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Author Topic: Epson 7900 from the inside - out  (Read 384051 times)
Sal Baker
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« Reply #1020 on: December 29, 2012, 10:44:51 AM »
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I agree.  I don't know what special magic Epson put in the 3880, but unlike all of my other Epsons it's been a clog-free machine.  It sometimes sits (covered) for a month at a time.  It required one standard nozzle cleaning about two years ago but that's it.  I still do nozzle checks before running an expensive sheet of 17x22 paper through it, but it continues to be clog-free.  A Google search reveals this is a common experience with most 3880 users.

What did Epson do different in the 3880?

Sal
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Alto
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« Reply #1021 on: December 29, 2012, 11:14:55 AM »
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Hi Eric

Today our vintage tractor ran out of diesel so I had to bleed the injector system which got me thinking as I was standing out in the rain. In an injector system even the smallest and I mean smallest amount of air will cause the pump to malfunction . Are the nozzles sucking air back into the system ? if the piezoelectric chamber is trying to squeeze air the air will just compress and we see no output.?  If the chamber has an incompressible fluid i.e. ink it will be expelled from the chamber.

Jon

I have been following from the start .
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Eric Gulbransen
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« Reply #1022 on: December 29, 2012, 11:47:10 AM »
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Mark D Segal, I've been wanting to bring this up for a while.  You own a 4900 don't you?  You seem to have your finger on the pulse of "X900" clogging issues so I ask you to think this over for a bit - in all of the reports we have heard about these X900 printhead killing terminal clogs, how many can you remember were 4900s?  I'm doing my best to remember, which has one of my dog ears cocked to one side.  Sure people mention clogging with 4900s, but how many dead heads...  ...any?  If there is a difference, and 4900s are indeed insulated from the most horrid of clogs - terminal clogs - then perhaps it's the very different angle that the 4900 head sits on it's rails.  I don't know, thoughts like these are my sheep to count late night.

iladi, that's an interesting point you bring up.  I know I've talked to HAL about some of his service calls on these X900s pushing out ecosolvent ink.  The stories are disgusting actually - how the lines get gunked up with muck and tar, it really sounds like a mess.  So perhaps this suggests there are solvents which could be used that won't do damage.  From what I could tell from the one channel that I did test with Acetone, none of the piezoelectrics seemed adversely affected, neither did the clear silicone (rubber-like) material surrounding all the microscopic wires on the underside of the channel.  The plastic framework of the head was not affected, the nipples were not affected, and neither was the rubber grommet that fits the nipples to the back of the head.  All clear there.  But there ARE two materials left which I am suspicious of, they may have been compromised.  The glue which adheres the channel to the plastic framework of the printhead, and the glue which fastens the tin roof to the face of the piezoboard.  It is indeed still difficult to remove an Acetone soaked channel from the printhead, but it doesn't seem AS difficult.  As far as the glue adhering the tin roof to the piezoboard, I have not tested that yet but I will.  I am paranoid about all glues now.. 
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Mark D Segal
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« Reply #1023 on: December 29, 2012, 12:00:58 PM »
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I agree.  I don't know what special magic Epson put in the 3880, but unlike all of my other Epsons it's been a clog-free machine.  It sometimes sits (covered) for a month at a time.  It required one standard nozzle cleaning about two years ago but that's it.  I still do nozzle checks before running an expensive sheet of 17x22 paper through it, but it continues to be clog-free.  A Google search reveals this is a common experience with most 3880 users.

What did Epson do different in the 3880?

