HP 4550 Service Manual - Page 265

Overhead transparency defects Note No image available Overhead transparencies can display any of the image quality defects shown in the previous samples. In addition, because transparencies are pliable while in the print path, they are subject to being marked by the media-handling components. Allow transparencies to cool at least 30 seconds before handling them.
Make sure that "transparency" is checked as the media type in the Paper Tab in the printer driver. Also, make sure that the media input tray is correctly configured for transparencies. When Transparency is selected as the media type and ColorSmart II is selected on the Color tab, the printer will use a color treatment optimized for projection.
If transparencies show lines and creases in the media and/or the printed output, compare the defect against the repetitive defect ruler (page 266) to help isolate the cause to a particular component.
Check that the transparencies meet the specifications listed in the HP LaserJet Family Print Media Guide.
If the transparencies have spots or smudges, reprint them being careful not to touch the surface of the media. Skin oils can contaminate transparencies, causing spots and smudges.
Small, random dark areas on the trailing edge of solid fill pages might be caused by transparencies sticking together in the face up bin. Try printing the job in smaller batches.
Send transparencies only to the face-down output bin. Transparencies created on the printer might look blurry, but they can still be used successfully on reflective-type (portable) transparency projectors. Dull or dark transparencies
If the transparency colors are dull or dark, ensure that the transparencies meet the specifications for this printer (part number C2934A for Letter, and C2936A for A4).
The selected colors are undesirable when printed. Select different colors in your software application or printer driver.
Spots and smudges appear in the background areas of transparencies when they are projected. Oil from your hands can cause spots or smudges on transparencies. Reprint the transparencies, being careful not to touch the surface of the transparencies.
You are using a reflective overhead projector. Use a standard overhead projector. Incorrect image on transparencies This might occur even though the correct media is loaded in the correct tray. Toner might not adhere to the media and an image might show up on pages where it isn't meant to appear. (See Full-page ghosting on page 258.) When this occurs on transparencies, the connections for the ITB cleaning roller (clutch 3) and for the secondary transfer roller (clutch 4) might be reversed. Repetitive defects on transparencies Overhead transparencies that have repetitive defects spaced 131 mm (5.2 in) apart indicate a defect on the upper fuser roller. 1 Turn the printer off and unplug the printer, allow 30 minutes for the fuser to cool, and then remove the fuser. CAUTION Make sure to wait 30 minutes before removing the fuser. The fuser will be hot. C7085-90921 Chapter 7 Troubleshooting 263