Zen V4 no power up (quick bit of help please)

[Rixsta]

I would like to say thanks to nelson pAsS for the great design of all his amps and having heard the penultimate zen which is what i am building, i notice why "class a" is so often talked about...

anyway my problem is one channel of my amp dosent even power up there is no voltage on the source or the gate of Q5.
I also test for voltages at the zener diodes and get no reading
..

so i guess either one of the five zeeners have been distroyed or D1 or maybee even Q5 itself.

of course theres the possibility that i am overly tired and can no longer concentrate properly, in that case forgive me for asking such a dumb question.

thanks for the help in advance.. (presuming someone will help...lol...duh)

[Panelhead]

Originally posted by Rixsta
I would like to say thanks to nelson for the great desighn of all his amps and having heard the penultimate zen which is what i am building, i notice why "class a" is so often talked about...

anyway my problem is one channel of my amp dosent even power up there is no voltage on the source or the gate of Q5.
I also test for voltages at the zener diodes and get no reading
..

so i guess either one of the five zeeners have been distroyed or D1 or maybee even Q5 itself.

of course theres the possibility that i am overly tired and can no longer concentrate properly, in that case forgive me for asking such a dumb question.

thanks for the help in advance.. (presuming someone will help...lol...duh)

If you have a 50 volt or so voltage coming in, check the solder connections to the transistor. But this looks like an open on the input line. Check for continuity.

George

[Rixsta]

cheers George

my connections all seem to be fine
it's
S t r a n g e indeed

[Rixsta]

ok iff all my connections are fine whats going on ?
This cant be normall can it ?

[skmenon]

hi rixsta,

You may try to check the voltages from the source backwards. Check volatage across capacitor C10. Check drop across diodes and zeners. There has to be some drop across the diodes.
If as you say, you measure nothing - then try isolating Q5 before you measure the voltage. In this way you can nail down the faulty component.

Hope this helps

regds

[Magura]

Try tracing the supply voltage from the PSU and inwards, you should be able to see that it dissapears somewhere. Once you can tell where that is, Im sure somebody here whom have built the ZV4 can sort you out....without that information its down to wild guessing.


Magura

[MikeW]

Is it possible D1 was in backwards and smoked R18?
Take D1 and Z1 out and see if there is a voltage.
Check the values of R17 and R18.
Are C9 and C11 in correctly?
Good luck, Mike

[Rixsta]

cheers all
im about to check out what you said.

where it says 46V on the schematic i have none or maybe half a volt or less. so once 50v crosses D1 theres no voltage.
and q5 (or something)

[Rixsta]

ok iv'e sused it
i just disconnected the five zeners and all is well
obviously i had them make up the wrong voltage

[Rixsta]

ok now i have a problem where across r0 and r1 theres 1.6V
iv'e checked for inverted connections on q3 and checked my wireing.
if i leave the amp on too long the risistor will go up in smoke..
so it's hard to get a good reading on any of the other voltages