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Hi!
So, I got 4 broken DMGs from ebay, I got them up and running, fixed the dead columns of pixels and cleaned them, so far so good.
The problem is 2 of them only play sound on the left channel, whether it's from the speaker or via the headphone jack.
I was wondering if someone already had that kind of problem at all and how to fix it...
I'm kinda clueless here, so any information/advice much appreciated! 
Cheers!
did you check the connections with the headphone port and the mother board? they might have come loose and need to be re-soldered
Yup, seems good.
But since there's no right channel on the speaker either, I'd expect the problem to come from somewhere upstream...
Anyway, I tested the volume pot and it seems clear as well.
the right channel being dead sort of seems like a trend to me, i've bought tons of junkers and it seems like if there is an audio problem its ALWAYS in the right channel
don't know the reason why though
Oh hey Kitsch!
I'm going through all this before I choose on which one I'll solder the RGBbb kit I just got from you, haha! ^^
Well, sounds bad...
Does anyone know if there's a diagram of the DMG pcb available somewhere? I searched but couldn't find one.
I could try and find out where the weakness is and hopefully fix it. Not very likely at this point, it seems, but hey! a man can dream...
there ye are!
#s 59 and 60 off the CPU, ROUT and LOUT
you can try to quick prosound it and see if its before/after the amp and all that. a 'pre-pot' prosound would get you between the 1k trimpot you see there and the two resistors farther up the signal paths (the ones right before the two 1uF caps).
or, solder to the + legs of these caps if you want to check directly off the CPU in case the cap happens to be busted or something
don't even need to solder at all if you are just probing it to see if you can find where the signal dies, or if its dead coming from the CPU
was just thinking about if it actually worked coming off the CPU directly...
if so, don't just solder it and leave it as your channel-fix for that side, go back and look at the circuitry (the resistors/caps you've bypassed), and either replace those parts on your PCB or recreate them on a little breadboard and solder to it.
Awesome!
I'll look into it and report back later.
Thanks a lot!
Ok, so after today's fiddling, 2 weird things happened.
1. The first DMG magically found its right channel back, both on headphone and speaker. I have absolutely no idea of the original cause of the problem.
2. The second one, that happens to be seriously corroded on the inside due to battery leakage (a.k.a how to learn the hard way to check for forgotten batteries when you purchase at a yard sale), lost any sound on the speaker, even before I opened it. However, the headphones port still works and I could establish that the right channel loss occurred somewhere in the volume pot thing (I could hear it when bypassing).
Which leaves me there, wondering how I could trust a DMG randomly losing its right channel and how to get the speaker to work on the other one (Edit: the problem definitely comes from the CPU board, though).
Also... I don't exactly have any valuable knowledge in electronics, but if the volume pot is the cause of the loss, there's nothing to do apart from replacing it, right? Edit : years later I had the same problem with GBCs and all it took was spraying contact cleaner to the volume pot to get back normal resistance on both channels.
Last edited by ArtyBoomshaka (Nov 20, 2021 11:20 am)