In particular, we will focus on these Epson models:
Epson Pro 7700
Epson Pro 7890
Epson Pro 7900
Epson Pro 9700
Epson Pro 9890
Epson Pro 9900
Epson Pro 11880
We get a few calls every month with a variety of issues relating to print quality. Today we're going to focus on what a bad print head typically appears like, and the process of diagnostics.
When attempting to diagnose what is causing print quality problems on these printers, there are really only three parts / assemblies that will lead to problems. The print head, the pump/cap cleaning assembly, or the valve/damper assembly.
If your printer has been sitting a while without use, this guide may not be the correct route, as the printer as it sits can develop a clogged print head, or a clogged valve/damper assembly which will require a much more thorough diagnostic.
However, if your reading this and have recently developed problems with one, or multiple colors not printing correctly when you do a nozzle check, keep reading!
First, you should always run a nozzle check before doing anything major. Below is a image of a good nozzle check from one of the above models. In particular, you want to ensure all the colors are present, and all have a good full pattern.
|Good Nozzle Check|
The nozzle check below though, is from another 7900/9900, and there are large gaps in multiple colors.
|Bad Nozzle Check|
If you look closely at either of the above images, focusing on just one (any) of the colors, you see almost a stair step pattern. Each of those 'steps' represent a hole on the bottom of the print head that shoots ink onto the paper. Each color has 360 nozzles - 12 across in each row, and 30 rows.
Whenever you see multiple missing rows, this is almost always a bad print head. However to help diagnose the problem, here are a few things to keep in mind.
1) If you are missing individual segments (nozzles) in the pattern instead of one or multiple rows, then you might have a problems with the cleaning unit. The cleaning method on these printers is fairly simple. A small suction cup lifts to the bottom of the print head and sucks ink through the print head to clean it. The unit then has a wiper blade that wipes any gunk from the bottom plate of the print head. This cleaning unit has multiple pieces of rubber tubing, which with age can develop cracks. Think of drinking a soda or a shake with a cracked straw. You end up getting air instead of whatever you are trying to drink. The same principle applies to the cleaning unit. If the tubing has a leak, the unit will not create the suction necessary to clear / clean the print head correctly.
2) If the missing segments move around on the nozzle check, it likely is not a bad print head. In our experience, if you have a bad print head, you will never get any print from the missing rows ever. If you are able to get print quality back by doing enough cleaning cycles, but the problem eventually re-occurs, you are likely looking at the cleaning unit, or the valve/damper assembly causing the problems.
In most cases, the approach we take when attempting to troubleshoot this problems is fairly straight forward:
1) Open the unit to physically examine the cleaning unit. Some bad cleaning units will spill/leak ink from that part. Once you open the unit, and if there is a puddle of spilled ink under the cleaning assembly, there is almost guaranteed to be a cracked piece of tubing on that part.
2) Remove the cleaning unit to expose the back of the print head.
3) Gently (very gently) clean the nozzle plate of the print head. We do this to introduce small quality problems intentionally. This is so that when you reinstall the cleaning unit, and run a cleaning, you can verify that the cleaning unit is doing its job, and cleaning all the other colors correctly.
4) Reassemble the unit, run a nozzle check before you do any cleanings (you should have a few missing segments in a couple colors). Run the cleaning cycles, run another nozzle check, and see if those small problems clear up or remain.
If the small quality problems clear up, that verifies that the pump/cap is working correctly. If the small quality problems persist, then you likely have a bad cleaning unit.
In some cases, you can have both parts bad (a print head and a cleaning assembly). I recently worked on an Epson 11880, with missing nozzles in the yellow color. I knew it was a print head from looking at the samples, so I arrived at the customers location and replaced the print head. When doing the initial cleaning of the new print head, I had quite a lot of problems getting any of the colors to print correctly. I then sat and ran cleanings on the color pairs (cleaning 2 colors at a time instead of all the colors). I was able to clear all the colors with the exception of the light black, and the light light black colors. I was able to then determine there was a problem with the tubing on that portion of the cleaning assembly, in addition to the bad print head causing the problems with yellow.
As a side note, the Epson 11880 seems to have more bad cleaning units then most of the other models listed above, but you can never rule out a couple parts causing the problems. I always advise my customers on the 11880 models that the cleaning unit is troublesome and they might consider replacing both parts at the same time to ensure operation.
A last note, depending on the model, these print heads are fairly expensive. As of writing this post, the print heads range in cost of between $1300 and $2000. That is for the part only. In most cases, we can replace a print head with two to three hours of labor.
If you are having this type of problem, and you are in the Phoenix area, give us a call at our store and we can advise / schedule a service call to get the problem resolved.
I hope you enjoyed this quick troubleshooting guide, and feel free to leave any feedback!