Re: Samsung SyncMaster 226BW
Nice pictures. I have taken the liberty of thoroughly marking up the picture of the bottom side of the board. Note the points circled in red. The outputs of the transformers go to the connectors for the CCFL leads. The voltage is reduce by means of a capacitive divider. Note the leads connecting the points circled in red to the points circled in aqua, the second parts of the voltage dividers. Those are combined and fed to the inverter controller (circled in yellow).
Note the four connector pins circled in blue. Those are the return lines for the CCFLs. The voltage there is fed back to a circuit (also circled in blue - I was running out of nice colors) which combines the currents and feeds the sum back to the inverter controller.
Inverter controllers can monitor the voltage across the CCFLs and the current through them. Depending on the design they can shut down if any of the following conditions occur for any CCFL: Voltage to low; voltage too high; current too low; current too high.
The quick test I suggest is measuring the voltage at the return line. It should be under 1 volt. If any connector has a voltage that is lower or higher than the others, suspect a problem with the transformer, the CCFL, or the monitoring circuit.
PlainBill
Originally posted by SLBEngineer
Note the four connector pins circled in blue. Those are the return lines for the CCFLs. The voltage there is fed back to a circuit (also circled in blue - I was running out of nice colors) which combines the currents and feeds the sum back to the inverter controller.
Inverter controllers can monitor the voltage across the CCFLs and the current through them. Depending on the design they can shut down if any of the following conditions occur for any CCFL: Voltage to low; voltage too high; current too low; current too high.
The quick test I suggest is measuring the voltage at the return line. It should be under 1 volt. If any connector has a voltage that is lower or higher than the others, suspect a problem with the transformer, the CCFL, or the monitoring circuit.
PlainBill
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