Technician on Duty

In previous articles we talked about general troubleshooting and replacement of dampers and pumps, as well as other related ink systems. Last month we reviewed some basic troubleshooting and maintenance (Maintenance Review December 2009) techniques related to pumps, and although we discussed pumps, we did not go into a lot of detail. Pumps are critical to the proper operation of your printer and failing or clogged pumps will seriously affect the flow of ink through your printer’s dampers, print heads and caps. This month I want to discuss just pumps and how you can eliminate (or confirm) them as the cause of your ink-flow problems as well as help recover deflecting or clogged print heads, caps and tubing. 

From The Beginning

Ink from the ink cartridges moves through the printer and down through the dampers, print heads and caps on its way out through the pumps and drainage tubing. We know that the pumps are directly responsible for moving ink through the printer, and if there is a break in the system anywhere along this route, it can effect the flow of ink to the print heads. Leaks in the cartridge system are rare, but do happen. Leaks in the ink tubes themselves are very rare. Most of the “flow” problems occur from the dampers and below.

The best way to isolate flow issues is to start on one end and work the problem back from there. Although clogged or damaged dampers as well as damaged and dirty caps will all contribute to reduced ink flow, proper maintenance and cleaning can often eliminate this altogether. Therefore, it’s recommended that you clean the caps and ensure proper maintenance. If problems persist, try eliminating the pump before replacing any parts.

Fortunately, this can be done with just a syringe and some tubing as we will see. But realize that this exercise won’t tell us exactly what’s wrong with the pumps; it only helps us determine if ink is flowing through the dampers, print heads and caps correctly. By testing the lines leading to the pumps, we not only eliminate the pumps as a possible problem, we also have a chance of clearing possible clogs both in the tubes, caps and within the print head nozzles as well.

Image 1: Just about any syringe should do; however. the tubing should be tested first to ensure it will not react with the ink. Another way to know for sure is to use some tubing from an old pump or drain line or by checking with your dealer or printer manufacturer for extra lengths of approved tubing.

Image 2: Here you can see how a simple connector allows for easy connection of pump tubing from the printer. Check each line one at a time.

Image 3: Here is a typical pump setup. Once the pumps are exposed, you should be able to easily identify the drainage and capping station lines/tubes by following them back to their source.

Image 4: Pump layout will vary from printer to printer; nevertheless, most printer pumps are located on the same side as the capping station, usually on the right and below or in front of the printer. You’ll likely have to remove a cover panel as well. Shown here is a pump system that has a broken drain line, but the layout should be similar.

Syringe and Tubing

I have talked about syringes before. Syringes can be very useful in diagnosing and eliminating many common ink-flow issues in printers. If you can’t find one, try to contact your local dealer or the printer manufacturer. I have had some luck at discount or .99 cent stores when purchasing ink refill kits, the ones for your desktop printer, which almost always include a syringe that is usable. You might even try a cooking supply store, where I have seen syringes sold for injecting spices. They may be large, but they work.

Make sure you test the syringe with some solvent ink before use. If the syringe gets warm, soft or begins to melt, don’t use that syringe and try to find one that holds up better against the solvent. The rubber plungers in most syringes will work for a while but eventually those will start to dry out, crack and stiffen or just deform so as not to make a good seal within the syringe shaft. Having more than one and even an unopened or new syringe on hand can be useful.

Once you have secured a syringe, you will need at least an inch or two of some tubing on the end of that syringe (see Image1.jpg) in order to connect it to the printer. Using excess or even old (but still flexible and unclogged) pump or drain lines will work fine here. Make sure the tubing is clean and free of old debris or chemicals that might react with the ink.

Your Printers Pumps

By exposing the pumps, you should be able to identify the waste (or drainage) tubing and the tubing that connects to the individual caps along the capping station. (Image 2.jpg) Since many pumps are a commonly replaced part on a printer, it should be fairly accessible and you should be able to disconnect the pump tubing from the printer without getting too invasive. Some pump tubes will connect directly to the caps by extended tubing. Other printers will have connectors or junction panels connecting the pump. Either way, the pumps must connect to the individual caps and further examination with a flashlight should allow you to observe (or take pictures if necessary) where the tubing leads to confirm this.

Once you have determined where each connection to the incoming pump tube is coming from, disconnect that tubing from the connector or panel leading to the cap(s). Do not cut any of these tubes. Gently disconnect the pump line and remember that each cap should have one tube leading into the pump. Most pumps have two incoming lines as well as two waste lines. Tubes going to the pump are typically shorter than the tubes leading out to the drain lines. Some printers can have three or more pumps. Remove one tube at a time to make it easier to remember where the lines connect. (see Image 3.jpg)

Now take the syringe described above with an appropriate length of tubing connected and attach this tubing to the connector on the tube that connects to the cap. Make sure to connect the syringe tubing just as the pump tubing was connected. (see Image 3.jpg) Essentially we have now bypassed or replaced the pump with a syringe instead.

Using The Syringe

Now begin to draw with the syringe. Note: Be careful here, you can damage the print heads and other systems if too much force is used. Make sure to draw on the syringe slowly and wait a minute or so after every few millimeters of ink drawn. It’s not unusual for it to take a few minutes for the ink to even start filling the syringe.

Also, note the resistance when drawing with the syringe. If there is little to no resistance, this may mean a leak in the line caused by anything from dampers to bad or missing ink cartridges. Too much resistance could mean a blockage. Check to make sure you have the ink cartridges installed securely and not empty before drawing ink through the system. One way to gauge resistance is to briefly and gently draw on the syringe with the ink cartridges removed and inserted. There should be much lighter resistance when drawing from the syringe with ink cartridges inserted in the printer. If the resistance feels the same with or without ink cartridges inserted, you likely have a blockage in that ink line that should be addressed before moving on.

Once we have ink flowing into the syringe, don’t stop, allow ink to flow into the syringe for about 30 seconds or so, making sure to move at least 10 CCs of ink into the syringe before stopping. Once we determine that ink is flowing into the syringe, it’s a fairly safe assumption that there is proper ink flow through the dampers, head and capping station. At this point I recommend a test print to see how/if quality has improved. The steps we have just outlined should produce excellent or at least very improved quality.

Remember, no extra cleaning is necessary because we have just filled the damper and head with a syringe, bypassing but performing the same job as the pumps.

If there are still dropout issues or missing nozzles in your test pattern, it’s likely the pumps have not been working at 100 percent and might have effected other systems. If this is the case, try repeated cleanings and ensure your caps and print heads are clean and free of dried ink. However, if your test patterns show no improvement at all and repeating this procedure still produces no results, you may have a larger problem. Pumps might be involved here and further troubleshooting by a trained service technician may be necessary. However, once the pumps have been eliminated, it’s time to consider the caps, dampers or even the print heads themselves.

The described technique is just one out of a toolbox of many. Although the old syringe-it trick may not be the best method of isolating ink flow issues, it works well enough and is inexpensive. Understanding how ink flows through the dampers, print heads, caps and pumps along with a decent solvent resistant syringe can go a long way... not only to help isolate possible bad components, but also to sometimes help clear up clogs or blocked nozzles. Theoretically, in a pinch, you might even be able to limp by on small print jobs using syringes until pumps arrive. You will have to watch the printer carefully at all times if you do and no manufacturer would ever recommend you try this at home. Nevertheless, at least now you should have a better idea whether your pumps are working correctly, which might at least translate into one less service call. Good luck!