Hello friends. I am trying to fix a faulty Korg M1. I've taken out the main board, and poked around with a scope. I am seeing signals like the ones in the attached scope screenshot. The signal is measured on the 74LS245. Top cyan signal is OE# (output enable, negated). Second, yellow signal is DIR (direction), third, purple signal is B7 and the last, blue signal is A7. It could be A6 and B6. It doesn't matter, on some pin pairs this happens, on some it doesn't. As you can see from the attached schematic snippet, it is an input/output buffer on the CPU data/address bus. I have literally desoldered all the ICs from the board that would use the data bus, and now it's just the CPU, the 74LS245, and some misc chips that should not interfere. I am seeing these ramps, sort of like a capacitor charging, perhaps, but I am stumped as to where they come from. I've replaced both the 74LS245 with new ones. There is a resistor array also pulling up the signal aparently, but I've tested those and they're all 10k. It's just the CPU and the buffer now. It might be the CPU, I am not sure though. This board is a 5V board that possibly got fried due to the power supply going up to 7V. In practice, it works intermittently. The LCD displays text, sometimes with garbage characters, but the keyboard itself makes no sound. I did get it to make sound at one point, and at another point it was sending MIDI data (the MIDI UART is inside the CPU, connected pretty much directly to it). I do not understand where the ramps come from, I am pretty sure it's supposed to be a clean square signal, not ramping. Do you guys have any suggestions please? Thanks.