~.
i
1 [
f i
II
I
-
r I
!
(5)
Overcurrent
protect
circuits
• +5V overcurrent protect circuit
The
voltage proportionate
to
the
output
current
is
created
in
R24. When it becomes equal
to
the
voltage
difference with R15 and VR4, it starts
to
restrict
the
current.
As
this causes
the
output
voltage
to
drop, it
also
reduces
the
R 15 and V
R4
voltage. (Fig.
6)
• +12V overcurrent protect circuit
The
voltage proportionate
to
the
output
current
is
created
in
R36. When it becomes equal
to
the
voltage
difference with
VBE
of
Q11
(R37 voltage), it starts
to
restrict
the
current.
As
this causes
the
output
voltage
to drop, it also reduces
the
R37 voltage. (Fig. 7)
R24
...
.1'\
R15
R23
15
M1
PVR4
"'C9
16
-
~
R16
-
Fig.6
+5V
overcurrent
protect
circuit
R36
R39
161-+-
...... --«:
M2
C16
151--+---+---'
Fig. 7 +
12V
overcurrent
protect
circuit
(6)
ALARM
signal
ON
~ACI'P",
OFF
OFF
i------+-----..,L4.5V
VCC_-----'I
1
Om
seC
7msec
1--------1
[ALARM
-'-'~...£....£...c...L.J
__
....J
Fig.8
ALARM signal sequence
+5V
07
,....----0.
ALARM
08
R43
Fig.9
ALARM signal circuit
-81-
-
MZ-5600
The signal ALARM
is
a signal
that
has a sequence
shown
in
Fig. 7. The input voltage
is
detected by
the
voltage which
the
power transformer secondary side
is
rectified,
to
create
the
signal ALARM. (Figs. 8 and 9)
The rising edge
is
delayed
at
power on by
the
network
composed
of
R40 and C21, and it
is
determined by the
discharge
of
C21, R41, R42, and VR3
at
power off .
(7) Adjustments
VR1 +5V
voltage adjustment:
5V
i
0.02V
VR2
+ 12 V
voltage adjustment:
+12V
i
0.05V
VR4
+5
V
output
current adjustment:
9.2
AiO.2
A
VR3 ALARM adjustment:
5ms
faster
than 5V
falling edge
16-3 Troubleshootings
(1) Hints and tips
Check
the
following points
to
achieve faster trancing
of
trouble cause.
1)
Do
not
try
to
remove
the
printed board at first.
Visually check open wire,
contact
failure, and im·
properly soldered wire,
or
burnt
resistor, etc.
2) Unfasten
the
power input connector (V1, V2: CN5)
and check for any
failure such
as
a failure
in
the
primary side
of
the
power transformer.
3) Observe
the
following causing
in
removing
the
printed board.
• Screw tightening
torque
• Tightening
torque
for
the
screw used
to
secure
electronic
component
with the chassis:
4kgfcm
• Tightening
torque
for
other
screws:
6 kgfcm
• Take care not
to
open
the
jumper (JP-1)
that
used between printed board.
• Handle
the
insulation sheet with care.
4)
Have
the
following tools ready.
• Oscilloscope
•
200
VAC power supply regulator (SLlDAC)
• Voltmeter
(1-50
VACIVDC)
•
Ammeter
(0.1-15
amperes AC/DC)
•
Dummy load (or
CPU
unit)
• Power supply transformer
To Next Page
Loading...
Need help?
General
