Want to build a peavey bandit 112 redline or Randall RX120D

[kin0]

but won't it burn again?

[joecool85]

but won't it burn again?

Have you made any changes to the circuit since the last one burned?  If no, they yes it will probably burn and you should figure out why it burned before firing it up again.

[kin0]

It's why I  asked. I HAVE NO IDEA what is wrong.

[J M Fahey]

I HAVE NO IDEA what is wrong.

And you won't, unless you measure.
Put a new one, have your multimeter ready on the 20VDC scale, turn it on and quickly measure *if* you have +9V across the Zener and *what voltage* you have across the resistor.
It should take less than 10 seconds each.
Maybe your resistor survives that long, maybe not , but now you'll know someting.
Based on that, you'll find a problem and won't burn the third one .
Good luck.

[kin0]

OK I fixed it. The zener was the wrong way. Thanks anyway. Now I am working on the pcbs.

[J M Fahey]

December 19th:

*If* you put the Zener the wrong way, it will drop only less than 1 V; the resistor will dissipate (worst case)= (15x15/330) W=0.7W=700mW; way too much for a 1/4W resistor=smoke and burn.

Ahem !!! Cough cough !!! 8|

[joecool85]

OK I fixed it. The zener was the wrong way. Thanks anyway. Now I am working on the pcbs.

Excellent.  Good to hear you got it working.