Help with dead PM-1200

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audiohacker
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Help with dead PM-1200

Post by audiohacker » Fri Dec 31, 2010 12:28 pm

My first post here - this looks like the place to get help with Carver Audio gear!

A friend of mine asked me take a look at her PM-1200. She was using it as a PA amp in a club, and it failed with copious smoke.

I opened it up, and it looks to me like the power transformer is fried - some of the windings look blackened. When I power it on, nothing happens, except there are soft crackling/popping/ticking noises from the power transformer itself.

Now, I'm not bad with tube gear, and I've had some success repairing solid state amps, but I found the manual and schematic, and clearly this thing is a little out of my league, so I'm hoping for some good advice from the collective wisdom here. I'd appreciate any answers to these questions....

Is this even repairable? Are parts available? How much beyond the transformer is likely to be toasted?

If it's repairable, is it worth it?

Is it something someone like me (with substantial general electronics knowledge but no experience with Carver designs) could repair, or is this strictly for the Carver specialists?

Is it worth anything in its present condition? Are there Carver enthusiasts who would want to acquire it on the cheap with the hope of repairing it themselves?

Or is it just e-waste?

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jjptkd
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Re: Help with dead PM-1200

Post by jjptkd » Fri Dec 31, 2010 12:45 pm

Welcome to the forum! Transformers are usually the hardest things to find and will typiacally render a unit unrepairable but you never know. Rita's Vintage Audio is a good place to start, good luck!

http://www.ritasvintageaudio.net/index.html
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kingman
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Re: Help with dead PM-1200

Post by kingman » Fri Dec 31, 2010 12:51 pm

it failed with copious smoke
AHHHHH!!!! The "magic" smoke....if the transformer is gone you may be able to buy a parts unit off ebay on the cheep. Best bet would be to buy another if that is the amp of liking. Alot of choices out there.
In reality, it only matters what it sounds like to YOU!!!

audiohacker
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Re: Help with dead PM-1200

Post by audiohacker » Fri Dec 31, 2010 1:37 pm

jjptkd wrote:Welcome to the forum! Transformers are usually the hardest things to find and will typiacally render a unit unrepairable but you never know. Rita's Vintage Audio is a good place to start, good luck!

http://www.ritasvintageaudio.net/index.html
Hey, thanks! I've got an e-mail out to them. Turns out they're within reasonable driving distance for me, I might just have to pay them a visit!

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mbskeam
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Re: Help with dead PM-1200

Post by mbskeam » Fri Dec 31, 2010 3:51 pm

what TOOK the transformer out?
if you do find one, better check the amp. you may have something down stream to look for ......
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BillD
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Re: Help with dead PM-1200

Post by BillD » Fri Dec 31, 2010 4:18 pm

Usually, the only thing that can take out the field coil is a technician trying to fix it wrong. The other thing that can take one out is a naturally occurring shorted triac (very, very rare).

Normally, the failure of a field coil is more explosive than smoky.
It should sound like it isn't there!
There is a difference between hearing and listening...
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Re: Help with dead PM-1200

Post by Scarabeo » Fri Dec 31, 2010 6:41 pm

Hello & Welcome and Good luck with the PM-1200. (Rita's)
BillD, You will be forever with us! RIP until we meet again on the other side...

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Re: Help with dead PM-1200

Post by audiohacker » Fri Dec 31, 2010 7:10 pm

mbskeam wrote:what TOOK the transformer out?
Like I said, it was being used for PA in a club. I wasn't there, but I'd bet some band cranked it up until the distortion was unbearable, then backed off just a touch. Sorta like having a nice Mercedes and hauling rocks in it.... I imagine it was just overloaded and that fried it.
mbskeam wrote:if you do find one, better check the amp. you may have something down stream to look for ......
After reading the manual and looking at a schematic, this thing has me a little spooked. Has anyone here worked on one of these?

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mbskeam
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Re: Help with dead PM-1200

Post by mbskeam » Fri Dec 31, 2010 7:14 pm

more likely as BillD said, the transformer is just Kaputss.... ](*,) ](*,)
Mbskeam

SILVER 7's
Amazing Line Source
2 SVS PB16 SUBS
#1 BLACK BEAUTY's made by the man, the myth, the legend Bob Carver
CARVER: TFM-75, TFM-45(3), SD/A-490T
SUNFIRE: Tube pre
WTL Amadeus GTA+DV DRT XV-1t
2 sets of ALS'3, set of SILVERS, set of PLATS
AUDIOCONTROL: phase coupled activator
KENWOOD: BASIC M2a (2)

“Youth ages, immaturity is outgrown, ignorance can be educated, and drunkenness sobered, but stupid lasts forever.”
― Aristophanes

The only thing I'll feel......will be the RECOIL
Necronomicon Ex-Mortis....... Klaatu Barada Nikkto
"We should seek the greatest value of our action"

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BillD
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Re: Help with dead PM-1200

Post by BillD » Fri Dec 31, 2010 7:25 pm

Many have been worked on, but few revived from what you describe. It is not a normal transformer, mind you. It cannot take full duty cycle AC on its primary or it will burn up (read: explode). But normally the amp will shut itself down before thermal overload sets in, unless these PM amps have that eliminated for road use.
It should sound like it isn't there!
There is a difference between hearing and listening...
Making life enjoyable through expensive electronics.
_________________
Carver: C-4000 & C-1 preamps, PSC-60 preamp/tuner, TX-11a tuner, M-400 (2), C-500, M-500, M-500t, M-500t Mk.II, A-500x, AL-III loudspeakers (2 pr.)
Sunfire:Theater Grand III processor, Ultimate Receiver, Cinema Grand Signature 400 ~ seven, True Subwoofer Mk. II, D-10 Subwoofer

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