Sal

Same experience with its predecessor the 3800, which was a breath of fresh-air from the previous 4800 and 4000 models both of which had clogging issues. So the question is what happened in the progression from the 3800/3880 series to the 4900. The new head technology is different - many more nozzles, hence smaller ones per square inch. The inks are named differently so the recipe may not be the same. The lines are longer between the cartridges and the print head. More than that I don't know. Epson did say - I believe in the initial promos - that the 4900 head was coated with a clog repellant material, but I have no idea what that would do for me if the clogs originate from drying ink within - or indeed if that's really what happens. This stuff is nano-technology, combining at least leading edge chemistry, materials technology, fluid mechanics and the relevant electronics; to really understand it I think requires a high level of very specialized education and experience.
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Mark D Segal (formerly MarkDS)
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raydee
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« Reply #1024 on: December 29, 2012, 12:10:28 PM »
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So maybe the piezo heads are just as much a consumeable as the thermo heads are. They just aren't labeled as such, are hard to aquire for the end user, need a trained $$$  technician to replace and cost so much that it means the printers end of life in most cases.
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Mark D Segal
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« Reply #1025 on: December 29, 2012, 12:11:25 PM »
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Mark D Segal, I've been wanting to bring this up for a while.  You own a 4900 don't you?  You seem to have your finger on the pulse of "X900" clogging issues so I ask you to think this over for a bit - in all of the reports we have heard about these X900 printhead killing terminal clogs, how many can you remember were 4900s?  I'm doing my best to remember, which has one of my dog ears cocked to one side.  Sure people mention clogging with 4900s, but how many dead heads...  ...any?  If there is a difference, and 4900s are indeed insulated from the most horrid of clogs - terminal clogs - then perhaps it's the very different angle that the 4900 head sits on it's rails.  I don't know, thoughts like these are my sheep to count late night.

................

Eric, yes, I own a 4900. I wouldn't say I have my finger on the pulse of "X900" clogging issues, but I do have a very clear perception of how MY 4900 behaves, and it behaves pretty much as predicted: use it regularly and there are seldom clogs; leave it alone for weeks on-end (as I need to do periodically) and cleaning will be required - sometimes repeatedly using a routine Epson Pro-Graphics advised me about some years ago (running prints between cleanings) and it always - eventually - recovers every nozzle. A nuisance to be sure, but no disasters - yet. The fact that there is so little forum noise about the 4900 indicates that few people are likely to be having fatal issues with them. I wouldn't have a clue why it *seems* to have fewer fatalities than the 7900, but these are not identical machines apart from size. The 4900 is a much more recent model - there was a gap of several years between the 7900 and the 4900, and the head technology is not simply a smaller sized clone of the 7900 head. They changed some stuff, but exactly what I don't know and it wouldn't mean much to me, not being a printer technologist.
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Mark D Segal (formerly MarkDS)
Author: "Scanning Workflows with SilverFast 8....." http://www.luminous-landscape.com/reviews/film/scanning_workflows_with_silverfast_8.shtml
Eric Gulbransen
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« Reply #1026 on: December 29, 2012, 12:14:12 PM »
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The one way valve (speed bump) would preclude you from drawing cleaning fluid backwards through the printhead? Or maybe I'm not completely following along with the path of ink flow...
Steve

Good question Steve.  My genius brought up the same ideas..  It's easy to visualize the piezo-walls flexing, then pushing ink out of the nozzle opening in the printhead face (tin roof).  But it can't be that simple.  The reason being, each piezo chamber has two walls - a left wall and a right wall.  OK so fine, the walls flex inward and ink gets shot out the nozzle opening.  But what happens to the ink on the other side of these two walls?  After all if they flex inward from the perspective of the firing nozzle, they flex outward from the perspective of the two chambers on either side.  This would create suction in those two chambers wouldn't it?  Seems to me that it would..  I don't know that the "speedbumps" are actually two way valves.  I am assuming this.  It is possible that since these bumps are indeed on the chamber walls, that they do make contact with the wall on the other side during a piezo firing.  If this is true, then it is also possible that this one way valve is only a one way valve during a firing.  When not firing the passage is clear for ink to pass.  Keep in mind that these chamber walls have both a roof, and a floor.  The roof is the tin printhead face, the floor is a very thin plastic-like flexible membrane.  

Sorry for getting this technical, but you asked for it...   Smiley

One theory the genius and I came up with, which "might" explain how two neighboring piezo chambers can fire at once, is that they can't.  Perhaps, and please I am open to anyone's opinions here, the neighboring piezo chamber fires when the head comes back on it's return run.  If you've ever watched your criss-crossing printhead produce a print, and I am sure we all have, it DOES seem to print only partial areas of the full footprint of the printhead face with each pass.  I measured our X900 nozzle lineup, it is indeed one inch full of nozzles.  So why then don't our printers print complete one inch wide bands per pass?  It is possible that this is the reason why, two (or three actually) neighboring piezo chambers cannot fire at once.

We know that there is indeed one nozzle for every chamber.  We know that the chamber walls flex when electrically charged.  We know how the electric charge gets to each chamber wall.  We know the flow of the ink.  The rest is up to physics (which I dropped out of in college), and common sense (the only sense I have).  

