CASIO EX-259
Instrukcja Serwisowa

[PWD signal] After plug the AC cord into outlet, VP voltage appears on the base terminal of transistor Q3. When the VP exceeds 16 volts, Q3 is turned on by the differential voltage between base and emitter terminal of transistor Q3. Then the PWD signal goes to GND level and informes � Power ON � to the CPU. When the VP drops less than 16 volts, Q3 is turned off. Then the PWD goes high level since the PWD is pulled up to VDD. When the CPU receives � High � signal of PWD, CPU goes to � Power failure process �. Note : During plug the Ac cord into outlet, all voltages are supplied to the PCB. If you open the machine for repair, make sure plug off. [Location for voltage check points] Actual value on the E259-1 PCB (unitV)

Check point Power ON Power cord off

1 23.8(AC) 0

2 31.4 0

3 25.2 0

4 7.61 0

5 24 0

6 8.2 0

7 8.1 0

8 0.6 0

9 0 4

10 5 0

11 5.6 0

12 5 0

1

10

4 6 2 3 5 11

8 9

7

12

10