Hey guys, I think I might need a little help.
I got this JP-8000 that’s got some issues I’m not sure I can repair.
Symptoms are this:
When powering on, it starts with the CPU, DSP, RAM and BATT check, all OK, then it shows a message A/D TEST AN7-9 NG
When I want to go out, it goes bezerk, settings go all over the place and pressing don’t help much until a point the JP demands some kind of action.
If, at this boot error, I go to option 3, the switch/led test, it jumps straight from 43 to 35 with a sound as if all those knobs are pressed at once. From there it’s sometimes possible to finish the 35 button tests while pressing these switches it gives sounds like more than one is pressed, but on other occasions it just jumps test 4 ot elsewhere.
I’ve replaced all the caps, as there was no sound at first too, battery ofcourse, measured the PSU, all the cables, connections, looking for shorts etc etc. I tried to figure out what these AN5-7 means, followed the schematics and replaced all UPC op-amps. This didn’t do much either. I’m thinking to replace all multiplexers as well as the flip-flops, as all these random acting up keys gives me the idea of ghosting (or what’s it called when the matrix acts up and random things happen when pressing keys)
In the mean time I still have no idea what the error message could mean. I haven’t found any kind of information that could help me explain this. The firmware is 1.04, can’t upgrade, as I can’t get into that menu.
I start to fear the mainboard is busted, but I’m nog yet ready to give it up though.