Tascam 388 - legible schematics anyone?

Hey guys,

I have a Tascam 388 that i have lugged around for almost 20 years and I cant do it any more.

It was my first tape machine, I loved it, I still kinda do, it worked flawlessly every time I needed it to - the last workshop move sealed its fate, but of course when i got it in the bench to give it a once over before selling it i found that im not able to record to one track.

I swapped the cards around (no easy task, those cards are in there TIGHT) and the fault follows the card, which is a good thing - everything else works as it should (20+ years and its still calibrated!)

So for whatever reason it seems im not getting to the record head - I am able to monitor the program or track input but on playback there is nothing - I was wondering if anyone had:

a: an extra Rec/Repro card for this machine they would be willing to part with...
b: a legible copy of the schematic - I have seen all the ones online and you cant read the component values from any of them..  Id pay for a good copy...

thanks everyone!
Timothy

is this the model?

https://www.ebay.com/itm/TASCAM-388-STUDIO-8-Service-Repair-Manual-Schematics/183381449599?hash=item2ab262db7f:g:LkIAAOSwR0JUODoA

If you can hear sig in the monitor but nothing gets recorded and the problem follows the card, that does narrow things down quite a bit. In my Tascam 234 the sig splits from the monitor just before the output pot (fader for you) and then goes:

bipolar transistor shunt switch to
level trimmer pot to
single op amp to
test point (TP1) to
bias oscillator trap to
connector to board w/oscillator feeding head

So it's probably similar for your machine and likely to be one of these things. If you can find this stuff use a scope to look for signal. My first guess would be a bad solder joint.

Squarewave,

wow - thanks, thats really helpful - and yeah - thats exactly how it is in this machine as well - I can trace the signal path thru the crappy scans - just cant make out any of the labels, values or part numbers...

here is something else interesting i just discovered - there is a 100Ω series resister in the +18VDC power rail that feeds a discrete dual FET amp stage, followed by an IC repro EQ stage and an IC output amp for the audio from the repro head...

this resister is  getting hot as a pistol. All that is after the resistor are a few decoupling caps, the 2 IC's and the discrete amp stage...

The +18VDC bar seems stable, so its not totally shorted out, but something there is pulling too much current...

Scott - thanks for that  - ebay picks the search category and  it wasnt showing up in my searches.



thanks fella's,
Timothy


here is a link to the available service manual in case it helps.
https://www.manualslib.com/manual/1019712/Tascam-388-Studio-8.html

Can you put that board and a good one side to side, supply them with the right voltages, and comprare the readings?

(Voltages and component reading)

post pics of the pcb

I'm having a similar problem. 388 has been fine until recently, it seems signal isn't getting to the record head on any channel. Signal is strong coming in and monitors just fine, and it will record a very, very faint signal over existing material.

Pulled the repro card, inspected for obvious problems, none found, applied Stabilant 22 to molex pins and reseated. No luck. Went on a search for legible schematics and found this thread.

1) Has anyone come up with legible schematics? Are the eBay ones readable?
2) Any likely culprits or specific places I should look for signal or voltage?

Thanks!

> signal isn't getting to the record head  .... Pulled the repro card

Why?? I'd be thinking Record card. (And all selsync switching, which indeed could be on a repro card..)

And check for supply voltage right off, since all channels are faint.

PRR said:

> signal isn't getting to the record head  .... Pulled the repro card

Why?? I'd be thinking Record card. (And all selsync switching, which indeed could be on a repro card..)

And check for supply voltage right off, since all channels are faint.

Click to expand...

Gotcha! Thanks!

To be fair, I pulled all the cards, even the VU driver boards, checked them and applied Stabilant.

Will check voltages and re-check repro cards today.

I'll try contacting Tascam about legible schems. If I'm able to get them I'll post a legible scan. Thanks fellas!

Did anyone ever find schematics for this?
I'm repairing one at the moment.