Hammond C3 Start/Run Wiring Problem

[Pudwell]

Hey guys,

I've been working on my C3 for a while here, and I'm having a lot of trouble with the wiring of the start/run switch.

Basically, when I hit the start switch, the amp would turn on and the tubes would start lighting up - and then stay running once the run switch was engaged. I knew this to be wrong.

I took a look at the line box on my M3, compared to the C3, and saw one of the AC wires coming from the amp going to the wrong terminal. I moved the wire, and now when the C3 is plugged in, the start motor automatically is engaged, the TW's start spinning, and the amp still starts -- all without the switch being touched.

I understand something is wrong - probably just one wire - but I am hesitant to keep messing around in that AC hotspot. I've taken a look at the schematics, and not had any luck in figuring it out. Anyone able to help? I can take pics, or perhaps one of you would send me a picture of how it should be correctly wired!!

Thank you so much

[Jaim]

Line panel color codes attached.

Jim

[Pudwell]

This is exactly what I wanted THANK YOU so very much

[Pudwell]

ALRIGHT still having an issue. Turns out (based on the diagram) I had it wired totally correctly the first time.

Any ideas why the preamp is getting turned on when the start switch is engaged?

[David Anderson]

Do you have the full service manual for the console organs? There's a B3/C3 wiring diagram that shows the Run switch wiring.

You might also need to test your Run switch to make sure it isn't broken.

The wire from the Start switch to the Run switch should go to the closest terminal on the Run switch, which will also have the Brown wire from the Line Panel attached to it. On the same end of the switch, there should be a Black wire from the Line Panel. At the other end of the Run switch, Yellow should be opposite Brown, and Blue should be opposite Black.

[enor]

ALRIGHT still having an issue. Turns out (based on the diagram) I had it wired totally correctly the first time.

Any ideas why the preamp is getting turned on when the start switch is engaged?

Sounds like a miswired run switch, or a replacement run switch of the wrong type.

[Jaim]

On the "RUN" terminal of the line panel, there should be the blue wire from the run switch, the black/red from the run motor and the preamp (blue). If the preamp turns on, then the run motor should also be on. Do you have a meter? I dug out a spare switch set from my parts bin.

Jim

[David Anderson]

Here's how it's supposed to work:

Start: Current flows through the Start switch, the jumper wire to the Run switch, through Yellow/Brown wire Run switch contacts (Brown to Yellow), and via the Yellow wire to the Start Motor. No current flows to preamp, etc...

Start & Run: Current flows through the jumper wire from Start switch to Run switch Brown wire terminal, through Brown wire, to the power resistor in the line box, through the resistor, to the Start Motor. Current also flows through the Black wire from the Line Panel to the Run switch, through the Black/Blue set of Run switch contacts, to the Blue wire returning to the Line Panel, to the Run Motor and the Blue/Grey wiring to the preamp and tone cabinets.

Run: Current flows through the Black wire to the Run switch, through the Black/Blue Run switch contacts in the ON position, and through the Blue wire returning to the Line Panel, through the Blue/Grey twisted pair to the Run Motor, preamp, tone cabinets, etc...

To summarize, with Run switch disconnected:

Run switch OFF: continuity through Brown/Yellow wire terminals, open circuit on Black/Blue terminals

Run switch ON: continuity through Black/Blue wire terminals, open circuit on Brown/Yellow wire terminals

[Drawbar Dave]

Have you replaced the run switch? Because the run switch is special in that one set of contacts are open while the others are closed and this is reversed when you flick the switch. Someone sold me a replacement once that didn't work because it was a "standard" switch. Tonewheel General sell the correct one.

[nonreverb]

AKA: 4 pole, single throw "OFF-ON"

[David Anderson]

I guess the OP either fixed the problem himself and forgot about us or forgot to unplug the organ while working on the switch....

[Pudwell]

Hey guys, sorry I was out of town for a couple days. I appreciate all the replies!

I ended up unsoldering all the connections, taking the switch out and making sure it was wired correctly, and then re-soldering everything everything back.

I'm not sure how, but it fixed the problem! It's a little confusing because I made sure all the wires were in the correct stops multiple times before unsoldering, and ended up resoldering them in the same positions...

Not sure if it's related, but the C3 this is happening on was totally frozen when I bought it. I've been working on getting it going for the last 4 months!!! I was having a lot of trouble getting the TWG running at full speed, but once I fixed the problem SHE FIRED UP FLAWLESSLY! again, I don't know if its related but currently things are working great and the C3 is running for the first time in 21 years!

[MBDiagMan]

Great work pudwell! It’s great to hear of another one saved. Now play music!😊