Cary V-12 blowing capacitors

I think imhififan nailed it. My bet is on that exact sequence.

@whataboutbob1 Hate to ask, but where did things end with Cary on fixing your amp? I recently picked up a stereo V12i and I’m really enjoying it. I know they ended ended production with the “r” racing series and I read it is the better amp. Really enjoying this amp and not sure why I’m even thinking of upgrading it, and after reading your post I’d be afraid to send anything to the Cary of today. Hope they’re standing by and fixing your amp as these are special. 

If the main PS Caps were already replaced and failed again, I would be looking at the rectifiers, its possible they may have failed and some AC is being seen by the caps. 

@whataboutbob1 There is a good point made in the posts immediately above. Since this cap failed its probably a good idea to have them all changed- in both amps.

Cary, IMO, owes you the repair on this one. Based on what they told you they had a serious misdiagnosis, on something that should have been rote.

https://linksharing.samsungcloud.com/hqXb6tP5HEDl

In this picture you can SEE the Hexfred were not replaced.. THEY were not upgraded. You can clearly see the old diode that Cary used in the original design.

Buddy not only were you sold a bill of goods you didn’t even get the basic service upgrade of hexfreds or super hexfreds in the PS, not to mention the filter caps.. This just keeps getting better..

The blown resistor is just that.. its a bleeder resistor.

NONE of this stuff would have happened if the filter caps (ALL of them) were replaced at once..

The pop was the coupling cap charging. Don’t flip the stand by switch so quick on a cold start.. give it 5 minutes at least.. The machine was hotrodded without a PS upgrade.. What did the tech expect..

Learn or expect to spend a lot of money in the future and ruin some fine amps.. 150.00 right now for all three.. :-) I’ll fix all three in 60 minutes..

You want to buy a watch? I got a watch.. You got a spare bedroom?

Corn I like corn on the cob.. You got corn.. I work cheap.. :-)

I own one, blind folded one handed.. One of the best amps EVER made.. I love um' The Red ones.. LOL

@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.

Not sure where those caps are but they blow Only becoz:

- used polar caps instead of bipolar 
- used lower voltage than they need to be
- something nearby is heating them up

and less likely:
- their ripple current capacity should be increased. 

"Its pure speculation, but adding the new components could have stressed out the older UCC’s. I don’t know for sure, but it’s quite possible. The original power transformer that was in it had a direct short and could have caused the UCC’s to stress."

Does that sounds like a reasonable explanation?

@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.

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.
 

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.

Here is what Cary Audio Had to say today:

"I pulled the Q/C sheets and got with Kellen to go over all the test points. Every test point on the sheet is perfect. We held on to the unit an extra week to make sure everything was in perfect working order. 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. We didn’t need to touch the UCC’s and the voltages at the UCC were well in spec."

 

"Its pure speculation, but adding the new components could have stressed out the older UCC’s. I don’t know for sure, but it’s quite possible. The original power transformer that was in it had a direct short and could have caused the UCC’s to stress."

Does that sounds like a reasonable explanation? 

Also I have been unable to find Dennis Had to ask him. I have been told he is now retired. 

It looks like a filter capacitor failed (the one with the screw terminals). If this was replaced earlier, I would expect that it is covered by warranty. If it was not replaced earlier, one would question why they replaced some coupling caps and not the filter cap, after 20 years it would be suspect. A failing filter capacitor can damage the power transformer feeding it. This is well-known; if the power transformers were replaced then the filter cap would have automatically been considered suspect.


It looks like that is the only damage, other than cleaning up the mess.

Send the amp back to Cary and have them fix it under warranty. I expect they honor their work; give them that chance.

https://linksharing.samsungcloud.com/9hkLk2oJpN82

https://linksharing.samsungcloud.com/harZeWotBE8J

https://linksharing.samsungcloud.com/lsTJNnoKUpBQ

https://linksharing.samsungcloud.com/hqXb6tP5HEDl

More

https://linksharing.samsungcloud.com/cv9C1AEPHF8w

http://https//linksharing.samsungcloud.com/cv9C1AEPHF8w

So although I really don't know what I'm doing I did take the bottom off the amp just to see what it looks like. Kind of a disaster in there. I took some pictures but I'm not sure how to post those here or if that is even something that can happen.

Anyone know how to reach Dennis had?

https://www.ebay.com/usr/radioman731/

https://www.ebay.com/itm/154575797502?chn=ps&mkcid=28&nma=true&si=9ITazm1UaWyJQkIu6DE1bw...

Dennis manufactures amps under Inspire name. Check various forums, someone there may have contact info. I see his amps periodically sold on ebay, don't see any at the moment. He seems to be keeping low profile these days, suspect he makes small runs of amps, generally I'll see only one amp available in his ebay sales.
If you're diy, oldhvymech may be on to something, unless you've damaged other parts due to leaking caps. What he suggest is not that hard a repair to effect. If you went diy route, and that didn't solve issue, may have hard time finding tech to work on it, many won't touch equipment that's had diy work done on it.

