Wiring Diagram and Background for Robbins & Meyers B2500A Window Fan

[Isaiah Sampson]

NOTE THIS IS NOT A QUESTION! JUST POSTING POSSIBLY USEFUL INFO

Hello to all.

While restoring a Robbins & Meyers Model 2500A fan, I accidentally cut the controls wire and had to rewire it between the motor and controls. I recorded the original wiring configuration before removing the cut wiring for future reference and am uploading it here it case it benefits anyone else, with additional reference information.

Unfortunately, I did not think to take pictures of the components to go with the instructions before reassembling. Here is my best description:

The "Controls" sketch refers to the male spade connector projections on the back of the control switch. Note that the projections are NOT symmetric; the power cord neutral male projections creates the asymmetry.

The "Capacitor" sketch is for the original capacitor, which was working. The orientation is such that the male spade connector tabs are closed to the "top" of the capacitor than the bottom.

The "Motor" sketch refers to the opened motor after removing the housing back but NOT trying to remove the blades and pull the whole housing apart. When the back cover is taken off, the coils are partially exposed and there are (6) individual plastic-insulated wires protruding from the depths of the housing amidst the coils. It is the individual wires to which the sketch refers. They shared insulation coloring, so I had to identify them by relative location around the perimeter of the housing.

The wire between the motor and controls was cloth-wrapped with (5) individual cloth-wrapped wires of unique insulation color for each. The wire colors in blue text are the original colors. I marked each original wire and my new wires with whatever color electrical tape I had laying around; these are the penciled in colors which sometimes did not match the original colors. The discrepancy in wire count is because (2) motors wires spliced to (1) control wire.

Note that the control wires were stranded aluminum are are easily replaced with stranded copper. However, the motor housing wires are single strand copper and could not be reliably twisted together with the new control wiring. The original wiring tacked each motor strand to the control wire with a dab of sodder, provided a loose twist, and covered with tape. I rewired in kind. The sodder dab is essential due to the flexibility/delicacy of the single strand motor wires.

Finally, the original wire insulation, both plastic and cloth, crumbled after any bending and I actually exposed most of the motor wire during manipulation when the old single strand wire insulation disintegrated down to the motor housing. I bent the wire to project vertically from the casing without touching anything else and dabbed exterior rated latex caulk around them to hold them in place so they wouldn't move and touch each other or the housing, then wrapped them in electrical tape.

The fan worked fan after the first re-wiring/re-assembly without issues. 

Robbins and Meyers B2500A Fan Wiring Diagram.pdf

[Isaiah Sampson]

My mistake...I did have two photos of the open housing after rewiring, but not before. You can see in the second photo where the green plastic insulated single stands appear out of the coils. The insulation broke there as well and I used caulk to isolate the wire from the soils.

[Juan Varleta]

Thanks for the wiring diagram!