On my Cobra 25 WX ST radio( not NW not a base station), when I turn the CB/Weather switch to the weather position, the power cord fuse blows. In CB mode, the fuse is fine; front panel lights come on, all other buttons and switches (ch9, ch 19 switch, 40 CH. sel switch, ST button etc...) all seem to work, in that they don't blow my fuse. When I try to use the mic, however, the TX/RX gauge does not respond but the TX/RX LED's do (when pressing the mic button), also the fuse remains intact. If I use my digital multimeter in the 200 ohm setting, and read from any chassis ground to the positive terminal on the TX/RX gauge, the gauge's needle will peg out. When using a higher ohm setting, the needle will not move as far. I've tried my antenna and mic on another CB, and the fuse doesn't blow.

Looks like this website does not like the apostrophe symbol in that it keeps replacing them with symbols and numbers. But back to the CB issue; I forgot to mention that my CB has a smaller card inside by the 40 ch sel. switch which has several places labeled as diodes, but instead of containing diodes, there are bare metal jumpers (solid core). The schematics do not indicate jumpers in these locations. I have checked under the board, and they are not under there either. There are two other components that are not on the main board/card, which I am unsure if they are supposed to be or not. My main board does not have R99 or L603. The R99 location has a turquoise wire from one of the holes leading i believe to the ch 9/19 switch; the other hole is covered in solder (on the bottom) and that reads to ground. I do realize that the board/card may be labeled for multiple models, and so it is possible that not all labeled spots will be filled.

I will check on the resistors and diodes you mentioned and get back with you. The WX/CB switch, however, is not on it s own board that i know of, it is in the front panel and has wires leading off of it, but I will try to follow those wires and see what components are connected via the runs. As far as muddy tracks goes; I bought this CB at a Best Buys store 9 years ago, and it has pretty much been in storage ever since till now. It was having issues back then too, but not the same issues. i joined the navy and never got a chance to take it back to the store. The CB appears to be rather clean, no real discoloration or obvious flux residue noticed, nothing burned that i can tell either. I am a 2M solder tech currently in the Navy, and have just recently moved to another work center that uses the Huntron (o-scope) system amongst others to troubleshoot, but I'm still very new to these tools. I may try using the o-scope to test some components while still in the board to decrease the wear and tear of de-soldering and re-soldering. The other guys in my new work center can probably show me what to do.

Thanks for the advice; I will get back with you after I check what you have mentioned so far.


Looks like this website does not like the apostrophe symbol in that it keeps replacing them with symbols and numbers. But back to the CB issue; I forgot to mention that my CB has a smaller card inside by the 40 ch sel. switch which has several places labeled as diodes, but instead of containing diodes, there are bare metal jumpers (solid core). The schematics do not indicate jumpers in these locations. I have checked under the board, and they are not under there either. There are two other components that are not on the main board/card, which I am unsure if they are supposed to be or not. My main board does not have R99 or L603. The R99 location has a turquoise wire from one of the holes leading i believe to the ch 9/19 switch; the other hole is covered in solder (on the bottom) and that reads to ground. I do realize that the board/card may be labeled for multiple models, and so it is possible that not all labeled spots will be filled.

I will check on the resistors and diodes you mentioned and get back with you. The WX/CB switch, however, is not on it s own board that i know of, it is in the front panel and has wires leading off of it, but I will try to follow those wires and see what components are connected via the runs. As far as muddy tracks goes; I bought this CB at a Best Buys store 9 years ago, and it has pretty much been in storage ever since till now. It was having issues back then too, but not the same issues. i joined the navy and never got a chance to take it back to the store. The CB appears to be rather clean, no real discoloration or obvious flux residue noticed, nothing burned that i can tell either. I am a 2M solder tech currently in the Navy, and have just recently moved to another work center that uses the Huntron (o-scope) system amongst others to troubleshoot, but I'm still very new to these tools. I may try using the o-scope to test some components while still in the board to decrease the wear and tear of de-soldering and re-soldering. The other guys in my new work center can probably show me what to do.

Thanks for the advice; I will get back with you after I check what you have mentioned so far.

