Wurlitzer model 4373 organ problem

[debert]

I've encountered a few Wurlitzer organs where some of the notes on the keyboard were either dead or exhibiting an odd sound (not the note). Usually it would be all the F's or all the C's, something like that. Often the higher octaves would be OK, and once one octave was missing, all the ones below would be gone, including the bass.

In every case that I have encountered with Wurlitzer, the problem was, what has been called in the industry, the "spider" chip, which is a chip that divides the frequency coming into it, to exactly half the frequency, thereby supplying the frequency for the next octave down. Naturally, if a problem occurs in the split, everything beneath it will be affected.

If you have a Wurlitzer that exhibits the same problem, that's likely the issue. It is easily repairable by a service tech.

There are a few other keyboards around which possess the same technology.

Thanks,
Dan

[debert]

The above organ had a dual amplifier system with one channel of the amp being bad. Replaced 6 different transistors, two resistors and an electrolytic capacitor in order to repair it. This organ was said to have been struck by lightning. I think I believe it. Lots of problems.

So far it had octave problems and amplifier problems. This doesn't include the Orbit III synthesizer section which is also not working. THat's next to troubleshoot.

If your organ has been struck by lightning, you might have a host of problems before it is fixed. But they should be fixable providing you can still get the needed parts and a schematic, which is sometimes questionable depending on the age of the instrument.

Dan