Toshiba M-9485C VCR

[R_J]

Re: Toshiba M-9485C VCR

Have a look at the back tension arm, it should be resting against the tape and actually pushing the tape to the side a bit. If there was too much tension it would be puting too much brake on the supply reel causing the tape to go tight against the drum.
Another place to watch is how the tape is riding between the capstan and pinch roller, if there is too much back tension that can cause the tape to ride down the capstan causing it to crinkle at the exit guide, this would also cause it to ride lower on the ace head loosing the control pulse causing the capstan speed to be eratic. watching the action of the back tension arm can tell a lot about whats happening

[mike_drz]

Re: Toshiba M-9485C VCR

Have a look at the back tension arm, it should be resting against the tape and actually pushing the tape to the side a bit. If there was too much tension it would be puting too much brake on the supply reel causing the tape to go tight against the drum.
Another place to watch is how the tape is riding between the capstan and pinch roller, if there is too much back tension that can cause the tape to ride down the capstan causing it to crinkle at the exit guide, this would also cause it to ride lower on the ace head loosing the control pulse causing the capstan speed to be eratic. watching the action of the back tension arm can tell a lot about whats happening

Today it started acting a little better, I found the crinkle is starting around the capstan shaft and pinch roller. The top is folding over. The back tension band on this machine is very old and worn out, the little copper band.

The head is still making noise as if something is rubbing. When I put that collar back on the head shaft, did I need to add pretension? There's a little wavy spring washer type thing, just below the collar.

One of the heads looks like it's lower than the rest, and is close to the bottom cylinder. Maybe that's what's rubbing? I also noticed the green mark on the top of the cylinder, approximately lines up with the pickup magnet on the bottom rotor housing. That's probably the factory mark, the way they had it lined up.

[R_J]

Re: Toshiba M-9485C VCR

The back tension copper band should have a thin felt on it, sometimes the clue would get old and the felt would fall off, it can just be glued back on. The band puts a bit of braking on the supply reel so the tape comes out smooth and with enough tension to keep it in contact with the drum. as for the drum motor reassembly, I can't help you there.
As for the heads on the upper drum. They are aligned at the factory. DO NOT TRY AND ADJUST THEM !!!! If one is lower that the rest it is broken and you will need a new upper drum (heads)
The actual heads are quite strong going in the direction of the spinning head BUT are very easily broken if force is put on them in the vertical direction.

[mike_drz]

Re: Toshiba M-9485C VCR

The back tension copper band should have a thin felt on it, sometimes the clue would get old and the felt would fall off, it can just be glued back on. The band puts a bit of braking on the supply reel so the tape comes out smooth and with enough tension to keep it in contact with the drum. as for the drum motor reassembly, I can't help you there.
As for the heads on the upper drum. They are aligned at the factory. DO NOT TRY AND ADJUST THEM !!!! If one is lower that the rest it is broken and you will need a new upper drum (heads)
The actual heads are quite strong going in the direction of the spinning head BUT are very easily broken if force is put on them in the vertical direction.

Thanks RJ, I'll just have to hope the head isn't broken, that'll be game over. I won't adjust the heads, they are in the upper head with hex screws. I've left those be the way they are. Maybe one got bent while I was taking it apart who knows. The head always had some drag to it though, even before I took it apart.

The felt on the copper band seems fine, but the band itself is really flimsy, doesn't feel like metal anymore. It has more of the tension of plastic after 27 years.

[R_J]

Re: Toshiba M-9485C VCR

The band is fine, its made that way. the only time I have had to replace one is if the plastic on either end broke or the felt fell off and the customer opened the vcr and lost it.
I don't quite get what you mean when you say the head had some drag on it.
The spinning upper drum has thin grooves (3 or 4) in it. these grooves provide a cushion of air between the tape and the spinning drum. The Heads actually push slightly into the tape making good contact with the tape.

[mike_drz]

Re: Toshiba M-9485C VCR

The band is fine, its made that way. the only time I have had to replace one is if the plastic on either end broke or the felt fell off and the customer opened the vcr and lost it.
I don't quite get what you mean when you say the head had some drag on it.
The spinning upper drum has thin grooves (3 or 4) in it. these grooves provide a cushion of air between the tape and the spinning drum. The Heads actually push slightly into the tape making good contact with the tape.

When I first took this unit out of storage, the head would make a crunchy noise, when I spun it by hand. It got better with time, but always was noisy when it was spinning.

When I had the head apart, I cleaned those air groves with a tooth pick. They were clogged up. Maybe that's what's changed the tape tension. I also had the idler motor apart when changing the idler wheel. Don't know if there could be a timing issue with that one. I also marked that rotor before taking it off just to be safe.

[R_J]

Re: Toshiba M-9485C VCR

There is no timing related to the idler motor, only with the drum motor as it needs to know where the heads are in relation to the tape so it knows when to start scanning, when to stop and switch to the other head. both video heads are different, each head gap is at a slightly different angle and if the scan is out 180 the picture will look bad but still show up.

[mike_drz]

Re: Toshiba M-9485C VCR

There is no timing related to the idler motor, only with the drum motor as it needs to know where the heads are in relation to the tape so it knows when to start scanning, when to stop and switch to the other head. both video heads are different, each head gap is at a slightly different angle and if the scan is out 180 the picture will look bad but still show up.

I spent some time farting around with the tape adjustment and back tension. I got the crinkle reduced. However it's still there. I also only get signal from one head from what I can see on the scope. I definitely think it's a time issue now.

There is an older service guy I called today, I told him the issue and he said he can take a look, free estimate. We'll have to see if it's feasible. Might be cheaper to just buy a used head. This one is pretty worn.

[mike_drz]

Re: Toshiba M-9485C VCR

For anybody who's interested, the VCR was fixed. It had one bad head, and a problem with the audio head alignment for some reason. Got it fixed for a reasonable price.

For anybody from the Toronto area in Canada, take your gear to Oscar from AMI electronics, he really is great. He's one of the few guys around that still does board level repair on anything you bring him.