L-100 Pitch Bend Modification

[clarkdjent]

Hello, this is my first post to the forums.

I stumbled across The Keith Emerson Experience article which talks about Keith's early life, career, and gear.

URL to article:
https//www.google.com/amp/s/www.emusician.com/.amp/artists/keith-emerson-experience


For much of Keith's career, his friend Al Goff was responsible for maintaining his Hammond organs.

Al Goff Stated:

“All of Keith's L-100s over the years were modified and repaired first by his techs in the U.K., and later by his techs in the U.S.,” Al continues. “One mod that enabled the ‘wailing' effect of Emo's various L-100s required a simple rewiring of the power to the L-100 amplifier to keep it [operating] when the L-100 power switch was turned off. However, the capacitor start AC motor used to operate the tonewheel generator would still lose power, slow down, and speed up whenever Emo turned the switch off and on quickly. That simple mod produced an eerie wailing, screaming effect as if the organ was in pain from Emo's knife attacks."

My Questions

1. Which specific amplifier is being described?
2. Which specific wires were rewired to obtain this effect?
3. Where exactly are these wires located and what color should they be?
4. How would you rewire it for the mod to work?

Quick Note:

• I own a Vintage 1963 Hammond L-103
• I replaced the original Reverberation set of Control Tabs with a Newer set which includes Brilliance!

The Brilliance tab substantially brightens the sound of the entire instrument and gives the organ a cool Zingy sound!! B-)

[enor]

1. All of them
2. The motor power supply needs to be isolated and put on its own separate switch.
3. There's a main power panel by the motor from which power is distributed to all of the bits in the organ. The motor is right nearby so just follow the wires.
4. See (2)

[andyg]

Many years ago, when I had an L100 and then a T500, our store's service engineer told me that the Brilliance control was a bit of a fake. The organ was 'normal' with the Brilliance control on, but deliberately mellowed a bit with the control switched off. Old wives' tale or a 'Hammond trade secret'?

Given that you only 'blip' the on/off switch and have valve/tube amplification in the L (and probably in any attached amps/leslies), the mod probably makes little difference to the sound, as the amps keep going just fine for the split second that the power is off. I used to do this with my L and all my T series and never thought about doing a mod. In fact, it still worked OK on an all solid state T402 and Leslie 760 combo. If you're doing it a lot (and I would not call once or twice per gig 'a lot') then maybe the mod would make things kinder on the amp(s). If you're doing it more than once or twice per gig, wouldn't that be overkill of the effect?

[KC9UDX]

It might be worthwhile to see what tpappano has done. He can do this and a whole lot more with the device he has constructed.

[KC9UDX]

[KC9UDX]

Also see this!

[kziss]

Many years ago, when I had an L100 and then a T500, our store's service engineer told me that the Brilliance control was a bit of a fake. The organ was 'normal' with the Brilliance control on, but deliberately mellowed a bit with the control switched off. Old wives' tale or a 'Hammond trade secret'?

Hi Andy.
It indeed is correct that the Brilliance switch is "fake" as it can easily be verified from the schematics that the "Normal" (up position) setting activates a resistor and a treble cut grounding capacitor whilst the "Brilliance" (down position) setting removes the resistor and the treble cut grounding capacitor from the circuit thus producing the brighter, non mellowed down sound.

The same applies to the other Hammond tonewheel organ models which have the Brilliance switch.

Because of this, the earlier era L-100 series organs which do not have the Brilliance switch correspond to the sound produced by the later era L-100 organs when the Brilliance switch on these later era L-100 series organs is set to the "Brilliance" down position setting.
All the best.
Kon.

[Hoaxel]

You need only to install a breaker For the engine Power. I did that in an T model and the Amp got No Problem

[clarkdjent]

Inside of the main power panel, there are 3 different solder outputs available .

URL to pictures: https://imgur.com/gallery/ZbFNF14

SOLDER OUTPUTS

Solder Output #1 - GY
• Grey Wire (Left) - Run Motor
• Grey Wire (Right) - ? (from 4 pin amphenol)

Solder Output #2 - BL
• Black Wire - Power ON
• Blue Wire - ? (from 4 pin amphenol)

Solder Output #3 - YEL
• Yellow Wire (Left) - ? (from 4 pin amphenol)
• Black Wire - Power OFF
• Yellow Wire (Right) - Start Capacitor

QUESTIONS

Question #1 - Can somebody identity the 3 colored wires from the 4 pin amphenol?
1. Grey Wire -
2. Blue Wire -
3. Yellow Wire -

Question #2 - From each of the 3 Solder Outputs, which specific wires do I need to unsolder?

Question #3 - (following of question #2)
After the wires get unsoldered, what wire goes to what solder output to make the motor power supply isolated?

Reminder: This modification will allow ALL amplifiers to continue operating during a pitch bend.

[enor]

I'm not sure exactly what you're talking about. "3 switches"? There's not a single switch in your pics.

If you want to add a switch for separate motor control, put the switch in the yellow wire from power terminal to run capacitor.

Oh and VERY IMPORTANT: Change your run capacitor before it blows up and spits toxic goo all over the insides of your organ. It already looks a bit "swollen" which is not a good sign.

[clarkdjent]

Ops, I meant to say "3 solder outputs".

*Re-edited the post & image link descriptions.

Thanks for warning me about the run capacitor, I will replace it as soon as possible!

[tpappano]

Here is a silly clip demonstrating the inertia of the tone generator when driven by a variable frequency drive. This is the E100, which has the self-starting/stall-proof motor 8)

https://www.youtube.com/watch?v=qeU9dZYDpJ0