glad you worked it out, just wanted to say that this thread is like a model for all troubleshooting threads to come...

It was the headphone jack insertion switch.

EDIT: I fixed this. It was the headphone jack insertion switch (a white plastic contactor on the top of the jack). Maybe this can help someone with a similar issue!

Wow, I just wrote up a huge post only to be plopped into an "access denied" page after clicking submit. Ugh. I'll have to make this short, thanks to that.

The Issue: The speaker is silent on my original DMG-01 handheld. The headphone jack works fine. I don't think it's the speaker itself. The unit powers on and loads carts fine.

Here's some damage to the PCB:
1. The copper plate on the right has oxidized down to the PCB under it, in a pinhole in the center.
2. A PCB route on the left seems to have oxidized a bit. I think it goes to the little brown board next to the headphone jack board.

I tested the following with my voltmeter:
1. Speaker conductivity. OK
2. Speaker lead conductivity. OK but only when unit is off. When unit is on the leads do not form a closed circuit.
3. Speaker lead for Ω. Nothing when unit is on.
4. Headphone jack solder points for Ω. An average of 0.6Ω is detected when music is playing.
5. I touched the speaker leads directly to a headphone jack. I heard nothing but the obvious pops and crackles as the leads rubbed on the jack.

Any ideas? I think it could be the headphone jack insertion switch or some damage on the PCB. I really need help on this as I do care about the speaker.