Help - just burned a ZV4 channel


I am building a ZV4. I made one channel, using point to point wiring. After checking everything I turned it on and adjusted R4 to get the 22V on the drain of Q1. It played about 1 hour and everything seemed OK.

But then came the disaster: on the other day I was turning the channel up and just saw R7 burn with a big flame. After checking I saw the pin of C9 in the V+ wire (just like a neddle). Q5 was destroyed. After replacing Q5 (and some carefull re-layout of the PSU circuit) I turned it up disconnected from the circuit and got the 42V from the regulated PSU. Then I connected it to the circuit but again saw the new R7 smoking (literally). I think this means that Q2 was gone too as R7 is on its gate.

Before I replace Q2 I would like to be shure that the other components are OK and I will not burn the new Q2. Is there any way to check Q3, Q4 and Q1? Or a way to replace Q2 by a new one and see if everything is OK without the danger of burning more MOSFETS?


:redhot: :hot: :boggled: :bawling:
Hi Karen,

Thanks for reply. I will send pictures of it, but I have not a digital camera, so have to wait untill I finish the negatives. I also have to build the other channel.

I am using all the parts mentioned in the ZV4 article, so R0 and R1 are 3W. What do you mean with page 3 of the article?

I will try to disconnect the Q4 path from the rest to see if it works. But Q3 and Q1 need all the circuit running to see if they are ok, after replacing Q2. If Q3 or Q1 are burned, what hapens to the other transistors?

This burning was not wiring errors or something like that, it was the neutral pin of C9 that found a way into the hot insulation of V+.:headshot:
hehe , last night i burned R7 R0 and R1 too .... but i used only 2W for R0 and R1. After drop in new Qs and the burned Rs it worked again. Only problem is i didn´t get the 46 V from the zehners because the 9,1V ITT zehners from Reichelt are not all really 9,1V, some are 8,5.

But i´m very happy. The ZVPs are still OK, and i have only 2 of them, everything else is easily replaced.