MJE 172 smoking, why???

[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??

[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?

[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.

[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!

[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.