148 GTL-DX problem

[mr_fx]

well I picked up this radio today for $10

however it does not turn on

voltage at ALL pins of driver, final, regulators, etc all all 13.8v positive... also the ground on the board is 13.8v positive

my gut says protection diode or something is shorted... (final driver?)

 

[Robb]

Chassis PB010 (late):
http://www.cbtricks.com/radios/cobra/148gtl_dx/graphics/cobra_148_gtl_dx_sm_pg33_34_sch.pdf

Chassis PC879 (early):
http://www.cbtricks.com/radios/cobra/148gtl_dx/graphics/cobra_148_gtl_dx_sm_pg04_05_sch.pdf

 

[mr_fx]

oh great two PCBs, guess I will mess with this AFTER work

 

[ExitThirteen]

Yep, I'd check the protection diode. and most likely if you can't turn it on, you probably took out the audio IC as well. Just repaired a Uniden PC68XL with this exact same problem... plugged it in, wouldn't turn on. Replaced the protection diode and the audio IC and it was rockin' again. Good luck!


~Cheers~

 

[mr_fx]

Yep, I'd check the protection diode. and most likely if you can't turn it on, you probably took out the audio IC as well. Just repaired a Uniden PC68XL with this exact same problem... plugged it in, wouldn't turn on. Replaced the protection diode and the audio IC and it was rockin' again. Good luck!


~Cheers~

yeah I noticed the audio IC has 13.8v + on all pins too,weirdest thing I have ever seen.

 

[mr_fx]

hmmm... protection diode is good, but even with it out the power still dumps to ground. Basically everything metal in the radio becomes hot (+) however with no power applied to the radio there does not appear to be a connection of any kind

Guess I will have to follow it from the power plug on down the chain until I find it