I've searched this forum, as well as elsewhere, but haven't found an answer yet, so it was time to join and post!
I use the "low gain" version of the VTA input board on my ST-70, using either 12AU7 or 12BH7's.
I've read Bob's post on what the voltages should check, but this was for the "high gain" 12AT7 version.
My B+ checks 417 VDC, which is within spec.
The voltage after R13 (47k) checks 247 VDC. After R11 (36k) it drops to 120 VDC, checked at pin #1 (plate) of V1, the center 12AU7.
Pin #1 on V2 and V3 check 220 and 222 VDC respectivly.
The way I'm reading the schematic, these voltages should be higher, since the dropping resistors (R11, R13, R19) have all been decreased in value, which should result in a lower voltage drop.
I used Dale and PRP metal films in these positions, except for R11, where I used a 2W Kiwame. Before I start unsoldering resistors to re-check their values, I'd like to know what the voltages should check on the low gain board.