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MX-M753N  ADJUSTMENTS AND SETTINGS  5 – 4

8)

Loosen the fixing screws of the developing roller main pole
adjusting plate, and make adjustments by moving the adjust-
ing plate in the arrow direction.

Repeat steps 3 to 6 until the developing roller main pole meets the
positional requirement.

 

* When developer is replaced.

NOTE:
• Be sure to execute this adjustment only when developer is

replaced. Never execute it in the other cases.

• When setting the toner density control reference value, pull out

the toner cartridge in advance.

• When not replacing the developer, do not execute SIM25-2.

1)

Remove the toner cartridge from the machine.

2)

Turn ON the power with the front cabinet open.

3)

Enter the SIM 25-2 mode.

4)

Close the front cabinet.

5)

Press [EXECUTE] key.
The key is highlighted. The developing roller rotates and the
toner density sensor detects the toner density, and the output
value displayed.
After execution of the above operation for 3 minutes, the aver-
age value of toner density sensor detection levels is set
(stored) as the reference toner density control value.
When the reference toner density control adjustment operation
is completed, [EXECUTE] key returns to normal from highlight.
This makes known about whether the adjustment operation is
completed or not.
NOTE:
If the operation is interrupted within 3 minutes, the adjustment
result is not reflected.
When [EXECUTE] key is pressed during rotation, the opera-
tion is stopped and [EXECUTE] key returns to the normal dis-
play.
If [EE-EU], [EE-EL] or [EE-EC] is displayed, setting of the ref-
erence toner density control value is not completed normally.

6)

Cancel SIM25-2, and install the toner cartridge.

 

NOTE: For adjusting the output voltage, use a tool which can mea-

sure the effective value of 1000M

 internal impedance.

Also use a high voltage probe together. 
(FLUKE87FLUKE80K-40 is recommendable.)

 

This adjustment is needed in the following situations:
* When the high voltage PWB is replaced.
* U2 trouble has occurred.
* The PCU PWB has been replaced.
* The EEPROM of the PCU PWB has been replaced.
* When the picture quality is abnormal.
1)

Remove the rear cover of the machine.

2)

Enter the SIM 8-2 mode.

3)

Select the middle speed mode.
When the adjustment value in the middle speed mode is set,
the adjustment values of the other modes are automatically set
accordingly in correlation.
To adjust an each mode individually, first adjust the middle
speed mode, then adjust the other modes.
If the middle speed mode adjustment is executed after adjust-
ment of the other mode, the adjustment value of the other
mode is automatically set. Be careful of that.

4)

Apply a digital multi-meter between the high voltage PWB con-
nector CN2 pin (3) and the chassis GND.

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Sensor output level less than 26, or 
sensor control voltage level over 197

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EU abnormality

Sensor output level over 200, or sensor 
control voltage level less than 49

EE-EC

EC abnormality

Sensor output level: Out of 108 

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MX-M753N  ADJUSTMENTS AND SETTINGS  5 – 5

5)

Press [EXECUTE] key.
The main charger grid voltage is outputted for 30sec.
If this operation is executed for a long time, the OPC drum may be damaged. Therefore, this operation must be completed in a short time.
It is recommended to install an unnecessary OPC drum to the machine and execute this operation.

6)

Check the output voltage with a digital multi-meter.
If the output voltage is not within the specified range listed in the table below, change the adjustment value. 
(Enter the adjustment value with 10 key, and press [OK] key or [EXECUTE] key.)

If the specified output cannot be obtained by changing the adjust-
ment value, it is presumed that some parts listed below are defec-
tive.
• High voltage PWB (MC/DV/TC)
• PCU PWB
• MC unit
• OPC drum unit
• High voltage circuit electrode

 

This adjustment is needed in the following situations:
* When the high voltage PWB is replaced.
* U2 trouble has occurred.
* The PCU PWB has been replaced.
* The EEPROM of the PCU PWB has been replaced.
* When the picture quality is abnormal.
1)

Remove the rear cover of the machine.

2)

Enter the SIM 8-1 mode.

3)

Select the middle speed mode.
When the adjustment value in the middle speed mode is set,
the adjustment values of the other modes are automatically set
accordingly in correlation.
To adjust an each mode individually, first adjust the middle
speed mode, then adjust the other modes.
If the middle speed mode adjustment is executed after adjust-
ment of the other mode, the adjustment value of the other
mode is automatically set. Be careful of that.

4)

Apply a digital multi-meter between the high voltage PWB con-
nector CN2 pin (7) and the chassis GND.

5)

Press [EXECUTE] key.
The main charger voltage is outputted for 30sec.
If this operation is executed for a long time, the OPC drum may
be damaged. Therefore, this operation must be completed in a
short time.
It is recommended to install an unnecessary OPC drum to the
machine and execute this operation.

6)

Check the output voltage with a digital multi-meter.
If the output voltage is not within the specified range listed in the table below, change the adjustment value. 
(Enter the adjustment value with 10 key, and press [OK] key or [EXECUTE] key.)