I already had that web site for CB Tricks. That is where I got my schematics and factory manual, but the schematics they have for the 25 wx st (not the nw one) barely has anything on it.

I pulled and checked D23 & R35. They read fine. The resistor is accurate to it s color bands, but the schematic has me confused. The value the schematic gives is 1KS. The resistor is 470K (yellow, violet, red, gold). What does the S mean? There are other such resistors that have the value of 1K followed by a letter on the schematic, but the actual resistor in that spot has 470K for its color band value indication. I will continue the hunt tomorrow. I already had that web site for CB Tricks. That is where I got my schematics and factory manual, but the schematics they have for the 25 wx st (not the nw one) barely has anything on it. I pulled and checked D23 & R35. They read fine. The resistor is accurate to it s color bands, but the schematic has me confused. The value the schematic gives is 1KS. The resistor is 470K (yellow, violet, red, gold). What does the S mean? There are other such resistors that have the value of 1K followed by a letter on the schematic, but the actual resistor in that spot has 470K for its color band value indication. I will continue the hunt tomorrow.

I found that for whatever reason there was a 4.7k ohm resistor in connection with the Weather control switch when the schematic for the Cobra 25 wx nw st says it should be 1K5; (with mine being only the 25 wx st, not the night watch version, i don t know if it was the right or wrong resistor value for that spot). I looked up 1k5 on the internet and saw that it means 1.5 k ohms. I removed the 4.7k & replaced it with a 1k resistor. The weather function does work now, and the fuse does not blow, but now my 40 channel LED display has stopped working. Also, I tried the PA speaker like you said, and my mic does work as far as that goes, but the TX needle does not move when trying to transmit in CB mode. The needle does move, however, in CB mode while receiving from others. It does not move in weather mode, but probably is not supposed to. Also does not move in PA mode, also probably not supposed to.

So now I need your help to solve why my 40 CH. LED display has quit working. When i turn the ch knob, it does change channels; i can hear the changes in reception. And I need your help to solve why the transmit function appears not to be working.

Thank you Tony. I found that for whatever reason there was a 4.7k ohm resistor in connection with the Weather control switch when the schematic for the Cobra 25 wx nw st says it should be 1K5; (with mine being only the 25 wx st, not the night watch version, i don t know if it was the right or wrong resistor value for that spot). I looked up 1k5 on the internet and saw that it means 1.5 k ohms. I removed the 4.7k & replaced it with a 1k resistor. The weather function does work now, and the fuse does not blow, but now my 40 channel LED display has stopped working. Also, I tried the PA speaker like you said, and my mic does work as far as that goes, but the TX needle does not move when trying to transmit in CB mode. The needle does move, however, in CB mode while receiving from others. It does not move in weather mode, but probably is not supposed to. Also does not move in PA mode, also probably not supposed to. So now I need your help to solve why my 40 CH. LED display has quit working. When i turn the ch knob, it does change channels; i can hear the changes in reception. And I need your help to solve why the transmit function appears not to be working. Thank you Tony.

