DAEWOO ELECTRONICS KOG-875T0S, Руководство по обслуживанию

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37
PRINTED WIRING BOARD
1.CIRCUIT CHECK PROCEDURE
1) Low voltage transformer (DMR-984FS) check.
The low voltage transformer is located on the P.C.B.
Measuring condition:
Input voltage: 230VAC/50Hz
2) Voltage Check
• Key check point (1~5: Micom Pin, 6: Display Pin)
• CHECK METHOD
Terminal
1 - 3
6 - 7
7 - 8
9 - 10
Voltage
230VAC /50Hz
10.5 VAC
10.5 VAC
2.6 VAC
1
9
8
7
6
10
3
5
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 +5VDC±5%
2 PIN 29, 32, 62 0V
3 PIN 28 +5 VDC
4 PIN 45
5 PIN 30, 31
6 PIN 1, 25 2.6 VAC (Display filament voltage)
NO. VOLTAGE
REMARK
KOC982T KOC984T/985T
1 +5 VDC Replace Q3, ZD2, R25, C12 Replace Q3, ZD3, R26, C10
2 +12 VDC Replace D2~D5, EC3, C11 Replace D7, D8, EC2, EC3, C14, C11
3 –24 VDC Replace D6, EC4, R28, R29, ZD4 Replace D9, D10, EC4, EC5, C15
NOTE :
The marks of the above corresponding voltages (+5, +12, –24VDC) are written on the PCB.
Each measuring points must be measured with GND points.
T
T
0V
0V
+5VDC
5V
T: 20 ms (50 Hz)
T: 0.25us (4.0MHz)
T=0.25us (4.0MHz)