OK, I've looked for a short to any of the FETS without any luck... Measured from the c3 pad to all pins of all FETs and also to Ref1 and Ref2.
I've ordered an replacement reference but I don't see how this would help. The smoking Ref2 is intriguing, I don't find any of the references on the schematics so I don't understand what else then the C3 short that can casue the high current/smoke in ref2.
I've checked all resistors and they seems to be OK.
I don't know what else to do...
I've thought about exchanging all FETS an see if it helps but it feels rather desperate...
/Fredrik
I've ordered an replacement reference but I don't see how this would help. The smoking Ref2 is intriguing, I don't find any of the references on the schematics so I don't understand what else then the C3 short that can casue the high current/smoke in ref2.
I've checked all resistors and they seems to be OK.
I don't know what else to do...
I've thought about exchanging all FETS an see if it helps but it feels rather desperate...
/Fredrik
BobEllis, I'm so greatful that you're not letting me down!
R11 is 49.5 kOhm
I had problems with some resistors, but I trimmed the pinns and not the PCB. I might have damaged the PCB though, it was quite tight when I fitted the resistors. It this is the case, how do I remove the surrounding groundplane? Hmm, now I see that it makes sense. If I connect any of the resistors to the groundplane I will short C3, Hmm...
/Fredde
R11 is 49.5 kOhm
I had problems with some resistors, but I trimmed the pinns and not the PCB. I might have damaged the PCB though, it was quite tight when I fitted the resistors. It this is the case, how do I remove the surrounding groundplane? Hmm, now I see that it makes sense. If I connect any of the resistors to the groundplane I will short C3, Hmm...
/Fredde
I used a Dremel tool (rotary tool) with an engraving bit to grind away the ground plane.
I guess I'd start by pulling the 1.5K resistors and see if the short goes away.
The positive terminal of C2 is connected through R3 and R4 to C3 -it should show around 44 ohms. Lift one leg of R3 I be that C2-Ground increases dramatically.
I guess I'd start by pulling the 1.5K resistors and see if the short goes away.
The positive terminal of C2 is connected through R3 and R4 to C3 -it should show around 44 ohms. Lift one leg of R3 I be that C2-Ground increases dramatically.
In the end everything make sense...
I've tested to remove the resistors and, finally NO SHORT!
So what I will do now is to use a dremel tool and cut a semi-circle around the pads of R2 and R7 to isolate the pads from the groundplane. Then I will solder the resistors to the pads and hope that I don't have any short. I think it is most suitable to cut from the back of the PCB, but how deep will I have to cut?
I will replace the smoking reference as well.
Is it likely that my abuse of the PCB during these weeks will severely affect the performance of the amp? The only visible damage is some tear on the R2/R7 pads. In the worst case I suppose I could hard wire the resistors to the positive pad of C3?
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