Recapped my Tascam M520, thoughts on putting Humpty Dumpty back together...

lo.fi.love

lo.fi.love

Functionally obsessed.
Hey folks,

I've largely been away from the forum, my budget and situation have forced me away from audio projects. However, back in December, I pulled apart my M520 and began recapping it as well as the PSU. That project is 99% done, I have one small card left in the Master section to recap and then I'm ready to put it back together.

So as I'm putting it back together, does anyone have any tips on how I should go about it? Here's what I have in mind, please add on whatever suggestions (or questions):

1. Plug in the PSU to the wall, turn it on and let it sit (.. and? Watch for smoke or bad smells?)
2. Put the master section back into the mixer chassis, reconnect its numerous connectors, power on the PSU, and.... any recommendations for tests, etc I should perform?
3. Begin putting in the channel strips one channel-group at a time and test them for signal passing through, EQ tests, etc?

I have a rough idea of how this all should go, but advice from anyone with first-hand experience on this will be VERY valuable and helpful. Are there any tests I can perform on each card/component/section before I reassemble it all in the mixer chassis? Anything I'm missing?

Your help is appreciated! Thanks!!
 
FWIW, I replaced the capacitors with the same values, etc as the original. No 'hot-rodding' took place. Except there's one cap whose value in the parts list is different from the one installed at the factory, and that one was replaced with a cap of the same value as the one installed.
 
Don't know your Tascam model but I would I have recaped the power supply / section first & got that working OK with the desk doing the rest of the job. It might have sounded fine even then without replacing all the rest of the caps & board parts.

I would test the power supply seperately first & check the voltages going out to the desk are OK, they will be higher without a load, maybe around 25% or more. Then add the various sections together. Can't see any major problems as you have just exchanged old parts for new, no mods involved so the desk should work fine. You just need to test the various inputs & outputs, to check it's OK.

As long as you can put it all back together, I know from experience that sometimes this is not as easy as taking it apart!!!
 
trancedental said:
Don't know your Tascam model but I would I have recaped the power supply / section first & got that working OK with the desk doing the rest of the job. It might have sounded fine even then without replacing all the rest of the caps & board parts.
Click to expand...

Yeah, in hindsight replacing each section while leaving the rest intact for testing purposes would have been the smarter way about it!

I would test the power supply seperately first & check the voltages going out to the desk are OK, they will be higher without a load, maybe around 25% or more. Then add the various sections together. Can't see any major problems as you have just exchanged old parts for new, no mods involved so the desk should work fine. You just need to test the various inputs & outputs, to check it's OK.

As long as you can put it all back together, I know from experience that sometimes this is not as easy as taking it apart!!!
Click to expand...

It seems like it should be a straightforward operation. I've been dreading putting it back together... all those tiny little connectors, I know I'll be cutting up my fingertips on all the stamped sheet metal inside. Sigh. But I wanted a project! I'm aware too that I could have gotten away with just recapping the PSU... I really like this board and want to keep it a long time, I figured a full recap would be good for its long term viability.
 
I think you're on the right track...and yeah that one cap in the PSU that doesn't match the parts list or schematic, you did right by replacing with the same value part that was in the assembly...10uF/35V IIRC?

So, yeah. Plug the PSU in and if you only did caps you'll know by the little *pop* or *bang* (depending on the size) whether or not you got one in backwards...heheh...you may not find out until you load the supply with the mixer though. And I agree with trancedental to check the voltages coming off the supply and if you don't have a scope then also measure the DC rails with your meter set to AC volts to look for AC components on the DC rails. Should be very small values here, like single-digit mV range.

Then connect up the master section and make sure it comes up fine and try to resolve any issues you can before connecting up the first I/O module assembly. When you DO connect up that first I/O module assembly do the one right next to the master section in case there are cabling issues further from the master section...that'll send your head for a loop if something's not working but it is just a cabling issue but you'll be spinning trying to find it so start close to the master section and move out from there.
 
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