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MJE 172 smoking, why???

PostPosted: Thu Apr 06, 2006 1:58 pm
by 3nity
I did power my C84 today.
i did applied 24/pin 1, ground/pin 2, -24/pin 3, ground/pin4, 48v/pin 6, ground/pin6.

Suddenly the led next to Q8 went off and then MJE 172 started smoking??

any advice??

PostPosted: Fri Apr 07, 2006 8:50 am
by tpryan
You say the LED "went off"? If the circuit is operating normally, the LEDs should never be on. Make sure you have all the resistors in the right places, the diodes the right way round, and that you haven't inadvertently swapped any transistors. Can you post a close-up photo?

PostPosted: Thu Apr 13, 2006 3:57 pm
by 3nity
Hi .
Sorry for the late post. missing some time.

Actually what goes wrong is the transistors..
i swapped them thinking they were right. Q8 to Q16 and vice versa.
Sorry gonna try to find some to change them.

PostPosted: Fri Nov 27, 2009 7:55 pm
by 3nity
Its been more than 3 years now and never worked....
I wonder why....i've built so many things like tube preamps, 1176,GSSL, 1272-1290 clones.
but this was the most cherished 225$ wasted of all time!

:cry:

PostPosted: Sat Nov 28, 2009 8:38 am
by tpryan
The only problem we've ever seen to cause the symptoms you report are incorrectly installed transistors. If you can't figure out the problem on your own, send an e-mail to rma@seventhcircleaudio.com for return instructions.