Hammond L122 1/4" output buzzing when connecting to Leslie Combo 1 preamp

[and]

Hello, I've been trying to troubleshoot this humming and buzzing that happens when I turn the Hammond and Leslie w/ combo preamp 1 on.
By process of elimination I've ruled out it is the Leslie or combo preamp as I can connect other keyboards with great results.
I'm hoping that someone can help me with this and have included a picture of the jack and resistor. When I plug a standard mono 1/4" cable into this jack nothing happens, until you pull it out a bit, then you have sound and Buzz. So I bought a stereo cable with two 1/4" mono male jacks and same thing happens even when I plug both into Combo preamp. Is it possible that:
1. this stereo jack is the wrong jack and it should be a mono jack?
2. is it possible that the resistor is blown or not properly rated?
Any help would appreciated, I've included a photo of the jack with resistor.
Thank you!
Andy

[Drawbar Dave]

Someone might have tried to make a stereo headphone jack which would be too hot for the combo preamp. I'm not too familiar with the L100 so I will leave it to others to advise on a suitable point to tap off.

[valotus]

Just my 2 cents, but to me L100 seems to be more prone to different kind of hum and grounding problems compared to console models. It's not issue with built-in speakers, but I have never got them completely clean and noiseless when connected to leslie. Any loud buzz in output signal would not be acceptable, though.

[Jyvoipabo]

Hello,

If the organ has a 3 poles plug, with one connected to the ground and the preamp too, when you connect the 2 by the jack cable, then you create a ground loop.

You can check by temporarily disconnecting the ground from the combo pedal.

To eliminate this loop, a transformer must be installed in the organ. A Di box can also do the trick.

Confined JP

[and]

Hello Confined JP, interesting the organ only has a 2 pole original plug, I was looking to replace it with a 3 pole plug. Any information as to how to upgrade this would be welcome.Thanks! Andy

[Drawbar Dave]

As I said in my post, the signal from the organ will be too hot for the combo preamp. You need to pad it or eliminate the preamp and connect the organ direct to the Leslie

[Jyvoipabo]

I made a plate with an isolated jack output and an IEC Socket.
No more attached wires.
Hum KO.
Security OK.
Works fine (on stage).

Schematic inspired of Jensen AS061 application note.
Transformer = Edcor WSM600/600

Rear panel with IEC Socket fused(important) + Isolated Jack
Front switch Speaker

JP

[and]

That looks great! Thanks for sharing.
So, I've been trying to get a decent sound out of the Hammond after its been dormant for say 5 years or so. I've owned it for about 10 yrs +. It used to sound great and loud.
I'm wondering if perhaps some tubes may need attention and or some resistors need replacing.
The reason is that:
1. when nothing is plugged in the volume is low almost faint.
2. When I plug in headphones the sound is "off" low and weird when applying Vibrato.
Please have a listen from past jams as I've posted from past years.
What DI box would be recommended in this case? I'm willing to try anything to play this beautiful organ in peace.
Thank you for your time.
Andy https://youtu.be/mKJbxiSxla0 https://youtu.be/Q9985P9EOjQ

[Jyvoipabo]

Hello,

This sound level problem needs to be fixed.

You explain that the vibrato does not work properly.

Now try to diagnose the percussion.
All tabs up and the drawbars pushed in.
Lock a key down on the upper manual.
Move one of the percussion tabs.
You can hear the percussion sound.
Try setting the cutt off on the percussion module till the sound fade away completly after the delay.

You can also try to disable the Vibrato. For this, simply remove the tubes on the Vibrato module.

Confined JP

[and]

Hello Everybody!
I've proceeded to replace the power cord on the Hammond with a 3 prong grounding it to the metal chasis of the power amp.
I've reseated every tube on both the Hammond and the Leslie including replacing the main cap on the Leslie.
Results: The Leslie sounds fantastic! no hum nothing.
The Hammond still hums.
Next I will replace cord on Combo preamp with three prong. And if nothing proceed to replace the 1/4" female stereo jack with a mono jack.
Any further suggestions are Welcome!
Thanks!
Andy

[and]

Hello, I checked the percussion module as per above and slightly adjusted - decreased it.
The humming seems to be between the stereo jack and the combo preamp.
Is there any other way to connect these two?
thank you!
Andy

[and]

Hello, Success! We have tapped out of the expression pedals output with a rca splitter and have a clean feed to the CPA Leslie 147.
Now I have to continue cleaning contacts as some keys make a bit of static when played...
Any further suggestions are most welcome!
Thanks! And

[and]

Hello, The RCA tap off the expression pedal yielded mixed results. Still would like to fix the original 1/4" tap off the speaker feed.
When I plug in now there is a loud howl - almost sounds like a cry.
Any comments are most welcome.
thanks you,
Andy

[andyg]

Question: You have an L and a 147. I just wondered why you're inserting a 1/4" jack and a CPA into the equation. Why not connect them as nature (well, Leslie!) intended, with a 26-1 connector kit, driving the 147 from the L's speakers?

[flatrockmobile]

That indeed looks like a headphone jack someone installed. The proper way is this:
http://www.dairiki.org/HammondWiki/LineOutFromASpinet
I've done this on a L111 and a E312 and both worked great, no noise. Sounds much better than the output from the preamp which I believe you're getting from swell pedal.
I used a 50w load resistor instead of the 10w in the diagram as they were close to the same price. The one I used was aluminum and a finned heat sink style. I just cut the speaker cable and installed a 1/4" switching jack inline so I could unplug the line out box that contains the components and the signal would go back direct to the console speakers if needed.
The 1/4" line out from the box went to a Leslie sim (Tech 21 Roto Choir) in mono then the output of the pedal to a small PA in stereo.