in the following thread I'd like to address the crashing/freezing problems I was experiencing with my NORD Piano 3 and how I was able to fix them.
Warning - Don't try this at home!!!
I don't recommend this kind of work on motherboards for beginners or hobbyists. I would describe myself as an electronics nerd whose work goes beyond basic "musician's cable soldering."
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One flaw the keyboard had from the beginning was that it would crash sporadically when using the transpose functions. This hadn't bothered me until now, as I don't need these functions.
Unfortunately, during my last gig, the keyboard started freezing mid-song. I tried to figure out what the cause could be, but I was led astray by Chat GPT and other internet forum posts.
At first, I thought I could solve the problem by restoring the factory settings and reinstalling OS V 2.04.
This turned out to be a bad idea.
After deleting the various piano sample sets, I couldn't reinstall them because the keyboard now also froze when synchronizing with the Sound Manager software. 
At that point, I had a keyboard I couldn't use live and no idea how to fix it.
Then, during my internet search, I found an interesting article about someone who replaced their NORD Stage main CPU chip:
Motivated by the thread starter's work, I bought a thermal imaging camera (I figured I'd probably need it again, since I often repair broken electronics).
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A reproducible error that no longer occurs when the circuit board is heated! This error pattern showed me two important things:
1. It wasn't likely that a chip was defective.
2. The cause was most likely a so-called cold solder joint, exacerbated by mechanical stress from gigging.
Initially, I thought the main CPU was also the culprit. I ordered various soldering supplies, flux paste, and even a circuit board heater from AliExpress. I then practiced on some old PCI boards I had lying around. The pins on the keyboard's CPU chip are only 0.5 mm apart (!). Therefore, I was very careful not to break anything.
I was very careful not to damage anything. So I completely resoldered the chip using the so-called "drag soldering" method. After reassembling and testing the board, I was disappointed: the problem was still there.
I was able to narrow down the area of the board where the problem lay. It involved the chips to the right of the main CPU. There are approximately 10 chips, each with 20 pins.
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After removing and reinstalling the PCB about 10 times, resoldering different chips each time (marked in red in the pic), I finally seem to have found the right one yesterday. I also used my hot air station to clean all the small resistor networks next to the chips. Perhaps that was the solution. I can't say for sure. In any case, the keyboard now works perfectly. No more freezes, not even... Regarding the transpose function.
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I'm aware that this soldering work isn't for beginners. However, anyone can easily warm the PCB at home with a hairdryer to see if a fault disappears. If it does, I'd recommend taking the board to an electronics technician to resolder the chips. There are service centers that specialize in CPU chips for laptops or graphics cards (people who solder in cell phones might also be able to do it).
Best regards
Gitarrenzupfer
for sharing this very interesting repair story!
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