On this repair, I got an APU fail error on the test cart with an additional BB code.
This error indicates an issue communicating with the sound sub-system. (APU stands for audio processing unit)
This board was a GPM-02 with CPU A. Given that CPU revision A is a common failure point, my first guess was a bad CPU chip. But after swapping the CPU with a known working one, the error persisted.
My next guess was the S-DSP chip in the audio sub-system. I was about to remove the S-DSP chip from the board when I noticed some corrosion on a few of the pins.
Testing with a multimeter confirmed that two of the pads were no longer connected to their traces. I removed the chip to get an even better look.
Yep. That would do it. I put the chip back on and tried bridging the gap with a bit of solder, which was unsuccessful. I ended up adding two teeny jumper wires to the legs of the chip – which worked!
Even though this one was “fixed” I will probably use the board for parts – the solution is a bit of a bodge, and I don’t like how much corrosion was already there. Nice to have a solve for the symptom though!
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