SMS death of a sound gen

[Ness7281992]

So, last week i had problems with my controllers not working in my Sega Master System, so I reflowed the ports a couple of nights ago. I played the only cartridge i have (yet), Phantasy Star, yesterday most the day, no problem, but when i started up the game again last night, the sound gradually incrementally (not steadily) got quieter, until nothing was audible. I don't know if it's the game (I know about the FM thing, though), or if I goofed something up repairing the controller ports, or if it's just because the SMS is so damn old. What i do know is i've never heard (pun not intended) of this happening before, none of the forums i frequent warned me of this happening; the closest i found was a guy who fried a ceramic capacitor when he did an unspecified (presumably FM) sound mod. I haven't had time to pop this unit open again yet, and i won't have time for awhile, so i haven't looked at the board yet.

So, any suggestions, Master System Masters?

[Ro-J]

I had a SMS once where you couldn't get any sound or audio through the RF output, but there was no problem getting both through the A/V output. Just a thought.

[Ness7281992]

Sorry, I forgot to mention that I've got it going through the A/V out. I don't have an official RF adapter, but if I wanted to, I could just use one from a S/NES, I assume, just like the Genesis.

[Ness7281992]

Yeah, i just tried playing through an rf adapter, no luck. It does the same thing.

[Ness7281992]

Hello? Anyone else available to help? I was able to find a pdf of the UK service manual, but from what I can tell, the schematic is clearly not the same as mine, which is unfortunately the made-in-China board. More caps aren't on the parts list than are, and I can't seem to find a fuzzed out cap with my multimeter. Can anyone find a service manual for Chinese-made boards, preferably for US owners?

[Niku-Sama]

huh that's an odd one. I've heard of caps causing muted sound but unless the caps died while you were playing it.....which I guess is possible?.

gradually over what amount of time? 5 minutes or 5 hours or?

[Ness7281992]

Well, at first it kind of faded out for like 2 seconds, then return to normal, but then when I started up the console again the next time, it would get quieter when certain sounds would play, but it only took 5 or so "steps" until it was entirely muted, so I'd say 10 minutes, maybe less. I don't really remember now, it's been a couple months, and the sound has never returned.

[Guntz]

Reminds me of a Game Gear I once had. The audio would be fine for a while, then it would get distorted and quiet, then disappear entirely. I suggest you re-cap your Master System and check for shorts or other issues.

[Niku-Sama]

Yea cap that board I'm at a loss still though