Pvision EPM-4200B power supply question

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Croxley

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Sep 10, 2014
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Hi. I have a Pvision EPM-4200B Plasma Monitor. The monitor switches on and off again after a few seconds. No picture appears on the monitor. I opened the monitor and found inside that it uses a LG screen. I found two 680uF/250V capacitors that are swollen on the ZSUS board (LG part number 6871QZH030B). I also found shorts between the outputs of the module on the YSUS board (LG part number 6871QYH027B ) and GND. So that module is faulty. I did not find any shorts on the ZSUS board. I then completely disconnected the YSUS and ZSUS boards from the rest of the monitor and measured the VS and VA outputs from the power supply. The VA voltage was correct according to the label attached to the screen, but the VS voltage was 165V instead of 190V. I can get a new YSUS board at a not too bad price and then replace the two swollen capacitors on the ZSUS board with capacitors from the faulty YSYS board. They have the same values and should work. My question is about the VS voltage that is lower than what it should be. Does that mean that there is a fault with the power supply as well or is the voltage lower because the YSUS and ZSUS boards are disconnected and therefore the VS output is not driving anything?
 
Solution
Darkbreeze
Available voltage should not decrease because a part is missing or disconnected. Voltage requirements to push through a set amount of resistance may INCREASE when connected as per Ohms law, but the available voltage at any specific testing site should not be decreased by anything further along in the circuit being disconnected. If your power is below spec at the circuit it is likely due to a failure or a lack of sufficient supply. Most likely voltage regulation in the power supply is faulty. Make sure you're not connected to any power strips or UPS units while testing.
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Darkbreeze

Darkbreeze

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Jun 24, 2014
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Available voltage should not decrease because a part is missing or disconnected. Voltage requirements to push through a set amount of resistance may INCREASE when connected as per Ohms law, but the available voltage at any specific testing site should not be decreased by anything further along in the circuit being disconnected. If your power is below spec at the circuit it is likely due to a failure or a lack of sufficient supply. Most likely voltage regulation in the power supply is faulty. Make sure you're not connected to any power strips or UPS units while testing.
 
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