Question about Cobra 25 WX-NW-ST 40-Channels Base CB Radio

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Blows fuses This radio was installed in my Volvo truck. The computer in the truck started having issues and over-voltaged the whole electrical system. When that happened the CB shut down and has never powered back up since. The inline fuse blew so I replaced it. It don't matter if the radio power switch is on or off it still blows the fuse. I seen somewhere that there is a reverse polarity protection diode on these radios. Where is it and what is it marked?

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  • Anonymous Mar 30, 2014

    now blows fuses and will not power on

  • Anonymous Mar 30, 2014

    reversed polarity, now will not power on , but blows fuse


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When you open up the radio and look at the component side (top of pc board), the diode you are looking for is D17. It is located basically in front of where the PA jack connected to the pc board. Just make sure when you solder the new one in place, observe the side that the grey band is on, which should be facing toward the point of the arrow pic.

You can pick the diodes up at most Radio shacks or online through I use Parts Express for all of my small electrical components and tools. They are very reasonable and very trustworthy. The diode you are wanting is called a Rectifier Diode. The part numbers range from 1N4001 and 1N4008. I use 1N4007 (the only one Parts Express stocks) and it works just fine. Here is a direct link to the page with this diode
They are only .09 each. I hope you get your radio back in working order.

Dean Pitts
Rollin CBs
Mt. Vernon, TX

Posted on Jun 17, 2008

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The diode used is a standard 1amp 50 volt you can get one from almost any junked electronic device...a 1 amp 400 volt will be fine also to use

Posted on Jul 03, 2008

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I have a friend who is a CB tech and when I did something like that to a Palomar amp I had, he replaced the diode in a couple mins and that did fix it. See if you can find a service manual for you make and model. It was located right by where the power lines came into the case. Make sure you install the diode the correct way. A diode is what is used to allow electricity to flow only 1 direction.

Posted on Jun 15, 2008

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