I asked him why he thinks the black UCC would explode and he said the only way for them to explode is if they were wired with reverse polarity.Or if they were wired with shorted rectifier diodes.
Cary V-12 blowing capacitors
Hi,
I have a pair of Cary V12 monoblocks one of which is blowing capacitors. It was initially sent in to cary as it was the 3 Amp fuses. They initially replace the capacitors and sent it back. It worked briefly and then started blowing fuses again. It went back to Carrie and this time they replaced both transformers. It did work for a couple of weeks but yesterday when I turn it on and was in the standby mode I heard a crackling noise from inside the amp and 3 amp fuse blew again. There was a large puddle of oil in the back of the amp which is from the capacitor. So it seems like something is still not repaired correctly which is causing the capacitors to blow which maybe is why the fuses are blowing. With it being to cary twice and they are not really sure what's happening has anyone else had this issue?
I have a pair of Cary V12 monoblocks one of which is blowing capacitors. It was initially sent in to cary as it was the 3 Amp fuses. They initially replace the capacitors and sent it back. It worked briefly and then started blowing fuses again. It went back to Carrie and this time they replaced both transformers. It did work for a couple of weeks but yesterday when I turn it on and was in the standby mode I heard a crackling noise from inside the amp and 3 amp fuse blew again. There was a large puddle of oil in the back of the amp which is from the capacitor. So it seems like something is still not repaired correctly which is causing the capacitors to blow which maybe is why the fuses are blowing. With it being to cary twice and they are not really sure what's happening has anyone else had this issue?
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The original power transformer that was in it had a direct short and could have caused the UCC’s to stress.I thought the opposite, shorted filtering caps stress upstream power supply components ( rectifier diodes, power transformer and fuse ) to fail. My guess is the 20+ years old leaking/shorted power supply filtering caps stressed and weaken the power transformer and rectifier diodes. Cary only replaces the power supply filtering caps for the first repair, but the already weakened power transformer caused failure and Cary replaces the transformer for the second repair. This time perhaps the bad rectifier diodes caused the filtering caps fail again. |
@whataboutbob1 No- its the other way around.The failing filter cap drew enough current that the old power transformer eventually failed (a short is a typical failure in this case). Since they didn't replace the filter cap, with the new transformer (which apparently is a bit more robust) it was able to sustain its current- and the defective filter cap overheated and leaked. Just so you know, the mechanism of filter cap failure is that when they get old enough, they can draw a little bit of current (normally the draw none of their own at all). This current causes the cap to warm up. As it does so it will draw more current. The insidious thing about this is it might take quite a while before the cap is drawing enough current to cause damage- but in the meantime the transformer is running hotter and hotter until eventually the insulation inside melts and it shorts. he said the only way for them to explode is if they were wired with reverse polarity.This statement as you can now see is false. It is true that if you wire them backwards they'll draw a lot of current and explode. Usually they do that pretty fast. But if the part has failed it can do this as well- the difference being that it usually takes longer. IMO/IME they should have replaced the filter cap at the time they replaced the power transformer. Transformers should last decades- the only die if overstressed, and filter caps can do that to them. Any competent tech that saw a failure like that would have been asking why it happened and looking for the cause. |
@whataboutbob1 - this is one of Dennis Had’s expired ads on eBay: https://www.ebay.com/itm/154590715291?hash=item23fe531d9b%3Ag%3AYA0AAOSwco1fV%7EaS&nma=true&... His eBay moniker is radioman731, you might try sending him a message via eBay. Scroll down the page until you see the listing details and over on the right you will see a link to contact the seller. |
- 45 posts total