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EPSON Stylus PHOTO 810/820/830 Revision B
Operating Principles Electrical Circuit Operating Principles 46
+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.