10 Mar
2007
10 Mar
'07
12:19 a.m.
E02B2 is at 0.55v, indicating the H745 in slot E is officially a problem
child.
That's a -15V brick, isn;t it..
E15A1 is at 0.95v and E01B1 is at 0.05v, so the +15v
regulator built into
The -15V bricks need a +15V supply from the PCB in the front section of
the H742, as well as the 30V AC input from the transformer. So there
might only be one fault here.
the top H742a is suspect. Noted that the small fan on
the top of the top
H742a isn't turning so likely the regulator is well-done.
You do have mains going to that supply, right? (yes, I know it's obvious,
but it's worth checking).
The PCB in the front (+8V, +15V, LTC, etc) is acutally quite simple
(IIRC, linear, not swtiching, regulators, for example). If that's where
the fault is, you've got a fairly easy day ahead...
IIRC, there's at least one fuse on that PCB.
The test points on the backplane for regulators B, C
& D are ok, as is
OK, so you do haev mains, and the transformer is probably OK.
the -15v from the bottom H742a.
That '-15V' is odd if it's the rail I think it is. The '+15V' output
of
the 'front PCB' is tied to the system ground rail, so the '0V' line o
nthat PCB is actually at -15V wrt ground. That's why the prints tell you
not to use the LTC, ACLO, etc pins on the lower H742 (they'd be
references to the -15V rail, not system ground).
-tony