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cathoderay57 · 12th Jul 2018, 5:50 pm

Hi folks,

I have been attempting the calibration procedure in the Avo Service Manual for my VCM163. In the Setting-up Procedure, Page 7 Para (s) it says "Connect the electronic multimeter across the red and brown (earthy) sockets on the amplifier board. Set the electronic multimeter to the 30mV range (or as appropriate) and adjust RV1 on the oscillator board until the multimeter reads 15mV".

There appears to be an error in the above script as there are no such sockets on the amplifier board and so I assume it should read oscillator board. Connecting to the red and brown sockets on the oscillator board, my multimeter (on 200mV AC range) displayed a voltage briefly then the voltage decayed away so I assume it was loading the circuit. Therefore, I used the scope instead. Since a meter would display RMS voltage, whereas I am using a scope, should I adjust RV1 for a 15mV peak voltage or 1.414 x 15mV=21.2mV peak?

Cheers, Jerry

12th Jul 2018, 5:50 pm	#1
cathoderay57 Nonode Join Date: Oct 2017 Location: Bristol, UK. Posts: 2,384	VCM163 Calibration Question Hi folks, I have been attempting the calibration procedure in the Avo Service Manual for my VCM163. In the Setting-up Procedure, Page 7 Para (s) it says "Connect the electronic multimeter across the red and brown (earthy) sockets on the amplifier board. Set the electronic multimeter to the 30mV range (or as appropriate) and adjust RV1 on the oscillator board until the multimeter reads 15mV". There appears to be an error in the above script as there are no such sockets on the amplifier board and so I assume it should read oscillator board. Connecting to the red and brown sockets on the oscillator board, my multimeter (on 200mV AC range) displayed a voltage briefly then the voltage decayed away so I assume it was loading the circuit. Therefore, I used the scope instead. Since a meter would display RMS voltage, whereas I am using a scope, should I adjust RV1 for a 15mV peak voltage or 1.414 x 15mV=21.2mV peak? Cheers, Jerry