-nick
Member
Hey folks,
I thought I would go through my service manual list of components to check on the old quad. Of course, I'm stuck at step 1, the regulated power supply adjustment.
I've found the correct circuit board easily enough. There is only a single variable resistor on the board, which should obviously be the one for the adjustment. I'm supposed to set the voltage to 25 +/- 0.1 as measured at terminal 18.
Terminal 18? Where are you?! I presume the positive multimeter lead goes on terminal 18 and the negative lead is just chassis ground. The manual also says set to QS Synthesizer. That doesn't make a lot of sense.
Also, I measured the voltage at the speaker terminals for the bias offset. This is with the volume and level all the way off and the selector on a blank AUX1 input. So there should be no signal to the speaker outs.
Still, the voltage was jumping around in the millivolt mode. Around -15 to around +30. Is this at all normal? I would have expected a steady reading. I can hear a slight bleed-through from the tuner when an AUX or etc. input is selected, so maybe that is where the signal is coming from?
I'm familiar with electronics basics, but am new to radios. Of course, adjusting via the variable resistors should be fairly straight-forward.
I appreciate any tips and feedback!
I thought I would go through my service manual list of components to check on the old quad. Of course, I'm stuck at step 1, the regulated power supply adjustment.
I've found the correct circuit board easily enough. There is only a single variable resistor on the board, which should obviously be the one for the adjustment. I'm supposed to set the voltage to 25 +/- 0.1 as measured at terminal 18.
Terminal 18? Where are you?! I presume the positive multimeter lead goes on terminal 18 and the negative lead is just chassis ground. The manual also says set to QS Synthesizer. That doesn't make a lot of sense.
Also, I measured the voltage at the speaker terminals for the bias offset. This is with the volume and level all the way off and the selector on a blank AUX1 input. So there should be no signal to the speaker outs.
Still, the voltage was jumping around in the millivolt mode. Around -15 to around +30. Is this at all normal? I would have expected a steady reading. I can hear a slight bleed-through from the tuner when an AUX or etc. input is selected, so maybe that is where the signal is coming from?
I'm familiar with electronics basics, but am new to radios. Of course, adjusting via the variable resistors should be fairly straight-forward.
I appreciate any tips and feedback!
