Uniden PC-122 stumped

TBenny · Jan 29, 2016

So I got a Uniden PC-122 ssb for free and so I tried powering it on in my car but it didn't power on so I checked it out and it was hooked up to the battery backwards. I bridged a burnt copper trace on the board and replaced the destroyed reverse polarity diode with a IN4004 diode and tried it again. It powered on but it has no static or sound and it's hooked up in my car with antenna. I only get tx modulation in USB but only goes up to 2 bars when I met and talk into the Mic, keying the Mic in any other band AM,LSB and the TX indicator led flashes repeatedly. Also the channel indicator display is a little mess up, the picture is of it in 29. Any help or ideas of where to start troubleshooting or replacing parts?

sonoma · Jan 29, 2016

these little radios have a problem with bad solder joints when they have been setting for a while. do not know what equipment you have and your experiance of soldering but I have 3 of these of my own and all 3 had problems when I got them. touch up all the solder joints in the area of the heat shield on the bottom side . just looking at the picture you posted I saw several solder joints that look bad. also under the little shild on the bottom you will more than likely find bad solder joints. the traces are so close together you will need a fine tip solder iron to reflow the solder on the joints and not splash it over to other traces. I would try that 1st and see what starts come back.the LED read out looks to have some of the digits out also. it uses the same read out as a cobra 29 radio if you get that far of getting the radio to work.
the trc-453, pc122XL and trc-465 all have the same problem since its the same basic radio.

TBenny · Feb 1, 2016

sonoma said:
these little radios have a problem with bad solder joints when they have been setting for a while. do not know what equipment you have and your experiance of soldering but I have 3 of these of my own and all 3 had problems when I got them. touch up all the solder joints in the area of the heat shield on the bottom side . just looking at the picture you posted I saw several solder joints that look bad. also under the little shild on the bottom you will more than likely find bad solder joints. the traces are so close together you will need a fine tip solder iron to reflow the solder on the joints and not splash it over to other traces. I would try that 1st and see what starts come back.the LED read out looks to have some of the digits out also. it uses the same read out as a cobra 29 radio if you get that far of getting the radio to work.
the trc-453, pc122XL and trc-465 all have the same problem since its the same basic radio.

I touched up most of the solder joints and replaced some of the caps cause there old. The 7 digit display is still missing a section. I have another older cb a cobra 19 ultra also has problems, switching to pa turns it off and it has no sound. I replaced the final, caps, speaker and still no static, nothing

sonoma · Feb 1, 2016

you have 2 radios here now. which one turns off the radio in PA mode?
did you make any head way with the 122 radio after touching up solder joints?
you more than likely will have to change out the led on the 122 after you get it working. that is another problem they have with the stock meters. the led elements go out after a while.

TBenny · Feb 5, 2016

sonoma said:
you have 2 radios here now. which one turns off the radio in PA mode?
did you make any head way with the 122 radio after touching up solder joints?
you more than likely will have to change out the led on the 122 after you get it working. that is another problem they have with the stock meters. the led elements go out after a while.

Yeah the 122 works now I replaced the led and it seems to be working fine thanks for the help on that. the cobra 19 just doesn't output any sound the speaker is fine and all connections seem good.

Sideways · Feb 5, 2016

TBenny said:
Yeah the 122 works now I replaced the led and it seems to be working fine thanks for the help on that. the cobra 19 just doesn't output any sound the speaker is fine and all connections seem good.

Those cobra 19 ultras have small pcb boards mounted to the main pcb. Try pushing around on the small boards and see if sound comes back. They're known to have bad solder joints where the smaller board mounts to the main pcb.

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Uniden PC-122 stumped

TBenny

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sonoma

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TBenny

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sonoma

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TBenny

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Sideways

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