Shopsmith Forums

Hi all, first post but longtime lurker.

As is typical, my Mark VII on/off/reverse switch died. I'd like to replace it with a new switch, so I got a 4PDT switch (rated for 15amps at 125 volts, 1.5 HP) from Gama Electronics.

However, even after reading through all the various Mark VII wiring/switch replacement/different motor etc posts, I still can't make the new switch work. Part of the problem is I haven't been able to find out exactly how the old 3 button switch worked (and my old one is dead so I can't check it), so I don't know which wires were connected with each button push. Without knowing that, I can't be certain my new switch is wired correctly.

I did briefly get it to work in one direction, but now it just hums in that direction, and nothing happens when I try the other way. I'll share the wiring diagram I made when I can get it uploaded, probably tomorrow.

The speed control is all the way on slow, and the sheaves are free. The motor spins freely by hand. I haven't made any changes to the circuit the SS is on, and it worked fine prior to the switch going bad. The inside of the external relay is clean, and the contacts are not burnt or pitted. The capacitor appears ok visually, I don't have a way to test it electrically.

I have the GE motor with external relay.

Does the new switch have a center off position?

Yes, it's this one:

It's not letting me post the url for some reason, I guess you'll need to copy and paste, sorry.

https://www.amazon.com/GAMA-Electronics ... hdGY&psc=1

Here is the switch as I currently have it wired:
The items in ( ) are the original Shopsmith switch locations. I wasn't able to determine what went to the second throw of Black (L1) since my original switch is completely dead.

I wired only one throw first (the top one) for a test, and it worked. Wiring the second (lower) throw as shown resulted in no response at all, not even a hum. I kind of expected that since Black (L1) is open. However, moving Blue (L1 Blue) to the lower throw of Black (L1) also resulted in no response.

I moved Blue (L1 Blue) back to it's original location at the top throw of Black (L1) and now I get only a hum on that throw as well.

Blue(L1) needs to go to both throws of the second pole(blk L1) similar to the white (L2)

The humming may be due to relay contacts dirt.

Your including the original switch terminal id helps to determine the red/black, violet/orange wiring appears correct.

I tried moving Blue (L1) to the second pole as you described, thinking the same thing, we need a complete circuit through what I assume is the main winding. When I did that, I got nothing at all, no hum or any response.

After further work today, it looks like you were right. I took the relay apart and although clean, it did stick a little. I polished the contact again and cycled it about 20 times. I then installed a jumper between the two throws of Black L1 so it connects to Blue L1 on both throws. After reinstalling everything per the diagram above, it all works now in both directions!

Many thanks to you, JPG, for all the work you've done in the past on the diagrams for the various motor/relay combinations, I never could have got this done without those!