tascam 34b problem

D

doug deeper

New member
hello i just picked up a tascam 34b and the 1st channel is either playing or recording intermitintly (i havent figured it out yet as it rarely plays)
when its not playing all i hear is a faint oscillating sound, first higher pitched then with a rhythmic lower frequency popping in every second or so (i though there was some synth stuff on the tape at first, thats how rhythmic it actually is!)
anyone have any idea where i should start looking to solve this problem?
thanks in advance!
 
Well the first thing I would look at would be the heads. Are they clean?
Also if it was a shipped recorder through someone like UPS that is well know for destroying many many good recorders I would take the bottom panel off and pull all of the channel cards out a little and push them back in to make sure they are seated well.
Sometimes in transport they can come loose.
Good luck with your machine its a great unit when working well.
Analog rules Digital sucks Nuff said;)
 
yeah i cleaned and demaged the heads first thing, also i bought it from a guy locally.
i'll have to pop it open and see if anything is amiss!
i also have a tascam 388 that i looove but im really excited for some 4 tracking!
(im also a heavy lurker of this board!)
 
well i tried reseating the boards and that didnt help, i did however narrow it down to being a playback problem on channel one as when i flipped the tape it played back fine on channel 4.
also when channel one did play back it sounded crystal clear without any cutting out or crackling.
what gives!
:D
 
  • Try some DeoxIT on the head connectors maybe? I've heard of that doing what you are describing...remove the head cover and you should be able to get to them...turn off the deck :eek::D, unplug the connectors, apply cleaner/DeoxIT and work it it by connecting/reconnecting a couple times. I'd recommend doing the same with the amp card connectors.
  • What happens when you swap amp cards as opposed to flipping tape? If you swap cards for channels 1 and 2 and the problem moves to track 2 then we can assume it is a problem with the card and then go from there.
  • Is the problem the same whether you are playing back from the sync head or the repro head?
  • Does the deck pass signal clean from the input side when monitoring the input?
 
ok here is where im at,
channel four is now not working sometimes both 1 and 4 work when in sync mode (i realize now that this was the only time 1 worked) but he sound is dull and distorted.
the tape head appear to be soldered in, and i cant get the amp cards to slide out (is there something im missing? i took the whole bottom as well os the back off and it just feels like they are going to break if i pull them any harder)
i still have the chance to turn back on this deal, but the guy only wants $60 for it.
how much would servicing on something like this run roughly?
 
I can't research in detail right now, but I'll look at my copy of the 34 manual later.

For $60 I'd take it.

I'm banking on oxidized amp card connections or sticking relays. If the head connections are soldered in then my bad...that's probably not the issue and I apologize for sending you on a chase.

The cards can get pretty challenging to pull if its been a long time. Make sure there is nothing in the way of the cards coming out...rock the cards slightly as you pull. Are there holes in the corners of the cards? If so you can fashion something like a coat-hanger as a handle to hook through the holes, again rocking slightly as you pull.

I'll check back later.
 
ok great!
just wanted to make sure there wasnt a hidden screw or something i was missing.
thanks for all the help thus far! i hope i can get this going!
 
There is the retaining bar But I'm pretty sure you have removed it. Just rock the cards one side then another till they come out.

-Ethan

also, Did you say what the heads looked like? A photo might be nice to see.
 
What Ethan said...

Sorry to say, I thought I had a full manual set for the 34 but it is just the Operations Manual so I don't really have any more insight at the moment, but I know the cards were a challenge to get out of my 58 the first time I tried.

What's the latest news?
 
yeah i took the bar out.
the head look pretty good, although they were pretty gunked up when i got it.
i'll try popping the amp cards out today.
 
ok!
well this has sat fo over a year so i dug it out today, i swapped the amp cards 1 for 2, 3 for 4 and the problems stayed on the same channel, so at least ive got 4 good amp cards!
:p
with channel one you can hear audio coming in and the needle moves yada yada, but on playback all you hear is a quiet oscillating sound with some popping.
with channel 4 you cant hear anything coming in and nothing plays back but the needles also moves while recording.
it doesnt seem to make much difference which head you monitor from (i dont think at least, and flipping the tape led to some really quiet something or other on channel one (had to say as its backwards and supper quiet/blurry).
any further advice?
 
Well now

Having good channel cards is a great line of division. Troubleshooting is all about divide and conquer. I don't recall that you tested sync head vs playback head. But you did record then swap reels so we know that the sync head is OK.

