DEC PDP-11/44

 
 Posted by at 18:08

In my last Haul was also a DEC PDP-11/44, equipped with all needed boards and in good condition.

First two days of time were spend to the Power Supply and capacitor reforming, followed by a voltage check and first functional tests.

First off all, the Power Supply is healthy, which is what I have heard not often the case specially in an /44. All Caps are in range and healthy. The fluid you see on the pics are from the rubber buffer. Puh if it were electrolyte it would mean the need to spend some bucks for new caps.

The PS is a big and heavy monster, which is not easy to remove from the main chassis. This is the same for the main Backplane. There are „flex print“ cables used, but they are more lie a massive metal plate with insulation as a flexible cable.

 

The only issue were two dead fans. Not a problem – Or? The Fans operates with 35VAC at 70HZ. Nothing I have in my basement, but thanks again to Andreas, who has spotted some on eBay. Not cheap, but no other option, as DigiKey and Mouser doesn’t have such types.

 

Biggest Problem for me was, to get a console cable, but I have found the pinout after some search. In general, you will find the pinout for all DEC PDP and VAX systems quite easy when you know how to look.

I have found the needed information in the 11/44 Print Set http://bitsavers.trailing-edge.com/pdf/dec/pdp11/1144/MP00897_11X44sys_Dec79.pdf On Page 41.

As I have many DB9 connectors I have used them except the DB25 > Translation below.

 

Greetings from a working DEC PDP-11/44.