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Millett amp problems...big problems

post #1 of 24
3/22/04 at 3:49pm
Thread Starter 
Well everything is wired up, and looks pretty good. (except for the tube sockets, I ordered the wrong ones so they are just wired up above the board.) Anyway, I was getting ready for my first test run, headphones in, source in. I plug in the jack and I see a spark between the female and male parts of the jack, then I smell a cap. Not as in capacitor, as in the smell of a cap in a cap gun. And absolutely nothing happens, not even the led lit up. Well, what have I wrecked and how can I fix it? (Btw, all of my solder joints look fine. I would love to use dmm to find where the problem is but I really dont want to have the thing plugged in).

Thanks guys!

EDIT:the jack smells like caps, not the wall wart.
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post #2 of 24
3/22/04 at 4:44pm
you can't by chance take pictures, can you?
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post #3 of 24
3/22/04 at 5:35pm
Thread Starter 
maybe I can, but it will be a pain. Everything is the same as in the standard picture of the amp except I used bigger panasonic caps and the tubes have crazy sockets. I used these sockets

SOCKET, 7 PIN, MINIATURE, SADDLE MOUNT, MOLDED

Bottom mount phenolic socket mounts in 5/8" chassis hole on 7/8" centers. No solder lugs.

part number P-ST7-205 from tubesandmore.com


I thought they were the correct ones but they look nothing like his. They have the seven pins and in the center there is a tube that sticks down. I just wired up the seven pins and left the middle thing empty. Other than that it is normal.

Thanks, Colin
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post #4 of 24
3/22/04 at 8:32pm
Colin, did you have the tubes installed when it blew?
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post #5 of 24
3/22/04 at 8:40pm
Thread Starter 
yes.
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post #6 of 24
3/22/04 at 10:03pm
Colin,

Quote:
I plug in the jack and I see a spark between the female and male parts of the jack, then I smell a cap.
Which jack are we talking about? Headphones? Power? Source? If it was headphones, I would fire it up just long enough to measure the DC or AC voltages on L out and R out to ground. Is this Millett built on the commercial PCB, or did you hardwire it?
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post #7 of 24
3/22/04 at 11:33pm
Thread Starter 
When I plugged in the power jack. Everything is built on the pcb board. I dont want to fire it up....done it twice so far....absolutely no signs of life and there is the cap smell.
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post #8 of 24
3/22/04 at 11:38pm
http://www.pmillett.addr.com/hybrid_head.htm
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post #9 of 24
3/23/04 at 12:34am
Thread Starter 
Ive seen that page many many times, doesnt help me troubleshoot.
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post #10 of 24
3/23/04 at 12:38am
If the LED doesn't light up, there is a short somewhere and the PTC fuse (PF1 in the schematic) is cutting off the power to prevent damage (to the power supply and other components). Unfortunately something may have already been damaged if there is a smell.

You should try to ascertain where the short is using a meter.

Also, this probably sounds like a dumb question, but did you install all the electrolytic capacitors in the right direction (polarity)?
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post #11 of 24
3/23/04 at 1:16am
Thread Starter 
I definately have them all in the right way. Like I said, I would love to be able to use a dmm to see where the short is, but I dont really want to plug it in again.

Colin
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post #12 of 24
3/23/04 at 1:22am
You don't need to plug it in to find shorts with a meter. Just look for continuity where it shouldn't be there.
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post #13 of 24
3/23/04 at 2:05am
Thread Starter 
You don't need to plug it in to find shorts with a meter. Just look for continuity where it shouldn't be there.


I dont know what that means...
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post #14 of 24
3/23/04 at 2:09am
Meters have a mode where they beep if there is an electrical connection between the two points you're probing. (Sometimes there is no beep, just something on the display.) Look at the schematic and probe around on the circuit board looking for connections where they shouldn't exist.
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post #15 of 24
3/23/04 at 2:21am
AFAIK the amp doesn't have to be plugged in for the multimeter to detect shorts...?
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