The 12V rail on the working TAU Core is making me scratch my head.
The chipset on the TAU PCB requires the following voltages +1V2 , +1V8, +2V5, +3V3 and +5V0
There is no obvious requirement for +12V that I can find on the PCB. Even the 'RS232' data link is 3V3 only.
The 5V supply rail is up converted to +12V and this is fed the Microbolometer PCB. On that PCB, the +12V feeds a LT1761 (marked LTGC) LDO +5V regulator. That regulator is intended to provide a well regulated low noise supply of +5V. No great mystery there, but why boost to +12V ?
If that is the only purpose of the '12V ' supply, then the +9V3 supply on the faulty unit would be more than enough to meet the needs of the LT1761.
Hmmm more investigation needed.
Fraser