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Original Message

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

Posted by middleground on December 31, 2005 at 07:11:19:
Some will say it doesn't take much; probably true.
I just got the new output tubes yesterday from thetubestore.com (great service, third time I order from them; this time and last time I ordered in the morning, they confirmed shipping late afternoon of same day and I got the tubes by Canada Post Expreesspost the very next day!).
I was lookig at the instructions on rebiasing posted by Abe Collins a while back on the Mk II and, as I knew, there are differences between the two models.
I popped open the hood this morning and what I see are four trimpots in light blue all on the same side of the amp (left side) towars the front, whereas the older model had one on each circuit board either side of the amp. What gives? Are two for one channel and two for the other? How does one adjust these trimpots? I understand from the instruction manual that one should: "adjust the bias in 2 places on each channel for 65 mVDC (.056 VDC) between test poits (across 0.5 ohm resistor)", this leads one to believe that of the four trimpots, there are two per side and not fur onthe same side of the amp.
I have not yet bought a multimeter, tweaker tool, clamps, etc. to do this. Many people tell me it's simple to do, I now wonder if I should pay the money to get it done by a tech.
Seemed so easy at first...