Introduction
Note: Epson doesn’t recommend or endorse the procedure described in this tutorial.
It’s unbelievable how Epson printheads get clogged. No matter how good they are, they get clogged for no reason and don’t unclog by themselves. Either you change the head or manage to unclog it by using a liquid made by Epson, which costs a small fortune – when you get to find it. So the poor technician has almost no chance to repair such printer.
First, let’s study how the system works. There is a tube (called “needle”) that makes a hole in the cartridge plastic and, by doing so, creates a pressure seal that helps prevent ink leakage and to create a kind of vacuum in the cartridge. If this vacuum didn’t exist, the ink would certainly flow completely though the head holes. That’s why when someone removes the cartridge (original or not) from an Epson printer, they cover the nozzle with a tape: the tape keeps the ink from flowing. When the cartridge is reintroduced in the printer, the tube makes a hole in the tape and creates the same pressure seal.
As you can see on Figure 1, the ink enters through that tube and goes to the head nozzle plate, passing by an ink filter and temporarily stored on the cavity, which is a small ink tank.
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Figure 1: Print head sectional drawing.
The expulsion area works with piezoelectric elements (a.k.a. PZT, Piezo Electric Element) that, when “energized”, move and expel ink droplets that fall to the paper. The ink course is not a straight line, as you can see on Figure 2. Because of that, it works as an one-way valve – you can drop ink up to down, but not the other way around.
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Figure 2: Ink course in the printing head.
The problem happens with the ink (original or not) deposit in the nozzle plate. The ink gets solid and clogs the hole. No matter how you try, the ink doesn’t come out. And it’s not good to throw a print head away...
Disassembling The Printer
Disassemble the printer. Almost all of them are similar to disassemble. First you have to remove the printer housing, by opening its cover, moving the paper type adjustment lever (a.k.a. PG, Platen Gap) towards (+) side, than removing the two or four screws available on the printer top.
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Figure 3: Removing the printer housing.
After removing the cover, you have to remove two bushings, one at each side of the carriage guide shaft. TAKE NOTES OF THE POSITION OF THE BUSHINGS BEFORE YOU REMOVE THEM. Those bushings regulate the distance between the print head and the paper (“parallelism”). If you put them back wrong, your printer will print wrong.
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Figure 4: How to remove the printer carriage assembly.
Disassembling The Printer (Cont'd)
The paper type adjustment lever (PG lever) is connected to the right bushing, so you will need to remove it in order to remove the bushing.
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Figure 5: PG lever mechanism.
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Figure 6: How to remove the PG lever mechanism.
If you remove the timing belt that moves the carriage assembly, remember to take notes of its EXACT position.
Now let’s see how to unclog an Epson print head to prevent you from buying another head.
Unclogging the Print Head
With the print head in your hands, take out the print cartridges and clean them with alcohol to remove the ink that accumulated on the surface. Also, use this opportunity to check how things work or fix any problem on the carriage assembly. After the cleaning, let’s move to the complicated part.
First you will need to make your own Epson print head unclogger. Get a 10 cc or 20 cc injection syringe with no needle. Then, go to the nearest model aeronautics store and ask for a 1-inch piece of model aircraft fuel hose. For those who don’t know, it’s a hose made of silicone, extremely flexible. You’ll cut a piece of around ½ inch and put it at the end of the syringe. That’s it! You’ve made your own Epson print head unclogger.
Now, let’s do the work.
Imagine print heads as a funnel. If you push down (narrow part) to up (large part), it’s easier than if you push from up (large part) to down (narrow part). First you will try to inject isopropylic alcohol (isopropanol) from up to down (regular alcohol is not recommended for containing water, that can damage the mechanism). You will fill the syringe up with alcohol, connect the hose that you fixed to the end of the syringe in the tube that goes inside the print cartridge, and force the alcohol out through the ink way. If you look under, you’ll see that there are several small holes that should all be unclogged. Check that out by injecting alcohol from above: there should be alcohol passing through all the holes, not missing a single one. Do that with all heads of the set (your printer can have two or four heads, depending on the model).
In case any hole is clogged, don’t try to inject alcohol from below, but try to PULL the alcohol from below. There lies the main use of that model airplane fuel hose. It’s so flexible (silicone) that the hose forms an excellent sealing around it, so the suction made by the syringe is so powerful that pulls out any clogging that may be on the head. Notice that TRYING TO PUSH UP WILL NOT WORK. The end of the funnel is facing down (facing the paper) and if you try to push the alcohol from down to up, you’ll clog the head even more. The thing is, SUCK the dirt under the head. Notice that it’s A LOT easier if you have, or make, a vacuum pump, but we use what’s at our hand…
Repeat the procedure until you are sure that ALL holes are unclogged. If you leave one single hole clogged, you’ll have to do the work all over again. And it’s painful. It’s a 2-3 hours activity and it’s a procedure that has to be done with all patience and calm.
After you have unclogged all the holes, calmly reassemble the printer, paying attention to the position of the timing belt and of the parallelism adjustment bushings. They have to be in the same place they were before.
After the printer is reassembled, put two NEW and ORIGINAL cartridges in place and perform the printer test for about 10 (yes, I said TEN) times, to be absolutely sure that all jets are working. If all jets are working, you can stamp the seal “OK” and charge your client a fair value. After all, a single color ink jet is very expensive!
Another important detail: every technician that repairs printers must know the qualities and limitations of each printer, and has to tell the clients to use best quality supply, original or not. Alternative supply may be cheaper, but I rarely see an Epson printer getting clogged with original ink. It works this way since dot matrix printers: the head lasted much longer if only original tapes were used – and they had INCREDIBLY better quality. But this is another issue…
Originally at http://www.hardwaresecrets.com/article/178
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