B3/C3 Pedal Switch Assembly

[TorontoBob]

Hi all. Newbie here.

I'm resurrecting a (hideously) chopped B3. This project has sat idle for about ten years but I'm getting back to it now.

Somewhere I acquired a pedal switch assembly (totally forgotten where.) It fits - but I'm not sure it will work in a B3. The wiring harness looks different from the one in my C3 - one side of the harness is a lot shorter than the other so it won't reach some of the TG lugs without some "extensions". Before I take it apart, buzz-out the leads, get migraines, etc. I thought I would ask here if I would be wasting my time with it.

The assembly has the letters "N96" stamped on it, and "G" just below that. It has 12 red and 13 black felts on the switches themselves.

Does anyone know what I've got here and if there's any chance of it working in a B3?

Thanks in advance!

Bob

[enor]

From the description, it sounds like your pedal switch assembly is from an older generator (up until mid -2 series) with the output terminals in consecutive order. You can still use the switch assembly but you need to make a new harness for it.

[enor]

Caveat: If the switch assembly is too old, it might be from an 82-tone-generator-ed organ. Then it won't work. Same if it's even older than that. (model A etc)

[TorontoBob]

Thank-you for the reply!

Maybe a bit more info will help.

The wiring looks really old - pretty coarse fabric/cloth sheathing.

The harness splits into two sides (No surprise there). On one side there are TG 25 leads. On the other there are 43. And, on that side exiting from the end is one heavier black lead a few inches long, and the brown wire (which on the C3 exits at the middle with the other three colored leads.)

I hope that helps.

If I can't use this thing, I would think there have to be lots of B3 switch assemblies out there - given how many Bs were chopped. But finding one …

B

[David Anderson]

The fact that this appears to be a 68 bass tone harness suggest that this pedal assembly is for a 91 tone generator.

But then, there are three different configurations of 91-tone generator:

1) Early 91-tone (1935 - approx. 1939)

2) 91-tone with complex tone wheels and sequential terminals (1947 - 1950)

Service Manuals says: "Both manuals and pedal switch are wired differently and are therefore not interchangeable with earlier models." Whether or not that is an insurmountable problem or a matter of re-routing some wires, I'm not 100% sure.

3) 91-tone with complex tone wheels and non-sequential terminals (1950 - 1975)

Sequential means that the tones on the TG terminal strip run 1-91, in numerical order, starting at the Start Motor side. The pedal harness on these has evenly-spaced wires and only runs part the width of the terminal strip.

On Non-sequential TGs, Hammond saved wire on the generator by simply connecting the tone outputs to the closest terminals, so they are not in order from 1-91. The pedal harness on these extends the entire length of the tone section of the TG terminal strip, but does not connect to every terminal.

So, by comparing your pedal switch wiring harness to the TG terminal strip and checking the wiring against wiring diagrams in the Service Manual, you should be able to tell what you're working with.

Pedal switch wiring harnesses from A-100 series Hammonds are also a bit different in terms of the length of the wires.

[TorontoBob]

Thank-you David.

I have some homework to do.

I have a Service Manual ("A" - "R3") so I'll get to work.

Thanks again!

[enor]

One long and one short "arm" of the harness sounds like a sequential harness.

[TorontoBob]

Arg.

If that's the case, and I can determine which assembly it is from the Service Manual, then I'll know the TG frequency each lead needs to connect to. I'm just crazy enough to attempt to make the connections reach by extending leads that are too short, and using heat-shrink over the extension joints. But I'm just (barely) smart enough to worry that this might introduce spurious "noise". (And the end result will be pretty darn ugly!)

How hard are you all laughing at this "plan" ?

:-)

[David Anderson]

Hammond's tone generator wiring all runs at low impedances to ground, and this makes the wiring less sensitive to noise pickup than it would be otherwise.

Some harness wires would end up being longer than they need to be; others would be shorter. If you wanted to do this, I would make up a jig, label the wires, and re-do the whole harness, spacing the wires neatly, hiding the splices, and tying it with waxed thread, just like the original. Do a neat job with it before installing it in the organ. It will be time-consuming, but it's your time. The worst end result would be finding out after you'd done all that that there were problems inside the pedal switch assembly you didn't know about until you had it installed.

You need to do a cost-benefit analysis of adapting this harness to a 3-series organ vs. finding a 1950-1975 B or C pedal switch assembly left over from a parted-out organ or a chop.

You can get black cloth-covered push-back wire from Triode Electronics -- or could the last time I checked.

I'm not laughing. This is a legitimate learning-curve issue.

[TorontoBob]

I get it. If I'm going to do it, do it right.

Thank-you for the advice and the "nudge".

I'll try to find a B or C pedal switch assembly 1st though. There has to be one somewhere in or near Toronto Canada.

Bob

Oh - "... low impedances to ground …"

Ya. Impedance. I tried to get my head around impedance but ran right into the square-root of -1. That was years ago and my head still hurts. :-P

[Wes]

Bob, I built exactly the harness you're thinking about building a couple of years ago. Not hard, just time consuming. The lugs on the switch assy are in tone order, tone one at the far bass end.

[TorontoBob]

Hi Wes.

I may end up doing exactly that - and it's the kind of thing I enjoy doing.

In reconnecting the manual harness to the TG, I was going blind consulting the wiring diagram in the Service Manual to buzz-out the correct frequency wire from the manuals. (I was doing this to double-check my work.) So to help with that - and the upcoming pedal switch hookup - I made an Excel spreadsheet showing the TG lug numbers, frequencies, and harness wire numbers. The list is split into four sections to match the four terminal strips on the TG. I'm uploading it here just in case it is of help to others. (It's in PDF format as xlsx files are not allowed to be uploaded.)

Bob

[TorontoBob]

Attached is a clearer version.

[Wes]

This is also a helpful interactive tool: http://www.dairiki.org/hammond/wiring/

I made a stupid error when building that harness, I didn't label the wires as I connected them to the generator, and I started at the generator end. If I had to do it all over again, I think I would wire up the pedal switch assembly mostly in place with the tube loose, fishing one wire down at a time. What I wound up doing was figuring out which wire was which with a frequency counter. Toning them out once hooked to the generator is impossible, the coil resistance to ground is too low.

I used wire from an R100, if you have a collection of old organs, see what you can extract. You don't want super-thick insulation.

[TorontoBob]

Ya, once wires are soldered to the TG there is close to zero resistance between them (just like the lugs o the TG). So you can't tell what is going on.