Does it playback the same with the sync head and the playback head?

Right now I'm thinking I would be looking for a connector that has somme of the pins cold soldered. (look for a crack int he solder around the pin) You can push on the connectors on the motherboard wile listening and hopefully find one that is the problem. Also look for cracks int he traces on the motherboard.

Should be an "easy" fix. Just takes time to find the problem.

Regards, Ethan

PS where are you located

OK I reread your post RE flipping tape and heads. Still I suspect some bad connector pins. I have run into this before.
 
evm1024 said:
Having good channel cards is a great line of division. Troubleshooting is all about divide and conquer. I don't recall that you tested sync head vs playback head. But you did record then swap reels so we know that the sync head is OK.

Does it playback the same with the sync head and the playback head?

Right now I'm thinking I would be looking for a connector that has somme of the pins cold soldered. (look for a crack int he solder around the pin) You can push on the connectors on the motherboard wile listening and hopefully find one that is the problem. Also look for cracks int he traces on the motherboard.

Should be an "easy" fix. Just takes time to find the problem.

Regards, Ethan

PS where are you located

OK I reread your post RE flipping tape and heads. Still I suspect some bad connector pins. I have run into this before.
Click to expand...


im in New Hampshire.
i just went through it again, took all the boards out cleaned the contacts, pushed every wire clip on connection dealy, checked for obvious bad cap, broken what nots.
no luck thus far!
i guess the next step is to search for cold solder joints! not a fun activity, but what can you do!
anyone happen to know of any repair people in my part of the country?
 
doug deeper said:
im in New Hampshire.
i just went through it again, took all the boards out cleaned the contacts, pushed every wire clip on connection dealy, checked for obvious bad cap, broken what nots.
no luck thus far!
i guess the next step is to search for cold solder joints! not a fun activity, but what can you do!
anyone happen to know of any repair people in my part of the country?
Click to expand...

I'll let others from the NE answer that question for You.

Fixing cold solder joints is not too hard ( perhaps you have some skill with this already - pardon). Just heat them with an iron and flow a little more solder onto them.

Most of the 2 pinn connectors onthe motherboard are the head connections. P161-164 are erase head, P151-154 are sync head and p121- 124 are PB head.

If it does not matter which head you select (and still get the same sounds) then it is most likely not those connectors (does not hurt to check).

In that case I would look at all the motherboard connectors for each channel card. You can just push on them with a wood or plastic probe to force any crack to make contact and listen for any difference.

I would also measure voltages on each channel card to verify that you are getting them to each slot.

Might be a good time to survey what is working and what is not. Starting with a known good tape with a pre-recorded signal in all channels (Would you risk an MRL....)

For each head (Sync and PB) for each channel there are 3 things to look for when playing back a tape.

1) do the meters move like you expect?
2) do the headphones give the expected signal
3) does line out give the expected signal

Then with a signal going into line in and source selected:

Same 3 questions.

Sorry for rambling so much. Being systematic will help figure this out. Do you have the manual?

Regards, Ethan
 
It may seem obvious to check and clean the heads. But especially if you are using old tape, you really have to look with a magnifying glass and flashlight. The smallest speck of tape gunk can cause havoc. I had some dried on gunk that was hard to remove, it was like paint.
VP
 
here is an update of the current condition!

channel one:
will only play back from the sync head.
also will not play back through headphone jack.

(channel 2 is fine)

channel 3:
vu meter isnt working but it records and plays back on both heads.

channel 4:
input (from either mic or line) makes vu meter move, but audio cannot be heard at the output and it does not record.


any ideas?
 
You mentioned the heads being dirty when you first got the machine.

How did you clean them and what chemicals did you use to clean them? If there was sticky shed oxide on the heads at some previous point, you may need to re clean them a few times with methanol and pay very close attention to how the gaps on the heads look on the edge tracks compared to the interior tracks. It's also important to use fresh tape on the machine once you are 100% sure the heads are spotless.

It takes very little baked on tape oxide welded to the head to block the signal transmission and your edge track problems indicate more of a physical problem rather then an electronic one.

Cheers! :)
 
ive cleaned them quite a bit!
the thing is that channel 4 doesnt pass audio even when monitoring the input, yet the meter moves.
channel one could be a dirty repro head though, as it will play from the sync head, i'll check into that!
thanks again guys, some day i hope to get this working!
:D
 
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