EPSON Stylus PHOTO 810/820/830

Revision B

†+42Vline over voltage protection circuit :

The output voltage line is monitored by ZD52 and ZD87. If the output voltage level of +42VDC line exceeds +48V, this circuit stops the operation of the switching FET Q1 via PC1,Q82 and Q83, and prevents high voltage from being applied to the secondary side.

†+42VDC line drop limitation circuit :

PC1 drives with +36V and ZD90 is monitoring the voltage supplied to PC1. If the supplied voltage level exceeds 36V, this circuit shuts down the +42V line temporarily and prevents the over voltage from being applied to the PC1.

†+42Vline over current protection circuit :

The output current level is monitored by the F51. When the abnormal current is detected by F51, F51 blows and cuts off the +42V line output to the Main board.

†+5V line over voltage protection circuit :

The output voltage level of the +5VDC line, which is generated on the C483/C484 Main-B board, is monitored by ZD53.

If the output voltage level of +5DC line exceeds +7V, this circuit stops the operation of the switching FET Q1 via PC1,Q82 and Q83, and prevents high voltage from being applied to the secondary side.

*+5V line constant voltage control circuit/+5V line over current protection circuit is not on the P/S board because the regulator IC51 is not installed.

Operating Principles

Electrical Circuit Operating Principles

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