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C100 Tech Tip (Will not work on Batteries) Resolution

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#1 Transistorized

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Posted 22 December 2017 - 08:58 PM

As many of you know, I recently acquired a non working Silver C100 on eBay and I have been taking care of the issues one by one. Figured I would take the opportunity to describe (with no pictures) how I fixed by model not working with batteries.


So today I charged up my D batteries after the M90 sucked them dry. I figured...hey why not try the Silver C100. I have not tried it with batteries. Popped them in and......Nothing! Let the troubleshooting begin.


First things first. How are the springs and pads in the battery compartment? Well, they were okay but did have some surface rust and my volt meter was having difficulty picking up battery voltage. So I cleaned those up. Still Nothing. Okay time to open her up again. Next step was to test voltage at the solder connections inside the box from the battery terminals. Yep 13.77 volts. Remove the harness from the battery box to the Power Supply terminal (red / white) connection. Hmm. Slight green corrosion on the negative (Red) terminal pin. Cleaned up and tested to Voltage at the solder joints below that harness. Excellent 13.77 Volts. That's a good start. 


So by this point I have removed the Power Supply board and I am looking at the traces and discovered that there are two switches. One that is activated by having the power plug in the socket and another spring loaded leaf style contact withing the 15V barrel DC  plug next to the AC Power inlet. With the electrical schematic floating in my head by tracing the flow of power from the battery terminal to the output terminal to the power switch, I found that the negative is a direct path from the battery. So I know it's getting Negative. The positive flows from the White wire pin to the outside barrel plug positive terminal to the side metal output terminal. That part looked green and corroded. Sure enough I tested the solder joints below the socket and it was NOT passing current through. I ended up needing to remove that barrel plug and cleaning the contacts really well. Once I got it passing current through it I tested the AC switch using ohms setting on my meter. It was working fine. Routing power through the bridge rectifier when AC plug is inserted (killing the battery feed) and restoring battery connection when plug is removed.


Not sure if everyone is following me since I didn't take pictures but in a nutshell, if you have a C100 or AKA and it does not work with batteries it's most likely the barrel plug has a bad connection. If you look inside you will see a center tap pin (negative) and at the bottom of the inlet you will see a metal tab that touches the outside of the adapter plug. When there is no adapter plug inserted that spring loaded flap of metal is supposed to spring upwards touching a cross brace tab internally thereby transferring power from the battery compartment to the AC metal tab switch. Then if there is not an AC power plug inserted and depressing that switch it passes the power directly to the radio circuitry and power switch. A fault in either one of these contacts will result in no power reaching the radio.


Obviously the battery compartment contacts need to be clean as well so that's the first thing to look at.


Hope this helps someone who has a C100 that is currently not working with batteries.

#2 Dbzerk

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Posted 25 December 2017 - 02:46 PM

Thanks mate. I haven't tested mine on batteries yet, but you've made it an easy fix if I have the same issue..