On Sat, 19 Jun 1999, Tony Duell wrote:
> OK, it _is_ an M930 terminator and not an M9302, then. I was going to ask
> you about that. The reason is that the later M9302 board can 'lock the
> unibus' if there are grant problems. An M930 won't.
Actually I tried the 930 and the 9302, but no differences. I stayed with
the 930.
>
> >
> >
> > The probe of J14 revealed the following:
> >
> > on 2&3: exactly 15VDC (this is the 15v source you ask about being
> > present and correct, isn't it?)
>
> Sounds perfect to me. And yet _both_ H745s are giving no output?
That's right. I rechecked the outputs and inputs on those H745s and it's
definitely getting +15 on the input, but not giving -15 on pin 8. It's
putting out about -2v still. Same scenario on both H745s. When I unplug
the CPU connectors, all PSU voltages are good. Doesn't it sound like
something's shorting out to you? Still no smoke, BTW...
>
> There should be an H745 in the rear slot of the top PSU. It has an 8 pin
> connector on top. Pin 1 is the -15V output. Pins 4 and 5 are a +15V
> (control-ish) input.
Checked it out. All true except for pin one. Same deal on bottom H745.
> > I have the 8-pin, flat power connectors on my CPU.
>
> I think _all_ 11/45 systems have the 8 pin connectors on the CPU
> backplane. The difference is how the extra System Unit backplanes get power
> On old machined (pre S/N 2000?) there was a PCB on the inside back of the
> CPU box. It had a number of 8-pin flat connectors on it. The system units
> plugged into that.
>
> On later machines there was a board on top of the CPU fram on the RHS
> (over the 'hole' that goes over the PSUs). System units had the
> conventional 15 pin and 6 pin connectors.
Oh, OK now I see what you're referring to. The little board way in the
back of the CPU cage... That one has three flat connectors. Very hard to
reach. My serial number is 273, by the way. Machine was originally
installed at Stanford.
> You mentioned that 'both -15V outputs are low' Which pins of which
> connectors are you measuring? At the PSU there are 3 -15V lines on my
> diagrams - pin one of P21 (top PSU rear slot H745), pin one of P25
> (bottom PSU, front slot, H745) and pin 4 of P22 (bottom PSU, 12 pin
> connector on transformer housing). Which (any/all?) of those are missing?
I'm measuring pin 1 on the H745s. I also checked P22, pin4. It gave no
reading. Not even -2 volts like the other messed up -15 lines.
Here's a strange thing I noticed: On connector P7 (on the CPU power input
cluster), there are two disconnected wires, a purple and a yellow, from
pins 4 and 7. It looks like it was done intentionally as they're wrapped
around the other wires and tucked out of harm's way. Is this normal?
I assume it's OK to have completely unpopulated plots in the 11/45
backplane. There are a few without even grant continuity cards. I guess
this would be a good time to list what's in my first backplane:
front
top bottom
|A-----||B-----||C-----||D-----||E-----||F-----|
01 |M9301---------||M787--|
02 |M8114-----------------------------------------|
03 |M8115-----------------------------------------|
04 |M8112-----------------------------------------|
05 |M8113-----------------------------------------|
06 |M8100-----------------------------------------|
07 |M8101-----------------------------------------|
08 |M8102-----------------------------------------|
09 |M8103-----------------------------------------|
10 |M8104-----------------------------------------|
11 |M8105-----------------------------------------|
12 |M8106-----------------------------------------|
13 |M8108-----------------------------------------|
14 |M8107-----------------------------------------|
15 |M8109-------------------------|
16
17
18
19
20
21 |M8110-----------------------------------------|
22 |G401------------------------------------------|
23
24
25
26 |M9200---------| |G747A-|
27 |M9200---------||M7800-------------------------|
28 |M930----------| |G747A-|
rear
Received on Sun Jun 20 1999 - 09:40:01 BST
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