8 Mar
2015
8 Mar
'15
12:15 p.m.
With the cable removed from the h742a connector, P9
says DC LO and AC LO
are 3.53v, which is lower than the expected +4.8v. This tells me there is
Have you confirmed these are steady DC voltages Or could the signals be oscillating
with that as the average value?
There is a capacitor in the H742 that if it fails (and it does...) the ACLO and DCLO will
oscillate at mains frequncy (or probably twice it). Certainly on the 11/45, this really
confuses the CPU microcode. It's the obvious smoothing capacitor for the supply to
the ACLO and DCLO circuit.
-tony