So I have a Roland XP-80 with a similar issue as this guy who shows us on Youtube how to replace the battery in the thing. The LCD backlight is on as is the LED on the disk drive. Apart from that – no sign of life.
For me it was an easy fix, as it was quite obvious what had happened:
Capacitor 201 (47µF, 6V) had blown up quite spectacularly. To remedy that, I soldered in one that I had lying around (not exactly the same type, mine has a rating of 25 Volt), and after that all was well.
The stain on the board was quite substantial, so I had to carefully scratch the sod away to try and see if the traces were still in good condition (it always helps if you have access to a service manual / service notes, you can find some at synfo.nl). And yes, all was still connected according to my multi meter.
This would have been a job for a few minutes if I had done that in a sensible manner – but no, I had to start too far down the path.
- Sniff the board – really, that was a dead give-away here. It stank of exploded component. I just ignored it.
- Visual inspection – if it doesn’t smell funny, you should still look for the sh*t stain on the board. As you can see above, another dead give-away. I just ignored it.
- Thou shall check voltages – And this is where I started at. At the power supply. Which was basically fine.
Now, after these steps you can start using your brain, try to check clocks – which was what I was going to do next, but luckily the chip I wanted to probe was close to the exploded capacitor. You can follow signals, measure in circuit, desolder components to measure outside of the circuit and what not.
But only after the sniff test and the visual inspection! Took me the better part of three hours because I didn’t.