Yeah, got it up and running.  Used a heavy DPDT switch so the user can select the internal amp or plug in and get the external amp.  Works great and the owner has been advised about no more than 50 watts.  He's happy and now he's brought me a Leslie 16 to do a couple mods to. 
Thanks for the ideas, warnings, etc..
Matt

Thanks for the idea.  I think that would be fine if he had a specific amp in mind, but I think the owner wants to be able to plug any amp into the cabinet, bypassing all of the internals.  He has the combo preamp which gives him 2 line input channels and controls the speed.  But I think I'll just mount a little jack plate with a DPDT switch and a 1/4" jack so he can disconnect the speaker from the internal amp.  I just wasn't sure if you could leave the internal amp hanging w/o a load on it without killing it. 
Thanks for the suggestion.

Good Day All,
wanting to bypass the internal SS amp of a leslie 825, so if desired can run a guitar amp into the speaker and use the combo pedal to adjust speed.  can I parallel an ext speaker jack to it?  Or should I use a shorting jack to disconnect the speaker leads from the internal amp?  If i just disconnect the leads and the amp is on will it damage the power amp?  I'll try and attach the schematic here. 
Thanks,  Matt

Thanks,  I have a set of MJ15003's on order.  Good to have a resource to ask questions of, while I figure this stuff out.
Matt

Just looking at it again and one pair of outputs is running 67v on the collector.  This is supposed to be a 60v device, maybe a little too close for comfort?

Popped in a couple replacements , seems stable, not lighting up my bulb limiter at all.

Still has the original giant cap in power supply (3500uf/80v).  I have no idea what kind of life span those computer grade caps have, seems to filter the b+ pretty good, little ripple.

Matt

Howdy All,

First off, I've been coming here for info for awhile and decided to get on board.  Thanks to everyone in the past for the great advice & insights.

My current project in front of me is an older Peavey Centry (200 series),  that I've worked on before had a couple blown output devices (original RCA 62792)  with weird noise and shorting problems.  Turned out to be broken leads on the driver transformer, and several burned resistors that i think fried when the trans shorted. 

Got that dealt with and replaced the blown outputs.  Six months later, it's back with 2 more blown outputs, one on each side of the transformer.  One of them was another old one and one of the new ones I replaced (2n3055 from RatShack).  With those out the amp turns on and plays ok with the remaining two outputs, albeit at half power.  I know I probably should have replaced all four, but I didn't, lesson learned.

I said all that to say I'd like to use a more reliable higher rated transistor than the  2n3055, and I know from digging that there are options.  From a design standpoint, should I look for something that has a higher voltage rating (MJ15015), but simiilar current & HFE ratings, OR  a device that has higher specs in every catagory (ie MJ15001, MJ15003)? 
I want this to be more reliable for the player and not have it back every 6 months to replace the outputs.  As far as I can tell nothing else looks out of place voltage wise, and I'm chaulking this up to marginal parts.

Any thoughts, suggestions?
Sorry, I can't seem to find the schematic on line.  I have a paper copy in front of me***