F
Findlay
Member
No, just 2 heads Dave.
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ecc83
Well-known member
jpmorris
Tape Wolf
If you do a new recording, are all four tracks messed up in the same way? I was going to suggest bypassing DBX, but it seems the 244 cannot do that.
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Sebi
New member
No problem, you're right. I think I'm capable of repairing mechanical stuff as I did it several times but it's the first time I opened a tape recorder and besides some basic electronics and soldering stuff I'm not really familiar with all of this. The good thing is though, that at my University, where I study Sound in my Masters, there is an old prof in the electronics department who worked as a broadcast engineer before and I asked for help and he offered to help me. He sais it's basically the stuff he has been doing for almost 50 years now. So I'm quite confident that I will gain some understanding of the stuff. On friday I will bring my machine to his lab and I will keep you updated. For this meeting it would be great to have the service manual. Is there anyone out there who has it? I only found one for the Tascam 246 on the web.
Yes, the recording I posted sounds fine on a working 4-track. Also it sounds the same with other recordings.
I can't tell you as I can't record at all. When I arm certain tracks or 4ch mode the record led is not blinking only shining very lightly. When I hit REC+PLAY it turns off.
No, the 244 doesn't have a switch or anything to bypass the dbx. On the circuits it looks like it's no big deal to unwire the dbx decoder/encoder section and just connect the inputs directly to the outputs on the pins. But then again I don't really now if my logic is too simple.
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sweetbeats
Reel deep thoughts...
The thought I keep coming back to with your symptoms is to check the power supply voltages when the machine is in record mode...I believe the servo system operates on a +15V power rail and the logic off of a +5V power rail...audio is +/-15V I think...but I have had *really* weird inconsistent unpredictable things happen when the logic rail is failing or being pulled down below functional threshold level by some downstream failure. So identify what each of the power supply outputs are supposed to be, and then measure them when the machine is operating. That's what I would do. If you choose to do this, be very careful...triple check your actions before you do them...milliamps can kill...careless errors can drastically roach your gear. I'm not responsible for any negative outcome if you dive in, but I know that's what I would be checking.
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Sebi
New member
Thanks for the advice! I'm going to check it out but together with the guy I'm meeting on friday (previous post). I wouldn't have tried out anything with the power connected on my own and I think he should know what he's doing.
F
Findlay
Member
I'm pretty sure it's against the forum rules to post a service manual. if you send me a PM I'll see if I can track one down for you from somewhere - so long as this isn't against the rules either - can someone please confirm?
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ecc83
Well-known member
I have wondered about this as well. I won't post my old companies circuits obviously but if I come across of .pdf of a schemetic or full manual for gear is it copyright? I have heard that just about everything on the net IS? People have been sent large bills.
Dave.
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Sebi
New member
Hm... That's of course always a sensitive case with copyright and stuff. Don't want you to take any risk.
Seems like we have to try it without the diagrams. Although it might be hard to judge the measurements that way.
Seems like we have to try it without the diagrams. Although it might be hard to judge the measurements that way.
Tried to PM you but it seems your inbox is full
F
Findlay
Member
Have just deleted some messages if you want to give it another try
PS Have just tried mailing you
PS Have just tried mailing you
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S
Sebi
New member
Ok, so here's a little update but there aren't many news I'm afraid...
Today I could ask the prof some stuff and we checked a few things with the multimeter but unfortunately there wasn't much time and it takes a while to get to the pcb's as it's a huge mess of cables and pins... That's why we only got to check the voltages on some IC's on the REC, PLAY and DBX panels. Those that were supposed to be 5V were correct and rest was 12 V+/-. I thought those were supposed to be 15 V but I might be wrong. Could there be any difference between the Japan 100V gear? I thought this only matters to the point of the transformer. Next time we'll disassemble it properly so all the parts can be reached and then we check it again and will trace the signal with a scope.
Any thoughts on the (rather short) news?
Today I could ask the prof some stuff and we checked a few things with the multimeter but unfortunately there wasn't much time and it takes a while to get to the pcb's as it's a huge mess of cables and pins... That's why we only got to check the voltages on some IC's on the REC, PLAY and DBX panels. Those that were supposed to be 5V were correct and rest was 12 V+/-. I thought those were supposed to be 15 V but I might be wrong. Could there be any difference between the Japan 100V gear? I thought this only matters to the point of the transformer. Next time we'll disassemble it properly so all the parts can be reached and then we check it again and will trace the signal with a scope.
Any thoughts on the (rather short) news?
F
Findlay
Member
Hope you can get it sorted next time. Maybe 12V +/- is ok......!
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skywaveTDR
Active member
From what I have read and I don't like long war and peace type posts. There is a whole lot of guessing going on with no effort to the problem at hand. The longer a post goes the more confusing it gets. Ideally one page should do it not guessing about rectifiers or fuses or other stuff that has never had a problem before.
A Technician will take the problem and go right to the parts responsible for the loss of the function. If all other functions are working it is senseless to look at rectifiers that would power a entire deck section when we know it is already working. A simple positive pin measurement with a DVM would remove that from the guess. I have worked on these since they cam out and the repairs were never that complicated- aggravating maybe but as one gains knowledge of the way these work, one becomes more proficient in repairing them.
Maybe it is time for a Technician rather than a professor to look at the deck. Professors can understand all the theories about electronics but even BSEE people and PHD's bring their stuff for me to fix. They are clearly smarter than me but I have the experience that make me more proficient as would be any Technician who works on these kinds of deck in the past.
I say this to allow you to get it fixed rather that ponder on this problem and most likely cause additional problems as you work on it. The deck are tight put together but there is an amount of aggravation tot he wires and harnesses that will cause other things to stop working. The deck is kind of delicate- most likely due to lack of higher grades of solder methods. Wave solder boards often have failed connections I fix all the time. my soldering will never fail as it is up to aerospace grade. Most good soldering by Technicians is like that.
So state a single problem then get the service manual out and focus on that single thing. If there are other problems do them after this is fixed.
A Technician will take the problem and go right to the parts responsible for the loss of the function. If all other functions are working it is senseless to look at rectifiers that would power a entire deck section when we know it is already working. A simple positive pin measurement with a DVM would remove that from the guess. I have worked on these since they cam out and the repairs were never that complicated- aggravating maybe but as one gains knowledge of the way these work, one becomes more proficient in repairing them.
Maybe it is time for a Technician rather than a professor to look at the deck. Professors can understand all the theories about electronics but even BSEE people and PHD's bring their stuff for me to fix. They are clearly smarter than me but I have the experience that make me more proficient as would be any Technician who works on these kinds of deck in the past.
I say this to allow you to get it fixed rather that ponder on this problem and most likely cause additional problems as you work on it. The deck are tight put together but there is an amount of aggravation tot he wires and harnesses that will cause other things to stop working. The deck is kind of delicate- most likely due to lack of higher grades of solder methods. Wave solder boards often have failed connections I fix all the time. my soldering will never fail as it is up to aerospace grade. Most good soldering by Technicians is like that.
So state a single problem then get the service manual out and focus on that single thing. If there are other problems do them after this is fixed.