Anyone got a schemo/pics of the johnhardy sony 3000 mic pre replacment parts. I got the one of the hardy website but still missing some details that I need...
The schematic on my web site is complete and is not missing anything. If you are looking for some other technical details separate from the schematic itself, please explain what they are.
The schematic on my site is for the revised version of the MPC-3000 card that I started making a couple of years ago. Prior to that the input bias current compensation circuit was done differently, using the +18V supply as the reference voltage instead of the dedicated zener diode and filtering that the newer card has.
Also, trimmer RV3 was not a part of the DC servo circuit of the earlier design. It is probably overkill to include it because the DC offset voltage would be below 150uV without it, but the addition of RV3 allows trimming the offset to below 10uV (basically to the point where you can't be sure what you are measuring anymore).
The schematic is available at:
http://www.johnhardyco.com/pdf/MPC3000.pdf
The "photos" are computer generated drawings of the p.c. board and the front panel. They are quite accurate in terms of the locations of everything, but the front panel is actually black with white markings. One of these days I'll take xome actual photos. Thank you.
John Hardy
The John Hardy Co.
www.johnhardyco.com