Received scan of 2501 card reader logic diagrams and wiring schematics

ASSISTANCE RECEIVED (ONCE AGAIN) FROM A EUROPEAN MUSEUM

A museum that has successfully restored a 2501 as part of an IBM 1130 system did have the diagrams I needed. They kindly scanned them and sent them by email. That is just what I needed to continue with the testing and restoration of the card reader. While the wiring diagrams are for the European versions of the device - 50Hz and 220V - but the differences are fairly minor. The convenience outlet on the 2501 where oscilloscopes or lights could be plugged in are 115V in the US and 220V in Europe, for example. 

INTERESTING DETAILS FROM THE WIRING DIAGRAM

The two main AC legs for 220V are wired directly to the poles of the CE Switch (a DPST switch that disconnects the mains from the rest of the power supply). Thus I only have to remove those two to complete the unhooking of incoming AC to the PS box that I wish to remove and put on the workbench. 

The small relay I saw at the bottom of the PS box, hooked in series with the +24VDC connections out to the logic gate and other machine parts, is used to drop the +24VDC immediately when the 220V mains supply to the transformer primary drops. I assume this blocks any unintended firing of solenoids while the supply capacitor still retains the majority of the 24V. The version of the PS box attached to a 360 model 20 does NOT include this relay. 

Some of the schematics mention a +20V supply, mostly to the different panel switches but also to the hold solenoid that keeps the picker-knives from oscillating unless the other solenoid is activated to overpower it. Since the Field Engineering Theory of Operations manually asserts that the power supply only produces +24VDC, +2.5VDC and 6VAC, I was confused by the mention of this additional voltage level. On close inspection, however, I see that a couple of series resistors drop the +24V down to create the 20V level.