Cobra 2000 GTL

[HavaV10]

thanks all that tried to help me out with this issue. Here is a little video.

 

[BayouRadioAmplifier]

I listened to your audio problem a few times.
the radios I had had more random loud crackling noise,
sounding like listening to 75 meter SSB on a summer
night with thunderstorms around. it was obvious the
TA7222 was bad, also knowing that the radios came from
noisy trucks where the volume was cranked up all the way.

and sounds like the TR53 mute circuit is working as brandon
pointed out with PLL unlock.

so with audio volume turned all off, there is an audio path
via the MIC audio circuit to the TA7222 amp. maybe something has
been hacked there. (ALC/AMC) or in the MIC switching in AM/SSB mode.
So do your test, with MIC input "DYNAMIC" control all the way down, full ccw.
And try in AM mode also.

you gotta strange problem there.

I have an old 142GTL here that somebody gave me to
check out. Let me see how it works.

 

[BayouRadioAmplifier]

never mind. I assumed this 142GTL main board is the same as a 2000.
I opened it up. this 142 is from an old guy and said it was in his closet
for many years. it looks like it was never opened up before. it still has/had the
paper gasket at the front of the cover, and it is all decomposed and falling apart now. I was waiting for the guy to bring me more radios and his MICs.

I see that the schematic is different. the MUTE on the 7222
is used. the board says PC-385AB
and Uniden stamped on the 120 VAC power transformer.
"Made in Taiwan"

so is this radio from before or after them 148 / 2000's?

Nomad? AudioShock? you guys would know.

 

[HavaV10]

never mind. I assumed this 142GTL main board is the same as a 2000.
I opened it up. this 142 is from an old guy and said it was in his closet
for many years. it looks like it was never opened up before. it still has/had the
paper gasket at the front of the cover, and it is all decomposed and falling apart now. I was waiting for the guy to bring me more radios and his MICs.

I see that the schematic is different. the MUTE on the 7222
is used. the board says PC-385AB
and Uniden stamped on the 120 VAC power transformer.
"Made in Taiwan"

so is this radio from before or after them 148 / 2000's?

Nomad? AudioShock? you guys would know.

thanks for your response. I'm done messing with it. It's works great other than the low audio sound no biggie really. Maybe someday I'll send it out to a tech for repairs. Thanks to all that responded.

 

[brandon7861]

I had a transistor sound just like that once. I don't know what equipment you have, but if it is a noisy component, it might be easier to track down if the radio is connected to a dummy load and all oscillators (crystals and VCO tank) are shorted to ground. This way there will be no AC signals inside the radio except for the noise source. A sound card input and a decoupling cap probing each active device's collector may find the source of the problem.