Bypassing switch + relay to test an A O Smith motor/relay

[JPG]

Per a PM request, I am starting this thread to describe how to hard wire an A. O. Smith Mark VII motor with external start relay so as to remove the power switch and start relay from affecting the motor starting.

"Normally" a red wire from the motor is connected to the power switch terminal "T5".

"Normally" a white with red tracer wire also from the motor is connected to the power switch terminal "T9".

"Normally" a yellow wire from the motor is connected to terminal #5 on the start relay. A second yellow wire is connected from terminal #5 on the start relay to "5" on the power switch and a jumper connects a second "5".

"Normally" a white with black(?) tracer connects power switch "2" to the trminal "2" on the start relay.

"Normally" a white with black(?) tracer from the motor connects to one of the start capacitor lug.

"Normally" a white with black(?) tracer connects the second start capacitor lug to "1" on the start relay.

I know that is a bunch, but should match the wiring diagram in Everett's Mark VII manual.

Now to bypass the switch and start relay.

This will be easier if the black and white motor wires are connected to a power cord black and white respectively. The power cord plug will provide the on/off function of the power switch by plugging in and pulling out the plug from a power receptacle(outlet).

Connect the red motor wire to the capacitor wire normally connected to start relay "1". Connect nothing else to them.

Connect the white with red tracer motor wire to the yellow motor wire. It may be convenient to keep the other yellow wires attached to the start relay "5" and the power switch "5".

Now plug it in briefly to see if it starts. Unplug it immediately if it hums. Also unplug it if it starts(so as to not leave the start windings connected since we have bypassed the start relay contacts).

That should suffice to verify the motor will start.

Enough for now! We can check start relay and reversing later.

[jerryricht]

JPG
Thanks for the quick response! It will be a couple of day before I can try this. I will let you know how it goes

[jerryricht]

I can confirm the wire routing is as described.

However I can also confirm there are difference in the wire colors from the relay to the switch.

From relay terminal 2 to switch terminal 2: SOLID BLACK, LABELED WITH WHITE UNDERLINED "2"

From relay terminal 5 to switch terminal 5: SOLID BLACK, LABELED WITH WHITE UNDERLINED "5"

That's cool, at least those two connections are idiot proof.

I assumed these wires are original, they certainly look like 50+ year-old wires!

If so, please accept my minor editing contribution to Everett's manual.

Photo attached. (hopefully)

[JPG]

Note that Everett mentioned that wire colors may vary. He specifically mentioned the 2 to 2 wire.

I surmise the use of wires that were intended for use with other makes of motors were used as they were 'available'.

The important thing is the wires consistently go the same places.

Also realize our sample size is very small and that there were errors in published manuals. Everett's manual contains the best we can conclude regarding them.

P.S. Your start relay appears to be different from those previously seen.

[jerryricht]

The motor runs, clockwise rotation of shaft. Only ran for a few seconds.

[JPG]

Now reverse the red and white with red tracer from the motor.

Repeat test. Motor should run reverse direction(CCW).

OVER

[jerryricht]

Yep..

[jerryricht]

Yep..

[JPG]

Reconnect the start relay.

Yellow wire from the motor(etc.) to start relay 5 and red motor wire.

White/RED motor wire to start relay terminal 2.

White/blk wire from capacitor to terminal 1.

Plug it in. Should run! TRY to determine if the start relay is picking(click).

I will be 'on the road' for the rest of today.

OVER

[jerryricht]

I cleaned the contacts on the old start switch and the motor runs perfectly, forward and reverse, (when I reverse the red and white with red tracer connections). The start switch operates silently. The motor also ran perfectly with the Supco universal relay.

JPG, Your original diagnosis that it was the switch , was spot on!

I connect the wiring to the switch per the first post and the motor runs in reverse but does not run when the foward switch was pressed with significant buzzing coming from the switch.

A quick look inside the switch revealed the contacts at L1 and L2 to be significantly damaged and the spring tension of the upper contacts not sufficient enough to close the circuit. L2 is probably damaged beyond repair.

If anyone has a MK VII switch, working or not... I am interested in buying!