The reason I post the pics that I do is that people more educated than me can share their theories as well.  We're all in this together.  So thank you, for both past and future contributions to this X900 clog clearing journey of ours.


« Last Edit: December 29, 2012, 12:20:07 PM by Eric Gulbransen » Logged

Mark D Segal
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« Reply #1027 on: December 29, 2012, 12:15:23 PM »
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So maybe the piezo heads are just as much a consumeable as the thermo heads are. They just aren't labeled as such, are hard to aquire for the end user, need a trained $$$  technician to replace and cost so much that it means the printers end of life in most cases.


No. Those heads are not meant to be a "consumable". They are essentially the printer, and they are meant to last a very long time.
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Mark D Segal (formerly MarkDS)
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Alan Goldhammer
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« Reply #1028 on: December 29, 2012, 12:38:26 PM »
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As the resident chemist who has been following this thread here are some observations.  Acetone is an excellent solvent and as we learned when we first took organic chemistry, lots of thing dissolved int it.  Dissolve is the operative word here, plastic doesn't melt as melting is a function of heat.  If there are any binders that are used in the construction of the print head, then acetone is likely a poor choice of cleaning solutions since these compounds can dissolve, weakening the integrity of the print head.  It would be better to try a more moderate solvent such as isopropyl alcohol which used to be used by audiophiles to clean turntable stylus and tape recording heads without fear of damage.  The Epson inks are suspensions of encapsulated colorants (carbon black or appropriate color dyes) or as we commonly define this 'pigments' and my personal believe is that the quality control of the particle size which is critical here.  As Mark and others have noted the 3880 which is highly resistant to clogging has half the number of nozzles per unit area compared to the x900 printers.  Thus, Epson require far better quality control of particle size for inks in the case of the x900 printer.  The only way to know if it is a QC problem in terms of clogging is to document clogs across all printers by the lot number of the ink which is nigh to impossible to do.

From what I've read in the Epson patents, it is likely that there is some heat generated at the print head by the charge put through the piezoelectric head but I doubt that this is significant. 
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Oldfox
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« Reply #1029 on: December 29, 2012, 12:45:53 PM »
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Alan, what about ammonia?
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iladi
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« Reply #1030 on: December 29, 2012, 12:53:38 PM »
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Mark, printheads are consumables. Roland gives a live span of 7 bilion shots per a dx4 head. For a dx7 head, much more sensitive, must be less. The fact is piezo elements fails in time. They will not keep their properties and will start missfire, fuzzyness will became more and more obvious in prints. For a normal epson printer user, yes, printhead last a life, for a heavy user, a copyshop, like mine, it will last only a couple years. I have used over 35 liters of ink in an epson 9700 printer in one and a half year. Yellow is dead now. On my roland solvent i change heads every 2 years, it is a fact that i'm aware. I have to replace heads that are not cloged at alll, just fuzzy prints and lack of power to fire.

Eric, I have a modified epson 4880, turned into DTS printer (direc to substrat). Althou the manufacturer claims it uses waterbased ink, MSDS  talks about ether and other stuff like this. And the ink smells alot like alcohol.lokks to me more like a lite solvent than water.  The pipes are originals, made by epson. No melting. Monday i will try to see what impact the cleaning solution bfor the dts printer has on original HDR inks and let you know.  Then i'll send you the MSDS.


Edit: maybe Alan will help with the MSDS.
« Last Edit: December 29, 2012, 01:02:38 PM by iladi » Logged
Mark D Segal
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« Reply #1031 on: December 29, 2012, 12:55:53 PM »
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Thus, Epson require far better quality control of particle size for inks in the case of the x900 printer.  The only way to know if it is a QC problem in terms of clogging is to document clogs across all printers by the lot number of the ink which is nigh to impossible to do.