If the specified output cannot be obtained by changing the adjustment value, it is presumed that some parts listed below are defective.
• High voltage PWB (MC/DV/TC)
• PCU PWB
• MC unit
• OPC drum unit
• Developing unit
• High voltage circuit electrode

MIDDLE

A

MIDDLE SPEED GB_K

Middle speed mode main 
charger grid voltage adjustment 
value

230 - 850

525

535

CN2

3

-540V 

 5

-550V 

 5

LOW

A

LOW SPEED GB_K

Low speed mode main charger 
grid voltage adjustment value

230 - 850

525

525

CN2

3

 -540V 

 5V

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MIDDLE

A

MIDDLE SPEED DVB_K

Middle speed mode developing bias 
voltage adjustment value

0 - 700

395

395

CN2

7

 -400V 

 5V

LOW

A

LOW SPEED DVB_K

Low speed mode developing bias voltage 
adjustment value

0 - 700

395

395

CN2

7

 -400V 

 5V

MX-M753N  ADJUSTMENTS AND SETTINGS  5 – 6

 

This adjustment is needed in the following situations:
* When the high voltage PWB (MC/DV/TC) is replaced.
* U2 trouble has occurred.
* The PCU PWB has been replaced.
* The EEPROM of the PCU PWB has been replaced.
* When the picture quality is abnormal.
1)

Enter the SIM 8-6 mode.

2)

Select a mode to be adjusted.

3)

Enter an adjustment value (specified value) and press [OK] key.
By setting the default value (initial value), the specified current will be outputted.
When [EXECUTE] key is pressed, the transfer current is outputted for 30 sec.

NOTE: The transfer current cannot be checked. If the output is presumed to be abnormal even though the adjustment value is set to the

default value, replace the high voltage PWB (MC/DV/TC).

If the specified output cannot be obtained by changing the adjustment value, it is presumed that some parts listed below are defective.
• High voltage PWB (MC/DV/TC)
• PCU PWB
• MC unit
• OPC drum unit
• High voltage circuit electrode

 

This adjustment is needed in the following situations:
* When the high voltage PWB (MC/DV/TC) is replaced.
* U2 trouble has occurred.
* The PCU PWB has been replaced.
* The EEPROM of the PCU PWB has been replaced.
* When the picture quality is abnormal.

1)

Enter the SIM 8-17 mode.

A

TC PLAIN BW SPX

Transfer 

current

Plain paper 

transfer mode

Front surface transfer mode

0 - 255

97

129

30

A

40

A

B

TC PLAIN BW DPX

Back surface transfer mode

0 - 255

97

129

30

A

40

A

C

TC HEAVY BW SPX

Heavy paper 

transfer mode

Front surface transfer mode

0 - 255

113

113

35

A

35

A

D

TC HEAVY BW DPX

Back surface mode

0 - 255

113

113

35

A

35

A

E

TC OHP BW 

OHP transfer mode

0 - 255

97

113

30

A

35

A

F

TC INTERVAL BIAS

Non-transfer mode between papers

0 - 255

97

129

30

A

40

A

G

TC ADSORPTION BIAS

Toner retaining mode

0 - 255

97

129

30

A

40

A

H

TC FRONT EDGE BIAS

Paper lead edge transfer mode

0 - 255

97

113

30

A

35

A

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MX-M753N  ADJUSTMENTS AND SETTINGS  5 – 7

2)

Select a mode to be adjusted.

3)

Enter an adjustment value (specified value) and press [OK]
key.
By setting the default value, the specified voltage is outputted.
When [EXECUTE] key is pressed, the transfer belt cleaning
voltage is outputted for 30 sec.

NOTE: There is normally no need to check the output. To check

the output, however, perform the following procedures.

4)

Apply a digital multi-meter between the high voltage PWB con-
nector CN2 pin (1) and the chassis GND.

NOTE: The transfer current cannot be checked. If the output is

presumed to be abnormal even though the adjustment
value is set to the default value, replace the high voltage
PWB (MC/DV/TC).

 

This adjustment must be performed in the following cases:
* When the high voltage PWB (MC/DV/TC) is replaced.
* U2 trouble has occurred.
* The PCU PWB has been replaced.
* When the EEPROM on the PCU PWB is replaced.
* When the picture quality is abnormal.
1)

Enter the SIM 8-18 mode.

2)

Select a mode to be adjusted.

3)

Enter an adjustment value (specified value) and press [OK]
key.
By setting the default value, the specified voltage is outputted.
When [EXECUTE] key is pressed, the transfer cleaning bias
voltage is outputted for 30 sec.

NOTE: There is normally no need to check the output. To check

the output, however, perform the following procedures.

4)

Connect the transfer section to the main body side using the
transfer extension harness (DHAI-3629FCZZ).

5)

Remove the front frame side cover in the paper transport sec-
tion, and remove the front frame side cover in the transfer sec-
tion.

A

TC 
CLEANING 
AC

Transfer belt 
cleaning AC 
output voltage

0 - 255

191

AC 4.5KV 
(p-p)

B

TC 
CLEANING 
DC

Transfer belt 
cleaning DC 
bias voltage

0 - 255

36

DC -100V 

 

10V

(1)

CN2

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A

TC 
CLEANING 
ROLLER +

Transfer 
cleaning roller 
plus bias voltage 
(+) (Transfer belt 
cleaning voltage)

0 - 255

211

+2.0V 

 

0.1V

B

TC 
CLEANING 
ROLLER -

Transfer 
cleaning roller 
minus bias 
voltage (-) 
(Transfer 
cleaning roller 
cleaning voltage)

0 - 255

205

-2.0V 

 

0.1V