Question about Superstar SS-3900EGHPA CB Radio

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158edx,no recieve audio

Believe radio hooked up reverse polarity, blew a diode and a capaciter, has trans. mod.,meter shows recive but no audio

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  • raybo_95 Feb 09, 2009

    had what i believe to be a reputable shop check cause i was out on road before realized wasn't working. they said voltages on audio chip were good, course bthey didn't have scematic for this radio. is there anything else it could be. will try to get recieve chip rechecked. thank you for response

  • mono_web Apr 21, 2009

    yes your main receive audio chip would be fried automatically with your protector diode,plus your 1000pf capacitor.



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Most of these kinds of radios will have two audio chips , on for transmit and one for recieve.sounds like you popped the recieve audio chip.

Posted on Feb 09, 2009

  • Tom Arsenault
    Tom Arsenault Feb 09, 2009

    Almost positive its the recieve audio chip. If you go to FL, the shops I worked at can fix this and are honest people. I-10 at the baldwin truck stop and I 95 exit 96 st augustine at the truck stop



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I know vhf pretty well. But cbs uhhhh. I have a cobra 29ltd classic. My. Buddy blew diode. Wired backwards. I replaced diode. Now it's making a constant humm from speaker. The swr meter stopped.

did you replace it with one that is equal to the one that burnt .The one you replaced should have been the reverse polarity diode which should have been right near the smaller transformer .If this is the radio it looks like you should replace some of those electriclytic caps also.Did you replace the diode with the arrow pointing in the direction the arrow is pointing ?

Apr 28, 2016 | Cobra Radio Communications

1 Answer

I hooked up the power on my corba 29 ltd by and I think I blew something inside. Is this an easy fix?

The Cobra 29, like most CB radios, contains a reverse-polarity diode whose purpose it is to protect the radio against accidental reverse-polarity hookups. Normally all you will need to do is replace the fuse, then hook the radio up correctly.

If that doesn't get you going, then possibly the polarity-protection diode is now shorted and will have to be replaced (or removed - not recommended).

Beyond that, my experience is that the next component most like to get damaged is the Audio Output circuit, either an IC or a power transistor (larger than a regular transistor). At this point you're going to have to take it to a repair shop.

Aug 04, 2014 | Radio Communications

1 Answer

I have a sharp cb 4370 i plug to the car and it blown it is not the fuse

reverse polarity the radio and put your nose to work and sniff out the area where the power wires come into the set. There is a little black diode in that area and it s called the rev pow diode. Check it to see if you blew it.if you did then replace itand make sure the arrow on the diode is going the same way as the number on the board shows.

Jan 29, 2014 | Midland 75-822 40-Channels Handheld CB...

1 Answer

I have a galaxy 55 v that will transmit and receive but has no swing

I would turn do the watts to about 3.5 and that radio should swing.Sounds to me like its trying to but the wattage is stopping it.Experiment with it and find where you want to set it.

Jan 26, 2013 | Radio Communications

1 Answer

447 will not take power from power suply

  • If you have an inline fuse make sure to check and replace it if needed. If the radio was hooked up backwards then you need to go to radio shack and pick up a replacement diode. 1N4001 will be the diode you need. It allows current to travel one way but not the other. When you hooked the radio up backward it blew, like a fuse. Here is the diode at Radio Shack.

  • When you pull the bottom cover off you will see this diode in the board right by the power cord connector for the radio. Most of the time they will be chipped or even split after blowing from reverse polarity. Pay attention to the little "arrow" on the diode because there is a negative and a passive to diode. Anode and Cathode as it were. The Anode flows to the Cathode. The "tip" of the arrow is the negative side.

  • Look with a flashlight to insure you did not blow a tracer too.

  • Hope this helps.

Oct 31, 2011 | Radio Shack TRC-447 CB Radio

2 Answers

My uniden pro510xl when hooking it up imediately blows the fuse like a dead short but if i hook up another radio it will work fine

The radio was probably wired backwards at some point. There is a reverse polarity diode inside that must be replaced to fix this. If you have continued replacing fuses and plugging it back in, there may be further damage such as finals or audio amplifier chip as well. you will need to take the radio to a qualified repairman for service. If it is simply the reverse polarity diode, your bill should not be more than an hour's labor charge.

Feb 06, 2010 | Uniden PRO510XL 40-Channels Base CB Radio

1 Answer

Transformer gets hot

Sounds like it has reversed polarity damage, hooked backwards on the red and black wires, blew the polarity diode and needs a technician

Dec 17, 2009 | Cobra 29 LTD CB Radio

1 Answer

Cobra 29 NW ST No Sound, litesup, keys up, needle swings

It sounds like it may have been hooked up backwards when hooked up to the battery charger. If so it probably blew the polarity diode (D23) (1N4004) and with no sound it probably blew the audio IC (TA7222AP) mounted to the case of the radio. Also look at all of the large capacitors and make sure that the tops are not swollen or busted open if so they need replaced also.

Dec 28, 2008 | Cobra 29 LTD CB Radio

1 Answer

Cb radio reverse polarity damage

The diode is there to protect against rev polarity. Simply replace it with soomething like a 1n4007.


Mar 10, 2008 | Audio Players & Recorders

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