[Boatanchors] Article on changing from 2 to 3 wire power cords

[Glen Zook]

With a 2-wire line cord and the AC line bypass capacitors, if the chassis is not connected to a suitable ground, there will be a very low current AC voltage equal to 1/2 of the AC line voltage on the chassis.  This is true of virtually all of the "boat anchor" units that are transformer powered and have a 2-wire line cord.  Such is because the bypass capacitors actually pass a very small current AC voltage to the chassis.  Since both sides of the AC line are bypassed, the voltage is divided and about 1/2 of the AC line voltage can be measured between the chassis and a good ground.  Also, if the chassis is not grounded, you can often feel a little "tickle" when you touch the cabinet.

Remember, when the unit was new, the instructions said to connect an adequate ground to the chassis before plugging the unit into the AC mains.  Adding the 3-wire line cord with the green wire connected directly to the chassis gets the chassis grounded and there is not a "tickle" when you touch the cabinet.
When you start on the AC / DC receivers, let me know the model numbers and I probably have schematics, etc., available and can tell if the unit is a "hot chassis" or not.  Also, I can usually tell you the safest way to wire the 3-wire cord.
Glen, K9STH 
Website: https://k9sth.net 

    On Wednesday, August 7, 2019, 09:08:51 AM CDT, Maury Guzick <w5io at sbcglobal.net> wrote:  
 
  I appreciate all the replies. 

I have been replacing worn out 2 wire power cords with newer 2 wire cords of similar style on radios with one side grounded to the chassis. 

I am at the moment looking at bringing back to life a HT-32 I got for $10. But the AC is or has been lifted off the chassis. There have been a number of mods under the chassis. So I want to have a better understanding of how to rewire the power cord. 

I also am looking at some antique radios that are AC/DC types that will need new cords, so this inquiry is multipurpose.