AR-C150 (serv.man42). Troubleshooting Copy Quality - Sharp Copying Equipment Technical Bulletin (repair manual). Page 11

GMA050702 

Sharp Electronics (UK) Ltd., Technical Services Group

 

 

 

 

 
 

 

 

 

Excessive background can be caused by one or more of the following:- 

 

1. 

Incorrect Developer set-up. 

2. 

Over toning (in low humidity environment). 

3. 

Incorrect exposure adjustment. 

4. 

Incorrect Colour Balance adjustment. 

 
 

 

 

 

 
 

 

 

 

Ensure ALL developer is acclimatised first before installation. 

 
 

 

 

 

Ensure ALL engine firmware is at the latest level, as stated previously within this 
bulletin. (The toner correction “look up” table has been changed). 

 

To reduce the toner concentration of the developer, use Secret Test Simulation 80-
02 and increase all values by at least 10 points (CMYK). The excess toner will then 
need to be removed from the developer units by executing Test Simulation 64-01  
 
Use the following settings:- 
 

 

 

 

 

Test Pattern  

13 

  Density 

255 

  Multi 

Count  10 

 

 

Paper 

A3 or A4. 

  Colour 

CMYK 

 
Once complete, perform Compulsory Process Control (Sim 44-06) and Colour 
Calibration (Sim 46-24).  
 
Exposure Adjustment 

Use Test Simulations 46-01 & 46-02 to adjust the exposure in both colour and B/W 
modes as per specification. 
 
Colour Balance 
 
In addition to the colour balance adjustment stated earlier within this bulletin, the 
following should ONLY be performed when excessive background is present:- 

 

After printing the first manual calibration printout, fold the page in half. (Notice that 
the gamuts for Cyan, Magenta, Yellow and Black drop off to the right of the fold.) 
 
Using the up/down arrows, adjust all four gamuts until they drop off at or near the 
fold. 
 
Note: Moving the drop-off point to the left reduces density in the full-tone and half-
tone areas, and moving the drop-off point to the right increases density in the 
background areas. 
 
  

 

 

 

Cont’d