What can cause black line in the center on printouts froman HP Laserjet M1136 MFP printer?
Are these horizontal lines (i.e. running from left to right) or vertical ones?
Vertical lines tend to be caused by dirt/toner on the fuser rollers. You may be able to clean the rollers or, if the damage is serious, you'll need to replace the fuser which may be uneconomical.
Horizontal lines can be caused by all sorts of things, so we would need a better description, but often they're caused by damage (scratches or otherwise) to the drum, which is part of the toner cartridge, so replacing the cartridge should sort them out.
The Laserjet M1136's drum is NOT part of the toner cartridge, the replacement part number for the drum is RX158OPC.
It really doesn't matter if the print defects are horizontal or vertical. The determining factor is the distance between the defects for the ones that recur on a page. A larger distance indicates the drum is the issue while a shorter gap between occurrences is an indication that the fuser roller(s) have a buildup of toner on them.
That said, vertical defects that run the length of the page can be either the drum or the fuser and, with certain models, there are could also be the possibility of other debris over the paper path. I have not seen the latter in more current printer models, but it was fairly common with HP LaserJets prior to 2002 to have paper fragments getting caught up between the toner cartridge and the fuser.
The lines are vertical near center of page. Please weblink illustration or video for user to clean / rectify the problem
Can you weblink to a photo/scan of a sample of the output?
Sunil, are the defects consistent through the entire length of the page or are there breaks where the defect repeats (line...blank space...line, etc)? If it has a repeating pattern, long is the blank space?
If there aren't any breaks in the line(s), you will need to visually inspect the drum and fuser roller. Most of the time, unbroken vertical defects tend to be an issue with the drum (it was scratched or otherwise damaged along the entire circumference and it can no longer hold a charge along that defect).
@Oron : Yes I would weblink to sample of output
@Bruce : There are breaks in lines , the lines form a patchy look along the length of output
The weblink to output sample is at https://www.facebook.com/photo.php?fbid=10152741386468594&l=8290f52d02
Please view the lines-patch at bottom of page
Thanks Sunil, this helps but unfortunately, I still can't quite make out the details in the photo. It looks to me like the marks start at or near the top of the page, and become more pronounced as the page progresses. Is this the case, or do they only start in the middle (around line 19)?
Also, it looks in the picture as if the marks are of a very particular pattern. Is this the case? In other words, is the shape, spacing and size of the marks identical throughout, or do they just happen to be similar?
Thanks for your endeavor. Yes , looks like marks becoming pronounced from top to bottom. But almost same through out length. Shape , spacing and size of marks are identical throughout the length.
Today , an engineer looked at the toner. Maybe toner is damaged.
Glad you got an engineer to look at it. A "ghost" pattern usually indicates a problem with the drum (the image is "burned" into it), but sometimes it can be caused by the fuser not being hot enough, and toner which is laid on the page sticks to it and is then deposited again and again on the page.
Thanks to the respondents who sincerely endeavored to resolve the discrepancy
Try swapping the toner with another to test
check cleaning page option if you have it: in the menu, configure device, print quality menu, create/process cleaning page
can be toner contact problem, try to clean that area