Emerson MW9107W, Service Manual

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24
1. CIRCUIT CHECK PROCEDURE
1. Low Voltage Transformer (DMR-602P) 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
PRINTED CIRCUIT BOARD
NO CHECK POINT REMARK
1 IC 1 PIN 7,41,42 -5 VDC
2 IC 1 PIN 11 GND
3 IC 1 PIN 23
4 IC 1 PIN 8 OR 9
NOTE :
Each measure point must be measured with GND points.
NOTE :
Secondary side voltage of the low voltage transformer changes in proportion to fluctuation of power source voltage
NOTE :
The allowable tolerance of the secondary voltage is within ± 5% of norminal voltage.
0V
4.3V
5V
0V
Terminal Voltage
4-7
LOAD
AC 12.6 V
NO LOAD
AC 14.7 V
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
T:16.7ms(60Hz)
T:250ns(4MHz)
1
2
5
4
3