The Defpom Forum, for RadioMods, S&M Software and Music by The Defpom

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.

Charlie,
All I can tell you is, if the PA is working then the audio chip is good and not the fault.

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

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