DAEWOO ELECTRONICS KOR-178HW, Service Manual

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26
1. CIRCUIT CHECK PROCEDURE
1. Low voltage transformer check
The low voltage transformer is located on the P.C.B.
Measuring condition: Input voltage: 120V / Frequency: 60Hz
2. Voltage Check
- Key check point
- Check method
NOTE
1. Refer to Circuit Diagram.
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
5-6-7
LOAD
AC 12.6 V
NO LOAD
AC 14.7 V
NO CHECK POINT REMARK
1 IC1 PIN 5 5VDC
2 IC1 PIN 8
3 IC1 PIN 35 OR PIN 36
T : 16.67ms(60Hz)
"#
$#
T : 250 ns(4MHz)
"#
$#
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, D11, D13, D14 NO LOAD
KOR- 1 78H