I pulled the zener. Measured resistance in both directions and one was higher than the other suggesting it is OK. Other zeners i have on hand measured the same. Double checked solder connections - measured resistance between both ends of zener and the rotary pot contacts and everything seemed fine. I replaced and still getting the same issue, 24v dc on the speaker terminals.
Do I investigate the mosfet next? The odd thing is that the amp was working fine for a year and then seems to have slowly gone bad which I guess suggests a part has gone bad?
Thanks for the help.
Do I investigate the mosfet next? The odd thing is that the amp was working fine for a year and then seems to have slowly gone bad which I guess suggests a part has gone bad?
Thanks for the help.
diode test of zenners ?
why not just replacing all cheap parts , thoroughly testing non cheap ones ?
why not just replacing all cheap parts , thoroughly testing non cheap ones ?
Looks like the simple resistance test is not enough to properly test zener. I will replace zener with a similar voltage that I have on hand and see if that solves.
Yes, might need to replace all cheap parts if there are no better suggestions...
Also, I have done the output degeneration mod so the circuit is a little different than that in post 1 of this thread (might help with troubleshooting).
Yes, might need to replace all cheap parts if there are no better suggestions...
Also, I have done the output degeneration mod so the circuit is a little different than that in post 1 of this thread (might help with troubleshooting).
there could be exact suggestions , but I can't connect your brain and mine
what's more needed than - check all semis , solder points , check resistors and wires
what's more needed than - check all semis , solder points , check resistors and wires
there could be exact suggestions , but I can't connect your brain and mine
what's more needed than - check all semis , solder points , check resistors and wires
Make sure C2 is not reversed.
Looking at the circuit again it doesn't look like much could go
wrong with the circuit to give you -24 volts at the output other than
a open Q1 but your rail voltage would have to be about 25 volts.
wrong with the circuit to give you -24 volts at the output other than
a open Q1 but your rail voltage would have to be about 25 volts.
Well darn I have to take that back, R13 being open would do the same thing. as will as an open trace connecting R13 and Q1 to the supply. Or a missing positive supply voltage.
Hi everyone , i am about to "start" my F6 , and i made some mesurement before that :
I have 164 ohms between + and out , same resistance between - and out , and 120 ohms between 0v and out , with no supply connected on the board ,on both channel , is that ok , or may i worry !!
tanks for your help ;-)
Fabrice
I have 164 ohms between + and out , same resistance between - and out , and 120 ohms between 0v and out , with no supply connected on the board ,on both channel , is that ok , or may i worry !!
tanks for your help ;-)
Fabrice
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That seems ok.
You have even resistance from each rail, which is good, and the sum of R1 and R2 from GND to out, which is exactly what you should expect.
You have even resistance from each rail, which is good, and the sum of R1 and R2 from GND to out, which is exactly what you should expect.
Tank you 6L6 , i can go further in my "starting" ;-)
it's an special build ( liquid cooled power mosfet ) and i want to be sure that resistance between mosfet drain is high enought .
.
it's an special build ( liquid cooled power mosfet ) and i want to be sure that resistance between mosfet drain is high enought .
.
Oh dear!
Let the magic smoke out of one side!
Checking bias and touched the lead of R2 (0.47r)
to R3 (100r)
Pops, hum then dead. 😱 😱
looks like a testing session, just hope the Jfets have survived.
Let the magic smoke out of one side!
Checking bias and touched the lead of R2 (0.47r)
to R3 (100r)
Pops, hum then dead. 😱 😱
looks like a testing session, just hope the Jfets have survived.
Hello,
At last times,i feel that sound is better before it warm fully. It lost a little detail and dinamics when it warm fully. Any opinion??
Bias:0.52v
Rail: 23.5v
Full warm Case temp: 57C
Full warm Mosfet: 52C
At last times,i feel that sound is better before it warm fully. It lost a little detail and dinamics when it warm fully. Any opinion??
Bias:0.52v
Rail: 23.5v
Full warm Case temp: 57C
Full warm Mosfet: 52C
It happened to me as well. It ran for weeks with no issues then suddenly - pop! I've got new mosfets to install when I get chance.
Hello,
I hadn't used my F6 for a while and hooked it up over the weekend and found
one channel buzzing/distorting. When I randomly tapped the PCB and the heatsink
on the offending side with a pencil it would sometime get better.
I'm guessing there's a bad solder joint on that channel somewhere and am
thinking of removing the PCB and reflowing all solder joints.
Does that seem reasonable? Is there anything else I should look into?
Thanks,
Dennis
I hadn't used my F6 for a while and hooked it up over the weekend and found
one channel buzzing/distorting. When I randomly tapped the PCB and the heatsink
on the offending side with a pencil it would sometime get better.
I'm guessing there's a bad solder joint on that channel somewhere and am
thinking of removing the PCB and reflowing all solder joints.
Does that seem reasonable? Is there anything else I should look into?
Thanks,
Dennis