Cb not receiving

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Joined: Friday 30th Nov 2012, 9:34
First Name: Charlie
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Cb not receiving

Post by mckinleyhorse2 » Friday 30th Nov 2012, 10:11

Radio Make and Model: Cobra 25 NW ST
PCB Number:
PLL Number:
Test gear available: multimeter, soldering iron, solder
Symptoms: no reception on any channel. The needle does not move. It will move to about 3/4 when you key the mic, but I do not know for sure that I am transmitting.

What is working: Lights up, powers on, -----PA works----- everything appears to be fine except no reception and the squelch, gain etc do not change anything.

What has been tried: Checked the speaker and mic.

Did it suddenly happen ?: It worked fine and one day I turned it on and the problem started.

Anything else that may be of help?: My antenna a wilson 5000 the mount broke and the cb was keyed up several times. Someone told be i had bad finals, and someonesle said if the needle moved when I keyed up then the finals were good and the audio chip is bad. I have a TA7222AP audio chip, I can get one for about 3 bucks. Should I test something first or am I way off.

I am not a cb expert, any help would be appreciated. I did search the forum first, but did not find anything similar. Thanks in advance to anyone who takes the time to help.

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Re: Cb not receiving

Post by zodiac » Wednesday 5th Dec 2012, 2:24

All I can tell you is, if the PA is working then the audio chip is good and not the fault.
How far is it.
Twice it's length from halfway.

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Joined: Tuesday 1st Jan 2013, 6:01
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Re: Cb not receiving

Post by Bowwowwow » Tuesday 1st Jan 2013, 7:12

Check Some caps around the audio chip, big and medum ones, if that doesnt do it, replace the audio chip.

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The Defpom
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Re: Cb not receiving

Post by The Defpom » Tuesday 15th Jan 2013, 20:39

I suspect that it has overloaded the front end of the RX chain, most probably the shunt diodes, D1,D2,D19,D20.

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