KPOWERSCIENCE KP3828 Series, Maintenance Manual

Page: 205 / 230

8-33
[2A No toner]
Procedure Points to be checked Remedy Checking method
1 Is there enough toner in
the developing unit? If YES, go to 2.
If NO, replenish
toner with the
toner-filling
cartridge.
When there is not enough in the
developing unit, an oscillation sound is
emitted by the toner empty sensor.
2 Is the KMPU board
normal? If YES, go to 3.
If NO, replace the
KMPU board.
Bring the positive lead of a digital
multimeter in contact with pin 2 of U39
(LM339MA) of the KMPU board and
the negative lead in contact with SG
(J7), and measure the voltage when the
“No Toner” error is output.
If normal, the voltage will be
approximately 5 V.
3 Is the toner empty
sensor circuit normal? If YES, go to 4.
If NO, replace the
KMPU board
(malfunction of the
toner empty sensor
circuit).
Remove jack J6 from CN6 of the
KMPU board and bring the positive
lead of a digital multimeter in contact
with pin 2 of U39 (LM339MA) of the
KMPU board and the negative lead in
contact with SG (J7), and measure the
voltage.
If normal, the voltage will be
approximately 0 V when the power is
turned on, and will be approximately 5
V when pin 19 of CN6 of the KMPU
board and pin 19 of U32 (ADC0804)
are shorted.
4 Is the developing unit
normal? If NO, replace the
developing unit
(toner sensor unit is
abnormal). Connect CN6 of the KMPU board.
Bring the positive lead of a digital
multimeter in contact with pin 2 of U39
(LM339MA) of the KMPU board and
the negative lead in contact with SG
(J7), and measure the voltage.
Confirm that there is enough toner in
the developing unit and perform the
toner supplying operation twice.
If normal, the voltage will be
approximately 0 V.