Alan, I expect the QC on all their inks for the professional series printers would be rigorous - built-in to the production systems. It just doesn't pay for them to do otherwise, because once it is routine it is cheap compared to dealing with damage and customer relations. I think the real fact of the matter is that they are truly on the leading edge of technology and they don't have a win-win solution in terms of avoiding *all* or *almost all* clogging. As you know, most design and manufacturing involves compromises. My sense of it is that they take a model design as far as they can within what they consider to be a technical improvement within an acceptable range of price and performance. If they had all the answers and they could bundle them into a marketable product, I have no doubt they would do so. And if they don't have all answers, having been the developers of this technology and the true specialists in it for the past several decades, one can never say never, but I'd be surprised if the rest of us will be particularly reliable at second-guessing them, as fascinating and courageous as much of this discussion has been. Remember the beginning of what must be this "Guinness Book or Records Forum Thread" - I'd still like to know *what really happened* to Eric's printer during the time it was in transit from the seller to his place. Of course the discussion has evolved a long way from where it started, and that's OK, but that lingering issue is...well, still lingering :-)
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Mark D Segal (formerly MarkDS)
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« Reply #1032 on: December 29, 2012, 01:03:53 PM »
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Yes, printheads are consumables. ..............

In the final analysis just about anything we use is "consumable". But the term has a specific meaning in this industry. When we say a printhead is "consumable", the meaning generally associated with that expression is that it is inexpensive relative to the printer and designed to be user-replaceable quite easily and at low cost - such as for example the printheads in an HP office inkjet printer. When we say it is not a consumable, we mean the opposite - it is a high percentage of the cost of the printer, and it is not designed to be user-replaceable - the case for ALL of these Epson professional series printers. The Canon IPFs are somewhat hybrid in this scheme - they are meant to be user-replaceable once enough of their nozzles get clogged, but they are not cheap.
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Mark D Segal (formerly MarkDS)
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« Reply #1033 on: December 29, 2012, 02:19:07 PM »
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Maybe you are right, althou my Roland costs 15000 euros, 2 heads are about 1500 euros, including labor, since are not user replaceable. But as i mention earlier, they last about 7 billion shots each head. And you miss my point: piezo DO  tears in time, each shot they fire. Maybe your head will not clog but will fail in time, the more ink, the faster. And canons are cheap. 350 euros for a user replaceable head and 4 liters of ink thru, it is cheap. Epson head is 850 euros the head, plus 450 euros labor and about 10 liter of ink by color.
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Alan Goldhammer
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« Reply #1034 on: December 29, 2012, 02:20:00 PM »
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Alan, what about ammonia?
Ammonia won't do anything if the clog is an organic molecule such as an ink particle.  You need to have an organic solvent.  In the old days we made stylus cleaning solution with isopropyl alcohol, water and a drop of dishwasher detergent.  It might be interesting for Eric to mix up a solution of 10-20% isopropyl alcohol (aka rubbing alcohol) and add a drop of Dawn to it (if it's good enough to clean oil soaked birds it should be good enough for an Epson print head) and see how this works.  It's pretty much the recipe that Windex uses but with more alcohol in it.
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« Reply #1035 on: December 29, 2012, 02:23:03 PM »
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Eric, I have a modified epson 4880, turned into DTS printer (direc to substrat). Althou the manufacturer claims it uses waterbased ink, MSDS  talks about ether and other stuff like this. And the ink smells alot like alcohol.lokks to me more like a lite solvent than water.  The pipes are originals, made by epson. No melting. Monday i will try to see what impact the cleaning solution bfor the dts printer has on original HDR inks and let you know.  Then i'll send you the MSDS.


Edit: maybe Alan will help with the MSDS.
I'll be happy to look at the MSDS.  If one looks at the Epson MSDS, the inks are waterbased but have organic solvents in them (mostly glycols and glycerol) to help keep the particles in suspension.
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Alan Goldhammer
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« Reply #1036 on: December 29, 2012, 02:26:27 PM »
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Alan, I expect the QC on all their inks for the professional series printers would be rigorous - built-in to the production systems. It just doesn't pay for them to do otherwise, because once it is routine it is cheap compared to dealing with damage and customer relations. I think the real fact of the matter is that they are truly on the leading edge of technology and they don't have a win-win solution in terms of avoiding *all* or *almost all* clogging. As you know, most design and manufacturing involves compromises. My sense of it is that they take a model design as far as they can within what they consider to be a technical improvement within an acceptable range of price and performance.
Mark, I agree 100% here.  I suspect that the only difference between the x880 and x900 inks are the particle size of the 'pigments'.  As you know I'm also in agreement that the cause of clogs might be multi-factorial and that the installed user base is quite high.
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Eric Gulbransen
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« Reply #1037 on: December 29, 2012, 02:27:27 PM »
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...to really understand it I think requires a high level of very specialized education and experience...

