Cobra 29 LTD ST not receiving or transmitting

[donniegilbert]

I would first like to thank those of you that put this site together. I am finding a wealth of information here that I didn't know was available. Thanks

I have a Cobra 29 LTD with Sound Tracker that would blow the fuse every time power was applied to it. Tracked that problem down to the diode on D23 that had shorted. The radio now has power but will not receive signals nor will it transmit any. The meter needle will move a little when you key the mic, but I noticed that it seemed to tremble or quiver in transmit mode. With the squelch turned to allow anything through and the RF gain at max, I can barely hear static through the speaker.

Things that I know... my mic is good as I took it off of the Cobra 29 XLR that I have been using. My antenna is working as I receive and transmit with the XLR also.

I don't want to speculate as to the problem on this one because you all really seem to know what to target, so I will leave this one to the experts.

Thanks so much.

Don

[thetnhillbilly]

I'm not sure myself, but if memory serves, when the reverse polarity diode goes it will sometimes weaken or destroy some of the electrolitics. I don't know if this is what the problem is, just something I remember hearing.

[Rick]

Hi Donniegilbert,

Try replacing TR23 if you are luck this is all you will need to do and if your not best to take it to the repair shop.

Rick.

[abitrulez]

Why dont you check out the audio ic TA7222AP

[donniegilbert]

Thanks for the ideas. I was poking around in the thing and when I got near the crystal, I could hear it popping. I flipped the board over and could see a pin moving where the solder was holding well. I hit the solder on a few of the pins to reseal them and it works fine now. I am not sure how that relates to the initial problem of the reverse polarity diode blowing out, but I am glad it is functioning now. Thanks again for the help and if I run into other issues, I will be sure to post those too.

Thanks

Don