The Digital Minc-11

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.

Local links:

MiniMINC page

Generic links (mainly in the real PDP-11s):

binary dinausaurs MINC-11 page
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Last update: 2014-05-17

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.