So, this is probably very similar to a number of threads regarding similar L##WD12 series RCA TVs with bum power supplies but I just want to confirm my initial diagnosis.
What I know:
- Pressing power button causes 1W SMPS relay to switch over, power LED blinks red.
- 1W SMPS 5.3V standby voltage appears to be good, drops to zero though when relay clicks
- Main PSU is getting AC when relay switches
- Main PSU PS_ON rail is getting 3.13V, neither 5V or 24V rails are coming up though.
- Applying 3.3V to PS_ON on the main SMPS does not cause the backlight or display to come on.
- No caps on 1W or main SMPS board are bulged or deformed in any way. Murphy's law dictates that my LCR meter needs a new battery, and I don't have an ESR meter either.
What I think is the problem:
- Could be the 1W SMPS output dropping when the mainboard tries to power up the main PSU, or it could be just an effect of it not having the main SMPS to back the 5V rail when it should.
- Main SMPS more likely the problem, since it still should power up once you apply voltage to PS_ON.
- Could potentially be either the 150uF 450V cap, or the +5V/+24V output caps that are bad since they're probably the most likely to be underspecced for ripple current/ESR. I have Digikey PN's for replacements with better specs than the SAMXON capacitors used but I'm holding off until I have a clearer idea if its the caps or not.
Now, I really hope it isn't another component buried in the SMPS since I only took this TV off a coworkers hands for free - he'd rather see it repaired and not landfilled. I'm only able to put so much time and money into it before I'll wash my hands of it as well though. Hoping the community here has some more specific thoughts.
What I know:
- Pressing power button causes 1W SMPS relay to switch over, power LED blinks red.
- 1W SMPS 5.3V standby voltage appears to be good, drops to zero though when relay clicks
- Main PSU is getting AC when relay switches
- Main PSU PS_ON rail is getting 3.13V, neither 5V or 24V rails are coming up though.
- Applying 3.3V to PS_ON on the main SMPS does not cause the backlight or display to come on.
- No caps on 1W or main SMPS board are bulged or deformed in any way. Murphy's law dictates that my LCR meter needs a new battery, and I don't have an ESR meter either.
What I think is the problem:
- Could be the 1W SMPS output dropping when the mainboard tries to power up the main PSU, or it could be just an effect of it not having the main SMPS to back the 5V rail when it should.
- Main SMPS more likely the problem, since it still should power up once you apply voltage to PS_ON.
- Could potentially be either the 150uF 450V cap, or the +5V/+24V output caps that are bad since they're probably the most likely to be underspecced for ripple current/ESR. I have Digikey PN's for replacements with better specs than the SAMXON capacitors used but I'm holding off until I have a clearer idea if its the caps or not.
Now, I really hope it isn't another component buried in the SMPS since I only took this TV off a coworkers hands for free - he'd rather see it repaired and not landfilled. I'm only able to put so much time and money into it before I'll wash my hands of it as well though. Hoping the community here has some more specific thoughts.
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