The Tascam 388

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Scodiddly
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Re: The Tascam 388

Post by Scodiddly » Thu Apr 30, 2020 5:24 pm

Dandna wrote:
Thu Apr 30, 2020 11:55 am
one last thing - after we had put it all back together as i unplugged my guitar (which i had been using as a sound source to check the problem) I noticed the needle on the VU meter went up to just below -20.
Every time i held the tip of the jack onto the metalwork of the guitar the meter seemed to register a very low signal (i was using a balanced XLR to 1/4" jack to plug my guitar into the XLR input of the 388).
Possible some DC leakage into that input which the guitar drains away. Check for leaky capacitors.

Dandna
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Re: The Tascam 388

Post by Dandna » Fri May 01, 2020 4:56 am

hi
yes, channel 4 can be routed to any track (other than 4) on the tape, and the other channels can be routed to every track except track 4. An old tape also plays back track 4 fine, and when I record onto track 4 it erases the previous material, so im assuming the erase head and play head are working.

Dandna
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Re: The Tascam 388

Post by Dandna » Fri May 01, 2020 6:51 am

Scodiddly wrote:
Thu Apr 30, 2020 5:24 pm
Dandna wrote:
Thu Apr 30, 2020 11:55 am
one last thing - after we had put it all back together as i unplugged my guitar (which i had been using as a sound source to check the problem) I noticed the needle on the VU meter went up to just below -20.
Every time i held the tip of the jack onto the metalwork of the guitar the meter seemed to register a very low signal (i was using a balanced XLR to 1/4" jack to plug my guitar into the XLR input of the 388).
Possible some DC leakage into that input which the guitar drains away. Check for leaky capacitors.
ok, thanks!

kslight
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Re: The Tascam 388

Post by kslight » Fri May 01, 2020 8:11 am

Dandna wrote:
Fri May 01, 2020 4:56 am
hi
yes, channel 4 can be routed to any track (other than 4) on the tape, and the other channels can be routed to every track except track 4. An old tape also plays back track 4 fine, and when I record onto track 4 it erases the previous material, so im assuming the erase head and play head are working.
Maybe there’s something out on the buss? Op amp or Logic issue maybe...I’m not sure, that’s above my pay grade.

Dandna
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Re: The Tascam 388

Post by Dandna » Fri May 29, 2020 3:59 am

okay, so latest on the 388 repair job. We've tried swapping over the input cards, no change, so its not the input. Managed to get to the meter amp PCB and swapped around the plugs for the meters for channels 3+4 (4 being the meter than isnt registering) with the plugs for the meters for channels 5+6, and hey presto 4 worked, but the problem was now on channel 6, as would be expected.
So the problem isnt the meter amp PCB (also checked continuity on those two cables, channels 3+4 and 5+6, theyre fine).

IMO this has narrowed it down somewhat to either Buss A, or Buss B. The input cards all go to Buss B first and are then distributed to Buss A. Buss B has the track select buttons on it, which all seem to be working, flashing red etc (and any channel can be assigned to track 4). Buss A is where the assigned inputs are then distributed to the track and therefore the meter amp PCB.

Any ideas what we might be looking for on Buss A PCB?

Other option is Ive found one on ebay for 48 bucks, but as im in the UK the seller wont ship it.

Bill B
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Re: The Tascam 388

Post by Bill B » Mon Jun 29, 2020 6:03 am

Hello there,

New dude from NL exact Same problem here
Did a fair deal of recapping, all is fine except channel 5,
Nearly any sound,
Checked everything but I think it’s some op-amp on bus A or B.

Can some body put me In the right direction??

Best Bill :blush:

Dandna
audio school graduate
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Joined: Fri Jun 07, 2019 6:04 am

Re: The Tascam 388

Post by Dandna » Mon Jul 20, 2020 1:05 pm

hey man,
I bought the second Buss A PCB and swapped it with the one in my 388 and... no change :(
now think were narrowed it down to the meter amp PCB (i know, i know, we thought wed ruled this out). have traced the signal through the meter amp card and *think* the problem might be a capacitor along the chain. there seems to be a voltage discrepancy on 4 that isnt there on 3...
might be a case of doing one at a time and keep checking as we go.

good luck with yours!
Last edited by Dandna on Mon Jul 20, 2020 1:07 pm, edited 3 times in total.

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