Glue or leaking caps? Please advise! - AVS Forum
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post #1 of 3 Old 09-06-2014, 05:06 PM - Thread Starter
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Glue or leaking caps? Please advise!

I recently purchased a Parasound 1205a 5 channel amp from eBay. I have been using it for a month now to power a 5 speaker Polk Lsi system without issue. I have listened as loud as 100db at peaks. Again, no audible "problems" other than a very low level hum that is only audible 6" from your ear. The hum does not ever get louder as volume is imcreased. From the research I have done so far it seems that the hum is ground loop related. I had a similar hum through my speakers with my last amp (adcom gfa-555ii). Seems to be related to the crappy electrical in my crappy apartment and not a fault of the amp.

All that being said, I just had a chance to remove the cover of the amp and have a look and there is a brown substance underneath the 4 rubycon caps that are located in a verticle line on the pcb of each channel. Note that the substance exists on ALL 5 of the amp channels, in just about the same quantity on each. The substance is on the bottom of the caps, with none anywhere near the top portion of the cap. The caps themselves do not appear to be fat or domed in any way I can see, and again, the amp sounds great. But I would like to know what the substance is. Seems reasonable to assume it is glue based on the fact that fc are often glued. But Ive not heard of people using a brownish glue that resembles filter capacitor leakage : /.

BUT, what are the odds that all 4 caps on each of the 5 channels are leaking in equal amounts (20 caps in total), and that the amp still works great?

Last edited by DenonPolkGuy; 09-06-2014 at 05:11 PM.
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post #2 of 3 Old 09-06-2014, 07:30 PM
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Glue can come in brown, green, white, black... I wouldn't worry about it.
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post #3 of 3 Old 09-06-2014, 09:26 PM
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It's glue.

First, Rubycon is one of the good companies, so it's very unlikely they would be problematic or leak.

Second, it appears that the goop is in neat orderly lines, something that never happens except deliberately. Especially evenly in all channels.

The goop holds the caps in place mechanically because during shipping and installation they can move and potentially break solder joints.
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