As you can see, very under construction.
|H786 test setup||
||A first short smoke test without cards (EK-KDF11-UG-PR2_Mar79.pdf,
page 02-20) revealed that the +5V looked ok,
the +12V was only 5.6V and -12V was zero. No special exploding caps or
smoke, so it could be worse. The next step was trying to find a service
manual, but no luck so far. I did found the
MP01074_MDL-23_MINC_Engineering_Drawings_Jun80.pdf, which contained the
connection names and cabling between power supply and backplane (page 01_13).
This solved the -12V mystery; it is not connected! Elsewhere,
at http://www.dunnington.u-net.com/public/PDP-11/QBus_chassis, I found
the H786 wants a minimal load of 2A for the +5V.
For proper testing, I removed the H786 and the mains entry unit from the system chassis. A load of 2 Ohm on the two spare contacts +5V and GND) on the H786 was a proper dummy load. This worked ok. +5V still ok and +12V too. The two 10-turn potentiometers on the right board are for tuning: left is +12V, right is +5V.
|Mains unit||The mains unit interior; it contains complex wiring for the mains voltage selector, a fuse, a big filter, a relay to disconnect mains and the mains inlet and outlet.|
|dual P7||Another small mystery is the dual P7 pin set on the H786 main board. It actually carries a few signals; PWR OK, RTC and DC OK according to the drawing. Checking for differences, I found none. All signals are the same.|
The MP01074_MDL-23_MINC_Engineering_Drawings_Jun80.pdf document at bitsavers.org contains much info on the Minc-23 system.
Generic links (mainly in the real PDP-11s):
Last update: 2014-05-17