Fostex R8 issue - please help!

[famous beagle]

Hello my analog brethren. I fired up my Fostex R8 today for its maiden voyage. Until this point, I had only made a few "testing, testing" recordings to make sure all the tracks recorded---which they did. Today, though, I tracked a full song with my band. Once we played it back, it took very little time to realize that it was playing slowly. It's not terribly slowly, but the song was about 120bpm, and it was probably about 110bpm. And of course, obviously, the pitch was flat too.

I tried fast forwarding through the entire tape. It did well for the first half of the tape, and then it started to slow down. By 2/3 of the way through (if that), it was moving at a crawl. When I hit RW from that point, it flew back all the way with no problem.

Any speculation as to what the problem could be and what I need to do to fix it?

Thanks!

 

[Steenamaroo]

There are a few possibilities.

The first one to check would be for sticky tape. If it's really bad it'll squeal due to the friction, and eventually slow to a halt.
Check the heads and tape path for debris.

If the belt is stretched or deteriorated, that could do it too. That's pretty common.

Another one is if the brakes are binding on a little bit. Sometimes tension needs adjusting; Sometimes pads need replaced.

Worst case is if the motor is failing. I'm pretty sure that's less common, but if you need parts, I have an R8 that's a few pieces short of being sellable.



I'm inclined to think it's the sticky tape thing, because anything else would be more consistent, and therefore harder to notice.
By that I mean the machine would have slowed down while you were recording, and then again while you were playing back.

Sticky tape would cause a much more noticeable slow down because the friction becomes greater with every passing of the tape.

 

[jpmorris]

Well, there's two systems at play here. Fast wind is a function of the reel motor, but playback speed is a function of the capstan - the reel motor is just to take up the tape, the capstan is actually the one pulling it from the left spool.

So for a motor failure to cause all this, it would have to happen both in the capstan and right reel motor.

It sounds a heck of a lot like sticky tape, though I would have thought you'd have thought of that. What kind of tape are you using, out of interest?

What will happen on these machines is that the capstan pulley on the motor can come loose and start to turn on the shaft. Gluing it on is the best fix.

With regard to the fast wind, it seems to be the case that when decks are having difficulty pulling tape, the motor will struggle if its side is full. Hence, although the rewind motor was running at full speed when the forward motor wasn't, you may find that the rewind motor would behave the same way if the tapes were the opposite way around. If that makes sense.

 

[famous beagle]

Hey y'all,

Thanks for the replies.

I'm a long time user of cassette 4-tracks, but this is my first venture into R2Rs, so I'm pretty green.

The tape I'm using is a brand new reel from RMGI. This is it:

RMGI LPR35 34511 1/4" X 1800' on 7" Reel TWO PACK


I'd be incredibly surprised (and upset) if it is STS, as the tape is brand new. Again, though, I'm a greenhorn at this, so maybe RMGI is known for it? Even the brand new stuff?

I'll check the tape path for residue. Of course, I've heard endlessly about sticky tape, but I didn't know that it could actually make a tape come to a crawl (and possibly stop altogether when fast forwarding---I stopped it before it had a chance to stop altogether, but it was "fast forwarding" slower than play speed at that point).

The only other thing I noticed is that it seemed that the reels (the take up one specifically), was slightly wobbly when the tape was moving, and so the edge of the tape was rubbing against the reel during part of the rotation. I thought this may have been attributed to the fact that it's a really cheap plastic take-up reel and therefore maybe not perfectly flat? I don't know though. It was all I had.

Anyway, if it is STS, will it be really easy to spot? Where should I look for it? All along the tape path?

Thanks!

 

[famous beagle]

I found this online:

"The symptom is obvious: tape guides and heads become contaminated by binder/oxide within seconds or minutes after the tape begins to play. In particular, you will hear the high frequencies disappear as buildup increases on the reproduce head and the tape may begin to squeal. During rewind or fast forward, the tape will slow to a crawl as the guides and lifters become contaminated."

Well, I just removed the tape and examined the tape path, and, while the above sounds similar to my experience (save for the "squeal"), I certainly didn't see any obvious signs. Everything looked clean to me (unless maybe the "sticky" stuff is transparent? And I have to feel for it?).

I did confirm, though, that the take up reel mount is ever so slightly crooked---in other words, the circular base against which the tape reel rests is not perfectly parallel to the unit's face. So I'm assuming that's accounting for the slight wobble in the rotation and the slight rubbing of the tape.

Could that be the problem? If so, why would the the FF start off fine (when it had a full reel of tape to pull) and then begin to give out at the half way point?

