TSR-8 tension arms

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jpmorris

jpmorris

Tape Wolf
TSR-8 issues (was: tension arms)

One of the machines, the one I'm trying to fix, has a loose tension arm. The actual spindle (which the roller sits on) is loose from the arm. Does anyone know how to remove them so I can swap it out for another one? And is the spindle screwed in or welded?
 
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I believe the shaft on the tension arm assembly is stamped. You can resecure it by using a center punch to spread the base of the shaft out from behind. I haven’t had my TSR-8 open for some time so I’m not sure, but the exploded view in the manual shows no screw.
 
Beck said:
I believe the shaft on the tension arm assembly is stamped. You can resecure it by using a center punch to spread the base of the shaft out from behind. I haven't had my TSR-8 open for some time so I’m not sure, but the exploded view in the manual shows no screw.
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Okay. How do you remove the actual rocker arm from the machine, then? It seems to be held in with a washer of some kind - I've never been sure how you remove those without destroying them. Or how you put them back afterwards, come to that..

Any ideas?
 
That washer has a tiny hex screw in one side that secures it to the rocker shaft. Be careful after you remove the top washer, because under it is one of those little black washers. You’ll also want to remove one side of the spring. Be careful again when you slide the assembly up because there is a second little black washer under it.
 
Beck said:
That washer has a tiny hex screw in one side that secures it to the rocker shaft.
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That's not what I'm seeing. It's a flat, 0.75mm horseshoe-shaped washer pressed from stamped metal holding down the small black washer. If there's a hex screw inside it it's a masterpiece of microengineering.

Have they changed the design or something? I haven't looked at what my main machine is like but on both of the spares, it's got these horseshoe things.

Sadly my digital camera is wholly unsuited for the task of photographing it.
 
TSR-8 issues (was: tension arms)

Okay - for now I've managed to superglue the tension spindle into position until I can work out a more permanent solution, but I've just discovered a more important problem.

The transport is working, but the entire audio system is dead. It isn't playing back anything, and interestingly enough it isn't accepting any input either. All channels.
I've checked the audio cards are all present (these were two parts machines, so you never can tell) and you can arm/disarm channels, but it won't play back or monitor. I have not yet tried recording.

Any ideas? At a pinch I could use the other machine as a base but I'd rather fix the problem than ignore it.
 
This is a tough one to communicate without pics as there are two shafts... one that the roller itself slides onto and the other that the rocker arm pivots on. You can only see the latter with the front panel off.

It sounds like you’re describing a snap ring on the roller shaft. The exploded parts view doesn’t show it because TASCAM sells the whole tension arm assembly as a single replacement part. They don’t break it down any further. So to get at the roller shaft to repair it, you have to lift the whole rocker assembly up and out of the machine. Then you can turn it over to look behind it – perhaps see why the roller shaft is loose. Maybe you already got that far. I wasn't sure if you had it apart.

If all the audio is out I would start checking the fuses. Audio has its own fuse, so it’s not uncommon for the transport to work with no sound. The fuse PCB is under the top panel closest to the take-up reel side.

It’s also possible that all eight rec/repro cards could have some oxidation if the machine sat unused for a long period of time. Removing and reseating the cards a few times will restore contact.

:)
 
Beck said:
It sounds like you’re describing a snap ring on the roller shaft.
Click to expand...

No, it is the pivot holding the rocker arm into the machine. There just isn't a grub-screw washer in these machines. On the other hand it's the sort of refinement companies sometimes make in order to cut cost. These machines are serial #320088 and #370019 - if you have a machine which does have a washer securing the pivot as the schematics appear to show, I'd be rather curious to know the serial number. At some point I'll have to see what the main machine is like but getting the cover off is a bit of a hassle.

Either that or I have the wrong end of the stick and the fat pillar at the bottom is the one with the grub screw. If it is, getting to it is not going to be very easy.
As for photos, I'll probably be able to sort something out but it will take a while.

If all the audio is out I would start checking the fuses. Audio has its own fuse, so it's not uncommon for the transport to work with no sound. The fuse PCB is under the top panel closest to the take-up reel side.
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Bingo. Now I'll have to find a replacement, or steal one from the other machine.

