DAEWOO ELECTRONICS KOC-995T0S, Service Manual

Page: 42 / 52

41
PRINTED WIRING BOARD
1. CIRCUIT CHECK PROCEDURE
1. Low Voltage Transformer check
1) The low voltage transformer is located on the Base.
2) Measuring condition (input voltage) : 230 VAC / 50 Hz
·
Secondary side voltage of the low voltage transformer changes in proportion to
fluctuation of
power source voltage.
·
The allowable tolerance of the secondary voltage is within
±
5% of normal voltage.
2. Voltage check
·
Key check point ( 1~5:Micom Pin, 6:Display Pin )
·
Check method
KOC-995T 0S/KOC-995T0S11
LVT : DMR-881FS1
Terminal Voltage
1 3 230VAC/50Hz
6 - 7 14.0 VAC
7 - 8 14.0 VAC
9 10 2.0 VAC
NO CHECK POINT REMARK
1 PIN 63, 64
+5 VDC
±
5%
2 PIN 29, 32, 62 0 V
3 PIN 28 +5 VDC
4 PIN 45 T : 20ms (50Hz)
5 PIN 30, 31 T : 0.25us (4.0MHz)
6 PIN 1, 25 2.0 VAC(Display filament voltage)
NO VOLTAGE KOC-995T 0S/KOC-995T0S11
1 +5 VDC Replace R24, R15, R25, ZD3, EC2, Q3, C10, C11, C12
2 +12 VDC Replace D4, D5, EC3, C16
3 +11.3 VDC Replace R35, ZD4, Q11, EC6, C17
4 -24 VDC Replace R34, ZD1,ZD5, D6, D7, EC4, EC5