I have to correct my last post.
If i short C5 the DC on the output disappears.
I had a bad connection with my jumper to C5.
If i short C5 the DC on the output disappears.
I had a bad connection with my jumper to C5.
Let me change the way I asked that.
During troubleshooting, when did the amp suddenly start producing DC at the speaker terminals?
Initially, it was simply refusing to bias.
During troubleshooting, when did the amp suddenly start producing DC at the speaker terminals?
Initially, it was simply refusing to bias.
I cant say because i checked several times for DC on the outputs and music played with light distortion.
Then i checked another time and i wondered why there is DC. Its possible that my probes have contact-problems.
I dont remember that something special happened, maybe a short during probing..
Then i checked another time and i wondered why there is DC. Its possible that my probes have contact-problems.
I dont remember that something special happened, maybe a short during probing..
Hi Perry!
I found R 309 open, its a 20ohm resistor and now DC on output is gone.
The amp is still not biasing.
Any ideas what to check next? I feel like i checked all diodes, transistors...
I found R 309 open, its a 20ohm resistor and now DC on output is gone.
The amp is still not biasing.
Any ideas what to check next? I feel like i checked all diodes, transistors...
What's the DC voltage across R206 and R306.
Do you have any 4.7k resistors that you could use to replace either of those resistors?
Do you have any 4.7k resistors that you could use to replace either of those resistors?
Q10:
B: 13.96V
C: 20,84V
E: 13.3V
Q11:
B: 0V
C: -13V
E 0.6V
Q201:
B: -13V
C: -0.66V
E: -13.7V
There is a pin labeled " SW " , what does it mean?
B: 13.96V
C: 20,84V
E: 13.3V
Q11:
B: 0V
C: -13V
E 0.6V
Q201:
B: -13V
C: -0.66V
E: -13.7V
There is a pin labeled " SW " , what does it mean?
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If you solder a jumper wire between the collector and emitter of Q10, does that allow you to bias the amp?
Set the bias pots to full CCW before applying power and watch for excessive current flow when you power up the amp.
Set the bias pots to full CCW before applying power and watch for excessive current flow when you power up the amp.
I'm not sure what the problem is. It could be that either Q10 or Q11 has low Hfe. If you have replacements, I'd try replacing them.
They measure fine in circuit.
I will replace them. I found that the resistor values around them arent the same as in the schematic.
R36 in schematic shows 2kohm but is 10 kohm
R38 in schematic shows 1 kohm but is 5.11kohm
Thank you very much, Perry!!!!!
I will replace them. I found that the resistor values around them arent the same as in the schematic.
R36 in schematic shows 2kohm but is 10 kohm
R38 in schematic shows 1 kohm but is 5.11kohm
Thank you very much, Perry!!!!!
Right, but the first one you posted in #36 was the same as the one originally posted. The second one (different file name and different file size) is different.