Tascam 388 stereo/pan issue

[Rayguar]

I had an intermitten issue for some time where my pan knobs on the channels would sounds thin and raspy when panned right, and my solution for this was to smack the lower left side wood panel a few times and like magic, the sound would be restored and full. Now it has stopped working. The right master meter is lower in volume output and is being read at 5 less than the left channel (when i have the pan knob at 12 o clock). This all gets fixed when i press the mono button. Both master meters sync up and sound is full again. No smacking is working on it, and its a shame as i just recorded stereo drums for the first time and they sounded great when left and right worked.

I opened my 388 and tried to find maybe something that was loose, that i used to hit to get it to work, but to no avail, found nothing. I reseated some connector pins but thats about it. Do you have any slight idea on what this issue may be?

 

[Rayguar]

UPDATE

I just moved that big green board that connects to every channel strip PCB, and it restored the sound! Can anyone tell me what that big green connecting board is?

 

[Rayguar]

This connector was loose, which is odd because its soldered. The left one is well fitted and fine as are the rest of them, but the one on the right is the one that is a bit loose. I shook it around and lost complete signal and shook it some more and got it to fit like a lego block, and full signal was attained and at proper levels, left and right

---------- Update ----------

 

[miroslav]

That connector doesn't appear to be soldered. I mean, each half of it is to the corresponding board, bit the two sides clip together.

So...if you're shaking it and smacking the side of the wood panel (that's not magic) to make it pass signal...the connections either have oxidation, which requires the boards be disconnected and the metal cleaned...or you have a broken solder joint, which is not uncommon on older gear...and smacking/moving things only makes the break worse. You need to find the one(s) and re-solder them...or hit all the points on the connector with fresh solder.

The way those are all designed with the light connectors and strips running across, etc...etc...with age they are prone to connectivity issues....and a PIAY to work on, because to disconnect one board, you kind have to disconnect a few others...and the more things get disturbed, the more chances you create additional connectivity problems.

Or next time...just hit it harder.

 

[sweetbeats]

That is the “buss PCB”, Ray. Think of it this way...instead of connectors with ribbon cable chaining from channel board to channel board, the ribbon cable is replaced with a long PCB with the connectors soldered to it. Those buss PCBs can have issues with cold or failed solder joints, or sometimes as Miroslav mentioned the pin and socket connections can become oxidized. The simple solution to the latter is to exercise the connections and ideally apply some contact cleaner such as DeoxIT D5. If the issue is the former, it’s time to get out your soldering iron and re-flow the solder joints.

So your issue is with all 8 input channels? If so, look for a failed solder joint toward the far right of the buss PCB. To further narrow down the issue you can look in the service manual and identify which two traces carry the stereo buss...that’s where your problem is.

Hope this helps. Good job identifying the nature of the issue.

 

[therealj]

That is the “buss PCB”, Ray. Think of it this way...instead of connectors with ribbon cable chaining from channel board to channel board, the ribbon cable is replaced with a long PCB with the connectors soldered to it. Those buss PCBs can have issues with cold or failed solder joints, or sometimes as Miroslav mentioned the pin and socket connections can become oxidized. The simple solution to the latter is to exercise the connections and ideally apply some contact cleaner such as DeoxIT D5. If the issue is the former, it’s time to get out your soldering iron and re-flow the solder joints.

So your issue is with all 8 input channels? If so, look for a failed solder joint toward the far right of the buss PCB. To further narrow down the issue you can look in the service manual and identify which two traces carry the stereo buss...that’s where your problem is.

Hope this helps. Good job identifying the nature of the issue.

Hey i’m having this same issue with my stereo L out and vu meter. i get nothing in the left out when i try to send to my computer, same with the headphones. In mono everything works fine, but in stereo if i pan any of the tracks left the audio disappears, my master bus pbc doesn’t appear to have any cold joints and j cleaned the hell out of it ! still nothing. where should i looks for this issue ? thanks !