5 Mar
2003
5 Mar
'03
7:54 p.m.
Thanks for your help, Tony and Patrick. I think I have this mostly
understood. Just a few things remain.
On Wednesday, March 5, 2003, Tony Duell wrote:
Oh, hang on.. I know what you're seeing, I think.
Those are the Vb
(battery-backed) lines. The battery backup interface brick fits in place
of the H745 -- the idea being that you only need the H745 if you have core
memory, which is non-volatile, and you only need the battery backup unit
if you have (volatile) MOS memory. The battery interface uses a different
8 pin mate-n-lock connector in the harness, though.
Ok, problem found: me. I got confused by the print set on the representation
of front vs back views, and thus I had my regulator positions backwards. We
were both also confusing the H745 and H754. Everything (except one thing)
looks fine now. Here's what I have:
Under Xformer +15V
Brick 1: H745 -15V
Brick 2: H7441 +5V
Brick 3: H7441 +5V
Brick 4: H785 +5VB, +15VB, -15VB
The H785 doesn't produce -5V or +20, so it is certainly OK that I'm not
finding those voltages on the backplane power connectors!
My current understanding (no pun intended) of the H785 is that when it is
not running off the battery, it produces +5VB, +15VB, and -15VB with current
from the mains transformer. Am I correct?
My testing shows that I have the correct voltages on all the right pins,
including -15V. However, the LED on the H745 (-15V) does not light. What
does this mean?
--
Jeffrey Sharp