18
R-1750
R-1751
R-1752
R-1754
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
Description of main parts
SYMBOL
PART NAME
FUNCTION
C11, C12
High voltage capacitor
High voltage capacitor for doubler circuit.
C2
Film capacitor
To smooth line ripple
C3
Film capacitor
Capacitor for resonant
CT1
Current transformer
To detect power current
D1
Bridge Diode
To rectify full-wave of power supply
D11, D12
High voltage diode
Full wave voltage doubler
IC1
Integrated Circuit (IC)
Inverter circuit controller
L2
Choke Coil
To smooth line ripple
Q1
Transistor
Power transistor for switching
Q2, Q3
Transistor
To drive transistor Q1 ON-OFF
T1
High voltage transformer assembly
High voltage transform for high frequency
Test procedure
1. Power transistor Q1
Check the transistor Q1 by using ohm-
meter as shown in Figure B-2
If transistor Q1 is defective exchange
Q1.
Check the bridge diode D1, transistor
Q2 and transistor Q3 by using ohm-
meter and replace them if they are
defective.
NOTE: When a digital ohmmeter is
used, reverse the connection
of ohmmeter leads against
Figure B-2.
2. High voltage diode D11 and D12
Check these diodes by using ohmme-
ter as shown in Figure B-2.
If one of the diode is shorted, ex-
change both diodes D11 and D12.
NOTE: When a digital ohmmeter is
used, reverse the connection
of ohmmeter leads against
Figure B-3.
Figure B-3. Check for high voltage diode D11 & D12
3. Bridge diode D1
Check the diode D1 by using ohmme-
ter as shown in Figure B-4.
If the diode D1 is defective, exchange
D1 and power transistor Q1 at same
time (Q1 is defective)
NOTE: When a digital ohmmeter is
used, reverse the connection
of ohmmeter leads against
Figure B-4.
Figure B-4. Check for bridge diode D1.
+
0
∞
20
OK
NG
x 1
Ω
OK: Normal
NG: Defect
G C E
(G, E)
(C)
Q1
-
UX-F0B
D11
UX-F0BL
D12
Anode
Cathode
+
0
∞
20
OK
NG
x 1
Ω
OK: Normal
NG: Defect
-
Yelow
color
White
color
Figure B-2. Check for Power Transistor Q1
+
0
∞
20
OK
NG
x 1
Ω
OK: Normal
NG: Defect
+
-
D1
-
+
-
and