Akai 4000D tension issue?

[cornwall60s]

I’m looking for a bit of advice. Please bare in mind I am a bit of a novice though!

I have an Akai 4000D reel to reel that I assume is suffering from tension issues.

It will FF fine, no problem.

It will Play and RW most tapes, as long as they don’t have a lot of tape on them. It struggles with any long tapes, or anything with even a vague semblance of sticky shed. Then it just grinds to a halt, clearly not having enough power/tension to Play or RW the tape. It will play anywhere between a few seconds and few minutes before stopping. These tapes will still FF OK though.

Even if it does play the tape all the way through, some of the longer tapes will get a little bit wobbly at the very end. I’ve replaced the clutches a different (Philips) machine which fixed this, but I think it might be something else on this Akai.

Does anybody have any suggestions? I’ve read elsewhere people having similar issues and it could be a tension issue, but if so I’m not sure how to fix that?

Any help gratefully appreciated!!

[dave walsh]

Hello-Novices are welcome but you must have noticed that already. As you fixed a recorder, that's a good start. This sounds clutch/pinch wheel related but I'm no expert. You will get plenty of responses as 4000's are quite popular with members. Do a search [above] while you are waiting and see if anything matches. These are great machines in my opinion but just not professional enough for some. The classic [very unfortunate] fault is a disintegrating cam [very difficult to replace as you will see] but that isn't related to your current problem-it just means exercise caution with the two drive levers!

Dave W

[cornwall60s]

Thanks! I did wonder if I needed a new pinch wheel. I've tried to restore with rubber restorer, but think it could do with replacing. It would be useful if anybody knows where to pick up a reasonably priced replacement.

[dave walsh]

I've now seen a reference to these sort of problems cornwall, linking the clutch mechanism and [especially] a shiny pinch wheel but I'm sure someone will advise further before you obtain any spare parts, perhaps how to roughen the surface?

Dave W

[cornwall60s]

Thanks Dave. I'm not 100% on how to fix the clutch, so if anybody can offer a fairy simple explanation that would be much appreciated! Richard

[red16v]

From your description it sounds as though what you are actually suffering from is 'sticky tape' syndrome rather than a tape deck fault. The fact that the machine will rewind tapes in either direction would lead me to think that the 'clutch mechanism' that you refer to is actually ok. 'Sticky tape', in layman's terms, is pretty much what it says and it manifests itself by a reluctance of the tape to allow itself to be wound off a reel because the tape is trying to stick to the previous layer of tape. This happens with old tapes as the chemical composition of the tape backing deteriorates over time.

You are confirming this (to me anyway) by saying that on long tapes the audio 'wobbles' near the end - this is a classic symptom - the layer of tape coming off the supply reel is reluctant to 'come off' because it is sticking to the layer of tape 'next' to come off the reel. Eventually the tape 'lets go' because the power of the capstan pulling it off the reel overcomes the stickiness and it releases itself from the reel. But this quite a sudden action (even though it looks smooth to your eye) and sets up a sort of shock wave down the tape longitudinally and this affects the tape to head contact where the tape is passing over the replay head. The result is the audio sounds very wobbly for a short period as the 'shock' is dispersed and things return to normal - usually only for it to re-occur moments later if not continually. I have the Akai X201D model which is mechanically very similar to yours with one important difference - it has a tape tension arm in the tape path between the supply reel and the first roller. Have a look at Akai X201D images on the www. This tension arm not only gets the supply reel path tension correct, it acts as a sort of mechanical buffer between the sticking tape and the first roller, acting as a 'soaking up mechanism' as the sticky tape reluctantly sticks/jerks/releases itself from the supply reel. I am quite sure Akai did not design it with this in mind all those years ago but as serendipity has it it certainly helps now many decades later!

Pinch wheels should only be cleaned with tepid soapy water, do not use chemicals as it will likely cause the rubber to deteriorate.

Old tapes with full reels slowing down and even stopping whilst rewinding them is also a sign of sticky tapes (in my experience).

