Troubleshooting Media JamsPrinthead Crashes
The failure modes "media jam" and "head crash" are grouped together because in many cases a media jam causes the media to lift up into the carriage path and cause a head crash, thus causing many media jam failures to be reported as head crashes.
1 Did the media jam occur when loading media?
• If the client has had media jams, it is common for pieces of media to get stuck in the media path. Clear the media path.
2 Is the customer using non-HP media?
• The use of non-HP media can easily be the cause of media jams and head crashes (especially head crashes because HP media is specially formulated to avoid cockle, one of the primary causes of head crashes). If the media is not HP approved, advise the customer to use HP media and check to see if the problem now solved.
3 Is the client using Best Mode on Coated Media in high humidity?
• In this particular case, head crashes could occur due to worst casing. Recommend a change of media, print mode, or humidity conditions.
4 What is the Firmware Revision? (Only applicable to HP DesignJets 2500CP and 2000CP)
• Must be A02.01 or more recent. If not, upgrade.
• Explanation - In earlier releases of firmware a media jam/head crash can be caused at the start of a plot. This can occur in the "POME" pen alignment or closed loop color calibration, because the leading edge of the media is brought back very close to the Media Separator edge. If the edges cross, the media can lift up when it is advanced, causing a media jam or head crash. It is more likely to occur the more curled the media is.
5 Check the Media Separator (Only applicable to HP DesignJets 2500CP and 2000CP)
• For units fabricated before Serial Numbers C4703A ESA7C04586 and C4704A ESA7C10343. If the Media Separator is detaching do not stick it down again, as it will detach again. Also, never reposition a Media Separator, because it has an extremely tight positioning tolerance. For Media Separators that are lifting off the Overdrive Assembly, replace the entire Overdrive Assembly.
• Explanation - The previous adhesive used under the Media Separator can detach from the Overdrive Assembly. New Overdrive Assemblies use a much better adhesive - it can be easily differentiated from the old adhesive because it is white instead of transparent. The Media Separator should never be repositioned; it has an extremely tight tolerance. If it is too far from the linear blade it can cause media crashes against the Linear Blade. If it is too close it can cause media jams between the leading edges of the media and the Media Separator.
6 Did the failure occur at the end of the media roll?
• There are two known failure modes in this case. One is with Vinyl media, in which case the end of the media was glued too strongly to the roll, which can cause a head crash. The other is with Coated Media, where some rolls have the final edge of the media bent in a "C" shape which could cause a head crash when passing under the carriage. In both cases the problem has been fixed and a new roll of media should solve it.
7 Replace the Overdrive Assembly and the Clutch t page 8-69.
• Explanation - For a unit fabricated before September of 1997 the clutch could cause intermittent media jams. Refer to the applicable Service Note. For a printer fabricated before July 1997 the linear blade could be too high, causing media jams.
8 Check for missing/blocked starwheels or starwheel mount assemblies.
• Explanation - These parts can lead to media jams if missing or blocked.
9 The Carriage is at the incorrect height in relation to the Drive Roller. Perform the Refill Calibration t page 5-9 and try to load the media again.
• The refill station positioning must be checked afterwards since it is affected. The refill station can be adjusted to accommodate the change in Printhead Height. The specification for Printhead Height is 1.2 -1.4mm. Printhead Heights higher than this can adversely affect print quality.
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