Output Jack Modification Help

[fenderguy81]

I picked up a used Peavey 5150 combo amp that has had some work done to it already. The previous tech added 2 new output jacks feeding off of the 16 ohm orange lead from the output transformer and corresponding speaker jack/ext.jack. The amp already had a normal output and external jack so I am just trying to wrap my head around what this mod is accomplishing and why it was done. The 2 new jacks are mounted/grounded to the chassis. Any help understanding this would be great as I want to ensure I am running the proper speaker load when using the various outputs. Here is a rough schematic of what was done with the new leads running to the tip of the jacks.

[pdf64]

I suppose the tip terminals of those added jacks should be linked together? Perhaps they were added because the stock, a 16ohm output has to pass via the ext jack switching contact, which may have become bad.
But I can’t see the point of more than 1 jack for 16ohms?
I can’t make sense of what those switching contacts in the internal speaker jack are doing. It the kinda thing where it’s generally best to use a meter to work out.

[sluckey]

I can’t make sense of what those switching contacts in the internal speaker jack are doing. It the kinda thing where it’s generally best to use a meter to work out.

They are not connected (N/C)

[pdf64]

Sorry, wrong terminology, I meant the link between the top ‘r 3’ terminal and the ‘g 6 5’ terminal.
Ah, r = ring 
So a stereo jack has been used for some reason.

[fenderguy81]

I think I might try wiring it back to stock and see if there are any issues.

[vintasonic]

My guess is that they may have been used to install some sort of power sink inline?  When not used a short jumper could be installed.  Or maybe just to have a direct connection to the 16 ohm tap without going thru jack normals?  In any event, it doesn't look like a good idea, it leaves the transformer in the position of being attached to no load. You should definitely wire it back to stock