Printed Wiring Board; Circuit Check Procedure - Daewoo KOR-616T2S Service Manual

PRINTED WIRING BOARD

1. Circuit Check Procedure

1) Low voltage transformer (DMR-814FS) check.
The low voltage transformer is located on the P.C.B. Measuring condition: Input voltage : 220V
A
B
NOTE 1
: Secondary side voltage of the low voltage transformer changes in proportion to fluctuation of
power source voltage.
NOTE 2
: The acceptable tolerance of the secondary voltage is within ±5% of norminal voltage
2) Voltage check
Key check point (MICOM PIN)
NO. CHECK POINT
1 PIN 21,24,32,33 OR 34
2 PIN 48
3 PIN 44
4 PIN 18 OR 19
5 DP1 PIN 1& 25
CHECK METHOD
NO. MEASURE POINT
1
2
3
NOTE : Each measure point must be measured with GND points.
C
D
E
F
REMARK
-5VDC
-27VDC
5V
5V
2.6 VAC (DISPLAY FILAMENT VOLTAGE)
MP 1
MP 2
MP 3
Voltage
Terminal
C-D
E-F
0V
T
0V
T
WAVEFORM
-5V DC
-16V DC
-24V DC
39
Frequency : 60Hz
LOAD NO LOAD
-19VDC -24VDC
- 2.1VDC - 2.2VAC
T: 20ms (50 Hz)
T: 250ns
REMARK
REPLACE Q4, EC2
REPLACE R6, EC3
REPLACE D12, D13, EC4