Saturday February 15, 2014

Fixing Chuck's Keyboard Part 4

It's been a frustrating week here at Kelly's House of Electronics. I was stalled for a few days trying to get parts and then get the time to put them all together. And on final assembly the new cirtuit board worked...partially. It functioned exactly like the old board, which is to say with everything working except Horns.

Which is where I was when I started.

I'm sure I'm dealing with the correct board; that's pretty obvious. All the switches that control the voices go through this board and it's the modulation of the tone generators from this board that goes to the output.I've replaced every part on that board except one.

The Mystery Component is the only original part on the new board. I originally thought it was a coil or choke, and the boys at RaElCo thought so too. But when we tried to measure it the readings were all over the place. So we tried to measure it as a capacitor (which was another guess) and got a solid reading, but he hadn't really seen one in this configuration. His advice was"we don't know what it is, but it doesn't seem broken so put it on the new board."

So I mounted it and tested it and it worked exactly like the original. And the horns didn't work. And the horns rely on the Mystery Component. I can't find a schematic so far in my search of the web which is a shame. Having one would identify the part and maybe solve the problem. At this point though all I have to do is rehab the foot pedal and it's good to go, minus one voice. It may have to do...


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