11/45 revisited

[Tony Duell]

> 
> 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