Cobra 142 no audio

It sounds like you had a cold solder joint. Leaving it in the sun probably temporarily corrected it. I would take it to a tech to have all the solder joints corrected, unless you are handy with a soldering iron. The problem will most likely come back.

All you have to do is pull the top cover off, which will show the bottom, or trace side of the board. Using a soldering iron, make sure any solder joint that doesn't fully look soldered and make sure the solder is fully covering the joint. If need you may have to add solder.

As for the frequency counter going nutty when you modulate, Don't worry about it. There is nothing wrong. Because when you modulate you are modulating the carrier signal you are changing the signal so the counter will interpret that as a different freq because it cannot differentiate. Freq counters are for use with carrier only. As long as the carrier shows correct, it is right.

the diode and missing resisters are and caps are probably the culprits.

Am power VR6
ssb power VR7
Modulation cut r-104

Could be TR41 or TR42. I would try TR41 first.

What radio?? Does it have single side band(SSB)? If not, then don't use SSB.

AM - amplitude modulation
SSB - single side band.

If you have SSB, there would be a switch on it to transmit in SSB. If not, it is AM only.

Second, Has this radio been worked on to be able to run on an amp? If not, you will blow the amp.

A CB radio transmits dead keys with 4 watts of power, and transmits with 4 watts of audio.

a 4 watt dead key is too much for a linear amp. You will smoke the transistors. Also, 4 watts of audio is not enough to drive it properly. You won't get full power.

The dead key needs to be around 2 to 2 -1/2 watts,or what ever makes the linear dead key half its peak wattage., and the modulation (audio) turned up all the way.

It doesn't sound like you know too much about CB radio's. Not a big deal, you can learn. For right now you may want to take it to a cb shop and tell them you want a peak and tune, and set up to run a linear.

You can find CB shops usually at truck stops. Some area's they are other places. Check the internet for local shops.

make sure that the rf gain is turned up all the way.Check diodes D-12&D-13.

check voltage regulator

tintlady, here is the info you requested;
the AM limiter is R 276

These are the variable adjustments inside,and what they control.
VR-1 AM S-METER
VR-2 SSB S-METER
VR-3 SSB SQUELCH RANGE
VR-4 AM SQUELCH RANGE
VR-6 SSB CARRIER BALANCE
VR-7 TX OFFSET
VR-9 RF METER
VR-10 FINAL BIAS
VR-12 DRIVER BIAS
VR-13 SSB ALC
VR-14 AM HIGH POWER
VR-15 AM MODULATION METER
VR-16 AM MODULATION
VR-17 SSB POWER
VR-18 AM LOW POWER
VC1-10.240 MHz Frequency adjustment

Hope this helps you out, let me know,,Mechanic

what cb is it ? it sounds like your am section is not getting powered up when you switch from ssb to am. If i know the model i may have a diagram of it here and suggest a place to start

you may have to scope the finals circuit on the modulation to see if all the "inline" caps are installed correctly... be sure your pc board is grounded in all areas as required by specs in your manual. Make sure there is no bleedover and you are sheilding your crystals from the modulation platform. al