DW 8000 Troubleshooting Issues!
2012-06-25 by natebit
Hi Guys, so I have a DW 8000 I picked up off craigslist that needed some work. I am a part time electronics tech, and have worked on several other keyboards, but this guy is leaving me scratching my head. It would not turn on, and so I checked the fuse. The fuse was blown so I thought "cool easy fix" not really, with new fuses, it continued to blow them. So I checked some of the caps, and the big caps were bad, shorting the power supply. I replaced the caps, and went ahead and replaced everything on the board. I plugged the thing in (without the heatsink, which was stupid) and it worked, thought the CPU board would get extremely hot. I figured out I was probably pulling too much current or something, and put the heatsink back on. The 7905 pulls its "0" from the heatsink, i didn't know this! It gave the right voltages +/- 1 volt or less so I figured it would be safe to try. I wired in the power supply again, turned the DW on and nothing happened, thought I could hear a relay on the left hand side turning on, which didn't happen before. I tried shorting the connections to no avail, it just made the relay warm. I found that if I hit one key rapidly as it turns on, i will hear those notes repeat, then fade away, and there will no longer be sound. It is as if there is a capacitor or something causing the issue. It is just strange that it spontaneously started doing this with a new, completely functioning power supply. The problem seems to lay in the output board KLM 663 but I'm not sure. Has anyone had a similar problem, or any sort of suggestions for me? I do know the sliders need to be replaced, but that is all so far. thanks Nate