Help Please~ Cobra 19 ultraIII Audio Problem ~

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themechman
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Help Please~ Cobra 19 ultraIII Audio Problem ~

Post by themechman »

Radio Make and Model: Cobra 19 ultraIII
PCB Number:
PLL Number:
Test gear available:
Symptoms: No output or receive

What is working: Everything except the audio

What has been tried: external speaker, pa, listening to another radio while keyed up

Did it suddenly happen ?: yes

Anything else that may be of help?: I need help fixing my cb radio problem. On my Cobra 19 ultraIII all the audio output and receive is gone. I tried hooking it up to a external speaker and still no sound, hooked it up to the PA still no sound output. Got anther radio to check to see if I could talk through it and no luck, but the radio powers up and one can see the display work like it suppose to. This happened to my old Cobra 19 ultraIII so I got a new Cobra 19 ultraIII and it did the same thing!!

Any help would be appreciated!
Thanks
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Warf135
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Re: Help Please~ Cobra 19 ultraIII Audio Problem ~

Post by Warf135 »

Have you tried another microphone on the radio?
Norm
themechman
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Re: Help Please~ Cobra 19 ultraIII Audio Problem ~

Post by themechman »

Warf135 wrote:Have you tried another microphone on the radio?
yep I did that, I am wondering if its the antenna or somethin like that cuz idk what else would just cause this to happen its like somthing is shorting out the radios.

Any Thoughts?
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Warf135
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Re: Help Please~ Cobra 19 ultraIII Audio Problem ~

Post by Warf135 »

Were you using an extention speaker on the radios? A faulty extention speaker could blow the audio chip in the radio. if it was a faulty antenna or coax I would have expected the RF power output transistor to blow and not the audio chip.

Let me confirm: The radio is working fine, TX power is OK, RX is OK, But there is just no audio from the speaker is this correct?
Norm
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Re: Help Please~ Cobra 19 ultraIII Audio Problem ~

Post by themechman »

yes but i could not talk out of the mic to another radio but you could see the signal increase when i keyed up on the other radio. And yes no sound at all from the speaker.
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Warf135
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Re: Help Please~ Cobra 19 ultraIII Audio Problem ~

Post by Warf135 »

So there is no audio going out or coming in...ok, let me try to find a schematic for this radio and I'll look into it for you.
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themechman
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Re: Help Please~ Cobra 19 ultraIII Audio Problem ~

Post by themechman »

ok thanks
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Warf135
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Re: Help Please~ Cobra 19 ultraIII Audio Problem ~

Post by Warf135 »

Unfortunately, I have been unable to locate a schematic for this radio, so I can not help...

If anyone has the schematic for this radio, please post it on here :!:
Norm
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Re: Help Please~ Cobra 19 ultraIII Audio Problem ~

Post by Kruser »

While this is not much help, I can only say I have a lot of these come into my shop with the same conditions you state. I consider them a disposable radio that is not worth investing $40 an hour to even attempt to repair. I have never had an owner disagree with me yet and most just ask if I want it for parts. Cobra really shot themselves in the head on this one.
As always.........just my three cents worth...................hey.....everything has gone up you know!
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Warf135
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Re: Help Please~ Cobra 19 ultraIII Audio Problem ~

Post by Warf135 »

Hey Kruser, thanks for that info.. I have since seen these radio's going for about $30 brand new, so in that case your probably right, its uneconomic to repair.

However, if it turned out to be a simple fix that the person could repair themselfs, then it could possibly be worth doing...

Interesting to find out that this is a common problem.
Norm
themechman
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Re: Help Please~ Cobra 19 ultraIII Audio Problem ~

Post by themechman »

hmm... yes I know that it is a cheap radio but I hope it is nothing on the truck or pa side of things when I go and put a expensive radio in my truck like I already have and then it quites.

And I still would like to know what part I would have to replace to get it to work.
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Re: Help Please~ Cobra 19 ultraIII Audio Problem ~

Post by Kruser »

I opened one up some time back, but I can't remember exactly now how it was set up and the parts it used. In most cases like this where the receive and transmit are not working it points to the audio chip which in most cobras is the TA7222P. These chips run very hot and I have seen many of them not soldered properly. As a matter of fact I just fixed a 29LTD where one leg of the TA7222P was unsoldered. Bad solder connections are the number 1 problem of new radios today. To compete the companies sacrifice quality control
Randy
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Re: Help Please~ Cobra 19 ultraIII Audio Problem ~

Post by Warf135 »

As long as the power supply lead for the radio is putting out around 13.5vDC you should not have any problems putting a new radio in... If I remember right, trucks run on 24v and you need a convertor to reduce it to 13.5v
If this convertor has gone bad it could have been the cause of the amp chip blowing.

Once you put another radio in the truck you can check the antenna/coax/kicker with a simple SWR meter. I would not expect to see a problem in the antenna line affect the audio chain in the radio.

A more probable cause for your cobra dying is as Randy suggests, poor quality manafacturing / bad soldering around the audio amp. (time to get the bright light and magnifying glass and inspect the board me thinks!)

If any parts need replacing, its probably not worth repairing... Good Luck!
Norm
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