This PCB is a direct drop in replacement for the TDA 0470 gating chip used in the (ARP) Solina String Ensemble.
These chips are half a century old so unsurprisingly they’re failing, a failed chip is usually characterised by a chunk of the keyboard not working, although other things could potentially cause this issue too.
To get this replacement, download the PCB files below and use them to create an order on https://jlcpcb.com/ and make sure to select SMT assembly. (Note, ensure you select tooling holes added by JLC when placing the assembly order, you also must solder the pin headers to connect the board to the Solina PCB)
