Specifications

REV.-A
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 +5 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.
Power Supply Board
r------------------------------------------------------------------------
Primary
r-l
Filter
Circuit
Switching
Circuit
t t
i Secondary
I
I
,
I
-D +5 VDC
I I
I
I
I
I
+5 line
I
Voltage
Overload
I
Protection
I
I
Circuit
,
Overload
I
I
Protection
I
Circuit
I
I
L - -35 VDC
! - Power
1
Switch
1
t
AC Input
Figure 2-16. Power Supply Circuit Block Diagram
2-12