o2 internal speaker problems

[stormy]

Just wondering if anyone has ever experienced this issue: on my o2, the default sound output is the internal speaker (which I quite like) if I keep it running for a length of time (not sure exactly how long, 30mins-hour) eventually the sound will just stop working. If I go into sound options I can change the output to the headphone jack, that will work fine. But going back to 'Audio out 1' (internal speaker) will still not work. A reboot will not fix it. but turning it off for a few hours will.

At first I thought it could be an NVRAM issue, since it seems hardware related with how it won't automatically fix itself after a reboot. So I replaced the NVRAM (followed the proper procedure by clearing and initialising the NVRAM too) But this hasn't fixed the problem.

The o2 itself is in wonderful condition, the circuit boards and chassis are completely dust free, almost factory fresh. So I don't assume any hardware degradation. It's really confusing!

Running latest 6.5.30 IRIX.

 

[stormy]

Just an update: I may have fixed it now. I decided to open up the sound module and inspect it. There were no electrolytic capacitors fortunately, but strangely there was a kind of yellow/green residue covering most of the chip legs of IC's. I doused the board in alcohol and rubbed all the chip legs clean with a cotton swab. I let it dry and put it back in the o2, and now the sound seems to be working properly.

Just as a side-note, for consistency. I also (at the same time) fixed an issue where I was getting an error constantly spammed in my console: 'rstat: Error 0'. Turns out that following the IRIX security hardening tutorial I disabled this service in inetd.conf, and obviously some service was constantly calling for it. Now, I don't know 100% for sure whether this problem was related or not, or whether it was simply cleaning the audio card. I just wanted to make sure I note this, just in case I ever run into the problem in the future.

This is the card before cleaning, you can clearly see the yellow / green residue especially on the IC's in the bottom right, and on the main decoder chip: