I just made a couple of measurements on my Corsair II:
Pins 3 and 5 of U2 are at "mid-rail" - about 4v. That's what you would
expect with the Reg supply being about 8v, and a mid-rail reference for
U2 being developed by the potential divider R11 (10k) and R12 (10k).
Please note that you have to be careful how you measure the DC voltages
on those pins; you are measuring through 1M series resistors R5 and R8
so you need to use a high input impedance meter. Clearly, the voltages
quoted in the table on page 3-19 for Pins 3, 5 and 6 are wrong - they
are inconsistent with the schematic and the other pin voltages; I don't
think it's a coincidence that all three are much lower than they should
be, and all three are fed via very high series resistors (1M, 1M and
1.5M); it looks like Ten Tec used a low impedance meter when making
those measurements :)
For reference, I measure 100mV p/p of audio at U2A pin 1 when I
"whistle" into a Ten Tec model 700 fist mic.
73,
Steve G3TXQ
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