Fuse blows in fuse box???

I would open radio and just take a look for obvious. I have had wire break off at mike connection inside on my TRC 427. Easy fix. Good a time as any as others suggest to get a multimeter.

 

What kind of radio is this? Seems strange it would have a green and white power wires. I assume the glass fuse is in the green (hot) wire, and what size of fuse is it? It sounds to me like the protection diode is shorted from the power wires being hooked up backwards, which would be easy to do with those colors for the power wires.

 

Yes the radio has an internal short as others have mentioned. Putting larger fuses in a radio that is shorted is a bad idea. The 25ltd is a good little radio. It only needs a 2 amp fuse in the power cord. A 4 watt radio usually only draws about 1.4 amps on transmit, and around 240 milliampes on receive. You’re on the right path by taking the radio to a repair shop.

 

A little bit of advice, when you get it to a shop, have them remove the defective part and replace it, do not have them just cut it like a lot of shops do, it needs to be replaced.

The part is a diode, it is there to protect the radio from having the positive and negative power leads crossed. It isn't an expensive part, I buy them for less than a penny but a lot of shops are hacks and will cut it leaving you without that protection.

Oh just to add this, sometimes it is another issue, some radios it will be the audio amp shorted out and some thn final will be shorted but this would blow fuses when the radio is turned on, not just plugged in.

 

Your radio has a popped diode in it. Very common with Cobra and Uniden radios. I forget which one it is. Been a few years since I even opened one up.

But it's a circuit protection diode.

 

It should be diode 17 per the schematics. I believe it’s just in front of the pa speaker jack.