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Re: ARC VT-100 Mk III, now I'm confused

Posted by boneman on December 31, 2005 at 18:19:34:
I have the VT100 MKlll and find it quite easy to Bias. As stated by others there is a trimpot per pair of 6550's and the resistors which need to be measured and trimpots are numbered. You should have received a ARC screw driver and bias adjustment tool with the amp. The 6h30's don't need to be adjusted so you just need to bias the 6550's. "For the VT100MKIII adjust the bias in 2 places (ie the numbered resistors and trim pots-this is my add) on each channel for 65mVDC (.065VDC) between test points (across 0.50 ohm restor). Caution: resistor is 420V above ground."-these last two sentences are from the manual. Make sure you are in a zero-signal condition and you have warmed the amp up for at least 15 minutes. Finally the work that Abe did to outline how to bias was extremely valuable to me even though I have the MKIII. Good luck