238s dolby problems anyone???

TASCAM MAN

New member
I just took my 238S out of the rack to plug it up to my surprise with the Dolby switches on TK8 LED is pegging at a +8 and that's with the sync&filter switch out ....anybody had a problem with that before? Also putting a tape in that has TKs 5&6 with a pretty strong level when I Pop in Dolby on group 5 to 8 they totally disappear/no signal ??? Pop the Dolby off and they come back on strong....???:(
 
Thank you arcaxis and yes the Dolby switches are in the back of the machine, they are for 1-4 and 5-8. I went back and forth with them enough times today to work any gunk out of them if that was the problem. The machine does beautiful with the Dolby off,but weird things happen when I turn them on.I read an interesting thing about the DBX and Dolby S version I found by Googling. Cant quote the guy exact but I did save the article in "My Faves" but he said that the DBX pc boards and the Dolby S boards are interchangeable.....another words I could put all are part DBX cards in place of the Dolby cards and it would work without any problem!!! A matter of fact he had fixed one for someone and put 4 DBX cards and 4 Dolby S cards in and it works great !! So....I got my eye on a broken down 238 (no S) which means its the DBX NR in it and I could start by changing the 2 back tracks that Im seeing right now and take it from there ....what ya think???:eatpopcorn:
 
I had a 238s years ago (bought it brand new). Pretty incredible machine (I also had the full featured remote controller as well). The Dolby S made recordings sound absolutely pristine when that baby was new. I packed it away during a move and it actually ended up in storage for a few years. I resurrected it several years ago and found that when engaging the Dolby S all I would get would be screeching noise on several of the channels. With the Dolby off it worked as normal. I actually sent it to Tascam and it seems that the Dolby circuits/chips had fried/failed on 4 or 5 channels. The replacement parts were no longer available. The Tascam repair tech implied that he had seen the problem before. I ultimately ended up selling it. Although it still worked well...it was suspect to a little "cross talk" on occasion (as well as "drop outs" if I really wore the tape out). I guess 8 tracks on a 1/4" piece of tape is a "bit of a stretch", even for Tascam. I still missed it, though, and coerced myself into buying a mint condition 134b (4-track version of the 238) a few years ago. It works great and sound fantastic. Anyway....I feel your "Dolby S" pain, Tascam Man. Cheers!
 
I had a 238s years ago (bought it brand new). Pretty incredible machine (I also had the full featured remote controller as well). The Dolby S made recordings sound absolutely pristine when that baby was new. I packed it away during a move and it actually ended up in storage for a few years. I resurrected it several years ago and found that when engaging the Dolby S all I would get would be screeching noise on several of the channels. With the Dolby off it worked as normal. I actually sent it to Tascam and it seems that the Dolby circuits/chips had fried/failed on 4 or 5 channels. The replacement parts were no longer available. The Tascam repair tech implied that he had seen the problem before. I ultimately ended up selling it. Although it still worked well...it was suspect to a little "cross talk" on occasion (as well as "drop outs" if I really wore the tape out). I guess 8 tracks on a 1/4" piece of tape is a "bit of a stretch", even for Tascam. I still missed it, though, and coerced myself into buying a mint condition 134b (4-track version of the 238) a few years ago. It works great and sound fantastic. Anyway....I feel your "Dolby S" pain, Tascam Man. Cheers!

Thanks my friend well,im not giving up just yet. I had read that the DBX cards are swoppable and yes it seems to work fine with the Dolby switches off.But now that I hooked it up to my mixer to here what it was doing,I also have a pitch problem on "fixed pich" but when I put it in "vari" mode I can speed it up to sound normal and seems like it stays at the right pitch. But back to using it without Dolby,the signal to noise ratio is really bad compared to with Dolby....Im bummed cause I love this machine and the transport seems rock solid :(
 
May not be much help, but the service manual can be downloaded from....
Service manual,| ElektroTanya | Service manuals and repair tips for electronics experts .

Below the document preview wait until you see "Get Manual"..

"This file is downloadable free of charge: Get Manual
(You are not logged in, only 2 downloads per day possible for you.)"

Does the 238 have two slide switches on the back for engaging the Dolby (my 688 has them on the back)? If it does it might be worth trying to give them a shot of DeOxit being careful not to get any into any rubber transport parts or belts and work them back and forth a bit..

I did detox the Dolby switches to no avail :(
 
This recently came up on Craigslist Tascam 388 8 track reel to reel, UNOPENED REELS, demag, manual, etc.. . Back in the day I always wanted one, but ended up with the 688 cassette based one.

That's cool I never had one but had a friend get me over to help produce and engineer on a recording session with one of them yrs. back, it sure looked cool for sure !! At the time I already had an 80-8 along with a StudioMaster board (forgot what model) along with several other recorders so,I was already used of separate units instead of...."SuperPortaStudio's" hahaha :D O Later I upgraded (after many demos) the MSR-24S/M3500 combo and still own them but not setup and running for lack of space at the moment :(
 

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In the Tascam line there are two unit or maybe three units to avoid entirely. They are 388, 238S and 302. Each has it own difficulties of repairs but some of them can not be repaired at all or at least at reasonable cost due to no technical documentation of any kind. Try finding a service manual for the 238S as all the Teac service guys I ask have nothing on it. The hybrid Dolby S items were an after thought that was so goofy they never made or had any documentation made for it that I could find and the cards like the 238 capstan motors with that garbage SMD caps all fail and eat up the board. I am working on one now and the card pots are not even in the same place. Pretty much if you get an S on the bench you need to find out what pots do what by experimentation. This is the sign that Tascam has gone over to the junk side of things when they made so much good stuff over the years- I guess money is the main goal not making good equipment anymore.
 
To be honest, I can not see how this exchange is possible as the audio cards are entirely different and the Dolby S daughter cards are on the audio cards. Is he talking about replacing all the Audio cards? I have the two different models in the shop and I doubt that it would be that easy. I later find out that there is a Denis Petrov in NY that says he can fix these cards- I don't know why he thinks so but I am going to let him try as I looked at the cards and there is absolutely no documentation on Dolby S parts- I asked all the old Teac Service Technicians I know and nothing. It is as if they never existed. Very bad support for this kind of product.
 
Well there is a guy who in New York can fix these but it was not going to be cheap. It was around $600 for the 8 cards.
If you need his contact info I can send it to you as I have his E mail.
So there is hope- he also back engineered the schematics so there is now some documentation which Tascam never provided.
 
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