[R-390] Power supply MOD

Jim Green jagreen3 at sbcglobal.net
Sun Apr 22 18:07:17 EDT 2012


Naturally I am not the first to have worked on this R-390. I found a  
MOD (Modification) in the Power Supply.

V801 is missing from it's socket. A wire is coming out of the center  
hole leading to a big 30 Ohm 18 Watt wire wound ceramic resistor. The  
big 30 Ohm is in the circuit between pin 6 of V801 and pin 8 of V801.  
I can see no other changes. It looks like this big resistor just drops  
the 285V Pin 6 voltage down to the 240V Pin 8 voltage. All the  
operational pins on the V801 socket are common to the same pins on V802.

This doesn't seem like a very good idea for some reason. Can someone  
give me a clue what the tech was thinking?

Jim


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