[HAM] Leslie 122 Amp Question

[Scott Hawthorn]

At 12:47 PM 6/4/2008, Jim Shanks wrote:
> > At 10:37 PM 6/3/2008, Jim Shanks wrote:
> >>Hi All,
> >>I have a Leslie 122R amplifier that's been subjected to some very
> >>creative repair.  Looks like whomever fixed it couldn't find the
> >>30/30/30/10 can cap so they just wired in a bunch of 22mf caps.
> >>Following the schematics, it looks like one of them is even wired
> >>wrong.  Plus wires were moved from original locations to accommodate the
> >>mods and other components a just plain wrong.  Not surprisingly, it
> >>doesn't sound like it should.
> >>Anyway, I have the right parts, and service instructions and
> >>schematics.  What I don't have is a photo of a 122 amp that's put
> >>together correctly.  A picture or diagram would be real helpful in
> >>properly placing the correct components as well as getting the right
> >>colors on the wires.
> >>Anyone know of a source or have a high res digital photo of the
> >>underside of a 122 amp?
> >
> > Jim, there are a couple of problems with this approach. If this amp has
> > indeed been modified so irresponsibly, the wire colors could well have
> > changed. What if, for example,  you were to see an orange wire in the
> > picture hooked up to C56 +, but the orange wire was now doing something
> > else? And, no matter how beautifully photographed, I don't think I would
> > be
> > at all comfortable with following what I think I see in such a photo. The
> > only way to wire this amp right, in my humble opinion, is with a complete
> > understanding of what you see on the schematic.
> >
> > The first, and easiest part, is that a terminal trip long enough to hold
> > the three or four largest electrolytics can have the ground side bridged
> > across the lugs with grounding wire.
>
>Hi Steve,

The name is Scott.

>I don't plan on trying to copy a picture to get mine right
>except to the extent that I would like the color codes and position of the
>components to match an original as closely as possible

It won't be easy finding orange or purple wire.

>the only other thing
>I see that's out of spec is the DC motor brake circuit was disabled by
>clipping one lead of the capacitor.

122s never came with brakes. What's the deal with that???

>I also noticed that the output tubes, while matched on brand, are not
>matched.  That doesn't mean they aren't biased correctly, but I doubt it.

Leslie amps are self-biasing; you don't bias them.