SERVICE BULLETIN

Bulletin Contact: Terry Ennis E-Mail: terry.ennis@xerox.com USSG SLDS Codes: B26, B34, B71 April 09, 2007 Page 1 of 1

Date Issued: 09 April 2007

SB 745

PRODUCT: Phaser 8400, 8500, 8550,8560, 8560MFP, WorkCentre C2424 SUBJECT: Criteria to Determine if Printhead Failure Caused by the Printer Being Tipped While Hot OPERATIONAL GROUPS: ALL

PROBLEM Several problems can be associated with a Printhead that tipped while hot including Massive Jet Loss, Ink Reservoir Overflow, and Ink in the Air Purge Hose. CAUSE Tipping the printer while the Printhead is still hot. The printer should be powered off and allowed to cool for 30 minutes before moving. SOLUTION

Overview The solid-ink printer, while in its powered-on state, contains liquefied ink. Only when the printer has been turned off and allowed to cool for 20-to-30 minute does this ink solidify. Once the ink has solidified can the printer be safely moved or shipped. While its ink is in a liquid state, tipping or tilting the printer allows ink to infiltrate upper portions of the printhead. This ink infiltration causes serious, multiple jet loss and well as ink overflows. The ink blocks the flow of pressurized air thru the purge hose into the printhead during a cleaning cycle; purges become ineffective. Similarly, air in the reservoirs is block by the ink so it cannot vent out as ink is melted into the reservoir. Since the ink cannot displace the trapped air, it backs up the ink reservoir funnel and overflows.

Tipping the printer allows ink in the reservoir chambers ...

to flow thru the hole surounding the ink level sense probe ...into the upper air chamber ...

where it can block the ink hose port.

Check valve

FunnelAir Hose port Figure 1. Cutaway view of printhead revealing interior features. The dotted line indicates the air spaces above the ink reservoirs.

SERVICE BULLETIN

Bulletin Contact: Terry Ennis E-Mail: terry.ennis@xerox.com USSG SLDS Codes: B26, B34, B71 April 09, 2007 Page 2 of 1

Air chamber

Ink reservoir

Ink flows in funnelthru the filter and then thru one-way check valve intoink reservoir

Hole connectingair chamber to ink reservoir

Ink level sense probe

Figure 2. View of printhead with plastic insulation panels removed

Ink in Air Purge Hose Look for: Ink in the purge hose where it connects to the printhead. This is a sure sign the printer was tipped while hot. Ordinarily the hose appearance is uniformly translucent. See Figure 3.

Figure 3.

Ink Reservoir Overflow Following an ink melt cycle, look for:

An abnormally raised level of ink in a reservoir (shown in the Magenta reservoir). Ordinarily the ink level is maintained even with the filters in the reservoir (as shown in the Black reservoir). Ink should not rise above the filters.

If the ink level rises high enough it overflows and leaks between the metal reservoir funnel and the plastic insulating panels. (See Figure 4).

SERVICE BULLETIN

Bulletin Contact: Terry Ennis E-Mail: terry.ennis@xerox.com USSG SLDS Codes: B26, B34, B71 April 09, 2007 Page 3 of 1

Look for: Ink accumulations under the printhead or on the

printheads circuit board. Successive ink melt cycles and overflows cause ink to accumulate under the printhead.

If there are ink accumulations under the printhead (Ink Reservoir Overflow), then the printer was probably tipped while it was in a typical user setting.

Ink accumulations often lead to printhead movement faults such as 7,010.43. (See Figure 5)

Figure 5.

The ink melted to fill the reservoir cannot immediately displace the air trapped in the reservoir. Instead the ink backs up in the ink reservoir funnel and overflows. Since the ink overflows between the metal reservoir and the printheads plastic panels it is not immediately apparent that the overflows are taking place. Only after numerous ink melt cycles, which may be hours or days later after the printer was tipped, does the problem reveal itself. Multiple missing jets may occur during high-coverage printing due to ink starvation. Since the ink is not refilling the reservoir, the printer prints to the point that there is not enough ink to supply the jets and they run dry. This failure will look similar to the illustration in the next topic, Massive Jet Loss.

Massive jet loss Look for:

Many missing jets in the same color. May be in multiple colors. See Figure 6.

If the lost jets occur when the printer is powered up, but there are no indications of Ink Reservoir Overflow as described earlier, then the printer was probably tilted (while still hot) after it was shut down.

Air bubbles form in the ink when the ink cools and solidifies following the shutdown. A power-up cleaning cycle flushes the air-bubble laden ink out of the printhead. If the purge hose is block by ink and cannot properly pressurize the printhead, then the purge cannot flush out the air bubbles that formed in the ink when the ink solidified. The jet loss is due to air bubbles in the printhead due to an ineffective purge cycle.