testing leslie 147 amp

Tech Questions Regarding Hammond Organs and/or Leslies

testing leslie 147 amp

Postby radowskm on Fri Jan 23, 2009 5:11 pm

I was playing my hammond through the old style (145/147) preamp pedal into a leslie 145. When I switched to fast speed at one point I lost my audio signal. Everything else on the pedal still works (power/speed control), but no audio signal. I took apart the pedal and used aligator clips to wire the pins from the pedal to the amp. Everything else is working, still no signal. Is there any way I can wire in an alternate audio source through pin 6 to test the leslie amp? I tried pulling the audio directly from a 1/4 cable coming from an organ tap off kit. Just hum. I'm not sure if that signal is too weak. Without pulling the leslie amp out and testing the output tubes with a voltage meter I'm out of ideas. Any help is appreciated, sorry for the legnthy post.
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Re: testing leslie 147 amp

Postby chriscarroll on Sun Feb 15, 2009 12:52 pm

seems you may have you lost the leslie amp. check internal fuse on high voltage lead and all tubes.
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Re: testing leslie 147 amp

Postby jordankersten on Tue Jul 20, 2010 7:54 pm

What type of Hammond are you using? If it is a 2 or 3-series organ with am AO-28 or AO-10 preamp, you take the signal from the "G" terminals from the preamp of the organ directly into the Leslie. There are two "G" terminals on a Hammond preamp. This provides a balanced output with respect to ground. The 122 Leslies were designed to accept this balanced signal and for that reason they were considered "Hammond-type" Leslies. The 147, however was considered by Leslie to be a "universal" type Leslie and had an unbalanced input. In order to connect this to a Hammond preamp, connect pin 1 of the Leslie to the ground terminal on the hammond preamp. This is marked be "GND" and is a brown wire. Then connect pin 6 of the Leslie (which is the signal input) to either of the "G" terminals on the Hammond preamp. DO NOT connect it to both of them, only one. These terminals have black and red wires soldered to them. You will have to wire a switch for speed switching, but this is the traditional method for connecting a 147-type Leslie to a Hammond Organ. The pins of a 147-type Leslie are as follows: Pin 1=signal ground; Pin 2=relay coil, Pin 3=AC Supply, Pin 4=AC supply; Pin 5=relay coil; Pin 6= signal input. The pins on a 122-type Leslie are as follows: Pin 1=balanced signal in; Pin 2=ground; Pin 3=AC supply; Pin 4=AC supply; Pin 5=300V B+ return, Pin 6= balanced signal in. It is extremely important to note that these two Leslie connection types are NOT interchangeable and if you plug a 122 into w 147 hookup or vice-versa you WILL burn up Your Leslie and Hammond amplifiers. I hope this helps.
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