Question about CB Radios

1 Answer

No sound Cobra 25 LTD Classic. I have power to unit. The mic keys high just not sound. My Cobra 25 NW ST was in a vehicle that developed a bad voltage regulator.  A large overvoltage problem caused the vehicle's battery to boil and the headlights to blow.  The CB was on at the time and it's inline fuse blew.  Upon replacing the fuse (and trying the CB in a different vehicle) the CB powered up and "appeared" to work with the exception of received audio.  With my ear close to the speaker I can hear received voice but there is no audio gain whatsoever.  Varying the controls has no effect.  Do you think the audio amplifier was blown?  I opened the unit and can see no "Visual" indications of a problem. Thanks, Mike

Posted by on

1 Answer

  • Level 1:

    An expert who has achieved level 1.


    An expert who has answered 20 questions.


    An expert that has over 10 points.


    An expert whose answer got voted for 2 times.

  • Contributor
  • 37 Answers
Re: No sound

Yes It sounds as though the audio amp may have taken the hit go to this link and download the service manual it will give you voltage info ...Chia
P.S. If you have an external speaker plug it in to the PA hole on the back put the radio on PA and see if you get any sound then if the dynamike is turned up it will be LOUD.If not I would replace the audio amp.If you need one let me know and ill directc you in the right direction...Chia

Posted on Jan 11, 2008

Add Your Answer

0 characters

Uploading: 0%


Complete. Click "Add" to insert your video. Add


3 Points

Related Questions:

1 Answer

What is the mic wiring for 636l to cobra 25 wx nw st

If you have not bought it yet some dealers may have them already set up.Cobra is a popular radio so before you buy ask. you could just match it up to a cobra 25 mic though.

Mar 14, 2013 | Cobra 25 WX-NW-ST 40-Channels Base CB...

1 Answer

I have a cobra 25 nw st and it will not transmit

Hi, my name is John. Welcome to FixYa. Turn your MIC GAIN or DYNAMIC to MAX. Try another mic on it , if that does not do the job, let me know I will have further. Thanks for choosing FixYa. good luck John

Oct 30, 2010 | Cobra 25 WX-NW-ST 40-Channels Base CB...

1 Answer

We have a Cobra 148 nw st Sound Tracker When

It could be..
Final blown : worst case
bad mic : try another one
CB/PA switch on PA instead of CB
CB/WX swithc on WX instead of CB :you cannot transmit on weather.
Broken wire on mic jack.

Try the mic and switches first, and if that doesn't help you may need to take to tech. You can find one at a cb shop usually at truck stops.

Oct 27, 2009 | CB Radios

1 Answer

Weather bleads Over on 21 LTD WX CLASSIC(*HELP*)

sounds like your wx receiver is being activated by a bad switch replace the switch to disable the wx when you dont want it to come thru

Jun 10, 2009 | Cobra 29 WX NW ST 40-Channels Base CB...

1 Answer


1 Shield 2 White 3 Red 4 Black if the radio keys up as soon as you turn it on reverse 3 and 4 I am not familiar with that mic.But the way I actually should have given you the wiring order is as follows:1Shield 2 Modulation 3 and 4 key up I hope this helps.

Feb 18, 2009 | Cobra 25 LTD 40-Channels Base CB Radio

1 Answer


Capacitor C-82, which connects the output of the driver to the input og the final, is leaky or shorted, putting +12 volts on the base of the final, which blows it immediately.

Mar 28, 2008 | Cobra 29 WX NW ST 40-Channels Base CB...

2 Answers

Codra 29 nw ltd classic

For the money,the Cobra 29 nw/st is just as good if not better than a Galaxy. Cobra is more durable by far. I have had 3 of these cobra's in the last 30 years. Only had to replace the last one because the tractor got hit by lightning.
Sure would not pay big money for a name.

Mar 19, 2008 | Cobra 29 WX NW ST 40-Channels Base CB...

1 Answer

29 help

hi, sounds like you have a problem with the SWR' S Probably too high. Tumbleweed01

Mar 12, 2008 | Cobra 29 WX NW ST 40-Channels Base CB...

1 Answer

No sound

The Cobra 25 requires the mic to be working for any sound to come out. My suggestion is that you first try a new mic. If this doesn't work, look real close at the board on the soldered side ( around the if section, thats the area that right under the waxed area on the component side of the board ) for cold solder joints ( broken lead solder) You may need a magnifing glass. Good Luck
NC Electronic
Mills, Wyoming

Dec 17, 2007 | Cobra 25 LTD 40-Channels Base CB Radio

Not finding what you are looking for?
CB Radios Logo

Related Topics:

426 people viewed this question

Ask a Question

Usually answered in minutes!

Top CB Radios Experts

Level 2 Expert

489 Answers


Level 3 Expert

3018 Answers


Level 2 Expert

204 Answers

Are you a CB Radio Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides