Epson STYLUS COLOR 580, Service Manual

Page: 44 / 149

EPSON Stylus COLOR 580 Revision A
Operating Principles Electrical Circuit Operating Principles 44
Figure 2-17. C367PSB/PSE Board Block Diagram
The C367 PSB/PSE board has the various control circuits to stop voltage output if a
malfunction occurs on the power supply board or the main board while the printer
mechanism is on duty. Following explains each control and protection circuit.
o
+42V line constant voltage control circuit:
The output level of +42V line is monitored by a R92, R93,Q91,ZD51.
When + 42V line reaches about 42.5V, ZD51 has a continuity with and PC1 start
the operation via Q91. Consequently, Q1 switching operation is controlled by this
circuit to stabilize the 42V line.
o
+42Vline over voltage protection circuit:
The output voltage line is monitored by ZD52,ZD87. If the output level of the
voltage level of +42DC line e48V, this circuit stops the operation of the
switching FET Q1 via PC1,Q82,Q83 and prevents high voltage from applied to the
secondary side
o
+42Vline over current protection circuit:
The output voltage is monitored by the F51. When the abnormal current is
detected by F51, F51 is fused and cut off the +42V line output to the Main board
o
+5V line constant voltage control c5V line over current protection circuit:
The output level of the +5VDC line voltage is monitored by the regulator IC51. If
abnormal voltage is detected, the information is fed back to the internal
comparator.
o
+5V line over voltage protection circuit:
The output voltage level of the +5V line is monitored by ZD53.
If the output level of the voltage level of +5DC line e7V, this circuit
stops the operation of the switching FET via PC1,Q82,Q83and prevents high
voltage from applied to the secondary side.
F 1
C 1 1
L 1
D B 1
T R A N S ( T 1 )
O v e r C u r r e n t
P r o t e c t i o n
F i l t e r C i r c i u t
F u l l W a v e
R e c t i f i e r c i r c u i t
S m o o t h i n g
C i r c u i t
M a i n S w i t c h i n g
C i r c u i t
Q 1
A b n o r m a l
F e e d b a c k c i r c u i t
Q 2 , Q 3
P h o t o
C o u p l e r
P C 1
D 5 1
A C I n p u t
S m o o t h i n g
C i r c u i t
C 5 1
+ 4 2 V D C L i n e
C o n s t a n t C o n t r o l
R 9 2 , R 9 3 , Q 9 1 , Z D 5 1
+ 4 2 V D C L i n e
O v e r V o l t a g e
L i m i t a t i o n
Z D 5 2 , 8 7
+ 5 V R e g u l a t o r
I C 5 1
+ 4 2 V D C + 5 V D C
+ 5 V D C L i n e
O v e r V o l t a g e
L i m i t a t i o n
Z D 5 3
+ 4 2 V D C o v e r
c u r r e n t p r o t e c t i o n
F 5 1