Curious waste ink issue : R1900

[websnail]

Hey folks... I appreciate this may well be a bit rambling and at times make no sense but hopefully that'll explain why I'm having so much trouble trying to understand what's happening.

Ok... scenario is this... Epson R1900 printer with 2 flexible waste ink tubes that fit the usual Epson design. Each flexible tube runs from the pump for a short distance and then connects to two additional extension tubes which then redirect the flow into the pads in the base of the printer. The initial flexible tubes are connected to the extensions by way of simply sliding the flexible ones over the extension. This presumably provides a small amount of constriction at the join but it's designed that way and works.

So, in theory, all that's required is for these flexible tubes to be slid off the extensions and then have alternative extensions (that lead to an external) tank, plugged in and that's all good....

Easy!... Erm?... For some reason it isn't!

If you plug the external tank in, the waste ink pushes through as you would expect, normally, but when you do a test nozzle print you immediately discover that the Gloss Optimiser, Yellow, Orange & Red inks all stop outputting. Further investigation shows that these are the nozzles that sit on the outside of each zone of the printhead... Ok, further explanation required...

The printhead has two nozzle zones made up of four inks per zone. These zones are then serviced with two parking pads and cleaning bays for sucking the waste ink out of them. As a result, you have:

Zone #1
Yellow, Magenta, MK, Red

Zone #2
Orange, PK, Glop, Cyan


Hmm... ok so the theory doesn't hold up too well on the Zone #2 as the Cyan should be empty and the Glop fine...



So, with all this in mind it gets weirder...

If you put all the waste tubes back as before you then discover that the red and the orange return!


I've talked this over with my father who's an engineer and he wound up telling me I was nuts and needed to drink less but it's what I'm seeing...

Anyway, as things go, the cartridges are now empty and I've got to wait until my bulk ink arrives so I can try to get the inks back to what they were before (by plugging everything back to "normal"). From there I should then be able to do some empiric research to see if changing fittings, tube diameters, etc... has any effect..


If ANY of this sounds at all familiar then I'd love to hear from you because frankly this has got my scratching my head in a serious, hair loss kind of way..

 

[embguy]

The waste ink tube at the waste ink pad is open to atmospheric pressure. Therefore, there is no back pressure between the inlet and the outlet of the purge unit.

If you redirect the waste ink tube to a sealed container, the back pressure may prevent the ink from coming out of the purge unit outlet.

 

[websnail]

The waste ink tube at the waste ink pad is open to atmospheric pressure. Therefore, there is no back pressure between the inlet and the outlet of the purge unit.

If you redirect the waste ink tube to a sealed container, the back pressure may prevent the ink from coming out of the purge unit outlet.

Ah... yeah... should have clarified that bit. There's a vent for the container.. so no back pressure.

I get the same issue if I just disconnect the flexible tubing and leave them completely open whilst emptying into an open container.

 

[RWP]

What about the elevation of the waste ink tubes? Were they routed in a generally downhill progression to the waste tank, with no part of the line being higher than the waste ink pump outlet elevation?

 

[embguy]

Let take the printhead out of the equation. If some nozzles are clogged, you don't get any ink coming out the purge unit.

Put Windex on the pads, where the printhead parks on during purging, until the pads are saturated with Windex. Then do a purge.
1. Is the Windex disappear?
2. Is there any liquid going to the external tank?

This tests the condition of the purge unit too.

 

[websnail]

What about the elevation of the waste ink tubes? Were they routed in a generally downhill progression to the waste tank, with no part of the line being higher than the waste ink pump outlet elevation?

Yep... considered this too... All the tubes are running to the same elevation as the connection point between flexible and extension tubes to the pads. If anything they are slighly lower.

One thing that has occured to me though is that the tubes are no longer bent in the same way as they were and this might be part of the issue... I'm going to try re-rigging the tubes and extensions to they are bent to the same degree as they were with the original fitting. If that works then try with extensions.. The bend could be important, perhaps less resistence or similar... Something to consider anyway.

 

[websnail]

Let take the printhead out of the equation. If some nozzles are clogged, you don't get any ink coming out the purge unit.

Yeah... I've completely negated clogging as the issue... If it's anything it's more likely to be air bubbles... Also the red and orange wouldn't spring back into action again so quickly.

Put Windex on the pads, where the printhead parks on during purging, until the pads are saturated with Windex. Then do a purge.
1. Is the Windex disappear?
2. Is there any liquid going to the external tank?

Yes and yes... The printer does clear out the parking/cleaning pad area very thoroughly so it's not lack of suction... There's also not more or less residue/liquid left in either of the two pads.


The more I think about it, the more I believe it's the bend in the tubing that's critical... I'm thinking it might be the way the tubing lines up or possibly even affects the position of the parking pads... Hard to explain but once I get my bulk ink I'll be able to test the theory better.

 

[embguy]

The more I think about it, the more I believe it's the bend in the tubing that's critical... I'm thinking it might be the way the tubing lines up or possibly even affects the position of the parking pads... Hard to explain but once I get my bulk ink I'll be able to test the theory better.

I agree, by the process of elimination, the problem may be the way that you run the tubing. Is there any liquid in any part of the tubing?

Yep... considered this too... All the tubes are running to the same elevation as the connection point between flexible and extension tubes to the pads. If anything they are slighly lower.

The tubing should be sloping downward. It should not have horizontal run at any part of the tubing. Horizontal run traps air bubble.

Flood the parking pads with Windex before testing after you get your bulk ink. This will eliminate the priming issue with the purge unit. I always wondering what the printer does at the begining to prime the purge unit when the porous pad is dry.

 

[websnail]

The more I think about it, the more I believe it's the bend in the tubing that's critical... I'm thinking it might be the way the tubing lines up or possibly even affects the position of the parking pads... Hard to explain but once I get my bulk ink I'll be able to test the theory better.

I agree, by the process of elimination, the problem may be the way that you run the tubing. Is there any liquid in any part of the tubing?

Yeah... I'm starting to think the same way... the curious thing is that the whole thing can't be much different from the R800 or R1800 and yet I've only got one other instance of this same behaviour happening with one of those. Hoping to confirm if the reportee can provide me with some pictures.

The tubing should be sloping downward. It should not have horizontal run at any part of the tubing. Horizontal run traps air bubble.

Yep... that's been considered... The R1900 actually lifts the tubes up to the connection point behind the side panel and then the extensions drop off to just above base level so I've mirrored this... In terms of position I don't think level is the issue here.

Flood the parking pads with Windex before testing after you get your bulk ink. This will eliminate the priming issue with the purge unit. I always wondering what the printer does at the begining to prime the purge unit when the porous pad is dry.

Good idea... It's probably going to be a week or so before the ink arrives but I'll let you know how it works out...

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