DAEWOO ELECTRONICS KOG-371G0S, Service Manual

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63
1. CIRCUIT CHECK PROCEDURE
1. Low voltage transformer check
The low voltage transformer is located on the P.C.B.
Measuring condition: Input voltage: 230V / Frequency: 50Hz
2. Voltage Check
- Key check point
- Check method
NOTE
1. Refer to Ciruit Diagram (point 4).
2. Secondary side voltage of the low voltage transformer changes in proportion to fluctuation of power source
voltage.
3. The allowable tolerance of the secondary voltage is within ± 5% of nominal voltage.
NOTE
Each measure point must be measured with GND points.
Terminal Voltage
4-7
LOAD
AC 25.8 V
NO LOAD
AC 28.4 V
PRINTED CIRCUIT BOARD
<KOG-371G/H0S, KOG-391G/H0S, KOG-86AH7S/86CH7S/86AH7P/90AH>
NO CHECK POINT REMARK
1 IC1 PIN 2, 21, 30, 34 -5VDC
2 IC1 PIN 35
3 IC1 PIN 31 OR 32
T : 20ms(50Hz)
T : 16.7ms(60Hz)
(KOR-86AH7P/90AH)
T : 250 ns(4MHz)
0V
T
—5V
NO MEASURE POINT WAVE FORM REMEDY REMARK
1 MP1 DC -5V±0.25V Replace VL1, EC1 NO LOAD
2 MP2 DC -12V±2.0V Replace EC2, D12,13,14 NO LOAD