Leslie 125 Low Volume and Distortion

[theseacowexists]

My friend's Leslie 125 suddenly lost most of it's signal volume and has increased in noise and distortion. The noise increases when switching to tremolo.

When he bought it last year, the entire Leslie was super quiet, and according to the previous owner, would overheat very quickly. We soon discovered that this was because he had the speaker plugged into the socket of the connector box, and not the socket of the amp. Plugged the speaker into the amp's speaker socket, and it has worked perfectly fine ever since (until now obviously).

The amp was sold paired with a Combo Preamp I (early single button model), and that is all we have used on it. I was able to isolate the CPA and by sending the signal to a known working guitar amp, and everything sounded fine, so my next step is to look at the Leslie itself.

And that's where I'm stuck. What is the next thing I should look at in the Leslie? I've included pictures of the amp and connector box, just so you can see if everything is hooked up correctly. Given what we know of the unit's history, I wouldn't be surprised if something still isn't hooked up correctly, or if something was damaged from how the previous owner had it hooked up.

[Jyvoipabo]

Hello,

It is hard to say if this wiring is good because there have been a lot of changes.

But there is more worrying in what you explain :
-It would overheat very quickly.
-Nothing was plugged in the socket of the amp.

May be also more reassuring.
-Suddenly it lost most of it's signal volume and has increased in noise and distortion. I deduce before it works well. But it is often like that.

Do the trouble noise sensitive with Volume control ?
Do the amp still overheat ?
What parts ? Tubes (observe in the dark), Transformers, Capacitors......

JP

[nonreverb]

If I were to take a wild guess, it might be that one of the power tubes is no longer operational. When you lose one of the two power tubes, the balance of the push-pull is lost. This results in only one power tube doing the work for two....and the output is lower and is distorted. Just as you describe. If you happen to have some spare 6L6's around, swap them out and see what happens.

[theseacowexists]

I finally had the chance to get the amp out of the Leslie and over to my house, and bring the tubes over to another friend who owns a tube tester. The tubes look to be relatively new (probably put in when the previous owner had it serviced), so it was not surprising that the tester showed the tubes to be in good working order.

What is still original is the electrolytic can capacitor. I've ordered a replacement for that, as I figure it should be replaced anyway.

Do the trouble noise sensitive with Volume control ?

The hum increases as the volume control is turned up, and the signal remains almost non-existent.

[Jyvoipabo]

Hello,

If hum is increasing with the volume you can be sure :
1 The volume control is working well.
2 On the signal path the humming source is before this control.

And if the signal is nonexistent, I'm pretty sure there is a something wrong in the wiring.

JP

[theseacowexists]

I found the problem, starting all the way back at the Leslie cable. Pin 6 (the red one) had come disconnected at the female end of the cable. Soldered it back together and everything is sounding fine. Thanks for pointing me in the right direction JP.

I'm going to replace that can cap while I've got the amp at my house, just cause it'd probably be good for the amp anyway.