Recently picked one up for a great price. Previous owner told me the PCB for the keys was corroded, and repairs were made, but the device gets stuck in a loop of turning on over and over when it is connected. Seems to work fine without it, even hooked up MIDI and was able to test the sounds. I’m at a loss.
What I’ve done so far -
Tested continuity from the connector joints to each diode; everything seems in order, and no overlap/bridging that I could detect
Tested the continuity on the ribbon cable from the holes on one end to the pins on the keybed, everything was connected
I’m comfortable with an iron, but I’m inexperienced in diagnostics. Seen a lot of issues online relating to dead keys, but no one with this specific issue. My concern is the shorting may have blown the 6500 IC, but I still have sound and display, so fingers crossed that’s not it. Any ideas?
Not opposed to trying to reflow the joints on the board, but I’d rather try anything else first (especially with all those reflowed traces being covered in hot glue. my god!)
If the keyboard is rebooting, it might be that there’s a short on the keybed causing the voltage to drop and a reboot. Can you check if the power supply pins on the keybed are shorted?
From what I can tell, they don’t seem to be shorted, although I’m wondering if I’m checking correctly.. (again, very inexperienced in diagnostics, so I apologize for the any dumb questions). I put the multimeter in continuity mode and checked every combination of connector pins, and nothing that wasn’t supposed to be connected appeared to be. However, when in resistance mode, absolutely nothing happens with any pin or combination of pins. I’ll attach some better pictures, the solder job is cutting it close, but it checks out.
I do see what looks like a burn mark on a couple of spots near a diode or two, and around the top. I’m wondering if that could be a clue..
Have you checked all of the resistors? I had a similar thing with my Mirage DSK 1, it was a blown resistor which i replaced and fixed the issue. I think this Fatar keybed is the same/similar to my Emax 1 and Ensoniq Mirage DSK 1. Ironically, i’m servicing my Emax 1 keyboard at the moment. Did you take note of where the spring resides between the upper and lower wire? Guess who didn’t? lol
