Prepared the power supplies and cable for the Diablo model 31 drive I am using with the Archiver - powers on

CONNECTED WIRING TO THE WINCHESTER MRA9 SOCKET CONTACTS

I bought three regulated power supplies to support the Diablo drive. Two of them deliver 15V at 7A for use with the drive motor and the rotary arm positioner, the third is a dual voltage +15 and -15V supply at 2.5A each which powers the circuit boards of the drive. The two high current supplies were hooked up so that one delivered +15V and the other delivered -15V. 

These have a common ground wire which will become contact C of the MRAC-14 socket. The high current +15V is wired to contact K. The high current -15V is wired to contact R. The low current +15V for the circuit boards goes to contact H and the low current -15V is wired to contact P. 

Diablo actually uses a single supply for +15V and a single supply for -15V, but routes two separate wires from each. The heavy current on one of the wires drops the voltage on that wire a bit but the other wire stays at the regulated voltage to more reliably power the circuit boards. 

I chose entirely separate power supplies to ensure the cleanest logic power to the Diablo. The power supplies were not expensive and could have other uses once the archiving is complete. I twisted all the wiring together as recommended by Diablo. 

The three power supplies were connected to the AC mains in parallel, so that all three come on or go off as the plug is inserted into the wall socket. If this will become a more permanent drive - perhaps as a second drive for my IBM 1130 - then I will mount the power supplies in something more professional looking (and safer than exposed terminals). 

Test fit of the contacts in the body

+15 rails are good

-15V rails are good

Test fit of power connector

DISCOVERED A GENDER ISSUE WITH THE MRAC 14 CONNECTOR

The part I bought appears to match the part that was installed on the Diablo - other than the Diablo side has the male contacts and mine has female contacts. This locks the tightening screw and body in place. I have to loosen the nuts on the side to let the screw and receptacle rotate to thread onto the Diablo side screw and receptacle, then tighten the nuts when it is fully pulled tight. Since I haven't glued the contacts in the body yet, I only tightened it enough to verify it fits and delivers power properly. 

WILL GLUE THE CONTACTS INTO THE MRAC-14 SOCKET BODY

I plan to JB Weld original epoxy to glue the connectors into the socket body, hoping it would provide enough strength to at least connect the cable one time. I did NOT sand the contacts because the spec sheet mentions they have beryllium in them and I will not risk inhaling any. I did clean the contact and the body with isopropyl alcohol first, then applied the epoxy. It required 24 hours to cure before I could attempt to move it or insert it into the drive. 

CABLE ONNECTED TO THE DRIVE AND DID A POWER ON TEST

The key was to see if the drive would power up and be happy. A bonus if I could get the motor to start spinning. I turned on the power supplies and saw the Power lamp illuminate as well as the Unlock lamp. The drive allowed me to open the cover to insert a disk cartridge. I put in a cartridge (but as i don't have the heads installed I won't spin it up to the point where the drive tries to load the heads) and got the motor spinning the platter for a few seconds. The servo was also locked in place unless I pushed the servo unlock button inside the drive.

The drive appears to be pretty healthy. This was not a checkout, thus we could have failed ICs or other issues yet to resolve, but power is good and the machine didn't do anything strange.