NEC MultiSync LCD1550ME Service Manual page 105

(5) H.V and balance circuit
The H.V connect to the lamps and supply the power to drive the lamps. The balance circuit is use L,C,R
resonant to control the output current. It can get the same output current even the load is different.
(6) Feedback circuit
The sense voltage of the feed back is set at 2.5 voltage. And the IC compare the sense voltage with
output current, and release the control signal to PWM.
(7) Protection circuit
The protection circuit is sense the output current and abnormal signal to protect the inverter.
(a) For output current
The protect circuit will be monitor the lamps current. If the lamps current is correct, it will be allow the
inverter to operating continually. In other ward if the lamps current is abnormal it will be shutdown the
inverter.
(b) For other abnormal signal in the inverter.
We sense the abnormal signal from PWM and Royer stage. If something wrong at power stage, the
protect circuit will be shutdown the inverter.
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