JVC VCR fast rewind issue, ideas on causes?

[D-fault]

Hello,

The VCR is a JVC HR-S8000U, what I noticed is that normal fast forward and rewind work, but when stopped only fast forward works but not rewind. When I do attempt to rewind when stopped itll start for a split second and roll the tape just a little bit before it stops altogether and returns everything to the stopped position. Additionally, I noticed that when it is doing any of these operations, the left side of the tape is spinning noticeably slower than the right. I have ordered some rubber renwer thats set to arrive on Saturday and Im going to clean the rubber on the middle idler. Something tells me that this might be a deeper issue as the symptom mentioned earlier about one side rolling slower than the other indicates that but I am not 100% sure, thoughts?

Thanks,

[lordsmurf]

It probably is deeper. Transport issues are often bands, or motors.

- Bands need to be replaced, not rubbed with goo/"renewer"/etc. That just makes a mess, and eventually causes it to harden worse.
- When the motor is bad, you're often screwed. Not easy to get parts for some models.
- Sometime gears are ground down. Same, screwed. No easy parts. 3D printing is not yet a panacea, too brittle over longer term use.

[timtape]

An old technician's trick for a moderately hardened and therefore slipping tyre is to carefully "deglaze" the tyre, hopefully exposing fresher and more "grippy" rubber underneath. We're looking only to remove the outer shiny layer, revealing a dull black surface underneath. Even just cleaning all the contacting surfaces can sometimes help. I normally start with perhaps 600 carborundom paper. Much easier to do this with the complete idler wheel removed from the VCR and working on it on a bench or even held in a suitable vice, being careful not to damage the wheel. Obviously there's some technique to learn with this and it may only partially restore function. Obviously the best long term solution is purchasing and fitting the correct new tyre part as per the service manual. This may nor may not be the solution in your VCR's case though.

[lordsmurf]

Quote:

Originally Posted by timtape

An old technician's trick for a moderately hardened and therefore slipping tyre is to carefully "deglaze" the tyre, hopefully exposing fresher and more "grippy" rubber underneath. We're looking only to remove the outer shiny layer, revealing a dull black surface underneath. Even just cleaning all the contacting surfaces can sometimes help. I normally start with perhaps 600 carborundom paper. Much easier to do this with the complete idler wheel removed from the VCR and working on it on a bench or even held in a suitable vice, being careful not to damage the wheel. Obviously there's some technique to learn with this and it may only partially restore function. Obviously the best long term solution is purchasing and fitting the correct new tyre part as per the service manual. This may nor may not be the solution in your VCR's case though.

These belts are usually so thin that's there is simply not enough to work with. Even 0.1 mm of change can cause the band to break, or no longer tightly fit.

The tight unforgiving tolerances are a VCR gripe going back decades. The result of cutting costs so heavily when manufactured.

Look at the early VCRs, and you'll find bands and chains (yes, chains) that remind you of bikes and lawnmower. Not flimsy rubber noodles thinner than an office rubber band.

[timtape]

I guess I meant this as much a way to diagnose whether the main problem is the rubber tire/belt. As I said, even a good solvent cleaning of the old tyre can effect a temporary improvement in fast wind power. If it does, a new replacement can often be found and fitted. Also tyres tend to hardness, eventually almost rock hard leading to very weak winding. That's a pretty good sign the tyre needs replacement. But I admit this sort of tech work is probably beyond many or most owners.

[D-fault]

I also think its the belt, heres a sample of what it sounds like: https://www.dropbox.com/s/3d1pruaxecnitgi/VCR.mp3?dl=0

You cant hear it that well but when it switches modes you can hear squeaking I tested this with a dummy VHS tape as I found it is sensitive to real ones if attempting to fast rewind. I think thats the belt slipping under tension due to being too loose. The good news is that it sounds like my motor is just fine, thoughts?

[SFtheGreat]

Could be the belt, I checked the bottom of the mechanism, there is only one large magnetic flywheel with a rubber belt attached, no gears, no teeth anywhere are broken off, or snapped, so the belt must be sliding, I will try boiling it for a moment.