I have a VAX 4000 105 "Cheetah-Q+" main board. No case, power supply, etc. I'm planning on mounting this board inside a much smaller custom enclosure, but don't have a power supply.

Does anyone know the power supply pinout? I'm pretty sure I can source a power supply with the necessary voltages and current, but don't want to destroy the main board if I guess wrong.

Google searches haven't turned up much, but if someone has specific knowledge or access to reference materials it would be a great help.

Regards,
Joe

I think I have to correct pinout --

This info comes from a discussion http://www.classiccmp.org/pipermail/cctalk/2020-June/053844.html

-------------------------------------------------------
For the VXT-2000 with an H7109-B the rated voltage and current values
are printed right on the power supply label:

+5.1V, 7.81A
+12.1V, 0.62A
-12.1V, 0.46A
-9V, 0.2A
Fixed width character pinout diagram:
+=================+
-9V | Yellow | Orange | +12.1V
+--------+--------+
??? | White | Black | Gnd
+--------+--------+
+5.1V | Red | Blue | -12.1V
+--------+--------+
+5.1V | Red | Black | Gnd
+--------+--------+
Gnd | Black | Black | Gnd
+=================+
-------------------------------------------------------

The H7819-AA is used with the VAX 4000 90/100/105/106/108 systems and the discussion referenced above seems to indicate that many of DecStation and Microvax systems shared the same power supply pinout and voltages, but with different current capacities depending upon system configuration.

Other than the -9V the voltages referenced all a used with common ATX power supplies. Using -9V regulator from the 12V rail would seem like a pretty straightforward way to adapt a cheap PC ATX power supply for VAX use.

The correct pinout for a KA53 (VAX 4000 model 105 mainboard) is: (Need to use a fixed-width font to view)

Connector as viewed on the Mainboard.
_______________________________________________
| 1 | 2 | 3 | 4 | 5 | 6 | 7 |
_______________________________________________
| 8 | 9 | 10 | 11 | 12 | 13 | 14 |
_______________________________________________
|======|
|======|

Table 2–3 System Module Power Connector Voltages

Pin Number Voltage Tolerance Color
1 – 12.1 Vdc 5% Blue
2 Ground - Black
3 Ground - Black
4 Ground - Black
5 +5.1 Vdc 5% Red
6 +5.1 Vdc 5% Red
7 +3.5 to +5.25 Vdc - Brown
8 +5.1 Vdc 5% Red
9 +12.1 Vdc 5% Orange
10 +5.1 Vdc 5% Red
11 Ground - Black
12 Ground - Black
13 – 9 Vdc 5% Yellow
14 – 9 Vdc return - White

-9V Measurement made with positive lead connected to pin13 and negative lead connected to pin 14.
Pin 14 is the Ground for the –9 Vdc supply (an isolated supply)

This was found in the manual: "VAXstation 3100 Model 76 Maintenance Guide" on page number 17 of the document (26th sheet of the PDF) in Table 2-3.

https://manx-docs.org/collections/antonio/dec/MDS-2000-01/cd1/VAX/VS31MMG2.PDF

I'm currently powering the KA53 mainboard from a Vaxstation 3100 38 power supply model H7821-00. So, at least this supply is compatible with the H719-01 used in the VAX 4000 Model 100/105/106/107

Reformatted pinout and table

___________________________________________
| 1 | 2 | 3 | 4 | 5 | 6 | 7 |
___________________________________________
| 8 | 9 | 10 | 11 | 12 | 13 | 14 |
___________________________________________
|====|
|====|

Table 2–3 System Module Power Connector Voltages

Pin Number Voltage Tolerance Color
1 – 12.1 Vdc 5% Blue
2 Ground - Black
3 Ground - Black
4 Ground - Black
5 +5.1 Vdc 5% Red
6 +5.1 Vdc 5% Red
7 +3.5 to +5.25 Vdc - Brown
8 +5.1 Vdc 5% Red
9 +12.1 Vdc 5% Orange
10 +5.1 Vdc 5% Red
11 Ground - Black
12 Ground - Black
13 – 9 Vdc 5% Yellow
14 – 9 Vdc return - White