Here is all the guy wrote me.  I had a picture, but a friend looked and he 
said it wasn't much help.  I don't know why I think there are two jumpers 
involved, but I do, although this guy talks like only one.  I just don't 
remember for sure.

Sorry to hear of your vision problem. If you remove the top cover with
the front of the 590 towards you, the jumper should be found on the
right hand side of the top board, towards the back of the unit, near a
cross head PCB mounting screw. If you want me to e-mail you a photo to
show your friend where I think it is, I can do that, I took some when
I did a repair on my 590 and added a buffer amp for a second receiver
/ panadaptor display.


73
Butch
WA0VJR
Node 3148
Wallace, ks.