cobra 29 question

The bigger fuse would not have done this,you pluged the 29's power plug in backwards. Its an easy/cheap fix as all radios have a fail safe built in just in case you do something like this.

 

Sounds liek you popped the circuit protection diode. It is an easy fix if you are handy with a soldering iron Any radio shop can replace it in no time flat with very little cost. I would give you the location of the diode but my brain won't let me access that info for some reason. LOL. it will come to me later. I think it is either D8 or D7 Oh well. But I have seen this many times especially using the power posts in trucks. If these posts are loose at all then it will happen. I have put in a few of these for our company drivers for free.

 

A pack of two diodes is about a buck and it would take all of maybe ten minutes to replace and that includes doing up a work order. I would say that most shops would do it for less then 20 bucks.

 

In the meantime, that shorted protection diode will continue to pop any fuses of the proper size until it's replaced, even with the DC line's polarity corrected.
Unfortunately, what some folks do is keep putting in bigger and bigger fuses until the little protection diode burns out. And if they've got the polarity reversed still, *then* they take out the finals, the driver, the audio chip, the voltage regulators, etc.
As a chum of mine likes to say, the amount of damage done will be in direct proportion to the size of the fuse that's put in the DC line
And as Carolina Thunder mentioned, most modern CBs recognize this feature as cheap insurance. I fix and refurbish lots of older radios, and always put in a diode to serve this function in the models that don't already have one, as any experienced tech will recognize it for what it is, and it's a life- (or at least a radio-) saver.
Ya' dodged the bullet! But isn't it amazing how much smoke they package into those teensy components at the factory?
-- Handlebar --