Daewoo KOC-870T0S, Service Manual, Page: 33 / 43

32
PRINTED WIRING BOARD
1.CIRCUIT CHECK PROCEDURE
1) Low voltage transformer (DMR-101FS) check.
The low voltage transformer is located on the P.C.B.
Measuring condition:
Input voltage: 230VAC/50Hz
2) Voltage Check
KMICOM PIN>
DISPLAY PIN
CHECK METHOD
Terminal
1-2
4-5
6-7
8-10
Voltage
230.0V
13.0V
35.0V
3.0V
1 4
5
6
7
8
10
2
NOTE 1 : Secondary side voltage of the low voltage transformer changes in proportion to fluctuation of power
source voltage.
NOTE 2 : The allowable tolerance of the secondary voltage is within
¡
5% of nominal voltage.
NO. CHECK POINT REMARK
1 PIN 63, 64 0V
2 PIN 29, 32, 62
-
5VDC
¡
5%
3 PIN 45
4 PIN 30, 31
NO. MEASURE POINT WAVE FORM REMARK
1 MP 1
-
5V DC Replace R24, J3, Q10
2 MP 2
-
12V DC Replace D1~D6, J8
3 MP 3
£›
27V DC Replace R28, R29, ZD4
NOTE :
Each measure point must be measured with GND points.
T
-5V
0V
T: 20 ms (50 Hz)
T
0V
5V
T=0.25us (4.0MHz)
PIN 1 & 25 2.6VAC (Display filament voltage)