MINC-11 boot problems

Thanks Tony. Made a bit more progress today then the 'scope went fizzle fizzle pop :( Looks like the +12V startup and -12V (actually -15) are fine. I'm pretty sure the fault is on the power monitor board. Op-amp E1 (LM339) has +5V @ the + input. The - input I believe is AC derived from the HF signals on the main board (pin J on the sub board). This signal seems to be approx 32KHz and is 14V p-p at E1 pin 8 and 16V p-p at pin 6. The curious thing (I'm learning as I go!) is that I'd expect the outputs (pins 1 & 14) to oscillate between -15 and +12 but they're both stuck at -15. I tried replacing the LM339 (E1) and get the same result. These signals feed the trigger inputs to the 555's and it is these that seem to drive the DC L and AC L signals. My understanding is the 555's are a one-shot that should be re-triggered regularly but since the output of the 339 isn't oscillating this isn't working. The coupling between the 339 and 555 is too complex to get my little brain around so I can't be sure this is how it's supposed to work mind you! Next step is to fix/replace the scope. BTW - if I tie the DC OK and PWR OK signals to +5 would you expect the system to boot? or is the timing of these signals coming up important somewhere? James