On/off volume pot replacement part 500c

[fahfisher500]

The replacement is a little different from the original in that the lugs for attaching the wires are straight except for the power attachments which had two sets of lugs which Mark told me to make a jumper to connect the two lugs. I took these to document what I was doing before disassembling everything. The longer straight connections helped me because some of the wires I had to solder were short (the were probably cut rather than desoldered when the part was replace way back when). I tinned the lugs and the replacement went pretty easily.

 

[fahfisher500]

View attachment 931932 Here's another

 

[fahfisher500]

 

[fahfisher500]

Sorry for the multiple posts, I'm trying to do this from my phone and clean up the pictures a little to show the connections. The attachments are prior bad attempts which I have deleted.

 

[larryderouin]

I like the straight fittings, rather than the holy one's. Makes it easier to wrap the wire around and solder.

 

[Csermonet47]

Wow that looks really nice. Very close to the originals. Thanks for the pics. My pot seems to have started working pretty well for the moment but if it goes south I will likely go that route.

 

[monkboughtlunch]

...the power attachments which had two sets of lugs which Mark told me to make a jumper to connect the two lugs. I took these to document what I was doing before disassembling everything.

Thanks for documenting. I'm installing a new switch too.

There are four lugs in the power section on the new pot. Which specific lugs did you jumper? And to which lugs to the original power wires connect?

 

[larryderouin]

Monk; Number them clockwise with the upper left being #1. With the switch closed ( Zero ohms), check continuity between 1 and 2 and 3 and 4. or it could be 4 and 1 and 2 and 3. If it's #4 and 1 and #2 & #3 you'd bring in the HOT lead (from the line cord) to the jumpered pair of #4 & #1. The other two (to the transformer and the switched outlets, each go to #2 and #3. Doesn't matter which one. This does not equalize the load (amps) between the contacts as Fisher originally wired it, OR Jumper #4 & #1 for Hot and Jumper #2 & #3 and wire as before. This will equalize the amperage between the 2 contacts and supply both the transformer and the outlets.

 

[fahfisher500]

The yellow are the jumpers. The white are the power with the two hot wires soldered to the top (2:00) and the ground to the bottom (5:00) positions. Mark said it did not matter which way (top vs bottom) the power leads were attached as long as they were not across the same jumper ( shorting it).

 

[fahfisher500]

My original ( which itself was a replacement) only had two connections in the 5 and 7:00 positions on the new switch.

 

[larryderouin]

fah. You're short one lead. 1from the cord to the switch. 2. from the switch to the transformer, 3. from the switch to the Aux plugs.

Put the #1 HOT LEAD on the top jumpered set. This will be input for out purposes. #2 and #3 leads will be on the bottom jumpered pins or outputs in this case. Because the whole load is now going thru both sets of contacts the load is distributed equally between the contacts which will end up giving you extended life in the new contacts.

 

[monkboughtlunch]

Larry,

Would you be happy to mark up the below photo to help clarify? I plan to install a new switch.

Thanks

 

[larryderouin]

Monk; Read post 28 above. It goes into detail on how to wire up a 4 lead switch. Note that the three wires are all a different shade of tan-brown. The difference is very subtle sometimes which is why you need to ohm out the wires from both ends too (I forgot to put that in.) You will have 3 wires. One from the cord (#1 wire) one to the transformer connection on the terminal strip near the power cord, and #3 which goes to the AUX POWER PLUGS. LEAD 1 goes on one side by itself, #2 & #3 are tied together by the jumper and the switch contacts.

 

[fahfisher500]

My original looked like this. I put the jumpers just like I diagramed them on my previous post. I then soldered the gold and white wire to the 2 o'clock connector and the greenish wire to the 5 o'clock connector. It works fine now.

 

[fahfisher500]

Like this

 

[larryderouin]

You can do it that way too. I like to have each wire on it's own terminal. You're still using both sets of contacts if you have the leads jumpered as you showed.