So, it appears that the PWR and Spkr GND's are connected.
I believe the problem is in the muting circuit and Perry Babin's suggestion to remove the fixative is a good one. Once you have replaced any obvious parts, the voltage checks I listed in post #9 should illuminate any addition failed parts.
I believe the problem is in the muting circuit and Perry Babin's suggestion to remove the fixative is a good one. Once you have replaced any obvious parts, the voltage checks I listed in post #9 should illuminate any addition failed parts.
So the resistor was a 470k like the rest. And a 2n4403 transistor. Now the audio is back on all channels. One channel on the rear right only had low audio and the tip35c transistor got to smaking hot is minutes. So either there is something leaking or a problem with the prebias settings. Something is amiss there.
Is it normal for the amplifier to run all channels on one set of inputs and the other set to just make a @ 100hrz hum when music is plugged into them?
This amp requires that the front channel RCA's are applied, no matter whether you are using one source to drive both front and rear or two different sources to drive the front and rear channels independently. Otherwise without a front channel input the rear channel input is not grounded and you will have hum.
It's likely that there is a shorted or leaky transistor in the biasing circuit on the rear channel you have an issue with. Remove the outputs transistors and measure the locators for low ohms or shorts. The rear channel locators are 300 series for the left channel and 400 series for the right channel.
Check QX07 through QX11 with an ohmmeter. They should all read relatively high in circuit after some capacitor charging, except QX09 which sets the bias.
QX09 will read ~1kohm between emitter/base, ~2kohm between base/collector and ~3kohm between emitter/collector. They are set by RX47-1kohm, RX46-1.9kohm respectively.
Be sure to check the capacitors in this circuit particularly the ceramic disks CX33 and CX36-121/C. They are known to become leaky.
Check QX07 through QX11 with an ohmmeter. They should all read relatively high in circuit after some capacitor charging, except QX09 which sets the bias.
QX09 will read ~1kohm between emitter/base, ~2kohm between base/collector and ~3kohm between emitter/collector. They are set by RX47-1kohm, RX46-1.9kohm respectively.
Be sure to check the capacitors in this circuit particularly the ceramic disks CX33 and CX36-121/C. They are known to become leaky.
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