HP Designjet H-Series HP Scitex FB950 Printer Troubleshooting vacuum issues 1
© 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. The only warranties for HP products and services are set forth in the express warranty statements accompanying such products and services. Nothing herein should be construed as constituting an additional warranty. HP shall not be liable for technical or editorial errors or omissions contained herein.
1 Vacuum system overview The HP Designjet H-series (former ColorSpan 5400UV series) and HP Scitex FB950 use an air vacuum and pressure system applied to the printheads. This document explains the system from the perspective of the observable symptoms when there is a problem. The goal is to assist users of these printers to troubleshoot small problems, prevent larger issues, and communicate accurately to HP Customer Care when things do go wrong and more help is needed. 1.
Figure 3 Current versions of the dual air tube assembly with ink-blocking filter (C). The tubing is flexible Tygon type. C A B Figure 4 Older revision of dual air tube without filter. In addition to lacking the ink-blocking filter, the tubing is semi-rigid LLDPE (Linear Low-Density Polyethylene). Each reservoir holds about 20 ml of ink. Without vacuum, any ink in the reservoir will find its way to the jetting orifices found on the bottom of the printhead and eventually drip out.
1.2 Vacuum system components The preceding section has already identified the following vacuum system components: Printhead reservoirs Carriage air tubes U-tubes The following additional components are used to deliver the vacuum to the carriage air tubes: Valve & manifold assembly Long tube in the track Vacuum assembly, also known as the IDS (Ink Delivery System) vacuum and sometimes as the Vacuum/Pressure or “VP” assembly. 1.2.
Figure 7 Location of vacuum assembly (inside printer enclosures) on Designjet H-Series Figure 8 Location of vacuum assembly (inside printer enclosures) on HP Scitex FB950 The vacuum assembly itself is a small, silver-colored aluminum box. On newer H-series printers and all FB950 printers, attached to the box is a white cylinder that somewhat resembles a bottle. Older H-series printers do not have this feature. The white cylinder is a filter for the air intake of the vacuum system.
Figure 10 Drawing of FB950 vacuum assembly with external filter 1.2.3.2 Sub-components of the vacuum assembly The vacuum assembly contains a number of individual components as well as tubing that are used to create, regulate, and sense the vacuum. The primary components include all of the following: Pump Regulator Restrictor fitting Circuit board Figure 11 shows these component locations in the FB950 and newer H-series assembly.
U-tubes and applies pressure on the Luer caps on the front of the printhead reservoirs. These caps sometimes loosen and create a vacuum leak; see section 2.2.2.4 for details. Figure 12 See-through drawing of a Luer retention clamp (spring not shown) Figure 13 Luer clamps installed The retention clamp was added to all FB950s, both new and already installed, in mid-2009.
2 Common vacuum-related problems and their solutions In this section we describe the most common problems that customers have reported involving the vacuum system, and offer techniques to help the printer operator determine the source of the problem and how to resolve the issue. 2.1 Definitions of “normal” Before embarking on a catalog of problems and solutions, it is important to establish what is normal and expected of the vacuum system.
The H-series control panel does not have this visual indicator, but the current vacuum level may be viewed by selecting the following: 1. Touch the top-center Printer Status area of the control panel. 2. Press the “System Info” button. 3. View the vacuum status on page 1 of 4. See Figure 16.
2.2.1.1 Causes and solutions 2.2.1.1.1 The vacuum pump is not running There is no power to the vacuum pump from either the main printer power or from the external auxiliary 24V power supply. To test, remove the external 24V power supply, if present. The pump should operate from main printer power. If not, reconnect the 24V power supply. If the pump is now audible, then the mini 24-VDC power supply in the printer has failed and requires replacement.
Figure 20 FB950 regulator adjustment location (A) 2.2.1.1.2.1 Adjusting older-style assembly (H-series only): 1. Use the keystrokes shown in Figure 16 to display the vacuum status. 2. If the vacuum level is less than 5.0 at its highest level during a pump cycle, turn the adjustment screw 1/8th turn clockwise and wait for the system to complete a vacuum pump cycle. 3. Watch the display showing the vacuum level. The vacuum level will rise as the pump runs.
