is this a dying electrolyt cap on igors sontec boards?

the stereo sontec was one of my 1st builds. igor designed the boards and they run well for years. suddenly one side of the stereo EQ distorted the sound. i opened the EQ and discovered this:



it seems that theres an fluid coming out of the caps. i think its cind of acid because the trace of the board seem to be broken. or is it oxidation? perhaps its too late?

what can i do?

If there's stuff coming out of the cap, I'd imagine it's bad. If it damaged the trace, shouldn't be too big of a deal to repair it or jump the circuit where it needs to go.

If you have a schematic or the traces are obvious, and know where the fault is, shouldn't take 10 minutes to be up and running...... If that's where the issue is...

PS....and replace all those electrolytics while you are at it.....Yikes...

electrolytic caps like that have a rubber bung sealing the can with a built in pressure relief valve... if they overheat, (or just leak) they can release liquid electrolyte. I believe the electrolyte is alkaline so could be caustic.

JR

thanks guys!! ordered some new and will try to replace

The blue film cap top right (C15?) shows.a discoloured leg. Went too hot aswell?

Yes those caps are really bad.

Whats the voltage rating of those caps?

As there seems to be space on that area, replace those 2 caps with Panasonic caps of the same uf Value but with an higher rated voltage and also choose Panasonic 105degrees caps instead of 85.

thanks for helping me out!
they are 35v 33uf.

i think its a heat related problem because it happend to the caps on the lower EQ board. i have some air holes in the top of the case, so the upper EQ board has some air. the ICs run pretty hot in that build... its on 24v. perhaps ill lower the voltage a bit too.

electrisizer said:

thanks for helping me out!
they are 35v 33uf.

i think its a heat related problem because it happend to the caps on the lower EQ board. i have some air holes in the top of the case, so the upper EQ board has some air. the ICs run pretty hot in that build... its on 24v. perhaps ill lower the voltage a bit too.

Click to expand...

yes, it seems is heat related, or you got a bad batch of 35v 33uf caps, it can happen also.
I don't recognize the brand of those caps you used in the build, they could be of lower quality, or they could be already in bad shape inside when used. Sometimes electrolytic caps spend decades in shelfs, so shelf life is an important issue.
Thats why I only buy electrolytic caps from a supplier that has a big rotation of stock like farnel or mouser. I only use good brands, like Panasonic or Nichicon.
I never had any of those electrolytic caps fail from use in a circuit built by me.

Do as I suggested, replace with a cap rated for an higher maximum voltage, that way the cap will be more robust to the circuit voltage and heat up less (less stress on the cap), I advive on 50V or 100V caps
Also buy Panasonic caps that are rated for 105 degrees, that way you also make sure you the caps are more robust to heat

I'm sure your caps are maximum 85degress

Any of this will solve your problem:

http://uk.farnell.com/panasonic-electronic-components/eeufc1h330/cap-alu-elec-33uf-50v-rad/dp/9692401

http://uk.farnell.com/panasonic-electronic-components/eca1jhg330/cap-alu-elec-33uf-63v-rad/dp/9693025

http://uk.farnell.com/panasonic-electronic-components/eca2ahg330/cap-alu-elec-33uf-100v-rad/dp/9694609