Old Pro melt switch died, PID workaround question

After more than 40 years of service,I saw the illuminated switch on my RCBS Promelt flicker,and also noticed that my lead was cooler and not flowing well. As I cycled the switch ,I noticed that it no longer had 2 distinct positions,but was instead gritty and much harder to cycle. I had the presence of mind to empty the pot before it froze.
I have never gone the PID route or even used a thermometer, and was wondering if a complete PID controller could be wired around the switch, thereby dragging me into the 21st century,saving an old pot,and getting me better control without the cool down issues of the Promelt 2. I say a complete PID because I’m not able to wire one together from components, but with directions could probably install a temperature probe and wire around the old switch. Any ideas from those selling or using complete PIDs would be appreciated.
In case it’s not the switch, I figure I could still use the PID on my old Lyman XX backup furnace. Thanks for your consideration.

You have a couple options if I am reading your post correctly.

Option 1
If the thermostat works fine you can simply drill a 1/2 hole next to the existing switch and use a 15 amp toggle switch like this one
Attachment 240594
Just connect the 2 wires from the old switch to the new switch and your good to go

Option 2
Connect the two wires on the existing switch together, bypassing the switch completely.
Plug your pot into a multi-outlet power strip and use the switch on the strip to turn it on and off

Option 3
Connect the two wires on existing switch together, bypassing switch.
connect the 2 wires on the thermostat together, bypassing the thermostat.
Build or buy a PID. Don't look back.

I personally would go with option 3 as your quality of your boolits will go up as you will be running a more stable temp because of the PID setup.

Give RCBS a call and see if they will send you a replacement switch.

When my switch went bad, I found one just like it on Amazon.

Simple job to replace switch, You have to drill out a few rivets to remove the cover. Install new switch.
Then replace pop rivets to reinstall the cover.

RCBS will likely send you a switch.

If they don't have one, try these folks: https://www.jameco.com/webapp/wcs/st...atalogId=10001

Frankly, as long as the thermostat was still working I would just bypass the switch.

Another great source for switches is McMaster-Carr.

https://www.mcmaster.com/electrical-controls

redhawk

Thanks to everyone for the rapid answers,especially with Hatch's outline of my options. I'll try the switch option first, and ask for more help if I screw that up which is likely.

Watch out! There are 3 wires on the Pro Melt switch. One is a Neutral Wire to power the light and mixing them up will trip the breaker.

For a 2 pole switch, use the wire that comes from the the thermostat and the one to the heating element. Don't use the white wire that is common to the unswitched side of the element which is for the light.

A sharp wood chisel will shear the pop rivets easier than drilling and #10x1/2 sheet metal screws will put it back so you can get back in when you need.

Quote:

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Originally Posted by HATCH

You have a couple options if I am reading your post correctly.

Option 1
If the thermostat works fine you can simply drill a 1/2 hole next to the existing switch and use a 15 amp toggle switch like this one
Attachment 240594
Just connect the 2 wires from the old switch to the new switch and your good to go

Option 2
Connect the two wires on the existing switch together, bypassing the switch completely.
Plug your pot into a multi-outlet power strip and use the switch on the strip to turn it on and off

Option 3
Connect the two wires on existing switch together, bypassing switch.
connect the 2 wires on the thermostat together, bypassing the thermostat.
Build or buy a PID. Don't look back.

I personally would go with option 3 as your quality of your boolits will go up as you will be running a more stable temp because of the PID setup.

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another option is to just twist the wires together and pull them apart when done :kidding:

I'll 2nd calling RCBS.

I might start by replacing the switch.
Does the light run all the time or just when the heating element draw power?
If it runs all the time any switch with a 15 amp rating should be fine. Just hook the power in tone side of switch, hook both the light wire and heater wire to the other side of switch.
This lets the light be on all the time.
If the light only lights when the heating element is drawing power, It will be harder to wire up. If I had a wiring diagram of you pot I might be able to tell you how.
Building a PID is easy. Wire it so your pot plugs into the PID. Fix your pot however you want. Once fixed just plug it into the PID, turn switch on and turn temp control all the way up. Insert temp sensor in the pot, turn PID on.
It will keep your pot a lot closer to the right temp than the stock temp control.
You will like that.
Leo

Thanks to everyone,I wound up replacing the switch,worked perfectly.