Saturday, April 5, 2014

Korg CX3- old style- with Leaky Electrolytics

Dual CX-3!

I am always skeptical when I receive these Cx3 organs for repair because of the known issues with the Seimens chips.. at the organ's heart are a couple of divide down oscillator chips that create the oscillations and gate them for each note. Their failure is a serious issue, because they are very hard to find and replace, and can only be replaced with other used chips that are probably very close to failure themselves. It seems someone was offering replacements, but apparently the supply dried up and I suppose they found it was no longer worth it to sell them.

But here was an instrument that didn't have that particular problem, rather it suffered from intermittent failures due to these badly leaking electrolytic capacitors seen below. The acid from inside of them ate through several traces on the boards, which had to be repaired.

The good news is that replacing them brought the keyboard back to life... the bad news is that there are about a thousand 10uF capacitors of this type sprinkled all throughout this keyboard. In this instance, due to financial and time constraints of the customer, we did replace only those that were seriously leaking... and left until later a full recapping, which is certainly necessary.

Currently the organ is working again, and sounding great, but most likely it will need some more caps replaced... unless the chips fail first!.

The failing capacitors were all 10 uF 16 volt capacitors. I doubt that it is coincidence... but it seems to me that the most frequent capacitors, in all gear, that I have to replace, are those rated 16 volts and less. I am not sure what is different between the processes used to make 16 volt caps and 35 and 50 volt capacitors, but I seem to rarely find failed 50 volt capacitors, unless they are too close to a heat source.

For this reason, I always use 50 volt capacitors, where possible, to replace them.

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