Fostex R8 speed fluctuation-revised, with pics.

[Mr Fruit]

Following on from this thread:

https://homerecording.com/bbs/showthread.php?t=281264

Ok Chaps, after ruling out sticky shed syndrome, the problem seems to lie with either:

1. The pinch roller
2. the drive belt
3. the motor.

Here is the pinch roller.

I have a link to buy a new roller, but its in Japan, and it may not be the cause of my problem.

Ok...the front of the machine.

In this pic, I have drawn on where the drive belt runs, behind the facia.

If you press play, the motor runs the untoothed belt, and turns the pulley with the capstan on it. the pinch roller closes on to it, which should pull the tape through, and it does, but on playback, there are massive speed and therefore pitch fluctuations.

If I hold the capstan or the motor pully, the motor slows down and struggles to speed up again. if you give the capstan a quick twist, it will speed up again. If you hold the roller so that you stop it from turning, it will not start again, until you give it a twist.

To me, in my admittedly unexperienced opinion, this seem like a weak motor.

if the motor was strong, surely, if i held the capstan, it would make the drive belt slip.

heres the motor from behind.

I reckon its the motor.

Anyone else have an opinion?

Are these motors still available?

Thanks in advance.

Phil.

 

[jpmorris]

When I first saw this I thought that the belt had melted, until I realised it was just scribbled on.

As for the motor, it looks like Nihon was bought out by Johnson Electric in 2004. They don't seem to do anything comparable, though you might be able to get a NOS motor or something.

What I have read is that it might be worth checking or replacing the drive transistors before you panic too much. I wouldn't know where they were on this machine, though.

 

[Mr Fruit]

Thanks for the reply, Mr morris, I keep noticing your name popping up on all my help threads, I appreciate it.

Hmm, drive transistors would be way beyond my capability. I can take things apart, and reassemble with new parts, but thats about as Far as I go.

Perhaps i'll have to do some research into a good UK repair shop.

 

[sweetbeats]

Some pinch rollers have roller bearings in them, many don't and just have a bronze bushing like you have there so your pinch roller looks fine.

In one of the pictures the pinch roller looks shiny, like its glazed. Is it hard and slick, or is it nice firm grippy rubber?

Is the belt tacky at all? Hard/checked/glossy or is it firm grippy rubber?

 

[A Reel Person]

The pinch roller looks hard and slick.

That doesn't bode well for the belt, either.

I'd say, replace the belt and try to recondition the surface of the roller with rubber reconditioner.

Your problem description does not sound like a motor problem. The rubber drive components are usually the things to fail.

 

[Mr Fruit]

I cant check the belt at the moment, because ive built it all back up, so i didnt lose any of the bits.

The pinch roller is a bit shiny, I wouldnt say it was as grippy as, say, a bike brake block. Its certainly not new rubber feeling, but then again its a bit subjective....im not experienced enough to know its suitability, and the only way ill find out, is waiting for the shops to open in japan, as they are closed till the 10th apparently....

That wouldnt unfortunately explain the reels stopping
every now and again though, would it?

 

[Mr Fruit]

That doesn't bode well for the belt, either.

I'd say, replace the belt and try to recondition the surface of the roller with rubber reconditioner.

Your problem description does not sound like a motor problem. The rubber drive components are usually the things to fail.

I can get hold of a belt and a roller, but ive watched it play with the outer case off, and the belt doesnt slip on the motor pulley, or the capstan pulley.

Capstan belt #FB17
http://www.openreel.net/parts_1.html

Pinch roller #PR13
http://www.openreel.net/parts_3.html


its just the reels/capstan stopping that is frying my head at the moment, making me think its not ONLY the pinch roller.

Unfortunately, until ive bought the above items, theres no way i can find out....

BUT if i pay £40 for the parts, then have to pay for the drive transistors to be sorted (as was suggested as another alternative solution above) , then possibly pay for a motor as well, and that being fitted, I'd have to have seriously thought about just getting another machine that just works...

Sheesh i dont know, i see why people use digital now.

 

[sweetbeats]

i see why people use digital now.

Well, I suppose I see your point but good luck getting a 20-year-old computer to do anything for you, and I'd rather replace a pinch roller than replace a hard drive and reubuild the OS any day. Its all in your perspective I'd say.

The pinch roller should be matte in appearance and should feel firm but grippy to your fingers. If it is shiny and smooth it needs to be replaced regardless of your current problem. That's my 2p. It is hardened and glazed.

If it were me I'd be replacing the capstan belt and pinch roller since the latter should be done anyway and if the pinch roller rubber is at that state the capstan belt is suspect too...then if that doesn't help the problem you're no further behind since those two parts should be replaced at this point anyway IMHO.

Then we can work on the capstan motor. Have you got a service manual for the thing?

I seriously think we expect too much of this equipment at times. Stuff does wear out but they are complex electro-mechanical devices that require maintenance and upkeep...just like anything does in order to keep going. I've spent plenty of time tweaking my studio PC and researching driver conflicts and maintaining storage mediums...restoring backups because some file got mysteriously corrupted blahblahblah. Neither is a silver bullet. But like I said I challenge anybody to show me a 15, 20, 30 year old computer that is still running great, if at all. My Ampex deck has taken a beating before I got it. It looks like it was neglected and abused and was into a new life as a parts deck. It needs work but in the end it is going to work great and it is about 40 years old. Obsolescence is in decades rather than years with an open reel deck. Not trying to lecture you. Just a bit taken by your exhaltation of digital this early in the process...