Yes, I bought it from a Best Buys store; but I m not sure that it came with its manual, so it may have been refurbished; i don t know, but it did come in its original box. I have downloaded the manual from the net. The mic connections and wiring look fine. The mic is in good condition, and it does produce sound through the PA speaker when plugged in. I've read out the mic with my meter and it seems fine according to the schematics; I have another one I will try, but the one i have been using came with the CB when i bought it and it is cleaner and in better shape than the other one i have. I have noticed that the mic gets a little warm when i have the CB powered up. Also the zigzag metal heat sink, ground, or what ever it is, in the rear of the CB, really gets warm and the transformer T1 gets hot enough that, what i suppose might be conformal coating starts melting on top of the metal U shaped housing that goes over top of it. I don't know if T1 was getting warm previous to my changing the resistor, but that zigzag metal was. The channel display worked up until i changed that resistor, but now there is nothing, no segments are lighting up, not even when switching between instant ch 9 and 19. Yes, when i change the channels, i do hear the different transmissions, and not just the knob clicking; in fact the RX meter needle shows variations in reception strength as i change channels too. I wonder if my CB model is supposed to have those jumpers in place of diodes on the smaller card that the channel selector and display are attached to, or if i need to replace those jumpers with the diodes that the Night Watch model schematics show. Maybe they are supposed to be jumpers for my model and diodes for the night watch model. I did go ahead and buy the diodes called for in the night watch model s factory manual for those locations. I know that the stripe side leg goes in the hole that the arrow is pointing at. It may be best to not change those though, because it was working fine before as is. Back to the mic issue, i just recalled that my mic was working in another CB i got at a yard sale when i tried it about a week ago; that CB is very similar to mine, it is the Cobra 25 LTD ST. With this CB, the needle in the RX/TX gauge did move while transmitting, so that confirms that is is supposed to, and that my mic itself is good. That CB is no longer good though because i have robbed that 1K resistor from it and have also robbed L7 when trouble shooting. I had accidentally damaged the L7 from my 25 WX ST CB beyond repair when removing it. Then i also damaged the L7 that i robbed from the LTD CB, but repaired it. I don't know where to buy new transducers since radio shack doesn't appear to carry them. I don't know that the L7 i put into my WX CB from the LTD one is even tuned properly for my wx CB. L19 may also be damaged in my WX CB due to me taking it out for troubleshooting; the copper wires in those are so thin and fragile. I did solder the wires back together in that one too, by using a magnifying glass to help see, but I don't know how long those two repaired L components will last. Based on the schematics I would say that the L components are transducers. These repairs were done about a week ago. I haven t had a chance to use the o-scope yet at work, due to having too much navy gear to test instead. Yes, I bought it from a Best Buys store; but I m not sure that it came with its manual, so it may have been refurbished; i don t know, but it did come in its original box. I have downloaded the manual from the net. The mic connections and wiring look fine. The mic is in good condition, and it does produce sound through the PA speaker when plugged in. I've read out the mic with my meter and it seems fine according to the schematics; I have another one I will try, but the one i have been using came with the CB when i bought it and it is cleaner and in better shape than the other one i have. I have noticed that the mic gets a little warm when i have the CB powered up. Also the zigzag metal heat sink, ground, or what ever it is, in the rear of the CB, really gets warm and the transformer T1 gets hot enough that, what i suppose might be conformal coating starts melting on top of the metal U shaped housing that goes over top of it. I don't know if T1 was getting warm previous to my changing the resistor, but that zigzag metal was. The channel display worked up until i changed that resistor, but now there is nothing, no segments are lighting up, not even when switching between instant ch 9 and 19. Yes, when i change the channels, i do hear the different transmissions, and not just the knob clicking; in fact the RX meter needle shows variations in reception strength as i change channels too. I wonder if my CB model is supposed to have those jumpers in place of diodes on the smaller card that the channel selector and display are attached to, or if i need to replace those jumpers with the diodes that the Night Watch model schematics show. Maybe they are supposed to be jumpers for my model and diodes for the night watch model. I did go ahead and buy the diodes called for in the night watch model s factory manual for those locations. I know that the stripe side leg goes in the hole that the arrow is pointing at. It may be best to not change those though, because it was working fine before as is. Back to the mic issue, i just recalled that my mic was working in another CB i got at a yard sale when i tried it about a week ago; that CB is very similar to mine, it is the Cobra 25 LTD ST. With this CB, the needle in the RX/TX gauge did move while transmitting, so that confirms that is is supposed to, and that my mic itself is good. That CB is no longer good though because i have robbed that 1K resistor from it and have also robbed L7 when trouble shooting. I had accidentally damaged the L7 from my 25 WX ST CB beyond repair when removing it. Then i also damaged the L7 that i robbed from the LTD CB, but repaired it. I don't know where to buy new transducers since radio shack doesn't appear to carry them. I don't know that the L7 i put into my WX CB from the LTD one is even tuned properly for my wx CB. L19 may also be damaged in my WX CB due to me taking it out for troubleshooting; the copper wires in those are so thin and fragile. I did solder the wires back together in that one too, by using a magnifying glass to help see, but I don't know how long those two repaired L components will last. Based on the schematics I would say that the L components are transducers. These repairs were done about a week ago. I haven t had a chance to use the o-scope yet at work, due to having too much navy gear to test instead.