[TIMTAPE]

Sticky Shed Syndrome tapes slow down because of the increased friction of the tape as it slides against the stationary guides and heads and deposits sticky gunk on them. Yes the tape layers do tend to stick to one another but this is not what slows the tape down.

Naturally the friction increases as more sticky gunk gets transferred onto the guides and heads, but also on a basic machine like the Akai, the back tension increases anyway as there's a smaller diameter of tape to pull as the reel unwinds and more pulling force is needed, regardless of whether the tape is sticky.

When the tape has really bad SSS the oxide layer gets ripped off as the tape unwinds. Then you've lost the programme.

The only solution is:
1. Dont play SSS tapes.
2. If you have to, learn how to properly treat them before playing.

If a tape starts slowing due to SSS deposits on heads and guides, almost certainly much of the the sound quality has already been lost due to "spacing loss", that is the tape can no longer contact the tape head intimately because the sticky gunk is caught in between the tape and the head, forcing the tape away from the head.

It makes no sense to play even a moderately sticky tape without prior treatment as it will sound terrible and it and the tape machine may be damaged in the process, the contents on the tape tape possibly compromised for good.

[Ted Kendall]

Sticky tape syndrome has been known about for nearly thirty years, and yet I get queries more often than I'd like from people who describe the classic symptoms, having already ruined the tape.

The advice has to be - if you have recordings on Ampex 406 or 456 particularly, or if the tape smells of urea, don't try to play it without treatment. Heating is the most popular route and is generally effective.

[dave walsh]

If his tapes, heads and guides are ok red16/Ted, will it be back to the clutch etc? I've a couple of decks running similar to the description but [luckily] I've never actually encountered STS although I know what it looks like from photos on here I suppose you will be able advise either way though.

Dave

[cornwall60s]

Thanks all.

I know that certainly some of the tapes suffer from sticky shed, and without prior treatment may be a lost case. A few tapes are visibly bad and haven't even been near the machine!

Some of the tapes though seem OK and I have played them a couple of times with no problem. They play on my other machine fine, no wobbly, etc. or anything else that you would expect with sticky shed, but still don't play or RW on the Akai. I've been digitising a large volume a lot of tapes recently (therein may be the problem!) and I'm now finding a larger number of tapes will not play than will, and tapes that previously played OK now are proving problematic. Which makes me think it might be machine related, rather than tape.

I've attached a pic of the pinch roller. To me it doesn't look like it's in the best shape, so could be at least part of the cause?

[red16v]

I can't advise you of potential clutch problems as I have no experience.

The capstan in the picture looks quite dirty - as you can easily see from the central band of dark brown contamination. I transferred a lot of tapes over last winter (my experiences are detailed on another thread in this section) and had similar oxide/contamination on the pinchwheel after a few a tapes. I cleaned mine in a tepid mixture of water and ordinary fairy liquid and gently scrubbed the surface as I did so with a folded up kitchen roll - nothing too abrasive. I found after 2 or 3 minutes of working over the surface of the roller in this way it completely removed the contamination. Inspect the surface of the rubber after you've given it a good clean, if the rubber surface is covered in what appears to be fine cracks or fine splits in any way then the chances are its past it's best I'm afraid.

Following on from Timtape's posting above, clean all the guides and rollers too as best you can to remove any surface contamination from them - I used ordinary household cotton buds soaked in alcohol and really gave the guides and rollers a good 'going over' in between each and every tape.

Edited to add. After cleaning my pinch roller I used to gently press my fingernail into the surface of the rubber. The rubber 'gave' way under the pressure indicating to me that it was still nice and semi-pliable. I would hazard a guess that a pinch roller that was 'past it' would appear to be more brittle and resistant to this simple test.

[cornwall60s]

I should have mentioned that the pinch roller has been cleaned several times already. The machine has had at least a couple fairly thorough cleans as well, and I clean the heads after every tape pass with alcohol. I'm pretty sure the pinch roller is shot, like you say. I notice there are pinch rollers tires available on ebay (from the US, so shipping to the UK won't be cheap), so it might give that a go first.

