@Jon - So how do PBC and your adapter differ in wiring? Don't have the time to check it myself atm, but here's a
The wiring I used is on the left, and the one from the schematic you posted is on the right. They are mostly the same, but the end of the address lines are different.
Retrode SMS plug-in adapter Power Base Converter
----------------------------------------------------------
MD Edge Signal SMS Edge MD CART PINNAME MS CART
B20 D00 F14 B20 D00 F14
B23 D01 B14 B23 D01 B14
B26 D02 F15 B26 D02 F15
B29 D03 F17 B29 D03 F17
B28 D04 B17 B28 D04 B17
B25 D05 F18 B25 D05 F18
B22 D06 B18 B22 D06 B18
B19 D07 F19 B19 D07 F19
B17 A01 B13 B17 A01 B13
B15 A02 F13 B15 A02 F13
B13 A03 B12 B13 A03 B12
B11 A04 F12 B11 A04 F12
B09 A05 B11 B09 A05 B11
B07 A06 F11 B07 A06 F11
B05 A07 B10 B05 A07 B10
B03 A08 F10 B03 A08 F10
F04 A09 F22 F04 A09 F22
F05 A10 B21 F05 A10 B21
B04 A11 F20 B04 A11 F20
B06 A12 F21 B06 A12 F21
B08 A13 B09 B08 A13 B09
B10 A14 B22 B09 A15 F23
B12 A15 F23 F06 A18 B19
B14 A16 B20/F08 F09 A21 VCC
B16 A17 B01 F10 A22 GND
F06 A18 B23 F30 !SR GND
F10 A22 F25 F32 !CI GND
F11 A23 F24 F28 XXX F25
F16 /C_OE F16 !0E F24
F17 /C_CE B19 F17 !CE B20-F08
B02 +5v B25
B31 +5v B08/F03
B01 GND F16
B18 GND B16
B32 GND B15
Incidentally, I only tried my powerbase/master base II/Pro Mega Master adapters when I first got my Retrode. I just plugged SMS Choplifter into the Pro Mega Master and then into the Retrode2, and some chunks of the ROM it produced were the same as the (working) ROM dumped via the SMS plug-in adapter.
It's late, I hope all of that makes sense...