IMPORTANT: Keep track of how far you move the regulator. If the vacuum status does not start to change after the equivalent of ½ of a full turn, it is unlikely that turning it more will have any effect. It is most likely that there is a leak somewhere in the air system. Return the regulator back to its original position before attempting additional troubleshooting steps. 2.2.1.1.
Figure 21 Removing a fitting from the manifold To insert the fitting, press down on the compression ring while inserting the fitting. Release the compression ring to secure the fitting. Wipe the bottom of the printheads with a lint-free cloth and HP printhead flush solution to clear away old ink, then observe for new drips. If the original printhead(s) resume to dripping, the problem is the valve. If the adjacent printhead(s) continue dripping, the problem is the tube.
Figure 23 Drawing of an unassembled reservoir and cover These pieces are assembled and sealed at the factory and are not intended to be separated at any time. However, mechanical stress or other events may cause the seal to fail. In some instances and depending on the location of the failure, leaking ink around the seal may reveal a failed reservoir. This ink leaking from a reservoir must be differentiated from ink that drips out of the bottom of the printhead.
Figure 25 Both tubes capped with Luer plugs CAUTION: Do not remove a single tube, cap it, and then remove the second tube. Capping one tube may create a siphon effect and begin to draw ink up the second air tube before it can be removed from the reservoir. Always remove both air tubes together and then cap each tube. 3. If the reservoir(s) is the sole cause of the air leak, the vacuum status should quickly go back up to the normal range and the vacuum system should stabilize.
loosen the jetpack-reservoir fastener when intending to loosen the printhead-carriage fastener. Use an Allen key to ensure that the fasteners are snug. Secures reservoir to carriage Secures printhead to reservoir Figure 26 Printhead and reservoir fasteners. Left: general view of the bottom of the carriage; Right: detail of one printhead-reservoir fastener and one reservoir-carriage fastener. 2.2.2.5.
2.3.2.2 Tube disconnected at vacuum assembly The long tube carrying vacuum through the track could have come disconnected from the vacuum assembly. This tube connects to the vacuum assembly by a twist-type connector. See item “A” in Figure 9 for H-series and item “B” in Figure 10 for FB950. Note that there are three tubes in total at the vacuum assembly. Two of the tubes are a softer, flexible tubing; these tubes go to the vacuum accumulator/reservoir located elsewhere.
Figure 27 Mini 24VDC power supply in the electronics assembly. Left: DesignJet H-Series; Right: FB950 If the pump cannot be detected as running and the auxiliary external power supply is not connected, connect the auxiliary power supply. If the pump begins to run, then the primary power supply may have failed. 2.4.2 Auxiliary external power supply failed When the printer is removed from main power altogether (i.e.
Figure 29 Cable connection to vacuum assembly. Left: H-series; Right: FB950. Inside the vacuum assembly there are one or more cable connections depending on vintage. The older assembly has connections to the vacuum sensor, vacuum switch, and vacuum pump. The newer assembly has the sensor and switch functions integrated, so there is only one remaining connection to the pressure pump.
2.5.2 Opening within the related vacuum components A primary candidate for an unexpected opening is the seal at the blue vacuum reservoir. This component is located away from the vacuum assembly. The two flexible tubes (“B” and “C” in Figure 9 or “A” and “C” in Figure 10) lead from the vacuum assembly to the vacuum reservoir. The reservoir resembles a filter housing, but there no filter material contained inside it.
Figure 31 Restrictor (A) and Regulator (B) It is possible to clean the restrictor with a very thin wire, such as American Wire Gauge 34, which has a diameter of 0.00630″ (0.160 mm). Remove the restrictor from its location in the vacuum assembly and pass the AWG 34 wire through several times. If AWG 34 or equivalent is not available, compressed air may be successful in removing some of the blockage. Alternatively, the restrictor may simply be replaced.
Figure 33 Detail of color coming back in following the drop out Figure 33 shows in detail how the color gradually comes back. It is important to observe the distinction between an abrupt, total failure of all colors and this gradual failure. An abrupt failure, where the drop out is a clean break all at once, is not indicative of a vacuum failure, but of a problem with the power cable to the headboard.
