I occasionally get questions on this mod, so here are my notes.
• Special order RE-0887 input transformer from Cinemag • Special order CM-3301 output transformer from Cinemag • Additional 100k resistor
For the CAPI VP312, non-DI version, rev. B/C schematic:
1) Omit C5 & C6 2) Omit C1 & R2 (the zobel network) 3) Put the 100k resistor Cinemag recommends for the RE-0887 in R3
For the the CAPI VP312DI, DI version, rev. D schematic:
1) Omit C8 & C9 2) Omit C1 & R3 (the zobel network) 3) Put the 100k resistor Cinemag recommends for the RE-0887 in R2
Note that R2 and R3 for the 100K resistor are swapped on these two versions of the mod—mix them up and you'll effectively take the 100K resistor out of the circuit.
That's it. A pretty simple mod once you have the parts in stock. Even the wire color codes on the CM-3301 output transformer matched those of the stock CAPI VP312 output transformer on my build, but double-check the datasheet just in case.