Anyone know how to reach Dennis had?

The problem is most likely a manufacturing lemon. Somewhere in that amp either a tiny section of insulation has been damaged, a small piece of wire or lead clipping lodged in a very inconvenient spot, or the wrong value passive component has been installed.

Repairing amps is like fixing cars -- throwing parts at the problem without identifying it is almost always a waste of money. The easiest route to take is to replace parts because if the parts are okay they just put them on the shelf and it costs next to nothing to essentially make a trade. Cary has to take that amp apart and find the bug. But that is a very expensive labor cost, which is why they are trying to fix it on the cheap. You have to tell them to find the problem instead of proposing which parts to change.

Hello "whataboutbob 1".  Do you have a "multiple voltage" version of the amp?  Is there a switch or dial on the back/bottom of the amp that lets the used select what the input voltage from the power lines is? Some products designed for International Sale have a switch so that the user in Japan or Europe can use the same product. It will have something like "100/110/120/220 volts" printed near the switch/knob/selector. Japan uses 100 volt mains and other parts of the world use 220 volt power lines. In the USA, our power is somewhere in the 110 - 120 range. At my California home, it is often 125 volts. If the input voltage selector got accidentally switched to 100, and the amp was plugged into USA power, the problem you describe would surely happen. It is worth a check. Has the amp been modified or upgraded recently? A well meaning technician might have accidently moved a switch or rewired the power transformer primary. Wishing you the best possible outcome. Boomer Bill

Cary needs a talking too. That’s friggin gross. How old is carry? How old are the capacitors?

   Loved the title of your post!,

put a smile on my face.

  Thanks, needed it!

🍻

Also, the first time I sent it out I am not sure if the caps blew or just leaked but Cary told me there was oil all throughout the bottom of the amp. That is when they replaced all three caps with the upgrade to munforfs. The monoblocks have three caps each and the stereo has four. Two days ago I call Cary and purchased 7 caps so I can upgrade my other monoblock and my stereo V12s. That was before this monoblock hit the skids again. I was pretty happy at that point because I thought the problem was solved and I liked the way it sounded with the new upgraded caps.

As far as the most recent meltdown, I haven't even opened the amp up to look in there because I really don't know what I'm doing. So the best I can say at this point is I heard the crackling sound from inside the amp and when I went to detach the plug in the back I saw the puddle of oil on the piece of maple it's sitting on.

Oldhvymec:

One week ago I installed 36 Golden Lion KT7
7s ( I have a stereo and the two mono block V12s). They're still new so I think they will sound better as we go along, but I am already thinking they may sound better than the rubies. I've tried several other tubes but haven't liked any better than the rubies to date.

I would love to be able to reach out to Denis Had. Do you have a way to reach him?

@whataboutbob1 Again, I'd suggest contacting Dennis Had, he designed V12. Nice guy, very helpful, he's the singular expert to get to bottom of your problem. Obviously, Cary hasn't effected solution, contact Dennis, he's still designing and building SET amps, low key one man operation,  selling on ebay.

At this point Cary has replaced the original Jensen caps with the mundorf caps. They also put in a new big transformer as well as the output transformer. They did the caps the first repair and the transformers the second repair. However after the new transformers were put in is when the caps blew again.

The new techs there at CA need to read and relay the updated manuals they never re-published. All caps in those amps not only require replacement, the transformers are now starting fail. If there are hexfred diodes (upgrade) inside the amp, check and replace all too if they are 10+yrs old. I had a bank of them go bad in my former V12R only after a few years. A few colleagues have been having to replace their transformers in V12/Rs, melted, particularly the big transformer. Also, if anyone has been messing with the bias and driving it up too high, you cannot trust the LEDs on each bank / per side, use a multi-meter.

The original V12/R manual shows up to 280ma per side. Working with one of the prior designers there we concluded 280 was way too much, 230 was tops and 200ma per side still sounded great and helped to save output tubes. There later versions had 4amp fuses, and others higher at 5. Proceed with caution on that. A competent tech can repair it, finding one willing to do it can be a challenge in some areas, so some people end up sending it back to Cary. Best of luck.

I meant founded Cary.

Your really need to contact Dennis Had, he founded and designed the V12. I previously owned Cary SLM 100 monoblocks, had cap issues, with Dennis' help I was able to effect repair at home. Cary had issues with Jensen copper foils in this era. Dennis still active selling SET amps on ebay, may find his email there.

Thanks for the input mastering92! 

I've had the amps for about 20 years and they've been working well. The other mono needed a transformer at one point but that was a isolated incident and was resolved with one repair.

I have been sending pictures as we go along. They seem to be stumped as to what's causing the issue and unfortunately it seems like they are just replacing one part after another hoping that might be it. Of course I'm no repair person and just a novice and that could me just being upset they can't repair it.