Service manual

58
1. CIRCUIT CHECK PROCEDURE
1) Low Voltage Transformer (DMR-604P) Check.
The low voltage transformer is located on the P.C.B.
Measuring condition : Input voltage ; 120V
Measuring condition : Frequency ; 60Hz
2) Voltage Check
KEY CHECK POINT
CHECK METHOD
PRINTED CIRCUIT BOARD
110
8
7
6
2
Voltage
LOAD NO LOAD
Terminal
6 - 17 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: 16.67 ms (60Hz)
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 45.)
1 MP 1 DC -5 ¡ 0.25V Replace ZD2, EC1, EC2 NO LOAD
3 MP 2 DC -24 ¡ 1.0V Replace R22, R25 NO LOAD
3 MP 3 DC -30 ¡ 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 norminal voltage.
NOTE : Each measure point must be measured with GND points
T
T
0V
0V
-5V
-14V
T:250nS