Problem with Yamaha YC-45D voices

[brigidelle]

Hello everybody !

I'm Brigidelle from France.
I have a problem with my Yamaha YC-45D organ and hope you can enlighten me with your knowledge.

The organ works fine. Powers up, all keys (contacts all cleaned up recently) working, all levers, tabs and pots working too,
with no scratchy sound whatsoever.

A few seconds after I powered it on though, whenever I engage the 8' or 4' voices levers, I can hear furtive crackling noises that go on and off irregularly,
then stop after a few minutes only to give way to a continuous signal,
sounding like I kept pressing the C key of the third octave.
This sound is always present, varies in volume but is most of the time loud enough to be heard over playing volume.
Still some crackling from time to time at this point, but way less.

This problem only affects the upper keyboard, all voices on the lower one work perfectly fine.

I've been searching through the web and this forum looking for someone coming across this specific problem, but couldn't find it.
Does anyone have any advice ?

If you have read me until here, thank you

[Organ Donour]

Hi brigidelle!

This problem seems to occur regularly... Since the 8´ and 4´ voices can be sustained, it seems reasonable to assume the problem to lie in the sustain circuit. According to the service manual for the YC45d (http://manuals.fdiskc.com/tree/Yamaha/Yamaha%20YC-45D%20Service%20Manual.pdf) the keying circuit ( "UE 1 - 5"; p. 9) shows four 15 uF / 16 V capacitors that are responsible for the sustain effect and supposedly need replacing. While you´re at it, do also replace the power smoothing cap for the board (1oo uF/16V). Actually, four caps seem a little few; I would recommend to check with the actual circuit board if there aren´t more. Besides, replacing all the bigger electrolythics, especially in the PSU, seems like a good idea (if not all, which would be quite a chore!).