The sympton of this amp is distorted output. The output signal is clean until any load is placed on it at the speaker terminals and then the lower portion of the signal is distorted. Very similar to a problem I had before on a class b amp. A 4 Ohm speaker looks slightly cleaner than a 4 Ohm resistor attached to the output terminal.
Someone else has been inside this amp before me.
I confirmed the installed components are what they are supposed to be with schematic, they are.
With a load on the speaker terminal, I have clean signal on base and emitter of Q211, Q212, Q214, and Q215.
I lose clean signal at Q201, Q202, Q217, and Q218. I checked the values of resistors in the area to confirm they are within tolerance, they seem to be. I verified the components in the area are making point to point connections and they are. I checked all the capacitors in the area in circuit and they charge. I removed all of the PNP devices to verify they are good and they seem to be. I also checked Q216 out of circuit, it is good also.
I measured +46V and -41.5V rail voltage and it does not sag much when the distortion becomes evident.
What should I be looking at?
Someone else has been inside this amp before me.
I confirmed the installed components are what they are supposed to be with schematic, they are.
With a load on the speaker terminal, I have clean signal on base and emitter of Q211, Q212, Q214, and Q215.
I lose clean signal at Q201, Q202, Q217, and Q218. I checked the values of resistors in the area to confirm they are within tolerance, they seem to be. I verified the components in the area are making point to point connections and they are. I checked all the capacitors in the area in circuit and they charge. I removed all of the PNP devices to verify they are good and they seem to be. I also checked Q216 out of circuit, it is good also.
I measured +46V and -41.5V rail voltage and it does not sag much when the distortion becomes evident.
What should I be looking at?
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