Tascam 38 transport problems?

gwargantua

New member
I've been working on my Tascam 38 for a while now attempting to get it working. I bought it a couple years ago and had it shipped to me. However it's only been in recent months that I"ve got around to actually testing/working on it. I've been having some problems but I've been able to repair many of them. However the latest one has got me stumped. First, here's what I've done so far:

- I had to reset the height of one of the take-up reel deck as it was hitting the screw heads has the reel turned. Looks like it took a blow or fall during shipping, the back of the case has a crack. The reel now rotates without scraping.
- I had to reseat all the channels cards as some would not pass signal. I also had to resolder the inputs on a couple of the PC boards of the DBX 150 units, as they would not pass signal either. Now I get signal/VU on all 8 channels.
- I've replaced both the drive belt and pinch roller with parts ordered from Tascam.
- I've throughly cleaned the heads, guides and rollers (which were pretty gunky) with S-721h. I checked the heads with a magnifiying glass and can dectect no signs of grooving or excessive wear.

Over all the unit is very clean, except for the small crack in the back of the case incurred in shipping. I also have a copy of the owners manual.

Here's the problem I'm having: I mounted a used reel of Ampex GM and threaded it correctly (according to users manual). I pressed play and it seemed to behave as though it was in fast forward. The heads didn't engage and the tape speed kept increasing. I tried a number of other operations, ff, rew, rec, and I'm not sure what did it, but it started working. The heads engaged and it played, but the speed seemed inconsistant. I then tried to record. Everything seemed to start properly, but after a short time the tape speed decreased and slowed to a dead stop. I noted that the take up reel tensioner arm was near the very top of it's travel. Pulling down on it, caused the tape to begin moving again. Is this tensioner arm supposed to behave like the one on the supply reel side? The tensioner arm on the supply side naturally falls to the bottom of its travel when no tape is present. The tensioner on the take-up side does not. It seems to stay where its left and won't drop unless I move it with my hand, though it doesn't seem to take much effort. It appears as though there's too much tension on the tape when in operation? The tape doesn't seem "sticky" or anything. There's also a slight squeaking from the supply reel as it plays. My best guess is that perhaps the brake on the drum is dragging and requires adjustment of some kind?

Sorry for long post, I'm just trying to provide as much detail as possible. I'd like to know if anyone's had this or a similar problem, knows the likely cause, and perhaps the cure? I've done lots of research and found some of the common problems people have (ie loose channel cards, sticky pinch roller), but haven't seen this one yet.

I'm REALLY looking forward to recording with this unit if I can just get it up and functioning reliably.

Thanks in advance.
 
There's an adjustment for back-tension. Sounds like it may be set too high. I forget exactly where it is, but I'd start looking there. It should be in the manual.

Don
 
Hello,...

The very first thing I'd check would be the head-load solenoid and the brake solenoid. These solenoids both have a flat rubber washer in the solenoid mechanism that's supposed to dampen the clakking noise as they engage and disengage. What happens, is that the rubber washers can become gooey in the solenoids, and prevent proper transport operation.

Based on what you've detailed,... I'd say the heads are not loading consistently and the brakes are not disengaging consistently,... which are usually due to the rubber washer deteriorating on the solenoids.

The fix to this problem is to (mark the inital position of the solenoids before removal), remove the solenoids from the chassis, disassemble, remove the rubber washer, clean the solenoid and replace onto the chassis. You may retrofit a generic rubber washer of the same dimensions, if it means that much to'ya, but it will run fine without them.

You're welcome!!! ;)
 
Probably right. I didn't think about the possibility of aging rubber parts. The last time I looked at a 38, it was practically brand new. :)

Good call, Dave.
 
Aye!

As well as the other DIY repairs he performed admirably, he mentioned specifically having to replace the belt and pinch roller. Then, the immediate symptoms as detailed would also lead me to believe it's the rubber in the solenoids having gone south and is preventing full and free solenoid action.

Eh,... I've had this experience first hand on my own v'83 Tascam 38, so I know it well. Let's hope it's that simple. He's done an impressive job on DIY repairs, so far. He just needs a slight push to get over the top!

