I see a lot of folks interchange PS-1 and QSI when asking about board. QSI made the PS-1 boards for MTH and it has ink print on the boards. But yes, a true QSI 3 stack set versus the PS-1 2 stack are not interchangeable because the bottom board is DCRU no power parts for QSI and the PS-1 board has power but no logic parts like QSI. The top boards are the same except the pin length prevents connections and the software can be incompatible.
Since taking a TP 392 I just assumed he needs help with a MTH PS-1 board as he called out in text, despite the title. G
