Cap Your 90's Midway Sound Boards Immediately

Awesome call out. Just got my mk1 a few days ago, bought the cap kit before i picked it up after reading this post.

Played a few rounds with family before I was going to do this and redo the panel, figured I'd do the sound board kit this morning. Had 4 leaky caps, was definitely on it's way out.

First real cap kit I've done and it went flawlessly, thanks 😁
 
I just recapped a MK1 and MK2 sound board and figured I would share my thoughts...

All of the MK2 radial electrolytic caps were leaking badly. None of the MK1 radial electrolytic caps were leaking. None of the MK1 or MK2 axial electrolytic caps were leaking.

Be very careful if you are rocking the caps out to remove them. It's easy to pull a pad when doing this. I added fresh solder, then removed the cap, then added more solder and used my Hakko gun to remove the solder. Ideally you want the tip of the gun to never touch the PCB. If it does, don't drag it laterally across the board or you will likely cause damage.

I also pulled the audio amps out to remove the electrolyte? that leaked from the caps and hit the area with iso alcohol and a scratch brush. You might as well clean the corrosion from the legs with a wire brush and install new heat sink paste while it's off.

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I keep petitioning to label them CVSD (Smash TV) and ADPCM (MK/T2/TC/NBA Jam) but in case anyone was wondering the kit linked above is for A-14732-43725 / A-15739 / 5768-13265 / 5768-12858-00 / A-5346-40025-9, A-14732-40009 and A-14732-40010 sound boards. +1 if you memorize this nonsense.
Ordered, thank you very much for the help!
 
Ahhh that Midway "DONG" after doing a successful capkit and its loud because before the cap kit your sound board was working at about 50 percent volume with leaky caps. This one an NBA Jam im restoring BOOMSHACKALACKA!
 
Just to circle back to points made earlier by others.

Recapped my house of the dead 1 sega sound amp and at least 7 caps were leaking. Seems to have heavily helped sound quality/level control.

Recapped the happ power supply as well and easily another 7 caps leaking.

Recapped a board on my time crisis 1 pcb stack and it looked like most of the SMD caps either already had leaked with crust, or were in the slow process of leaking. Also swapped the power supply.

Have some time off work this month so figured it was a good time to really dig into preventative maintenance and it appears to have paid off. Cap your stuff!
 
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I didn't realize the SMD caps are leaking too. That's going to prevent many people here from fixing them because they're not set up to replace SMD components.
 
I didn't realize the SMD caps are leaking too. That's going to prevent many people here from fixing them because they're not set up to replace SMD components.
the plus side is, you can carefully caveman those off.

It seems to definitely be a YMMV type thing depending on if the electrolyte has weakened your pads to a point where they're pretty brittle, but i just took a pair of pliers pushed down and carefully wiggled back and forth until the legs eventually snapped off. Sounds scary but it actually worked pretty well and i replaced the caps with through holes of the same value.

Think i replaced somewhere around 10-12 forget how many specifically. not a single pad had an issue. Just had to heat the now separated legs up and push them off the pad, tinned the pads with solder, placed the through holes on with the legs snipped and bent in an L shape and heated them up.
 
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"Aw, shit. Here we go again." Some spooky cap leakage on this Halloween evening. EVERY radial cap was leaking. Cleaned the board, replaced all the caps, replaced the two TL084 opamps due to some crackling that was present before and after the rework - crackling is gone, and it's working great again.
 

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So leaving the new caps slightly raised off the board — is that so you can observe under the cap in the future? When I've recapped monitors I usually seat the caps flat on the board. Is that not recommended?
 
"Aw, shit. Here we go again." Some spooky cap leakage on this Halloween evening. EVERY radial cap was leaking. Cleaned the board, replaced all the caps, replaced the two TL084 opamps due to some crackling that was present before and after the rework - crackling is gone, and it's working great again.

What board was that, Zeno?
 
So leaving the new caps slightly raised off the board — is that so you can observe under the cap in the future? When I've recapped monitors I usually seat the caps flat on the board. Is that not recommended?
The cap legs come bent and without manually straightening them, the caps don't sit flat on the board. There's no advantage/disadvantage to having them up off the board like that.
 
The cap legs come bent and without manually straightening them, the caps don't sit flat on the board. There's no advantage/disadvantage to having them up off the board like that.
I would say there's a couple of advantages:
Being able to visually inspect, and being able to cut the legs off in the future for easier desoldering and replacement. As someone who struggles with soldering, I'd much rather find raised caps I can cut off.
 
I would say there's a couple of advantages:
Being able to visually inspect, and being able to cut the legs off in the future for easier desoldering and replacement. As someone who struggles with soldering, I'd much rather find raised caps I can cut off.
True.
 
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