Question about Radio Communications
No power.. plugged it in, the radio went on and off real quick. checked pos. and neg. they were good. plugged pack in, and the radio, again flashed on then off. thought it was a fluke.. dummy me... try it a 3rd time. all I got was a little smoke out of the back of the radio.
With no power connected read resistance across power leads---likely protect diode just inside back of radio from red power lead is shorted to ground
THE ONLY THING THAT CAUSES THIS IS THE RED AND BLACK GETTING HOOKED UP BACKWARDS---NOTHING ELSE WILL DO IT.
IF YOU READ A DEAD SHORT WITH RADIO NOT HOOKED TO POWER AND POWER SWITCH OFF--THE RADIO GOT RP(reverse polarity).
Posted on May 19, 2012
When you reversed the polarity of the power and negative, if it did not blow the inline fuse, then all you did was burn the protection diode. Sometimes it can do more damage, but usually its just the protection diode that goes. They are a cheap fix and if you have a local cb shop, tell them what you did, and they should, repair it for $10 to $15. If they try to charge more, then they are trying to rip you off. If you don't have a cb shop to go to, and you can unsolder and solder components on a pc board, email me at [email protected] and I will walk you through re-placing the diode. The diode can be purchased at Radioshack.
Mt. Vernon, TX
Posted on Jan 25, 2008
SOURCE: wired backwards
In many CB's there is an internal diode that is connected across the DC line. When the power is connected correctly, the diode is reversed biased and does not conduct. When the power is swapped, the diode is forward biased and conducts. When that happens, it causes the in-line fuse to blow. Was there an inline fuse in the power leads? I would take the cover off and see if there is a burned diode where the power cord enters the radio. Take a look and see what's burned. Let me know what you find and we'll go from there. If there has been a lot of damage, it may not be worth fixing.
Posted on Jan 28, 2008
SOURCE: cobra 25 ltd wx wont power up
You most likely blew a Diode that is back near the power plug.
It is easy to fix the diode but if you continued to apply power you may have damaged other parts including the audio chip.
Posted on Jan 02, 2009
SOURCE: Hello there
If you remove the screws that hold the top cover on
and remove the cover look by the front of the unit and you will see a small inline glass fuse (50x250) .
simply remove this fuse and replace it with a new one
also check all of the other fuses that is going to the power cord too ok
I hope that this has helped you out a lot
best regards michael
Posted on Nov 13, 2009
Testimonial: "wow that did it sorry it took so long to get back to you went to the radio shack and got the fuse now all is well love this radio"
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