| Author |
Message |
    
Jimmyhoffa
Junior Member
Username: Jimmyhoffa
Post Number: 10
Registered: 1-2021
| | Posted on Monday, March 07, 2022 - 3:59 pm: | 
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i recieved a trs challenger in a deal... doesnt power on from the wall cord...i have tested the cord comming in for voltage... 124v ac ...then out of the transformer is where it goes weird.. i would think it would be DC volltage...supposed to be 20v unregulate and 13.8 regulated.. i get like 17v but have to not have a ground... i also record like 4v ac on the case side... but if i inject 12v to the main board where its supposed to come from the rectifer the radio will light up... but seems backwards..like on is off and off is on... someone sloppily installed a expo kit(extra channels) i want to remove that... can i just unsolder or cut it out of the radio ...or are they inline with something? thanks |
Tech833
Moderator
Username: Tech833
Post Number: 2515
Registered: 8-2002
| | Posted on Monday, December 05, 2022 - 1:53 pm: |
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Check the transformer output. Should have something between 13 and 26 volts or so (AC). Assuming you have 17 volts or so of AC on the transformer out, check the diodes. You should have around 20 volts DC on the output of the diodes (bridge rectifier). Assuming that is good, move to the voltage regulator(s). You should have something over 13 volts going in, and around 12-13 volts DC coming out.
Most likely, one of the filter capacitors has shorted or gone very leaky and took out a component or two.
Your radio 'Mythbuster' with Copper Electronics since 1998
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Jimmyhoffa
Junior Member
Username: Jimmyhoffa
Post Number: 15
Registered: 1-2021
| | Posted on Monday, January 30, 2023 - 12:21 am: |
|
Well it was the transformer, just a little update.. using a laptop power supply at the moment untill I can either repair or find a Nos transformer for it . Thank for the help! |