....I'd be surprised if the rest of us will be particularly reliable at second-guessing them...

Don't worry I'm not fragile.


Listen I'm just a lowly 47yr old college drop-out carpenter who loves photography and (still) races motorcycles.  You're not gonna learn much from me here and I'll be the first one to tell you that.  But do keep in mind the genius buddy who I continually make reference to - he actually has a very specialized education which applies to more than just one aspect of these piezoelectric printheads.  While I respectfully appreciate that you might expect a "genius" reference from a carpenter's perspective to simply mean "Wow that guy's smart," what I actually mean is - he's a genius.  Keep in mind where I live.  I used to wave to Steve Jobbs on my way to work in the morning, he literally lived up my street.  The flip-phone was born above the very wood floors I'm writing this from.  This area that I live in right now, which I don't even understand how I live here, is a mecca for the mindful.  And our resident genius - who has access to more people just like him - has earned his his seat among the best of them.  It's a safe bet you hold in your hands today, Mark, something our very genius made yesterday.  Literally

I feel incredibly fortunate to have the very specialized help we do here.  There's not as much "guess work" going on as my goofy nature  conveys.  Would you like me to explain exactly how just forty six microscopic brass leads inside a channel's tiny ribbon wire can deliver firing charges to seven hundred and twenty individual Piezoelectric nozzles - all needing different information?  Because I can do that - all the notes are scribbled on three napkins from Thursday night's dinner at California Pizza Kitchen.  That's the type of specialized education we are fortunate enough to have access to here.  I have to brace myself before I ask questions.  Seriously some of the answers I get leave me feeling pretty dam helpless.  It's common I'm lost at the first sentence, never mind the last.  

As for "that lingering issue is...well, still lingering :-)," consider this fun fact and then tell me YOUR answer:  The 9900 that I bought in Colorado had a reported 75% of it's green channel missing.  I bought that printer in August, where it was dragged from the back of a mini-van packed with four hundred suit cases and bicycles and juggling apparatus's piled on top of it.  For a week it baked in the back of my cargo van in the high (dry) desert heat (110+).  Once I got it home that machine lay inactive, never even turned on, for 4 months more.  So it's been abused - subject to horrid neglect, super high temperatures, super dry environments, banging, smashing, vibrating and the like.  You name it this 9900 has endured it.  For sure way more than my shipped 7900 ever endured.  The 7900 was back up and running in only ten days time from the day it was shipped, which was also the day it reportedly fired it's last print - and it had terminal clogs from (my) day one.  So what would you expect a nozzle pattern to deliver on this 9900, after all this time and abuse?  Maybe not one channel firing one nozzle at all?  Well you'd almost be right, only magenta was 100% clear.  The rest of the channels/nozzles were pretty much gone.  After just one series of pairs cleanings (about three per pair), this 9900 was 100% clear and ready for printing - except for the very same 75% of missing terminally clogged green nozzles that we missing before I got it.

I don't know what this does for you, but it pretty well wraps up my view of the 7900 that I bought used.  



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Mark D Segal
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« Reply #1038 on: December 29, 2012, 02:36:53 PM »
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Good to hear you're getting knowledgeable help Eric.

That comparison between the 7900 and the 9900 is truly intriguing and it's encouraging to see how much abuse that 9900 could absorb and still work. Maybe that says something for the intrinsic quality of these machine builds, but very little about specifically what causes some of them to fail so completely.
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Mark D Segal (formerly MarkDS)
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« Reply #1039 on: December 29, 2012, 02:48:45 PM »
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Ammonia won't do anything if the clog is an organic molecule such as an ink particle.  You need to have an organic solvent.  In the old days we made stylus cleaning solution with isopropyl alcohol, water and a drop of dishwasher detergent.  It might be interesting for Eric to mix up a solution of 10-20% isopropyl alcohol (aka rubbing alcohol) and add a drop of Dawn to it (if it's good enough to clean oil soaked birds it should be good enough for an Epson print head) and see how this works.  It's pretty much the recipe that Windex uses but with more alcohol in it.

You are right. Once i had some cleaning solution for my waterbased mutoh printer. It was alcohol, soap, some glycol and water.
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