Cobra 2000 talkback?

[kb6led]

Cobra 2000 speaker feedback problem

I am working on a cobra 2000 and it appears to have talkback installed I am trying figure out how to disable it. I have done some searching but as of yet I have not found any talkback info on the cobra 2000, anyone ever play with this mod on this radio?

 

[sonoma]

have you looked at the speaker jacks in the back of the board and see if some one put a resister across the 2 legs. that will give talkback

 

[melaza]

Hi, only one resistor.

<gotproof> :drool:

Greetings from the Caribbean!!!

 

[kb6led]

The board on the back with the speakers and PA jacks looks to be stock but I will pull it part later to make sure something on the flip side has not been mod’ed . The mic plug look to have been changed what is the set up for mic plug talkback? I am trying to figure out the mod so I can un do it .

 

[psycho]

Someone put talkback on a Cobra 2000?????? Using talkback and/or echo on a Cobra 2000 is the mark of a total idiot.

 

[sonoma]

The board on the back with the speakers and PA jacks looks to be stock but I will pull it part later to make sure something on the flip side has not been mod’ed . The mic plug look to have been changed what is the set up for mic plug talkback? I am trying to figure out the mod so I can un do it .

if they put it on the mic and pa jack it would be on ther solder side of the board. not on the parts side.

 

[kb6led]

Thanks for the input I will take a closer look at that this evening..

 

[kb6led]

Audio feedback

After looking around in the radio at this point I am certain that it does NOT have talkback so it’s so a problem with the radio, here is the symptom.
Feedback through the speaker when you talk (but only on AM)
I have had a few cobra 2000’s over the years and I seem to remember when you unplug the mic it mutes the receive audio, this one does not mute the audio with no mic plugged in I don’t know if it’s related to hearing my voice on the speaker I had a radio years ago that had a similar problem and it turned out to be the headphone jack in the front of the radio the insulating washer was broke, but not the case with this one anyone have any thoughts on this issue?

 

[Grinder74]

Sounds like you need to check the wiring to the mic jack and the jack itself for shorts.

 

[kb6led]

Ok problem solved! I will post this in case anyone else if having the same problem.

A local asked me to fix his cobra 2000 that had no receive audio so I was able to fix that but then noticed when I talked on the mic I could hear myself coming through the speaker (I thought someone had added talkback) after I realized there was no talkback mod added I checked the headphone jack in front of the radio, knowing that there is a small isolation bushing in there and if its cracked or installed wrong you will get mic audio out the speaker. When I pulled it apart the received audio completely went away finally I decided to check the mic and found it was wired incorrectly. Pins 3 and 4 had no continuity (needed to un-mute the receiver while in RX) so I rewired another mic and all is good now. Bottom line on the feedback problem it was actually the bushing on the headphone jack causing it but mic being wired wrong added time to trouble shoot it.

 

[jw46011]

I have this same problem but I checked the headphone jack and seems fine I dont know why it has talkback so its worthless I cant even use it

 

[loosecannon]

check the headphone jack with a meter just to be sure.
there should be NO continuity between the metal body of the jack and the metal chassis of the radio.

if that's not your problem, look at the rear right corner of the solder side of the PC board (radio upside down, knobs facing you) in the mobile versions of this radio, there would be an external speaker jack and a pa speaker jack soldered to the board.
in a base station like you have there will be wires leading to the chassis where the jacks are mounted.
look in this area for a resistor that looks aftermarket, or two wires running up to a switch.
remove whatever you find and you should be good.
LC

 

[nomadradio]

Most common way I have seen for this to happen is for the plastic insulating washer under one of the speaker jacks, or the headphone jack to go missing.

The metal bushing of the headphone and each speaker jack has a plastic shoulder washer between the jack and the panel, to insulate the inside rim of the hole in the grounded metal panel. Another plastic flat washer is under the round mounting nut. That nut can come loose and get lost. If the plastic washer also disappears, a new metal nut will short the bushing of the jack to the chassis.

Same goes for the headphone jack. The story we see is that the headphone jack was removed, and taped up inside to use that hole for a modification, like a carrier control, channel kit or echo control. Later, that modification is removed and the headphone jack goes back into the hole where it came from.

Minus the plastic flat washer.

But that's where I would look first, the speaker and headphone jacks.

73

 

[jw46011]

found it someone put it on the mic jack

 

[nomadradio]

Rock on!

Good to hear you found it.

73