Coliseum Slave VU meter

[george]

Just putting the finishing touches on this Slave (circa 73'). I replaced the burnt out lights with 6.3V grain of wheat bulbs and had to ground the "-" terminal on the VU meter to get them to light up. Anyone have any ideas how this VU meter works in the 117V mode? I don't get any reading on the meter when the switch is in that position.

[mckinnon audio]

  Hi George,sounds like a shunt resistor might be open,that's why no AC reading.I take it the meter works in the audio path,I don't have a schematic for the meter circuit,shouldn't be too hard though,good luck,Mel.

[george]

Yup the meter was taken out of the chassis and it works fine with audio signal into it. I've done all the normal checking of external components - I was wondering if anyone knew how to calibrate the meter for audio and then AC mains voltage (the meter is connected to one side of the secondary).

[loudthud]

Here's a link to a thread with a copy of the Coliseum Slave Schematic. The meter just reads the AC voltage on the transformer secondary in the Line position. I would just calibrate the meter to read the correct line voltage. Vu meters aren't very accurate, a 10% voltage swing is only 1 dB.

http://sunn.ampage.org/sdp/index.php/topic,5077.0.html