2.7 Vacuum status is “Unknown” The vacuum sensor has a limited range. If the vacuum is too high, such as may occur from a badly adjusted regulator, or if the regulator was adjusted upwards while there was a leak and then the leak is detected and repaired, the actual vacuum may exceed the range of the sensor. When this occurs, the vacuum status will show as “Unknown”. Isolate the vacuum assembly as described in section 2.5.
3 Using the Vacuum Troubleshooter on the control panel The printer has a User Diagnostics menu that includes several guided troubleshooting routines to assist you. One of these routines is for the vacuum system. To access the diagnostic, select “Tools | User Diagnostics | Vacuum Pressure”. 3.
b. If the vacuum level is less than 5.25 at the end of the pump cycle, the regulator is set too low. Turn the regulator adjustment screw (see Figures 19 and 20) clockwise 1/8 of a turn. Repeat steps 2 and 3 as necessary until the vacuum is 5.25 or greater. 3.1.3 Run automated tests to look for leaks This section pressurizes each color channel (printhead or pair of printheads by color) one at a time and monitors how long it takes the vacuum to recover.
4 Other tests The printer has additional tests found on the control panel. 4.1 Air valves The air valves may be tested by selecting “Tools | Service Printer | Ink System Tests | Air Valves”. This test allows you to manually toggle each valve individually between “Off” (allows vacuum to pass) an “On” (allows pressure to pass). Toggling the valve should produce a faint yet audible “click” from each valve.
5 Pressure components In addition to the components that create and carry vacuum (negative air pressure) on the printer, there are a number of components that create and carry positive air pressure. Positive air pressure is used when servicing (cleaning) the printheads and for emptying the printheads of ink prior to some printer repairs or transport of the printer. 5.1 Unique pressure components These components have no function except to create pressure for the printhead servicing or related functions.
5.2 Shared components There are numerous components that are shared by the vacuum system and the pressure system, and will carry one or the other depending on the moment in printer function. Most of these components are located on the carriage. 5.2.1 Manifold and valves The manifold assembly (see Figure 6) receives both the long tube for vacuum and the long tube for pressure.
6 Table of related part numbers The table that follows provides HP part numbers any of the orderable components that have been described elsewhere in this document. This information and part availability is subject to change without notice; contact HP for the most current information. The indication of “all models” in the “Used in” column refers to all printer models specifically addressed by this document only.
Table 1 Vacuum system part numbers Common name Part number Used in Note Vacuum pump CH104-67002 FRM,N,PUMP,PRESSURE All models Exactly the same as the pressure pump Pressure pump CH104-67002 FRM,N,PUMP,PRESSURE All models Exactly the same as the vacuum pump External 'bottle' filter CH108-60004 FRM,AIR_FLTR,LARGE_V OL,L Newer Hseries and FB950 Complete Assembly CH971-91543 FRM,VAC_ASSY,N All models Auxiliary power adapter CH971-91083 FRM,AUX_VP_PWR,ABCD HIJ,ROHS All models Luer cap for p
Table 1 Vacuum system part numbers Common name Part number Used in Printhead reservoir CH104-67001 FRM,N,KIT,RESERVOIR All models Note Image (not to scale) Long CH154-67023 vacuum tube FRM,TUBE,VACUUM,LON for track G,Q FB950 only 241″ (612 cm) No photo available Long CH971-91547 vacuum tube FRM,TUBE,VACUUM,LON for track G,N H-series only 166″ (421 cm) No photo available O-rings CQ114-67216 between FRM,PH_RESERVOIR,2_O printhead -RING_SETS,U and reservoir All models No photo available U-tu
Table 1 Vacuum system part numbers Common name Part number CH971-60068 Mini 24VDC PWR_SPLY,11W,24VDC,R power supply OHS Used in Note Image (not to scale) All models For more part information and availability, check the HP Partsurfer at http://partsurfer.hp.com or the HP Parts Store at http://www.hp.com/buy/parts.