[red16v]

Originally Posted by dave walsh

If his tapes, heads and guides are ok red16/Ted, will it be back to the clutch etc? I've a couple of decks running similar to the description but [luckily] I've never actually encountered STS although I know what it looks like from photos on here I suppose you will be able advise either way though.

Dave

I can't answer your question but would consider this, in normal 'play' mode the capstan and pinchwheel will be pulling the tape past the heads. I would think the supply reel will have some simple back pressure applied to it to stop the tape running off it - I would imagine this back pressure would be supplied through the supply reel motor. Similarly I would expect the take up reel to have a gentle forward pressure applied to it so that the tape is spooled in uniformly and most likely this would be supplied by the take up reel motor. I do not know, but I would not think any clutch mechanism would be involved in this? I do not know what happens when the tape is spooling at high speed in either direction.

edited too add.My experience is only with the X201D machine which has 3 motors, perhaps the 4000D only has one motor and uses mechanical clutches etc?

[red16v]

Originally Posted by cornwall60s

I should have mentioned that the pinch roller has been cleaned several times already. The machine has had at least a couple fairly thorough cleans as well, and I clean the heads after every tape pass with alcohol. I'm pretty sure the pinch roller is shot, like you say. I notice there are pinch rollers tires available on ebay (from the US, so shipping to the UK won't be cheap), so it might give that a go first.

Try my finger nail test? Does the rubber surface feel nice and rubbery or hard and stiff. In my opinion the pinchwheel in the photo looks very dirty - sorry!

[cornwall60s]

It is indeed quite grubby! It does need a clean at present, but should have mentioned that I have cleaned it a few times and it doesn't make much difference once cleaned up. At the moment it feels somewhere in between, a bit of rubberyness but the hardness is certainly starting to set in.

[red16v]

If I understand correctly, in fast forward or rewind you indicated some old tapes slow right down. In this mode the capstan and pinchwheel are not engaged and have no effect.

It would indicate to me that the problem is old sticky tape being reluctant to 'unwind' off the reels in either direction, and as Timtape has said, tape sticky residue contaminating the guides and rollers meaning they are no longer affording a smooth surface for the tape to glide over - 'glide' being the important word here! I appreciate you have said you have cleaned the tape head but have you really really thoroughly cleaned the guides and rollers? I don't want you to spend money on a new pinchwheel if its not needed.

If you have time, perhaps have look at this old thread I started on my similar experiences to you earlier this year.

https://www.vintage-radio.net/forum/...d.php?t=143966

[cornwall60s]

Interesting read! Sounds like you had similar problems to me. The tapes I'm transferring are also 40 odd years old (mostly home recordings from a folk club) and recorded on all manner of different tape brands. I have some recordings that play at a fast speed on a Revox I currently have on loan and tried to half speed with Cool Edit (old software but works well for me). Speeding up works great in Cool Edit, but slowing down sounds dreadful. You say Audacity worked well and sounded OK?

[red16v]

Yes, Audacity worked well for me in that mode (Speeded up when recording into the software - then slowing it back down to 'normal' speed). It is free as you may know, so no harm in trying it.

[dave walsh]

Further to your comment red [post 13*] yes the 4000D does have a single motor etc but manages to do a lot with it. It gave purchasers a much valued affordable opportunity to step up from purely domestic machines in the seventies but opinion is divided.

Dave

[julie_m]

Three heads and one motor is still better than two heads and three motors; at least, that was the theory on which these machines were sold. They were launched when cassettes were improving and on the verge of becoming true hi-fi, but not quite there yet; the three-head system offered the "killer features" of direct off-tape monitoring and sound-on-sound recording, plus some interesting possibilities for learning to play an instrument or speak a language, as reasons for choosing an open-reel recorder over the new compact cassettes. And the open head block with no pressure pads was perfect for splice editing.