Epson 4900: Abrupt Loss Of Single Channel

[John Caldwell]

What is our current consensus regarding complete loss of a 900 series single channel (LK) upon rebooting the machine after an 8 hour interval of non-use?

Features include perfect operation of all channels, over more than a dozen prints, only 8 hours earlier; other channels appear 100% intact on Nozzle Check; no improvement after shutting the machine down for a one hour rest; no improvement after 2 regular pair cleanings interspaced with a test print that heavily exercises the LK channel.

I'm tempted to reach for the extended warranty coverage, believing that this is not a clog but a problem in the pre-head signal chain.

Thanks,

John Caldwell

[Paul2660]

John:

I don't have the 4900, however if you have run pairs cleaning 2x and still no ink at all is coming through, more than likely it's air trapped somewhere in the line, or damper.  You might try one of the more power cleaning cycles as they should purge the air out.

It may be electrical also, which more than likely the additional cleanings will not fix. 

Does the 4900 have the M/A mode like the 9900/7900? If so, you might try the CL4 level or one super Strong (whatever it's called on the 4900 that exercises all channels)  It's a lot more ink however.

I would consider the upgrade, warranty extension,  I don't think Epson comes on site, but it's printer replacement on the 4900.  I might have that wrong however. 

Paul

[John Caldwell]

Thanks Paul. Yes, there is a service mode boot on the 4900, but I don't know about the cleaning intensity levels available. I'm annoyed to keep throwing away ink dollars in the high-level cleanings, naturally.

Epson has a local guy who does make a site visits for the 4900 and, thankfully, I do have the warranty extension.

Will update as a solution is found.

John-

[phototoyo]

John,

In my experience (although forgive my lack of the exact terminology...it's Friday), a complete loss of a color channel is usually signs of a bad "pump unit". The head is usually still intact, but the pump fails to send ink to the head. The facility I oversee has several 4900's and this has been an issue with a few in the past. A quick call to my local Epson repair tech for service has always solved the issue.

Paul is correct tho, you can always call Epson and they will simply swap out the entire printer (we've also done this a couple of times). Seems to me the ones that have been serviced on location by a certified technician have been extremely stable thereafter. Plus, then you don't have to pack/unpack your printer!

Best of luck!
Matt

[Ray R]

I have read that if the ink is not getting to the head and you do numerous cleanings without ink getting to it there is a danger of damage to the head.

I lost 3 channels a couple of weeks ago, I had left the printer on for Harvey Head Cleaner to run and I think Windows 7 prevented it running.

I did a nozzle check in the morning and in the afternoon I attempted some printing. This showed 2 nozzles not working.

The local Epson dealer couldn't help (not authorised for the 4900) so I downloaded the maintenance program (paid) and carried out a initial charge on that side of the printer.

The channels came back and after a week seem okay. (Just uses a bit of ink)

Ray

[Ernst Dinkla]

usually signs of a bad "pump unit". The head is usually still intact, but the pump fails to send ink to the head. The facility I oversee has several 4900's and this has been an issue with a few in the past. A quick call to my local Epson repair tech for service has always solved the issue.

Where is that pump for feeding ink located?  The 4900 like all its 4xxx predecessors has no air pressurised ink feeding system. If ink is pumped it should be within the printer itself and on all the inklines, no pump or air pressurised chamber exists on the cartridges.

--
Met vriendelijke groet, Ernst

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
April 2014, 600+ inkjet media white spectral plots.

[jferrari]

no pump or air pressurised [pressurized] chamber exists on the cartridges.

Please cite references to support this opinion.

[Ernst Dinkla]

In questions like this I usually rely on my own observations. Take carts apart. References hardly exist on this topic and what is written either is confusing or simply not true. There have been threads on the subject before where people state that there is an extra air feeding connection to the cartridges. I have taken two 4900 carts apart and there is no extra connection like that. I have disassembled carts since the Epson 3000 and up to the 11880 and the differences between air pressurised carts and gravity feeding carts are distinct. The air pressurised carts all have pressurising chambers with a sealed membrane with the ink pouch inside and an inlet for air. The 4900 carts do not have that.

There is one thing I may have overlooked and that is that the inkflow compartment with flow sensor I first  have seen with the 11880 range now could also act as a pump on the 4900 models. There is some similarity with HP cartridge membrane pumps on the outside. Cut one open and it does not have an electric actuator that could make it a membrane pump. An actuator in the printer can not access that membrane, it is encapsulated in the carts' body.  It looks more like a part for controlling the flow along the ink flow sensor, local air pressure having an influence, similar to the 11880 cart version, that cart is air pressurised though. I also cut open the valve in the cartridge ink connector to the printer's ink slot. The valve has an unusual long stroke which I thought may act like a pump too, I doubt that based on the construction but cutting the backflow valve open that sits at the ink pouch side I see things have changed there since the 11880 cart. The backflow valve is directly behind the ink outlet valve body and with an actuator in the printer's cart slot the outlet valve might act like a pump. Probably not efficient but with a high frequency motion it could build pressure. This would be enough to get round HP's  patents I guess.

So if my observations are right I was partly wrong: the pump part could be the outlet valve itself driven by the printer's ink slot connector. Very strange construction compared to what I have seen in ink feeding technology so far. Edit: I have still doubts that there is any pressure made in the carts, if the ink feeding is pressurised it is done in the printer so my question remains, where is that pump?

--
Met vriendelijke groet, Ernst

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
April 2014, 600+ inkjet media white spectral plots.

[Ernst Dinkla]

In my experience (although forgive my lack of the exact terminology...it's Friday), a complete loss of a color channel is usually signs of a bad "pump unit". The head is usually still intact, but the pump fails to send ink to the head. The facility I oversee has several 4900's and this has been an issue with a few in the past. A quick call to my local Epson repair tech for service has always solved the issue.

Could it be the maintenance waste ink pump you refer to? The one that sucks at the ink channels during cleaning cycles when the heads are capped on the maintenance station.

--
Met vriendelijke groet, Ernst

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
April 2014, 600+ inkjet media white spectral plots.