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Hammond Glitch - intermittent Audio Loss


Brad Kaenel

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I'm still trying to do a thorough diagnosis and discern any failure patterns, but I thought I'd ask for some "try this" debug suggestions up front...

 

My '59 RT-3 is experiencing a weird audio problem. I'll just be playing along, not doing anything unusual (no knives, no small animals, etc.), when the audio will just go silent. If I keep playing, usually it will just come back on it's own after about 10 seconds, but sometimes I actually have to stop playing for a few seconds to get the audio to return. When it goes, there's no pop or crackle or anything; the organ just goes silent, like it loses power or something. But during the "silent" moments I can still hear the motor running.

 

For a while I thought it had something to do with the Percussion, and it does seem to occur more frequently when Percussion is engaged, but it happens with Percussion off, as well.

 

Now there are a couple of "non-standard" things about my RT that could be involved. First, it has a 1/4" audio out tap. Second, I play it thru a Leslie 2101.

 

Obvious things to try that I haven't done yet:

1) change the 2101 out for my QSC K8, to see if it's the Leslie's problem

2) ditch the 1/4" audio, and switch to my PR40 cabinet to see if it's the tap

 

I've played this RT for over a year thru a Ventilator and my K8 with no problems. It's only been in the last month that I've been playing thru the 2101 (the Vent is gone), so naturally I suspect that first. But the Leslie doesn't give me trouble when paired with other gear like my SK1.

 

The audio tap out is VERY hot; so much so that I have to ratchet it down with a passive mixer before sending it to the 2101 (or the K8). Is it possible the Leslie is getting too juiced and is shutting down to protect itself?

 

As I said, I've still got several things to try that may shed some important light. Are there other things *you* would do to help diagnose the glitch that I haven't mentioned? Anyone have any preliminary guesses or intuition? Or solve a similar scenario in the past?

Legend '70s Compact, Jupiter-Xm, Mojo Suitcase

 

 

 

 

 

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Can you run both the Leslie 2101 and the K8 at the same time? Then when the audio cuts out, you will know if it's the Leslie protecting itself due to the hot input signal because it would not cut out in the K8. I'd start there.

 

If they both cut out, I would say the problem is in the organ, but I really doubt it. I think your theory of the 2101 protecting itself is a good one.

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My '59 RT-3

 

Sorry, Brad, I have no clue... But I do have a '59 RT-3; Wanna tell me your serial. Just for fun? Mine is also modded with a 1/4 out, and the signal is hot, hot, hot. When I run it thru my 3300, I use a Mackie mixer to cool it down before it hits my Speakeasy AMA (or Vent,), but my Leslie 142 handles it just fine. Hopefully, it's the Leslie ducking...

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But I do have a '59 RT-3; Wanna tell me your serial. Just for fun?

 

Serial number: 6068; likely manu'd late '59 or early '60

One owner; living-room centerpiece; never moved since delivery; AGO member

 

In case you missed it, here's the thread about how the RT-3 found it's way to me:

 

https://forums.musicplayer.com/ubbthreads.php/topics/2289506/1

Legend '70s Compact, Jupiter-Xm, Mojo Suitcase

 

 

 

 

 

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Can you run both the Leslie 2101 and the K8 at the same time? Then when the audio cuts out, you will know if it's the Leslie protecting itself...

 

Yes, I can. Great suggestion; thanks Jim. I'll have a report tomorrow...

Legend '70s Compact, Jupiter-Xm, Mojo Suitcase

 

 

 

 

 

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Solved. I *was* seriously overloading the power amp and triggering a protection circuit. And my own rookie-ish fault, too -- I never turned the Leslie around so I could see the back of the unit while I was playing. There's an "Overload" LED right in the middle of the panel, and I was hitting it pretty hard nearly all of the time; eventually the Leslie would just say 'that's enough' and duck out.

 

I also had the 2101's input gain at about 15%, but was running the mixer's output at about 80% -- bass-ackwards. Reversing these so that input gain was high, but the mixer output low, solved the power amp overloading (duh!) and I was able to achieve comparable volume levels with ne'er a blip on the protection circuit LED.

 

Such an obvious gaffe -- I just couldn't see it...

Legend '70s Compact, Jupiter-Xm, Mojo Suitcase

 

 

 

 

 

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But I do have a '59 RT-3; Wanna tell me your serial. Just for fun?

 

Serial number: 6068; likely manu'd late '59 or early '60

One owner; living-room centerpiece; never moved since delivery; AGO member

 

In case you missed it, here's the thread about how the RT-3 found it's way to me:

 

https://forums.musicplayer.com/ubbthreads.php/topics/2289506/1

 

 

Great thread! Mine is 6016 or similar, I'm not really sure. My RT3 is anything but pristine, it's a road dog chop with plexiglass front (facing the audience) and no pedals. The whole organ was rebuilt in 1978 and has some disco era stylings - for instance, there's a row of lightbulbs behind the drawbars...

 

http://i28.photobucket.com/albums/c213/analogaddict/bild15.jpg

 

http://i28.photobucket.com/albums/c213/analogaddict/7549ea2d.jpg

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