Introduzione
I was given a Proscan 32LB30Q flat screen LCD TV that was described as working intermittently less and less over time.
When I plugged in the TV, after vacuum cleaning and wiping down with 91% Isopropyl alcohol and a damp towel, I found the red LED on the face of the TV by the power On button comes on and I here a relay click in the middle back.
When I pressed the power button, I heard the speakers make a brief low volume static noise that goes silent and then the previously red LED flashes blue seven times and then stays solid blue with nothing other than a black screen the whole time.
When I cleaned the system... I did notice what looked like discoloration above and maybe on two of the transformers (top two) on the CCFL power supply or maybe is called an inverter board more accurately. I didn't notice any leaking or bulging caps or burn marks anywhere else on any of the other boards.
The Power Supply Board voltages outputs were in specification. However, the CCFL Inverter Board input at the connector was found to have the MOD-SEL PWM reading 4.0V and the BLON wire reading 0.0V.
After testing the BLON (red) wire during the power on process, I found the voltage reading went up to 4.9V after pressing the ON button and then before the second blue LED blink, and around the time of the audio static noise, the reading went back to 0.0V.
The T-Con and Main Board will also be described regarding how to replace thanks to others feedback regarding replacement when a sound is present during, and primarily no display on, startup.
I found in the above noted scenario, after replacing the Inverter and T-Con board with no change in effect, the Main Board required replacemen and the original Inverter and T-Con boards were left.
Strumenti
Ricambi
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Be sure to unplug the TV from the power outlet.
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Lay TV face down on a flat clean surface.
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Remove back cover screws using the #3 Phillips head screw driver.
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Remove the four base stand screws using the #3 Phillips head screw driver.
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Remove stand by sliding out.
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Remove back cover by lifting off.
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Clean the inside, and outside if not already, of the back cover using a damp towel and vacuum first if heavily soiled. I prefer to use a towel dampened with 91% isopropyl alcohol.
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Inspect components for burn marks, bulging capacitors and loose connections. Note observation(s) for future reference.
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Remove the inverter board screws using a #3 Phillips head screwdriver.
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Carefully disconnect the connections to the inverter board, unless only changing the T-Con Board where you then can proceed to Step 4 for further instructions.
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Remove the inverter board and replace with a functional inverter board that meets the original board manufacturer specifications (same model board or recommended replacement).
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Remove the T-Con board cover screws using a #3 Phillips head screwdriver. You will also need to remove the 4 screws holding down the main board bracket and slide the bracket down to access the remaining 2 T-Con board cover screws.
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Carefully disconnect the connections to the T-Con board.
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Remove the T-Con board and replace with a functional T-Con board that meets the original board manufacturer specifications (same model board or recommended replacement).
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Remove the Main board screws holding the face of the external connectors using a #3 Phillips head screwdriver. You will also need to remove the 4 screws holding down the main board.
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Carefully disconnect the connections to the Main board.
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Remove the Main board and replace with a functional Main board that meets the original board manufacturer specifications (same model board or recommended or suitable replacement).
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Follow the directions in reverse to replace the back cover and stand using all the screws where originally found.
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To reassemble your device, follow these instructions in reverse order.
2 commenti
I have the same exact tv doing the same exact thing. I have not taken it apart or anything yet, but was wondering if you found it necessary to change all of these boards or was it done as a process of elimination? I just don't want to buy them all unnecessarily if I really only need to replace one. Any info you can give would be greatly appreciated.
Jenny -
@jrsummersill1 My experience at the time based on my limited knowledge regarding what I "thought"; so yeah, process of elimination.
Looking back at what info I have, the situation seems to be this is a mainboard with the EEPROM having issues and needing that EEPROM to be replaced which can be finicky so you don't damage. I've not done a EEPROM repair yet and haven't worked on the TV's for a few years since improving my skills where my goal was to practice on free TV's first.
I also see there is a note for all the found main board different part numbers listed when searching "Proscan 32LB30Q" on Shopjimmy.com noting and I'll post here: "Part number can be found on a sticker. Please Note: This board has a jumper at CN4 that can either be set at 5V or 12V depending on the panel. Please make sure your voltage is set correctly, if not there will be no display on the tv." Good to know for future reference.
I'd contact Shopjimmy and see what they think. Their customer service is excellent even when you don't order anything.