 

[A Reel Person]

2 things:...

1) I've not taken apart an R8, but the previous Fostex's reel tables were also belt driven.

2) The reels do not pull the tape in Play motion, the capstan and pinchwheel do. The reels just provide take-up and back tension. If the capstan/pinch roller fail to move the tape, the reels will also stop accordingly. If the reels slow down or stop in FF/RW, it would still likely indicate a problem with the belts.

 

[sweetbeats]

The reel tables are indeed belt-driven on an R8 via toothed belts from individual reel motors.

 

[Beck]

When you buy used analog deck (not many new ones out there) the first thing to do is replace the pinch roller and capstan drive belt no matter what. The drive belt and pinch roller WILL be bad (in most cases unless the previous owner recently changed them).

If you can't find a replacement pinch roller have the old one rebuilt by Terry's rubber rollers.

http://www.terrysrubberrollers.com

The only reason not to replace the rubber is if the heads are gone, the machine is DOA or otherwise unusable and you don't want to invest anything more into it.

Rubber goes bad with time, whether the machine is used or not. The problem with trying to troubleshoot a machine with old belt and pinch roller is that these will always interfere with your ability to access functionality.

In your case the belt and pinch roller are available and inexpensive. Changing those out would be my next step in your situation. The company in Japan is reliable and easy to buy from.

You may or may not have motor problems. For example, reel tension could be way off among other calibration issues.

 

[trancedental]

The pinch roller looks similar to my Fostex E-16, I'll attach a picture to this post for the experts here to look at, I have cleaned it usually with a very small bit of soap & slightly warm water using a cotton head cleaning swab stick.

There's no ball bearings on mine, the outer plastic cap just screws in to connect the roller onto the Fostex, my old Fostex A8 had the same roller cap which was a silver colour

 

[cjacek]

I'm with the guys on this, you need to replace the pinch roller and capstan belt. The problems you're experiencing echo issues with machines operating with bad rollers and belts.

It's incredible how many mechanical / electronics problems a bad roller and belt can mimic. Seriously, replace those inexpensive items. I've also ordered from the JAPAN folks and they're incredible.

UNTIL YOU REPLACE THE BELT & ROLLER, DON'T DIG ANY DEEPER.

 

[trancedental]

Mr Fruit, does your R8 have a screw cap for the roller like the picture I've attached in my previous post?

It look's like it needs this for the pinch roller & capstan to work properly & all the R8 google image pictures I've seen have them on.

If you don't have one of these caps on your pinch roller it might explain some of your problems?

 

[Mr Fruit]

Thanks again for the replies.

No, it doesnt have the outer cap on the pinch roller, it doesnt have any thread on the shaft to "screw" one on, although it has a groove which looks like it may take a small circlip. if you check out the thread in the first post, it shows pics of 2 R8's, one with the black cover, and one without.

Due to the overwhelming pinch roller/belt concensus of opinion, ill just bite the bullet and but them, and then come back and stalk everyone of you if it doesnt work.....

Seriously though, I know thats the best bet, logic suggests that it would be a good idea, i just didnt want to start paying out cash, when i may end up buying another R8 after finding out there was too much wrong with this one.

PS, I seriously doubt ill ever buy digital, im too much of child of the 80's.

 

[Mr Fruit]

here you go trancendental...

mine looks like this (not mine)

rather than this:

 

[trancedental]

The cap is actually metal not plastic & it has a built in screw attachment that screws into the pinch roller. The cap with attached screw keeps the pinch roller in place.

If the cap is not fitted the pinch roller will move about I would presume, because there's nothing to keep it in place once the tape starts running at speed?

The screw caps are the same exact type as on the larger tape rollers, they should unscrew & watch out for the springs!!!!!


I've taken another (bad fuzzy) picture to show the exact details

EDIT The Cap Screw cover screws to the pinch roller spindle even without the pinch roller fitted. As I mentioned earlier all the Fostex machines have similar setups, from the A8 / B16 onwards & your R8 is just a later MIDI featured version of the M-80 / E-8 so very similar to my E-16.

Screw size diameter at the base appears to be 2.5mm length is around 4mm according to my calliper, you might be able to use a screw (not bolt) with a large pan / button / round / truss head wider than the pinch roller hole

I would contact the seller to see if they have the cap screw cover?

 

[Mr Fruit]

Im not sure if im understanding you, But I think I am....there is no thread on the pinch roller shaft at all, for anything, just a indented slot for what i presume is a circlip....ill take a pic to show you.

I agree in principle with your logic though, I just dont see HOW i could attach a cap.

I cant contact the seller, I bought it from Ebay over a year ago, its been stored while I got my studio room ready.

heres the end of the pinch roller shaft.

 

[Mr Fruit]

From your picture, its obvious that your cap wouldnt screw into my existing pinch shaft, so unless its been replaced, Ive got to presume:

1-They changed the design to some sort of circlip retaining clip
2-My pinch roller shaft and mech, has at some point been replaced.

 

[trancedental]

Does your pinch roller have a clip or something else holding it in place? Looks like they changed the design on some on the R8's later on.

Mine appears to be a different earlier design. See pictures below

I've never seen a service manual for any of the Fostex R2R machines, has anyone here got one?