Tascam M-30 mixer - problem with submix panning

golf_richards

New member
Hi,

I have received a ton of useful information getting my Tascam 38 set up with my Tascam M-30 mixer.. so thanks for that to this forum!

Anyway - I have run into this problem with the M-30's submix section. I use the submix section to monitor inputs and tape playback (selecting between post and tape) and can pan things left or right on all but 2 channels.

On channel 2 and 4 of the submix section, you lose all sound when you pan left. I have cleaned the pots and sort of checked out the submix card that these channels are both on but haven't tried to remove it.

Unfortunately, this all happened right at the beginning of a recording project (of course)

Does anyone have any idea what the problem might be? I figure it's got to be an internal issue to the submix. I hooked up another mixer to my 38 and could hear the tracks that I recorded through the M-30 and they seemed to have hit the tape correctly, so the problem seems to just be with the monitoring of the submix.

the only other thing I can figure that might have something to do with it is that the headphone jack seems to be messed up as well. I get around this by using a headphone amplifier connected to the submix out.

When I plug headphones into the headphone jack you have to mess with the plug in order to hear stereo... like keeping the plug pulled just a little bit out of the jack which never stays in the same place for long. Otherwise it will seem to be in mono or just left or right depending.

I love the M-30 for it's vibes and convenience, but taking it in to my local service center will be expensive, so i was hoping there was something i could do on my own...

Help!:confused:
 
So, because the issue occurs in all outputs fed by submix channels 2 & 4, and because the issue only occurs with those two channels, that really narrows down where the issue might originate. Unfortunately I don’t have an M-30 service manual; just the operations manual. Do you have the service manual? I’d need the schematics to help further.

Do you hear *anything* from the left side of submix 2 or 4? Or is it completely dead? How about if you hit it hard with signal? Do you get anything intermittent, like crunchy something with the transient peaks?
 
Thanks for helping me troubleshoot this!

Alright.. I turned my preamp up to 10 and could hear my distorted voice now on the Left side of both channel 2 and 4... so the left side isn't completely dead.

I do have the manual and could take pictures of the schematics for you. Most of them fold out so it's hard to scan them
 
I took some pictures... hopefully you can read them! I have to zoom in. The block diagram is cut off on the left but it's just Channels 1-6 and then 7-8 (with the 1/4" jacks instead of xlr)

I also included the schematic for the submix amplifier pcb assembly.
 

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Thanks for the effort, but what you called the “schematic” is not the schematic...that’s the PCB layout. I need the complete electrical schematics that show the circuits at the component level. And I don’t think pictures are going to work. I’d need scans, and preferably full scans of the fold-out “tabloid” pages and not sectioned scans.

I’m not expecting you to do that, it’s just what you need for the next step.
 
OK I see what you mean, well here's the submix amplifier schematic, perhaps you can read it despite the dodgy photo quality.. I don't have a way to scan at the moment but there is also a schematic for the inputs, master monitor amplifer, power supply and the wiring.
 

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There is a free Tone Generator app for iOS devices. That will work for this. You’ll need a way to get tone from the iOS device to the M-30, and then a multimeter to sniff the tone on the submix B PCB.
 
Audacity (or any DAW) can generate sine and noise. Record 30 secs of 1kHz (say) and play back on a loop. Even the 1/8" internal soundcard jack should give you enough signal for tracing but a modest interface would of course be better.

No test meter? Hope you can solder! Best of.

Dave.
 
You're welcome, happy to help.

I scanned it back 2014 and uploaded it for I think, someone on Tapeheads.

The foldout pages were scanned in sections and then joined together in Photoshop Elements and printed to "pdf" via "CutePDF" print driver to European A3. The normal pages where scanned direct to "pdf" as European A4.
 
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