 

[Steenamaroo]

Hi,
No, the residue would be pretty obvious as soon as you look for it.


I very much doubt that a wonky reel has anything to do with it.
I don't think I own a straight reel.




Hmmm..As pointed out, it can't really be the belt because there are two different motors ay play, so my guess is the brakes.
(Duno if they're actually called brakes in r2r machines; That's what I call em).

There's a brake that has constant light pressure on the supply reel to prevent it from being able to freewheel.

If this brake was binding on, it'd ruin playback and FF, but not rewind.
Get yer tools out, methinks.

I can't just picture this on the R8, but on any other machines I've looked at, there's been some kind of spring tensioner. Chances are there's something you can adjust, or at worst, a spring or pads will need replacing.

 

[famous beagle]

Hi,
No, the residue would be pretty obvious as soon as you look for it.


I very much doubt that a wonky reel has anything to do with it.
I don't think I own a straight reel.




Hmmm..As pointed out, it can't really be the belt because there are two different motors ay play, so my guess is the brakes.
(Duno if they're actually called brakes in r2r machines; That's what I call em).

There's a brake that has constant light pressure on the supply reel to prevent it from being able to freewheel.

If this brake was binding on, it'd ruin playback and FF, but not rewind.
Get yer tools out, methinks.

I can't just picture this on the R8, but on any other machines I've looked at, there's been some kind of spring tensioner. Chances are there's something you can adjust, or at worst, a spring or pads will need replacing.

Hmmm ... Alright, I'll look into that. Is is external or internal? I don't have a problem opening it up and doing some work, but I just want to make sure I know what you're referring to. Thanks!

 

[Steenamaroo]

This is inside the machine.

See in the picture, there are circular metal strips which meet near the middle between the two spindles?
Those strips will have felt pads inside them and will tighten as external drum brakes.


Listen, this is definitely what I'd be looking at, but I'm pretty new to reels myself and I don't mind taking stuff apart for the experience.
If you'd rather wait for 2nd/3rd opinions, there'll be no offence taken here.

Admittedly, it's much more common for the brakes to fail in the other way; Not enough pressure.

 

[jpmorris]

Yes, I'd definitely check the brake bands. Now that I think about it, there was at least one other guy here who had something obstructing the reel table internally and causing this kind of problem...

 

[Chilljam]

The brake bands may be 'holding' the reels as they spin but more likely that they have fallen off/out of alignment and this is what is causing the problem.

If it's not this, make sure you check the plastic pulleys on the thin metal motor shafts (that they are not slipping or fallen off) and that the plastic belt attached to the pulley still has teeth and is properly attached. Those plastic pulleys are the R8's Achilles' heel and I wouldn't be surprised if they were causing the issues.

 

[Steenamaroo]

The belts and plastic pulleys are terrible.
Any experience I had with failure of these parts resulted in complete failure to play, or FF/RW, but it's definitely worth checking them.

The RW/FF belts are toothed and visible in the photos I put above.

The pulley a few people have mentioned would only affect playback, but either way, it's visible through a window in the front of the machine plastics are off.
It tends to move along its spindle resulting in the belt being thrown, or just spin freely, or rather, stay in place as the spindle spins.
It's awkward, but if you ever need to you can remount the belt through the window and put a little glue on the shaft to prevent the pulley from moving again.

 

[Chilljam]

The belts and plastic pulleys are terrible.
Any experience I had with failure of these parts resulted in complete failure to play, or FF/RW, but it's definitely worth checking them.

The RW/FF belts are toothed and visible in the photos I put above.

The pulley a few people have mentioned would only affect playback, but either way, it's visible through a window in the front of the machine plastics are off.
It tends to move along its spindle resulting in the belt being thrown, or just spin freely, or rather, stay in place as the spindle spins.
It's awkward, but if you ever need to you can remount the belt through the window and put a little glue on the shaft to prevent the pulley from moving again.

I wouldn't call it terrible... it is poorly designed but is an easy fix and it's a good 'wear indicator' for any second hand R8 you are looking to buy. I bought one recently that looked like it had barely any use and when I checked the plastic pulley and belt, you can see that it hadn't ever fallen off and it was attached solid as a rock to the motor shaft. My first R8 I got for free because the 'seller' thought it wasn't working - a bit of glue on the plastic pulley and it's still going strong after 4 years of continuous use.

Also, if the pulley has fallen off the shaft (or the belt has slipped off the pulley) then you will hear the motor running but the reels won't rewind.