Cobra 29ltd classic ( Rick, Please Help )
Posted: Friday 7th Dec 2007, 19:25
Hi folks, the name here is Hawk
I just got a used cobra 29ltd classic (and I'm trying to find out what is wrong with it. Ok, some info on the model:
-Manufactured October 00
-Main board has this stamped on it: KEPC-060H, A068A-5
-I belive the main chip is this one: NPC D2816C
-Radio does transmit and recieve. I used an old flashlight bulb as a dummy load and the modulation makes the bulb go from fairly bright to extremely bright when saying "ahhhhhhh-deeee-ooooo".
-Recieve is having problems, I get plenty of static/noise in the speaker but don't hear anyone talking on any channel (no reply also when asking for radio check).
I'd love to have a few pictures of the internals to compare to mine because it's missing some parts and was modded by the previous owner.
Some pictures of the bottom of the board would be good for comparison too because there's some resistors and stuff installed there... The biggest problem I'm having is a a buzz (feedback?) that comes through the speaker on receive about every 10 seconds (on every channel). It makes the meter move when it happens also. The poor cobra is more like a garden snake right now... it's missing capacitors C53 and C61 ( I would gratefully appreciate info on the values of those capacitors). Someone also snipped one end of Resistor R55 for some reason. Someone installed a "variable turbo mod" at location JP36 but I removed it and replaced it with a jumper to see if the strange buzz/tone would stop. I'd really like to learn about cb radio repair and put this radio back to stock. I have a mitral valve problem with my heart and I don't work so I have plenty of time on my hands. Also, transistor c2078 has a plastic bushing on the screw to keep the transistor from grounding to the heat sink, are the others that are mounted with screws supposed to have bushings too?
If needed, I do have a digital volt meter, and soldering experience.
73's
Hawk
I just got a used cobra 29ltd classic (and I'm trying to find out what is wrong with it. Ok, some info on the model:
-Manufactured October 00
-Main board has this stamped on it: KEPC-060H, A068A-5
-I belive the main chip is this one: NPC D2816C
-Radio does transmit and recieve. I used an old flashlight bulb as a dummy load and the modulation makes the bulb go from fairly bright to extremely bright when saying "ahhhhhhh-deeee-ooooo".
-Recieve is having problems, I get plenty of static/noise in the speaker but don't hear anyone talking on any channel (no reply also when asking for radio check).
I'd love to have a few pictures of the internals to compare to mine because it's missing some parts and was modded by the previous owner.
Some pictures of the bottom of the board would be good for comparison too because there's some resistors and stuff installed there... The biggest problem I'm having is a a buzz (feedback?) that comes through the speaker on receive about every 10 seconds (on every channel). It makes the meter move when it happens also. The poor cobra is more like a garden snake right now... it's missing capacitors C53 and C61 ( I would gratefully appreciate info on the values of those capacitors). Someone also snipped one end of Resistor R55 for some reason. Someone installed a "variable turbo mod" at location JP36 but I removed it and replaced it with a jumper to see if the strange buzz/tone would stop. I'd really like to learn about cb radio repair and put this radio back to stock. I have a mitral valve problem with my heart and I don't work so I have plenty of time on my hands. Also, transistor c2078 has a plastic bushing on the screw to keep the transistor from grounding to the heat sink, are the others that are mounted with screws supposed to have bushings too? If needed, I do have a digital volt meter, and soldering experience.73's
Hawk