Thanx!! ;)
 
That sounds like the pinch roller solenoid to me but could be all or any of the ones that Reel mentioned. Good luck with your machine.
 
Quote/Paraphrase:...

"The tape did not seem to contact the head...
The tape moved at an unregulated speed..."

both are indicative of the head/load solenoid: tape not contacting head and the pinchweel not contacting the capstan.

Then,...
"The tape ran very slowly and the tension arm was at it's fully upmost position"...
is indicative of the brakes not fully releasing.

Both are issues with the solenoids, of which there is one for head/load and one for brake/release.;)_
 
:rolleyes: Correct, it probably has 3 or rubber washers gummed up preventing the brake linkage and pinch-roller to engage.
Be sure to clean each solenoid shaft very carefully so all old rubber is gone.
Small crud left can create problems later..been there done that. :mad:
Of course replace the drive-belt when you doing the surgery. :)


Good Luck
 
After reading your post again I forgot to suggest check the right tension-roller spring, sometimes these comes off.
And test with annother tape and see if for some reason the Ampex tape has "dry syndrom". :cool:
 
Thank you very much for ALL of your comments and advice.

Last night I disassembled my 38 and indeed found bad rubber washers on both the brake and head/load solenoids. The latter was in the worst condition and no longer even resembled a washer, just ring of sticky black goo. I removed the ring-clips from each solenoid and spent the remainder of the evening removing washer material and cleaning out the goo. I used several dozen cue-tips dipped in acetone to wipe away all residue from the shafts, clips, and housings. I also cycled the solenoid shafts repeatedly and kept cleaning until they stayed clean. I have not yet reassembed the unit for testing. Do the solenoid shafts require any lubrication? I'd like to replace the washers, so I'm going to stop at the hardware store after work to see if I can find a suitable replacement. I'm hoping to find a pliable silicone based washer that won't deteriorate the way rubber does. Otherwise I'll reassemble and test without them. I have only just read the last post, and did not check the right tension-roller spring, but will look at it tonight before reassembling the unit.

Thanks again!
 
Gosh,... the solenoids,... who'd'a thought?

....................... :eek: :confused: :rolleyes: ;) :cool:

I don't think the solenoids require any lubrication, but I don't think it would hurt anything. ;)
 
I didn't get to the hardware store to find washers, but I couldn't wait and elected to reassemble the unit anyway. Before doing so, I checked the tension arm spring and found it was still attached. I cleaned the area where it pivots which had some dust or slight corrosion caked around it and applied a light coat of silicone dabbed on with a cue tip. This seemed to free it up considerably. I also applied a light coat of silicone to the shafts of the solenoids. I noticed that the heads already seemed somewhat dirty again, presumably from the brief amount of time I ran a used tape during testing. I cleaned them once again and after the unit was assembled I mounted a brand new reel of 456 for testing. I tested all functions FF, REW, Play, and REC. There is indeed a "clack" when the transport engages, and I only had time to record/play on tracks 1 and 2, but everything seems to be working 100% now.

Thanks once again for all the comments and advice! Now I can actually begin using it! :D
 
Hi a newcomer ,
Firstly thanks for the advice placed here. I have a Tascam 38 I have opened up removed the face the back and the bottom I have worked through how to slip the rubber belt onto the capstan etc and replace the pinch roller the partrs are now in transit from the USA. Both these were melted tar!
One thing though for me (I used to be known as a wrecker of technical equipment hence needing knowledge ). I wish to look at the solenoid rubber washers and wondered if someone kind could describe how to get to these washers?
On the internet they say you can use tap washers has anybody got an opinion on this please?
Hope you can help.
Many thanks
Steve NZ
 
Nice.

The solenoid washers can be visually inspected with the front cover removed. To replace them will require removing the solenoid from it's mounting. I'd say generic-washers-ok, but they should be the type with firm rubber with embedded fiber reinforcement. Short of that, nearly any firm rubber washer of proper size and thickness will do. It will also function without the solenoid washers, at all, but the deck will be noisier when it engages.
 
Thanks Bob I should have purchased some from the USA I just ordered some parts. Bob have you any idea what thickness I should go for? Will a tap washer do?
Thanks for tuning in.

Steve
 
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