It's also possible that all eight rec/repro cards could have some oxidation if the machine sat unused for a long period of time. Removing and reseating the cards a few times will restore contact.
Click to expand...

Out of interest, how is this done? The schematics seem to show them just sliding out, but they are very stubborn. I'm reluctant to pull too hard.
 
Okay, I now have one of the machines operating. The other one has the dodgy tension arm, 2 broken track buttons on the front panel, the blown fuse and a very strange problem with the audio subsystem (which is probably why the fuse blew).

During bootup, all 8 channels are filled with a very loud sound at mains frequency but not your normal sinewave (unless perhaps it's extremely distorted). About the time the boot sequence is completed, the channels go out one by one in apparently random order except for #2 which has the sound at a low level (about -15). If you enable DBX, they all have the sound again.
I turned it off shortly afterwards to avoid losing the fuse - I don't know of any shops around here which sell internal fuses and a household fuse of that rating won't fit easily.

Anyway, that's the 'parts' machine now, I think. The other one appears to be functioning happily.
 
Is anyone good with power supplies? I've just discovered that both the new machines have 125 volts on the chassis! (Yes, I found it the hard way)

This is exactly half mains potential so I don't think it's anything as simple as one of the leads coming into contact with the casing. I'd very very, very surprised if this is not what blew the audio fuse and causes the load mains noise in the 'parts' machine.

Any ideas?
 
I don’t know much about UK electrical wiring standards, except that they are different.
Do you have the 3-blade plug with two flat blades and a grounding blade?

Here in the US, you can get that kind of problem when the electrical connections at the wall or in the device are miss-wired. Here the chassis ground is tied to neutral inside of the device, but if the hot and neutral wires are reversed at some outlets you can get shocked. Nearly every house I’ve lived in I’ve found outlets, even in the same room, that weren’t in agreement.
 
Beck said:
I don’t know much about UK electrical wiring standards, except that they are different.
Do you have the 3-blade plug with two flat blades and a grounding blade?
Click to expand...

Yes. But the TSR-8, like the Revox has no earth, the mains lead is a two-wire cable and the earth pin is left unattached.

Here in the US, you can get that kind of problem when the electrical connections at the wall or in the device are miss-wired. Here the chassis ground is tied to neutral inside of the device, but if the hot and neutral wires are reversed at some outlets you can get shocked. Nearly every house I’ve lived in I’ve found outlets, even in the same room, that weren’t in agreement.
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Ah. That sounds quite plausible. Yes, according to the schematics it appears to be using neutral as ground. That still sounds a bit disturbing, since it would have a 125v potential difference between chassis ground and the signal ground from the mixer, wouldn't it? Still, it seems to work on the main machine.

The one I'm working on has some really weird plug arrangement - I think it may have been a European import since it has a German 'shaver' style plug inside some kind of adaptor. I need a special tool to open the adaptor though, so I can't find out which polarity it is without stripping the machine down again and doing a continuity test. I might just fit a new plug on and make sure it's right.

Thanks for the suggestions, I'll look into it..
 
jpmorris said:
Yes, according to the schematics it appears to be using neutral as ground. That still sounds a bit disturbing, since it would have a 125v potential difference between chassis ground and the signal ground from the mixer, wouldn't it?
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Eh, nevermind, I seem to have been carrying an incorrect understanding of how single-phase AC works in my head for the last 25 years. I always assumed that Live and Neutral swapped over at 50hz - looks like Neutral is at 0v and Live changes polarity with respect to Neutral. Duh.
 
Heh. It looks like the problem is that the TSR-8 is designed to be plugged into something and uses the signal ground for earthing.

If you just power it up in the middle of the room with no audio connections, you get this weird floating voltage at about half-mains level. I have just double-checked this by disconnecting my main TSR-8 from all its I/O and then taken a measurement on it and lo, when isolated like that it gets around 120v on the chassis. Now I just need a loom and a rack stand for it..
 
i am looking for an arm tension roller for this machine. does anyone knows where to get one ?
 
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