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Uniden pc122xl no tx or rx


Not a heck of a lot to go on. Could be a dead PLL. Could be corrosive glue ate one or both leads off the 10.240MHz crystal. Possibly the 8 volt regulator fried. Or maybe just a bad cap somewhere.

Not trying to be a jerk, that just comes naturally, but the more detail you can provide the easier it will be for the site members to offer suggestions on where to start looking.
 
Hi
Just looking for a few hints as to where i should start i found one bad cap but that didnt fix it i dont know how to fault find all i know there is no tx no rx checked mic seems ok channel display comes on no tx light when i key up
I have Very limited electronic experience
Thanks joe
 
Hi
Just looking for a few hints as to where i should start i found one bad cap but that didnt fix it i dont know how to fault find all i know there is no tx no rx checked mic seems ok channel display comes on no tx light when i key up
I have Very limited electronic experience
Thanks joe
Does the S-meter move at all when connecting to an antenna and checking out the different channels? This is with RF Gain all the way to the right.
If there's some activity on the S-meter then it is likely to be receiving.

The reason your tx lamp is not lighting up could because you're using a microphone that's not correctly wired for the radio. That could also explain "no sound"..

Just guessing and starting by the most simple reason.
 
Hi
Just looking for a few hints as to where i should start i found one bad cap but that didnt fix it i dont know how to fault find all i know there is no tx no rx checked mic seems ok channel display comes on no tx light when i key up
I have Very limited electronic experience
Thanks joe
You can find the schematic here: https://cbtricks.org/radios/uniden/pc_122xl/graphics/uniden_pc122xl_sch.pdf

Some really basic checks.

Is the 8 Volt regulator working? IC4 pin 1 should be at 8 Volts as long as power is applied. It's a L7808 three pin regulator.

Is the 10.240MHz reference signal working? Should be on pins 12 and 13 on IC2, which is the PLL. It's a uPD2824 22 pin DIP IC.

Either one of these could cause the symptom you're seeing. Or like 19wrc333 said, an incorrectly wired mic could do it.
 

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