Yamaha Electone HS-8 stops producing sound at random intervals

[SteelRehn]

Got a Yamaha Electone HS-8 used a month ago, I really like it since it was in excellent condition and had MIDI functionality; however, the organ occasionally stops producing sound. When this happens, all of its lights still remain on, except for the light on the selected combination preset button between the two manuals, pressing any of the other preset buttons will have the lights on the individual settings reflect the combo change but the button itself still remains off and there is still that comes out.

Normally this happens after about 30 straight minutes of playing, afterward it will only take a couple minutes for it to recur after I turn the organ off and on again.

I appreciate if anyone has an idea on what exactly is going on here? I'm clueless on why it's happening since everything else works fine and turning it off and on again resolves the issue, albeit temporarily unless the organ is left by itself turned off for a while.

[mscheo]

I recently repaired my HS-8 when it gave high-pitch sound continuously several minute of playing after power on. The interval got shorter with every power-off-then-on. Finally, it just gave sharp hissing noises upon power on. So I recapped every electrolytic capacitors on the Power Supply Board. That solved the problem. Then I noticed that the heat sink get rather hot after maybe 20 to 30 minutes of playing (which I suspect might the the cause of your problem). This could be due to the many other old leaky capacitors in the many boards (i.e. drawing out more "ambient" current.) So, I installed two small 12V brushless fans to blow at the PS board and heatsink. (You'll need to tap the 12V from the PS board.)

Hope this will help you in some way.

[SteelRehn]

Thanks, alot I'm not lost anymore on what exactly could be causing it. I agree with you on your suspicions, as it never happens when the organ is used plus an hour of inactivity, but when it happens, it happens more often until it is left alone again. Where did you learn to do repairs like this? I've read the service manual and I have "some" experience with working with circuit boards but I've never worked on an organ before. Thanks again!