Members David E H Posted November 4, 2012 Members Share Posted November 4, 2012 Hey all. I've been gone for a while, but I came back 'cause you've always been such a help. Here's my latest project.I got a good deal on a KAWAI EP-608 recently. Portable, upright, piano lined with piezos. I can't get the preamp to work though, and can't figure out what exactly is wrong. It runs off a 12vdc xlr power supply which is reading out at 18vdc. Is that an issue?Here's a couple other things I've found.1. The power is in fact making it to the PCB, but the marked -12vdc line is running at .5vdc. Am I getting a short somewhere? Or did I lose a diode?2. I'm measuring the full 18vdc at the power switch and across the LED, yet the LED won't light on. I pushed a 9v battery up against it and it turns on. So it's not out. What's going on? Is polarity reversed or something?HELP! (also, would anyone know a good Boston area tech?) Link to comment Share on other sites More sharing options...
Members David E H Posted November 4, 2012 Author Members Share Posted November 4, 2012 added schematic, layout, and picture of piano. Link to comment Share on other sites More sharing options...
Members David E H Posted November 4, 2012 Author Members Share Posted November 4, 2012 Alright, this is embarrassing. I took one last shot at fixing this, and decided to reverse polarity. It totally works. Some idiot before me must have soldered the power cable backwards. It looks like factory work, though! I don't know what happened, but I just have to resolder this part now. /thread Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.