Hammond L-122 volume problem

[gientke]

Hello!</p>

I'm new to Hammond organ world. I've just bought L-122 and Leslie 147 and they sound absolutely beautiful.</p>

I have just oiled the organ, I have removed the dust from tubes and TG, cleaned all the keys and checked the Leslie.</p>

When I bought the organ everything was ok.</p>

Today I played it for like 30mins and suddenly the volume dropped down (just before I could hear some buzzing and clipping).</p>

When I turn the organ on the volume is ok for like 10 seconds but then it gradually fades out - not completely, I can still hear the sound.</p>

It doesn't affect Percussion. It's loud and clear. Vibrato or Reverb does not change anything. </p>

I could hear some strange noise occasionally when playing the organ before.</p>

Apparently it hasn't been played for 3 years before I bought it - hopefully the tubes need replacing.</p>

Does anybody know which tubes do I need to replace?

Thanks</p>

Kris
</p>

[TheAdmiral]

Re: Hammond L-122 volume problem

Welcome to the forum and congrats on the new acquistions. The first thing I would do is get some DeOxit spray cleaner and clean the tube sockets and tube pins. Tubes aren't usually stressed enough to wear out that much although it still happens. You might want to wiggle the tubes just a little as when you cleaned them dust may have fallen into the sockets and made bad connections. The DeOxit spray will also be needed for the drawbars. There are others on here in the UK that can help you.

[gientke]

Re: Hammond L-122 volume problem



Thanks!</p>

I used DeOxit for both tubes and drawbars few days ago. I will try to reposition the tubes but I doubt it will help.</p>

I wish they had tubes for sale in the UK. I will have to wait whole week berofe I get them. </p>

Cheers</p>

Kris
</p>

[TheAdmiral]

Re: Hammond L-122 volume problem

I'm surprised to hear there are not valves (tubes to us in the US) for sale there. Maybe some others in the UK will chime in if there are. The Sovteks are good and made in Russia so I would think they would be available. Have you tried ebay in UK? If it's not valve connections my next thought is capacitors and then resistors after that. I still think it's related to your cleaning and possibly disturbing something.

[gientke]

Re: Hammond L-122 volume problem



To answer your first question: I've looked on eBay but the only option was US eBay so I bought them. I only hope they will make my organ work again because I payed nearly £100 for them :-) But probably I haven't looked very carefully - maybe someone in EU knows where to get them cheaper/faster?
</p>

As for cleaning - I only removed dust from valves and from the top of TG and oiling funnels and also from the motor. I'm usually afraid of 'disturbing' something that's why I didn't look in any amp. I only sprayed deoxit on valves' pins and sockets. I heard disturbing noise from the organ before and it sounded like... a thunderstorm without reverb :-) I heard the same noise just before the volume went down.
</p>

I should ask somebody to service the organ for me but I can imagine cost of repairing Hammond would be quite... scary :-) I'll try to solve the problem myself if somebody would like to help me with this.
</p>

As far as I understand L series organ have pre-amp &amp; percussion amp in one box and reverb &amp; power amp in another box. </p>

1. Could it be something wrong with the preamp/vibrato amp? Would percussion still be ok if the power amp was faulty? </p>

2. Is there a possibility to disconnect vibrato amp, just to check if vibrato doesn't cause the problem?</p>

L-100 diagram:</p>

</p>

I would really appreciate your help guys.</p>

Cheers</p>

Kris
</p>

[TheAdmiral]

Re: Hammond L-122 volume problem



Wait till some others on here who have L's answer. I don't have one so I can't say first hand but most of the spinets have similarities. You should be able to uplug the vibrato and percussion via RCA plugs. In other organs, the thunderstorm sound is quite often from the vibrato scanner. Your percussion should not work if the power amp is bad. Sounds more like preamp problems or at least before the power amp.
</p>

Where is the rest of the cavalry? (Are they all on holiday at the same time?) They should be able to save you a service call.
</p>

[Guest]

Re: Hammond L-122 volume problem



Dont stress too much buddie over this. Its probably a simple fault. You're doing right by changing the valves etc, but dont get lulled into thinking its a major problem.</P>


I fixed a wrecked solid state Hammond today (Aurora or something) with similar symotms.</P>


It could well be poor contact with valves, sockets etc or even the main smoothing capacitors in the power supply, they have a tendancy to break down, cause humms, crackles and loss of volume and......Thunderstoms.</P>


I'm no Hammond Guru but what i can tell you from experience with P.A. Your symtoms are indicative of poor contact, dry soldered joints and general ageing of components,especially when they are stressed for a while after being dormant. After all, the main power supply does all the donkeywork and carries all the current for everything else. Thats where i would be looking first.</P>


Not much of an answer mate i know, but it might point you in the right direction for starters.</P>


Biffo.</P>

[gientke]

Re: Hammond L-122 volume problem

OK, looking at schematics, I have managed to bypass the vibrato amp.The volume still fades away after few seconds. I have looked on the schematics again and I'm sure there must be something wrong with the preamp. It's got 12AX7 valve so I can't replace it till I get the new ones. I'm gonna check resistors and capacitors in the preamp with my multimeter.

[tonewheel1966]

Re: Hammond L-122 volume problem

[quote user="gientke"]

Thanks!</p>

I used DeOxit for both tubes and drawbars few days ago. I will try to reposition the tubes but I doubt it will help.</p>

I wish they had tubes for sale in the UK. I will have to wait whole week berofe I get them. </p>

Cheers</p>

Kris
</p>

[/quote]</p>

 </p>

Hi </p>

I live in the UK and use this guy on ebay UK;</p>

http://stores.shop.ebay.co.uk/AC-DC-...__W0QQ_armrsZ1</p>

He is on holiday until the end of may though.</p>

If you type the exact type of tube into ebay UK search you will find them.</p>

Cheers</p>

Dave </p>

 </p>

 </p>

 </p>

[TheAdmiral]

Re: Hammond L-122 volume problem



[quote user="gientke"] It's got 12AX7 valve so I can't replace it till I get the new ones.
[/quote]</p>

That tube is a notorious troublemaker. To check the caps and resisters properly you will need to unsolder one end to get a good reading.
</p>

[gientke]

Re: Hammond L-122 volume problem



I have bought 12AX7 on Hot Rox UK website. Sadly, it's not the valve. I can still hear the 'thunderstorm' and it is located in the preamp section (im 99% sure). I bet it is one of the capacitors. I'm gonna check it later this afternoon.
</p>

[tonewheel1966]

Re: Hammond L-122 volume problem



I had persistent thunderstorms on my RT3/122 rig and it turned out to be a percussion tube after I had cleaned the socket and bent out the pins for the umpteenth time. Have you tried wiggling each tube while the organ is on?</p>

Cheers</p>

Dave </p>

 </p>

[gientke]

Re: Hammond L-122 volume problem



Hi, I tried to wiggle them several times. I used DeOxit on both - pins and sockets.</p>

It must be something in preamp section:
</p>

1. I disconnected/bypassed the vibrato amp - nothing changed apart from little gain.</p>

2. I removed 12AX7 which is preamp tube and the thunderstorms vanished</p>

3. I turned percussion on (percussion is mixed to the signal just before power amp) and percussion is loud and clear (no thunderstorms) on its own.</p>

There is something called Matching Transformer in my AO-42 (preamp) - I wonder if that's what it is.</p>

Tkanks </p>

Kris
</p>

[gientke]

Re: Hammond L-122 volume problem

I opened the preamp and the organ worked for a while then the thunderstorms returned...


</p>

</p>

[gientke]

Re: Hammond L-122 volume problem

Right, I've looked into preamp/percussion box and I've found two possibly bad resistors. I should replace them as soon as I get new ones. I hope it will cure my L122.