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Author Topic: 7900 nozzle pattern weirdness  (Read 7241 times)

Wayne Fox

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7900 nozzle pattern weirdness
« on: February 18, 2011, 12:33:51 am »

I've never seen this before and I've owned and used a large number of Epson printers over the years, as well as sold and supported quite a few with my new store.  Had to clear a couple of clogs, the next nozzle pattern printed like this.  All of the nozzles are clear, but as you can see from the nozzle check, the printer is firing a sequence of the nozzles out of order (only in the VM channel). I can't find anything on this.  Anyone seen this?

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natas

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Re: 7900 nozzle pattern weirdness
« Reply #1 on: February 18, 2011, 01:56:32 pm »

I wonder if doing a head alignment would fix this. I have never seen this before, let us know if you figure it out.
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BradFunkhouser

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Re: 7900 nozzle pattern weirdness
« Reply #2 on: February 18, 2011, 02:11:30 pm »

It could be several deflected nozzles.  You might need to do a super sonic cleaning, which uses vibration to dislodge debris.  You could also try moistening the head cap.  I've found that works wonders on my 9900.  It's the key to my happiness.

- Brad
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Farmer

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Re: 7900 nozzle pattern weirdness
« Reply #3 on: February 18, 2011, 04:15:07 pm »

Is the mis-alignment repeatable?  In other words, is it always exactly the same?

Can you check it under a loupe and have a look at the dot placement and see how uniformly they're forming and whether there are any satellites or apparent split drops?

I'm thinking something physically stuck on the head (a hair, something like that) causing a deflection - not so much due to directly hitting the fired droplet, but just due to proximity.
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Phil Brown

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Re: 7900 nozzle pattern weirdness
« Reply #4 on: February 18, 2011, 04:42:07 pm »

Hi Wayne,

As Phil mentioned, I'm wondering about the repeatability of this anomaly.  In many ways it reminds me of an issue I had with one of my 7600 printers a couple of years ago, which resulted in a new print head being installed. It's been working fine since. Fortunately I haven't seen anything like this on the 9900, yet. I have had a couple of issues and one service call under warranty. I'll be interested in finding out what could be causing this as well.

Gary
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Gary N.
"My memory isn't what it used to be. As a matter of fact it never was." (gan)

Richowens

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Re: 7900 nozzle pattern weirdness
« Reply #5 on: February 18, 2011, 04:43:39 pm »

I had something similar once, except it was lines in skies. Turned out to be a cat hair stuck over the cyan nozzles, deflecting the ink.

Washed it with paper towel strips and warm water.

Rich
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Wayne Fox

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Re: 7900 nozzle pattern weirdness
« Reply #6 on: February 18, 2011, 08:13:13 pm »

Thanks to all.  I did try several of the mentioned ideas, including SS clean.  I also suspect a deflection, but I've seen lots of deflections over the years and this doesn't seem to be the same, although it is the most logical scenario.  One odd thing is the pattern seems perfectly repeatable, and there doesn't appear to be any stray dots.  Oddly enough I can't detect any issues with printed output ... I thought I would see at least some banding or dark streaks.

Sounds like I need to try and clean the surface of the head, something I haven't done on a 7900 before. Any tips appreciated.
« Last Edit: February 18, 2011, 08:18:46 pm by Wayne Fox »
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cybis

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Re: 7900 nozzle pattern weirdness
« Reply #7 on: February 18, 2011, 08:18:22 pm »

I think your first explanation was the right one. Nozzles are firing in the wrong sequence. It's weird. And mysterious.
Maybe they are just firing in the wrong sequence for nozzle check patterns. Does it make a difference if you run the pattern from the computer or from the printer?
 
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davidh202

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Re: 7900 nozzle pattern weirdness
« Reply #8 on: February 18, 2011, 08:52:01 pm »

I had something similar once, except it was lines in skies. Turned out to be a cat hair stuck over the cyan nozzles, deflecting the ink.

Washed it with paper towel strips and warm water.

Rich
Rich and others who dare mess with the print heads.
Wouldn't using paper toweling to wipe or moisten the heads run the risk of introducing more paper fibers onto the head?
And just for my possible future referance, how does one access the print head to accomplish this cleaning maneuver?
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Farmer

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Re: 7900 nozzle pattern weirdness
« Reply #9 on: February 18, 2011, 09:11:12 pm »

Wayne - before you resort to wiping the head (I wouldn't ever recommend this), check your firmare version and see if you can update it.
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Phil Brown

BradFunkhouser

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Re: 7900 nozzle pattern weirdness
« Reply #10 on: February 19, 2011, 11:48:27 am »

I've had a lot of success on my 9900 keeping the head clean by moistening the head cap columns whenever there are nozzle problems of any kind.

Gently dab one or more of the 5 color-pair head cap columns with a small wedge of clean wet foam, then let the printer re-seat the head onto the moistened head cap.  Wait a minute to let the water do its work, then perform a basic cleaning, which fires ink (and the moisture you added) through the head cap pads and pumps it into the maintenance tank.

