Toshiba FC-22 manual Background Fogging

(4) Background Fogging

Cause/Defect area	Step	Check items	Measures	Remarks
Density reproduction	1	Image density reproduction defect	Perform automatic adjustment of	Go to step 5
			gamma correction.	If defects
				occur.
Printer	2	Check printer image.	Output test print image (04-231) for
			each color and check it.
Parameter adjustment	3	Check image processing parameters.	Check the value of offset amount of
value			processing background.
	4	Adjust image processing	While checking the above encircled
		parameters.	image, remove background fog by
			adjusting offset amount of processing
			background.
Scanner stain	5	Is the original glass or mirrors	Clean them.
		or lens filter dirty?
Auto-toner	6	Is the auto-toner sensor normal?	Check operation of auto-toner sensor
			and re-adjust.
	7	Is the toner supply operating constantly?	Inspect motor and circuits.
Main charger output	8	Is the main charger output normal?	Check circuits. (Note)
Developer bias	9	Is the developer bias proper?	Check circuits. (Note)
Developer unit	10	Is the contact between the drum	Adjust doctor-to-sleeve gap and pole
		and developer material right?	position.
Developer material	11	Is the developer's life finished?	Replace developer material.
Drum cleaning blade	12	Is it cleaned properly?	Inspect drum cleaning blade pressure.
Toner dusting	13	Is toner accumulated on the seals of	Remove toner and clean.
		the developer unit?

Note:

If the main charger and developer bias outputs seem to be abnormal, replace the main high-voltage transformer of the color likely to be abnormal with another transformer of another color likely to be normal, and then, output the chart again.

If the same color remains abnormal, check if there is any disconnection of harness between the LGC board and the main high- voltage transformer, disconnection of high-voltage harness, the power supply defect, or stain on the main charger wire.

If the color changes as the result of replacing the main high-voltage transformer, this fogging trouble is caused by the main high- voltage transformer defect. Therefore, replace the main high-voltage transformer of the abnormal color with new one.

After this checking, return the other main high-voltage transformer back to the original color position.

FC-22 TROUBLESHOOTING 4 - 60 January 2000 © TOSHIBA TEC