Pioneer A-88X - Main Filter Caps looked "bloated

[Tangerine]

"Hello all,

Just received this machine the other day, it's exhibiting issues with front panel switching needing a good clean.
So, off came the lid and I noticed that the four main filter caps (71V, 10,000uF) had stripes on them. It took a few secs to realise that they were touching the lid and the stripes were in fact accumulated dust.

I think the attached photos will give you a better idea of what I'm on about.

If, as suspected, these need replacing`, are such things still available and what would be the cost?

Cheers,

Les.

 

[HPMguy]

The plastic cap on those often distorts with age and bulges up. If you can push it down level with the sides they are likely fine.

If the actual metal top of the cap is bulged, they need to be replaced.

Replacements can be a problem, especially if those are four on caps. Mostly out of production, but you can use standard snap caps with 10mm lead spacing with some modifications. Four pin replacements could cost $20 each, snap caps are likely to be $10 or so each, I have not needed 10,000uF 71V caps and haven't priced any lately.

Mouser or Digikey.

 

[Tangerine]

The plastic cap on those often distorts with age and bulges up. If you can push it down level with the sides they are likely fine.

If the actual metal top of the cap is bulged, they need to be replaced.

Replacements can be a problem, especially if those are four on caps. Mostly out of production, but you can use standard snap caps with 10mm lead spacing with some modifications. Four pin replacements could cost $20 each, snap caps are likely to be $10 or so each, I have not needed 10,000uF 71V caps and haven't priced any lately.

Mouser or Digikey.

You are spot on!
The tops did readily move under thumb pressure and pop back into place, so they seem to be ok.

Thanks for your insight.

 

[larryderouin]

To elaborate on HPMGuy's explanation. The plastic (vinyl wrap) around the cap shrinks with age and heat cycles and will physically pull on the thicker top (which also softens and eventually lifts or bulges.)

71v caps are practically extinct. Bump the voltage on the caps to 100v and you'll find a good assortment to choose from.

 

[rcs16]

Choose more common 80V or 100V
Select to match for diameter, you can up to 12000uF, stock and selection are dwindling
35 or 40 mm diameter?

 

[zebulon1]

Those large caps normally vent from the bottom. Smaller caps from the top.
Can’t say (so far) if I ever saw a bulged vintage cap unless I did something wrong which is always the case.