This way you never touch the head itself, you're just adding a little water to the cleaning process that goes on within the head cap assembly.
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dtsiapas

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Re: 7900 nozzle pattern weirdness
« Reply #11 on: February 21, 2011, 01:07:31 pm »

I also have a nozzle in Magenta that seems missiligned on my Epson 7900 when i print the nozzle check pattern. I have had it for several weeks and but i didn't try to repair it with head alignment because it didn't cause any problems on the output. Probably my problem matches with what Wayne has with his printer but in smaller scale.

Quote
I've had a lot of success on my 9900 keeping the head clean by moistening the head cap columns whenever there are nozzle problems of any kind.
BradFunkhouser

BradFunhouser how did you manage to have access to the head cap? I have seen the Epson technician dissasebling my Epson 7900 three or four times but I don't think that I can repeat this procedure in order to access the head cap. How did you manage to move the print head to the left in order to reveal the head cap? I there an easy way to have access to this component of the printer, like a lever or a special menu in the service mode menu?

BradFunkhouser

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Re: 7900 nozzle pattern weirdness
« Reply #12 on: February 22, 2011, 06:20:31 pm »

When the head is moving across as it checks paper size, open the front cover.  The head will stop.  Turn the printer off.  Then you can gently slide the head assembly to the left and get access to the head cap columns.  I've never done anything other than dab them gently with clean wet foam.  Close the door and start it up.  The printer safely returns the head to its home position as part of the boot sequence.

A technician had to replace a print head because of some bad nozzles, then several weeks later he had to replace the entire head cap assembly because it wasn't sealing properly.  Through all of this, I got to study the printer's guts, how cleanings work, etc.  I watched him shoot water into the head cap assembly with a syringe to moisten it and to prime the pump that sends the ink into the maintenance tank.  That was an epiphany for me, especially since our dry winter days have historically resulted in major nozzle problems.  Not any more though.  :-)
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dtsiapas

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Re: 7900 nozzle pattern weirdness
« Reply #13 on: February 23, 2011, 03:42:08 am »

Quote
When the head is moving across as it checks paper size, open the front cover.  The head will stop.  Turn the printer off.  Then you can gently slide the head assembly to the left and get access to the head cap columns.
I just saw your post and I have to tell you that yesterday I tried a similar procedure ;)
When the printer was initilizing I opened the front cover and the print head stopped!! Then I moved the print head to the left as far as it went because I was afraid it could come back!! Our difference is that I didn't shutdown the printer. Then I moistened the head tap and closed the front cover and the print head came back to its place and I continued with nozzle checks and printing.
I have to add that i tried this procedure both in normal and service mode.
Also i tried to open the front cover after the printer had initialized and this caused a head cleaning! So, don't open the front cover and move the print head after printer initialization as this fires up an unwanted cleaning cycle!

Doombrain

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Re: 7900 nozzle pattern weirdness
« Reply #14 on: February 23, 2011, 07:08:18 am »

I've seen this before on an 11880 a long time back.

What had happened was the head was hit by an object which bent the metallic surface over the ink channel and distorted the flow of jets. Sorry, but I think your head is damaged.
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bellimages

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Re: 7900 nozzle pattern weirdness
« Reply #15 on: February 23, 2011, 04:55:34 pm »

This post will not help to solve this issue. But it brings to mind a question that I've had for a long time .... what kind of money am I looking at if I would ever have to replace a print head on my 7900 (parts and labor)?
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Jan Bell, Owner/Photographer, Bell Image

Wayne Fox

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Re: 7900 nozzle pattern weirdness
« Reply #16 on: February 24, 2011, 02:35:10 am »

I've seen this before on an 11880 a long time back.

What had happened was the head was hit by an object which bent the metallic surface over the ink channel and distorted the flow of jets. Sorry, but I think your head is damaged.

a little work with a wet micro fiber cloth today alleviated quite a bit of the problem, and there was a lot of ink on cloth.  I think it's a case of dried ink.  Hopefully another go at it will fix it.  I don't think it's a damaged head (although hopefully my cleaning efforts won't turn it into one)
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Farmer

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Re: 7900 nozzle pattern weirdness
« Reply #17 on: February 24, 2011, 04:27:51 am »

Microfibre's a decent choice.  Be sure to run a regular clean once you're finished and it should be fine.  I still reckon it'll be a hair or similar stuck on the head.
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Phil Brown

Doombrain

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Re: 7900 nozzle pattern weirdness
« Reply #18 on: February 24, 2011, 05:29:11 am »

a little work with a wet micro fiber cloth today alleviated quite a bit of the problem, and there was a lot of ink on cloth.  I think it's a case of dried ink.  Hopefully another go at it will fix it.  I don't think it's a damaged head (although hopefully my cleaning efforts won't turn it into one)

Happy days!
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