This piano was sold as "non working condition". It was cheap, and later inspection revealed its action looked quite new and barely used, so I think I scored a good deal.
As soon as I had this delivered at my door I couldn't help myself but to inspect the insides and get my clumsy hands dirty... I noticed this blown fuse, and it was Friday night so I couldn't source a replacement until Monday... so I just replaced it with a thin wire and it suddenly came back to life... for a while though. I know (and I knew then) I should've stop right there till Monday, but I was so excited that I couldn't stop playing and I didn't, so I ended up with a loud pop, some smoke and a blown power amp transistor. Fuses are there for a reason. Blown fuses are blown for a reason. I know, please don't tell me about it...
According to my tech, it was this Motorola 142349 voltage regulator that was damaged, fuse wasn't there to protect, boom! Broken wurly.
He couldn't find a proper replacement, so he had to replace it with some newer "somewhat equivalent" part (I will edit and include some pictures later). 3 pins instead of 14, I think we're missing something there, but he's the tech not me, and he keeps insisting this part serves its purpose. He also replaced this blown power amp transistor (I can't recall if just one or both), apparently with a matching part this time. And he also replaced an electrolytic capacitor he didn't like for some reason.
Ta-da! The amp now works. Kind of. I didn't had the time to notice if crossover distortion was there at the beginning, so I don't know if any of this replacements could be the cause for this malfunction.
And it's been like this for a decade. Distortion is just present through speakers or phones, line out is "fine". We'll address this later, I know there's room for improvement.
But this is mainly used as a playing instrument, now that I have time to actually play, and it's something I'd like to fix.
I know mouser now stocks a direct replacement part for this 14 pin voltage regulator and maybe I could start there and try.
Also, I recently got myself another original amp + preamp I still have to test. I'll keep you posted.