Question regarding an old Johnson 123A

[guitar_199]

I am just going through a bunch of my acquired radios to catalog the various illnesses that they may have and one is Johnson 123A.

What I ran in to is certainly not a show stopper...

For power, on the rear there is a little red plastic fitting that appears to hold a male spade lug... inset a bit. So apparently the power lead had a spade lug on it and you just plug it on.

My question is... where did they attach a ground wire??? I would have expected to see a specific "ground lug" where you would attach the ground wire of your power cord but ... no.

Of course I can certainly find a place to clip the ground lead so I can power it up..... but... "back in the day" when you were doing a neat installation... where did people attach the ground wire???? Surely they didn't just loosen a case screw and wrap a wire under it......

Thanks in advance......
Bob

 

[AudioShockwav]

Yes, the manual shows a short wire used to ground the radio from a case screw to the mounting bracket.
Item number 8 short wire with screw terminals on it.
See attached

73
Jeff

 

[AudioShockwav]

Be aware Johnson sold a kit to use these radios in positive ground vehicles, after installing the kit there was a sticker that was to be placed on the back of the radio to inform anyone else that it has been changed.
Make sure you have a lower value fuse in the power cord first time you hook it up or check inside to see if there is a small PC board mounted beside the power plug inside the chassis.
If someone changes it and forgot the sticker, and you just happen to hook it up negative ground with no fuse, well it lets lots of smoke out
Don't ask me how I know that

73
Jeff

 

[guitar_199]

Be aware Johnson sold a kit to use these radios in positive ground vehicles, after installing the kit there was a sticker that was to be placed on the back of the radio to inform anyone else that it has been changed.
Make sure you have a lower value fuse in the power cord first time you hook it up or check inside to see if there is a small PC board mounted beside the power plug inside the chassis.
If someone changes it and forgot the sticker, and you just happen to hook it up negative ground with no fuse, well it lets lots of smoke out
Don't ask me how I know that

73
Jeff

As it turns out... the protection diode appears to be shorted on this one... (low ohms BOTH ways across power.

I scanned over that procedure you are talking about and it actually makes circuit changes inside the radio.

But I really would not have expected to use a case screw for power supply ground.... but... there it is!!!!!!!

Thanks for the info.