Shaded backround on pages Xerox 5830. What could be the cause?

Background on this machine can be caused by a variety of areas.
A bad high voltage power supply can cause this problem.
A bad developer housing can cause this problem as well.
When the developer housing is inserted, it has to connect to the blue plug correctly.
Sometimes the plug on the machine falls off, and the developer housing does not connect very good causing these types of problems.
A bad copy cartridge can cause these types of problems.
A copy cartridge reciever( the frame that holds the copy cartridge cracks and falls off, dangling, can cause copy quiality problems as these.
The mirror tabs that hold them in place can cause poor quaility problems.
A bad lamp can cause background problems even though the lamp does light and appears to be normal, a exposure lamp can cause these types of problems.
Good luck.

Tryit has it right. Btw, it is VERY IMPORTANT to be sure the copier is powered off and unplugged before working in the optics area. If you happen to lean against the start button while the optics is open and your fingers are in there you risk exposure to high voltage and possible injury from the moving carriages.

There are two other issues when cleaning your optics on this model. On the left hand side of the glass is the registration strip. (That's the green label where you line up your copies.) On the underside of that strip, there is a white strip that must be clean. When the machine sets up at power on, it uses this strip as a white level reference. (That's what is happening when the lamp comes on for a few seconds at power on.) You do not have to remove the registration strip to clean it. Just reach underneath the label while you have the glass off and clean its underside. The white strip runs the length, front-to-rear, of the registration strip. A lint-free cloth with an alcohol-based cleaner will work just fine.

The other possibility is a bigger problem. The clips holding the bottom mirror on the half-rate carriage (left most set of mirrors) will sometimes break. The mirror should not move at all. If it is wobbly, you will get some weird effects. That would probably require a service call.

Good luck

2 things primarily.
1 is dirty optics. Remove the glass, and the black optics tub. clean all the mirrors the lens and the lamp and the surrounding area around the lamp.
2. The copy cartridge may need replaced.

If the backgroung remains pretty consistant, it is most likely the optics.
If the backgroung get worse as the machine runs, or is different every other page, the problem is the copy cartridge.