[AMRadio] Jackson Model 648-2 Tube Checker

[BUDW2GLN at aol.com]

I am in the process of troubleshooting a problem with my Jackson Model  
648-S tube checker.  
 
I an trying to trace out a problem with the loss of filaments voltage to  
ALL the tube sockets.  All I have is the print the is stapled inside the  
case....This unit is a colored wire nightmare.......Does anyone know if their 
is  any additional service information that is available to help with this 
problem  ???........There were several of the 648 and 649 series built back in 
or around  '60 through '65...
 
It is an excellent tube checker and I am sure lost without it   :-)
 
I would appreciate any information and help
 
Thanks 
 
73
 
Bud  W2GLN