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SE/30 Missing capacitor?

Posted by: desertrout on 2020-05-23 08:47:20 I'm in the process of ordering caps for my SE/30, which I use reasonably often and it works very well but I noticed the speaker has gone pretty quiet. I cleaned and inspected the main board recently and there was definitely some leakage and a little corrosion. However, I also noticed that capacitor C1 (at B1, next to the RAM) was completely missing - the pads are clean and tinned, there no corrosion or any sign of damage that may have caused it to fall off.... it's almost like it was never there to begin with. Is that possible? I've been looking at cap lists and pics of other SE/30 boards, and that cap is there on all of them... but I'm wondering, should I add it to my board? You can see for yourself in the attached image, it looks like it was never there...

Posted by: maceffects on 2020-05-23 08:56:46 If I'm not mistaken I've noticed this missing on other boards.  And I think it is used for +5v.  I don't see any harm in adding one, however, I'm not sure it will have any effect on your sound issue.

Posted by: desertrout on 2020-05-23 09:56:14 Curious. Yes, apparently it's for +5v supply, functions as a decoupler. We'll see what a recap does for the sound, as I understand it it's often a symptom of bad caps.

Posted by: desertrout on 2020-07-15 00:16:19 All recapped now including C1, boots up loud and clear (i.e. the sound is fully functional again). I did clean/reflow any badly corroded pins I could find, though I didn't touch the Sony IC's, which are looking just a little green on the top side. Anyway, all good in the hood. I was going to ask whether or not I should recap the analog and PSU as well, even though I'm experiencing no issues, but I think I'm just going to go ahead and do it as preventative.

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