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The Bb note on my pedalboard on my Gulbransen 401 is constantly on. The only way it stops is if I play a lower note on the pedalboard. I checked the contacts and they are not touching the brush bar thing. It shouldn't sound, because the circuit is not completed. Can anyone help me? I don't have any competent organ repair specialists in the area that I know of.
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Re: Gulbransen 401 Pedal Stuck On
Can anyone give me any advice at all? Anything? -
Re: Gulbransen 401 Pedal Stuck On
The pedal circuit is connected directly to the pedals.
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The contacts go into logic IC's. Bb would first go into IC 2 pin-5, hex inverter that outputs to pin-6. Since it's an inverter stage, the 20Vdc input when the pedal is down, would cause a low or near ground output at pin-6. If pin 6 was to output a low all the time because of a faulty IC 2 that might cause your symptom. If that is OK or normal, (changing with the pedal action) then the second IC stage is IC 4. 8 line to 3 line priority encoder. </p>
IC 2 = 801806</p>
IC 4 = 801842</p>
You might just replace both... (shotgun approach) [:)]</p>
BTW, if the IC's are socketed, just plug in new ones.,. If they are soldered in, I would recommend installing sockets, then plugging in the new ones. The PC boards on Gulbransens are delicate and too much soldering can damage the traces.</p>
Hope this helps,</p>
George
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