Sharp JX-8200 Service Manual page 76

SHARP SERVICE MANUAL JX8200SM [8] ADJUSTMENTS
(2) Details
1) Enter the normal diag mode and select the VOL TEST MAIN CH
mode with the MENU key.
2) Press the FORM FEED key to turn on the main charger. It can be
turned off by the RESET key.
3) Measure between the main charger grid voltage electrode and the
ground (chassis) with the digital multi meter.
4) Check that the voltage is within the range below.
–645V ±7V
If the current is not in the above range, perform the following
procedures.
* Check for any current leak or disconnection.
* Replace the high voltage PWB or the OPC drum unit.
(3) Precaution
* Be careful of the high voltage when checking.
(4) Troubles generated by abnormal output
* Picture quality defect
* Developer drop (splash)
C. Developing bias voltage check
(1) Outline/purpose
In the diag mode and the print mode, let the developing bias voltage
to be outputted, and check that the proper voltage is outputted.
The voltage in the diag mode serves as the base developing bias
voltage.
In an actual print operation mode, there are two output modes and
the corrected voltage is outputted.
A voltage of –250 ∼ 550V is outputted to the developing unit which is
in developing operation.
A voltage of –420 ∼ –681V is applied to the developing unit which is
not in developing operation.
Check must be performed for the developing operation mode and non
developing operation mode.
(2) Details
(Non developing operation mode)
1) Enter the normal diag mode and select VOL TEST MAIN CH
mode with the MENU key.
2) Select the (BL/CD/MD/YD) BIAS mode with the ü key and é key.
3) Press the FORM FEED key to turn on the developing bias. It can
be turned off with the RESET key.
4) Set the output level to 400 with the ü key and é key.
5) Measure between the developing bias output (the color selected
in 2)) on the high voltage PWB and the ground (chassis) with the
digital multi meter.
6) Check that the current value is within the range below.
–400V ±20V
If the current is not in the above range, perform the following
procedures.
* Check for any current leak or disconnection.
* Replace the high voltage PWB or the OPC drum unit.
(Developing operation mode)
1) Perform printing in the full color mode.
2) Measure between the developing bias output (Y/M/C/BL) on the
high voltage PWB and the ground (chassis) with the multi digital
meter.
3) Check that –250 ∼ –550V is applied to the developing unit which
is in the developing operation.
If the voltage is not within the above range, perform the following
procedures.
* Check for any current leak or disconnection.
* Replace the high voltage PWB or the OPC drum unit.
(3) Precaution
* Be careful of the high voltage when checking.
(4) Troubles caused by improper output
* Picture quality defect
* Developer drop (splash)
D. Transfer voltage check
(1) Outline/purpose
In the diag mode, let the transfer voltage to be outputted, and check
that the proper voltage is outputted.
The voltage outputted in the diag mode serves as the base voltage.
In an actual print operation mode, the corrected voltage (1000 ∼
2800V) is outputted.
9 – 2
BL
C
M
Y
BL
C
M
Y