I have a bunch of older Optiplex GX620 machines that don't need internal audio so the speakers were removed.
I recently obtained some Optiplex 990 and we didn't get the internal speaker but now it turns out we could use it.
Can I recycle the GX620 internal speaker into the 990?
,
The GX620 speaker plug does fit the 990 socket, though the pinout is different. A GX620 motherboard has a gap on pin 4 while the 990 motherboard socket has a gap on pin 2. The white wire would not be connected with a GX620 speaker plugged into a 990.
I don't have any 990 speakers to know if the power and ground are in different positions, too. The socket pinouts for either a GX620 or 990 internal speaker are not documented anywhere.
I have not tried powering up the 990 with the GX620 speaker plugged in as I do not want to accidentally let the magic smoke out of the motherboard testing this.
,
GX620 INT_SPKR (internal speaker) plug pinout: 1- Red, 2- White, 3- Black, 4- (gap), 5- Green
Unnumbered solder pads on speaker: P5V_IN (5v DC in), SPK DET (Speaker detect?), GND (ground), AUD MONO (mono audio)