unrealistic? I do only what I know, can and for what I have necessary tools. No tools - do not start. That simple. For audio I have nearly all (except few Nakamichi head alignment tools rarer than hens teeth, but I have alternative). For VCR I have some of necessary tools, at least test cassetes, video head testers etc., but not all and I can not align mechanics perfectly. So I simply replace it if something is wrong. Keep head drum and replace mechanics. It works. But never mess with mechanics if you do not know what you are doing.

I'm the same. I dont have every tool and the tools I have have their own limitations. I try to use them knowing those limitations. There's an old saying: "do not make the perfect the enemy of the good"

Inversely, don't be lazy/sloppy, and utter the BS phrase "good enough", which is a euphemism for "crap".

There is a middle ground between lazy/junk and unrealistic/utopia/"perfect".

Find that middle ground.

The middle is also not binary, but exists in a range. Better/worse/mid.

As an example:
- thrift story VCR = crap
- better-quality Sony/Sharp VHS models = middle-worse (combined with ES10/15 type)
- non-TBC JVC S-VHS = middle-mid (combined with ES10/15 type)
- with-TBC JVC/Panasonic = middle-better
- VCR that tracking everything always, sharp like HD, etc = unrealistic

When it comes to VCRs, that range between middle-worse and middle-better is still quite wide. But it's simply not broken junk, nor imaginary decks.

All tools have strengths and weakness.
- The best tools have many strengths, few weaknesses.
- The worst tools have many weaknesses, and sometimes zero strengths.

Solved!
 

Okey, here's a small update from the thread starter. I actually think I've managed to "SOLVE" this issue now :eek:

After replacing both the "Pinch roller arm Assembly" AND the "Guide arm Assembly" (see attached image) from another perfectly working VCR, the VCR now seems to be playing perfectly fine! There has been no more eating of tapes after I replaced both these parts earlier today, and both video and sound quality is exactly as it should be (I've compared it with a perfectly working JVC HR-S7700 and they seems to be equal) :congrats:
I almost can't believe it myself :huh1:

It might looks like I made a "mistake" when I changed the pinch roller, simply by "tightening" it a littlebit too tight to the axl. After loosening it a little bit, it now plays fine also with the original "Pinch roller arm Assembly", but the "Guide arm Assembly" must be replaced. Thankfully I do have other VCR's I can "borrow" it from :)

I haven't had this VCR for a very long time and I don't know anything about it's past. But there's really no signs of heavy usage and wear inside of it, but it looks like it might have been handled roughly, with several nicks and marks on the outside. It was also not packaged very well when I received it in the mail a while ago. That might explain why the "Guide arm Assembly" must be replaced? :question:

Thank you so incedibly much to each and every one of you who has participated in this thread! I could never have done it without your help :congrats: :congrats: :congrats: