Tascam 48, impossible to record

Syntiz

New member
Hi everyone,

I have an issue and hope you could help me.

Context:
I have A Tascam 48 (with two DX-4D) since a long time. It always worked well. I didn't use it for 3 or 4 years. Today I re-pluged it to my console. The reading of all tracks works well. But when I try to record it doesn't work.

Details:
When I set "OUTPUT SELECT" to "Input" and "FUNCTION SELECT" to "rec" on my track I see the meter (not sure if it's the right term in English because I'm french) moving when I play => so the sound goes well to my Tascam 48. When I press PLAY+REC, the red light becomes fixed, then I play what I want to record.

Issue:
Then I go back to "OUTPUT SELECT" to "Repro" and switch off "rec" on my track. But when I press Play there is nothing: the meter doesn't move and of course no sound (whereas on the same track it works well with my old previous recording).

For information, I have the documentation and tryed to understand what I did wrong but can't find. Do you think it could be due to a fuse (or something else) which would disable the record?

Thanks
 
When recorders are left standing for a long time the REC/PLAY swich contacts tarnish slightly and cause all sorts of troubles, one can be failure to record because the 'Bias Oscillator' is not starting up.

Does the machine ERASE an old track? If so the BO is working and there is another problem in the REC circuits, still could be the switch. Try banging it in and out of REC mode a dozen times, moving the switch contacts* can often fix things. You could try some switch cleaner such as De-oxit but be very careful not to get it on belts and other drive surfaces.

*Could of course be a bad relay. Not familiar with the machine.

Dave.
 
Thanks for your quick answer ecc83
I didn't try to only erase (but I think this feature doesn't exists on my Tascam 48, I will check in the manual). I will also try the manipulations you suggested (when you say "banging it" you talk about the rec head?).
For information, I checked all of the 10 fuses and they're all good.
 
When I record a track, it's well erased but nothing is writen on it => So read and delete work fine. It's only writing which doesn't work (keeping in mind that sound arrive well in Tascam because meters are moving)...
 
When I record a track, it's well erased but nothing is writen on it => So read and delete work fine. It's only writing which doesn't work (keeping in mind that sound arrive well in Tascam because meters are moving)...

I was being a bit 'poetic' about "banging" not literal. So, if it erases the BO must be running. To see if audio is actually getting to the record head try a signal that pushes the meters hard into the red, even hits the endstops and preferrably one with a high HF content. Then listen carefully to the playback on headphones and if you detect a weak, distorted, squeaky signal, bias is not getting through but audio is.

Could still be a switch/relay but I think you need a technician.

Dave.
 
Just to be sure, am I correct this problem is with all tracks 1~8? And playback of your recording also doesn’t work when you set the output select to SYNC?

And also to sure, am I correct that, while recording and you see meter activity and hear sound with the output select set to INPUT, if you switch the output select to REPRO (again, doing this while you are recording) the meters instantly show no activity and there is no sound coming from the 48?
 
Thanks ecc83 and sweetbeats.
ecc83: I will test your solution
sweetbeats: you're right, the problem is with all tracks (1 to 8). I think other symptoms you mention are right too, but I will check and let you know. If it's the case, do you have something in mind?
 
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I did all the tests:
- ecc83: When I record High frequency at a very High level, and then play and listen (with headset and high gain), I actually hear what I recorded (but the sound is very weak).
- sweetbeats: You are right on all your points. I reproduce all what you described.
 
The 1st thing Id check would be if it plays back a pre-recorded tape properly. If it does, I'd try a different reel of blank tape. Attention TASCAM multitrack owners - The playback head on all decks made after the 70 series is for ease of alignment. The sync/record head is meant to be used for record, sync, & playback.
 
I did all the tests:
- ecc83: When I record High frequency at a very High level, and then play and listen (with headset and high gain), I actually hear what I recorded (but the sound is very weak).
- sweetbeats: You are right on all your points. I reproduce all what you described.

That really sounds like bias is not getting mixed with the recording signal. Tech time IMHO.

Dave.
 
RRuskin : Play back of a pre-recorded tape works fine for all tracks. I tryed to record on two different tapes (both on already recorded part or blank part). But all my tapes are old Ampex 456.

That really sounds like bias is not getting mixed with the recording signal. Tech time IMHO.

Dave.

Thank you for your diagnosis ecc83, I'm a little bit affraid of the cost
 
RRuskin : Play back of a pre-recorded tape works fine for all tracks. I tryed to record on two different tapes (both on already recorded part or blank part). But all my tapes are old Ampex 456.



Thank you for your diagnosis ecc83, I'm a little bit affraid of the cost

As we all are! The difficulty is, such a fault is going to be hard to find without recourse to some decent kit, an oscilloscope being the main one.

One good start would be a serious trawl of the internet to find a schematic. So armed, any competent 'radio' tech should be able to diagnose and fix the problem. He will not however likely have that information and will not be prepared to spend time (and thus your money!) on finding such service information.

Dave.
 
AMPEX 456 ???????

After all these years I would seriously look at the actual tape (Ampex 456 has turned out to be a disaster !!!) and then look very closely at the record head to see if it is dirty.

I do not know the recorder but if it has three heads then look at the head on the left hand side (usually the erase head) and see if it is dirty.

Using something like metho or isoprop give everything a good clean and see how much muck comes off.

THEN find another brand of tape and do a recording to see if it is better.

However, it could also be electronic and need a good service.

David
 
I would not bang anything as that is sure not to help. There are no record play switches in this as this deck is 2 to 3 decades after those were used. The problem is very strange if the deck erases and then does not record at 8 channels it is either head dirt or some common logic line to all the cards. I have worked on a lot of these deck and have two in my shop now and they are very reliable units. There are the Bias amps that can go out now and then plus the master oscillator but if it erases then that is working. Your symptom does not match any regular failure in these decks that I know of and I have worked on them (at Teac Chicago) since they came out. I think the problem may be simple to fix once you find it but it will take more than a bang on the deck to fix the problem or to find it.
 
CSP : yes my tapes are old. But I hesitate to buy new ones if my Tascam doesn't work. Moreover, I can understand that a record on an old tape has a bad quality, but do you really think that it could be the reason why nothing is recorded? At last you're right, my heads were dirty, but I cleaned them with alcohol and Q-tips. I will post a photo this evening to have your opinion about their state.

skywaveTDR : your comment recomfort me a little even if I still don't know what is the issue. But I used my Tascam long time ago (more than 10 years I think) and it always worked properly. And since it has been stored under dust protection (with no transportation, no shock). That's why it seems strange to me that the breakdown happened during this period.
 
I would not bang anything as that is sure not to help. There are no record play switches in this as this deck is 2 to 3 decades after those were used. The problem is very strange if the deck erases and then does not record at 8 channels it is either head dirt or some common logic line to all the cards. I have worked on a lot of these deck and have two in my shop now and they are very reliable units. There are the Bias amps that can go out now and then plus the master oscillator but if it erases then that is working. Your symptom does not match any regular failure in these decks that I know of and I have worked on them (at Teac Chicago) since they came out. I think the problem may be simple to fix once you find it but it will take more than a bang on the deck to fix the problem or to find it.

I say again Skywave, I was being POETIC when I said "bang into rec and play mode a dozen times" and I apologise all round if the wrong impression was given.

The term "banging" is used here to mean 'Great' 'Super' (and another, scatalogical meaning!) Our friends in Oz say "ripper"!

So, no OP, DO NOT thump, hit or in any way subject your deck to any abnormal acceleratons!

BTW we had a vcr in the trade (Hitachi) that suffered instabilty, howling sound and that was due to little fingernail sized relays where the contacts had tarnished. A squirt of Electrolube and the VCR worked on until VHS tapes were obsolete!

Dave.
 
But I used my Tascam long time ago (more than 10 years I think) and it always worked properly. And since it has been stored under dust protection (with no transportation, no shock). That's why it seems strange to me that the breakdown happened during this period.

You may think it's not going to cause any issue to leave these types of electronic devices off for 10 years...and then just power up them up and everything is OK...
...but that's not the case....especially anything that has switches, relays and EPROMs...etc.

I power up that type of gear every so often and leave it on for a couple of hours...with the tape decks, I'll run a tape through it a couple of times to exercise everything.
With my Otari MX-80...an Otari guy told me never to leave if off for too long. Just a couple of days ago I had it powered up for like 2-3 hours...but I haven't recorded with in awhile. It helps to "juice" up electronics every so often, and especially the electro-mechanical devices.

Anyway...don't have a Tascam, so I can't give you any specific help info...just saying that when you get it working again...keep it working. :)
 
My friend your tape path including heads are completely coated with a layer of sticky shed. You need to get some new tape, get rid of the old tape, and thoroughly clean your entire tape path. Then try again to see if you can get it to record normally.
 
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Thanks sweetbeats. If that's it, it's pretty good news. I'll try to find some tutorial to clean the entire tape path (because from now I did it with alcohol and Q-tips).
 
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