Black Copies I am getting either very dark or solid black copies. I have a relatively new toner cartridge which has worked fine up until now. What do I have to do to correct this problem?

fuser drum is bad. photocopier use electricity to transfer the toner to the paper, then it is heat fused to paper. it appears that the problem is occurring around the time that the toner is attracted to the paper.

The cartridge or Toner is splitting out more ink.... Remove the cartridge Clean it and place it again.

Hello,
on analogue copiers, if You have dark copies, that means that You need to clean optics ( mirrors and lenses - maybe some toner get to them ) or check/clean/replace the fixing film!

Regarding poor copy, clean/vacume/change the transfer roller ( beneath the drum unit - on paper path from drawer/bypass, before fixing unit ).

Hope that helps!

A couple of possibilities. Basically if your exposure lamp is coming on, the light is not getting all the way to the drum that is in the toner cartridge. It could be you have a mirror out of place. When the exposure lamp comes on, the light is reflected off the original and then off a series of mirrors until it gets to the drum. If one of the mirrirs has been knocked out of place, like due to a recent cleaning then that would cause black copies. The more common cause would be the drum protection "gate" that is on top of the toner cartridge is closed and thus blocking any light from getting to the drum. You can slide out the toner cartridge and look on top. There is a gate or panel that flips open to be able to see the drum. This gate must be opened when installing the toner. Also it is possible to have a bad cartridge but that rarely causes completely black copies.
Good Luck and Thank You for using Fixya.

Most often on the PC940 this means your toner cartridge is getting low on toner. To prove this is the cause, just remove the toner cartridge and while keeping it relatively level, shake it side to side a few times. This will re-distribute the remaining toner in the cartridge. Re-install and make a copy. The black streak/faded copy should be much better. If so then I would go ahead and get a new cartridge on the way.
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I recommend to clean out an optics. Take apart a cartridge and well blow through, clean the rollers and contacts.

Dirt on the narrow glass will cause streaks through the Auto feeder, but copies should be clean if using the main contact glass if that's the case. Dirt/toner anywhere else (ie:laser optics) would cause light areas on the copies- not dark. Did this happen the very first time you used it, or shortly after? In other words, could it be coincidental? It sounds more to me, like the PCU (photoconductor/drum unit) needs replacement, or a fuser roller.
If cleaning the glass doesn't help, then one of these 2 things is causing your problem.

Hello sir; That problem not caused by toner, is by drum cartridge, replace it will take care your problem.

You need a service engineer to clean and service your copier.

Hello sir; Just replace drum cartridge it will take care your problem, GOOD LUCK!