1100a2 bias question

[mnhiphop101]

When i turn the pots nothing happens.

 

[Perry Babin]

Are you saying that there is no change in idle current, no matter the position of the pot?

Do both channel produce full power and clip symmetrically?

 

[mnhiphop101]

Correct no change in idle current

 

[mnhiphop101]

The amp is not producing audio.

 

[seankane]

Is this in one channel or both?

 

[mnhiphop101]

Both

 

[Perry Babin]

What's the DC voltage on pins 8, 9 and 14 of the LM339?

 

[mnhiphop101]

pin 8: 5vdc

pin 9: 5.72vdc

pin 14: 18.69vdc

 

[Perry Babin]

DC voltage across R208 and R308?

 

[mnhiphop101]

.01mv for both

 

[Perry Babin]

Are Q10 and Q11 in the circuit?

If so, post the DC voltage on all 3 terminals of each one.

 

[mnhiphop101]

yes

 

[mnhiphop101]

i believe i found the problem. i put a 5D diode in q10 by mistake. thanks

 

[Perry Babin]

Set the bias pots full CCW before applying power.

 

[mnhiphop101]

ok the bias pots are working again but still no audio

 

[Perry Babin]

Set the crossover cards to full range.

Have you operated all of the pots and switches through their entire range while listening to the channels to see if audio ever played through?

 

[mnhiphop101]

this amp doesnt have crossover cards but it is set to full

ok i have signal but its only a few mv

 

[Perry Babin]

Photo of the board and PC#?

 

[mnhiphop101]

Here ya go

 

[Perry Babin]

Have you operated all of the pots and switches through their entire range while listening to the channels to see if audio ever played through?