Power Supply Board - Epson LQ-1070 Service Manual

Second, there are four circuits to protect the supply circuitry and avoid danger. The +5 VDC line
contains a current overload protection circuit and a voltage overload protection circuit. The current
overload protection circuit is part of the + 5 VDC supply circuit. It cuts the + 5 VDC line if the current
is too great. The + 5 V voltage overload protection circuit cuts the supply if the voltage reaches or
exceeds + 7 VDC. It stops the switching circuit operation, which stops the output of the +35 VDC line.
The +35 VDC line has a voltage overload protection circuit and a voltage drop protection circuit. The
+35 V voltage overload protection circuit cuts the supply if the voltage reaches or exceeds +36 VDC.
It stops the switching circuit operation, which stops the output of the +35 VDC line. The voltage drop
protection circuit protects the printer from such damage as might occur from short circuiting in the
secondary circuitry of the +35 VDC line. If a voltage drop is detected, it stops the switching circuit
operation, which stops the output of the +35 VDC line.
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AC
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Power Supply Board

Figure 2-16. Power Supply Circuit Block Diagram
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Power
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