Question about Uniden GRANT LT 2-Way Radio

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Blown fuse and reverse polarity diode

Changed them both in a uniden grant still dead

Posted by fwsykes on

  • Anonymous Jan 26, 2009

    radio is dead no transmit or recieve just keeps blowing fuses



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Check around the pcboard where the dc goes to the board, sometimes the foil will burn. Also chec the transformer, Chec that one of the wires did not come off the plug in the back. When you replaced the protection diode did it blow again? If not keep checking for opens on the pc board. When you said it was dead do you mean no lights at all or no tx and rx?

Posted on Jan 26, 2009


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1 Answer

What is the main function of a reverse polarity diode, what would happen if it was blown

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My radio would not turn on yesterday. I have checked the fuse and fuse connections. The fuse was black, so I put a new one in. The fuse connections were good. The connections to the battery are good, the...

The black fuse means it blew from a fast, heavy short circuit instead of an overload of some sort. The high current vaporizes the wire inside and coats the glass, giving it the black look. In an overload, the fuse link melts.

A common cause is failure of the reverse-polarity diode in the radio. It's there to cause the fuse to blow if you get the battery connections backwards when hooking up the radio. The diode can short, and this will cause the blown fuse. If you check the fuse and find it's black again, you should check the diode with an ohmmeter. Look for the diode near where the battery lead connects to the circuit board in the radio.

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My Uniden UM525 is blowing fuses the instant I plug it in. I don't know what happened to it but I'd like to fix it. If anyone has any ideas I'd love the assistance. Thanks in advance,

Hey Marked,

First check the diode in the B+ line . Probably it is shorted due to a reverse polarity connection.

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I reversed polarity on my 93 dodge grandcaravan. The altinator is good. the battery keeps a charge till you run it. Tried wiring from altinator to battery and it ran but noticed the interier light 20 amp...

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1 Answer

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