49
1. CIRCUIT CHECK PROCEDURE
1) Low Voltage Transformer (DMR-604FS) Check.
The low voltage transformer is located on the P.C.B.
Measuring condition : Input voltage ; 220V
Measuring condition :
Frequency ; 60Hz
2) Voltage Check
KEY CHECK POINT
CHECK METHOD
PRINTED CIRCUIT BOARD
1
10
8
7
6
2
Voltage
LOAD
NO LOAD
Terminal
6 -
1
7
24V
30V
8 - 10
2.4V
2.5V
NO.
CHECK POINT
REMARK
1
IC1 PIN 6,10,11
-5VDC
2
IC1 PIN 1
-20VDC
T: 20 ms (50Hz)
3
IC1 PIN 22
4
IC1 PIN 8 or 9
5
DP1 PIN 1 & 25
2.4VAC (DISPLAY FILAMENT VOLTAGE)
NO.
MEASURE POINT
WAVEFORM
REMEDY
REMARK
(See Page 51.)
1
MP 1
DC -5 ± 0.25V
Replace ZD2, EC1, EC2
NO LOAD
3
MP 2
DC -30 ± 1.0V
Replace R21, ZD3
NO LOAD
3
MP 3
DC -27 ± 1.0V
Replace R21, R22, EC5
NO LOAD
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.
NOTE : Each measure point must be measured with GND points
T
T
0V
0V
- 5V
-14V
T:250nS
T : 250ns
T:16.67ms (60Hz)
