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currentcreation
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L25500 ink pressure issues

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L25500
i was having print quality issues, so I decided to make sure the ink tubes didn't have air bubbles. Light cyan is being difficult though.

I have been successful in bleeding all colors except that one. When I try to draw ink through the lc line, it resists. Seems to have a pressure issue, like a suction, where the ink doesn't draw through nicely and will even retreat back into the line when I release the syringe pressure.

Then, when it is priming the system through the initialization, it begins to leak.

Once the printhead has been removed, ink continues to bleed out of the printhead nozzle. When I pull the air line for lc, the bleeding stops.

These are New printhead nozzles and couplings installed.
Air pressure system checks out fine via diagnostics.

What am I missing?
Is there a way to test the relief valve?
Where is the relief valve, if it may be the problem?

Thanks.
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davidzuts
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You are worrying about the wrong item. Where is the leak as that is the problem area. The way the system works is quite simple. You have an ink tank with a hose input. Air is fed into the hose which then goes into the air tank and forces the ink into the tube assmbly where there is a nipple at the end that the printhead needle is inserted to feed the ink to the printhead to replenish ink used for printing. Leaks occur most times when a fitting breaks usually at the bottom the feed line of the ink tube connects to the fittings that go to the nipple. If ink is leaking out of the nipple that I would assume the nipple is defetive.

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currentcreation
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I wonder, could it be the ink cartridge causing the problem?
It Is a new genuine HP and only about half way through the volume though.
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davidzuts
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Sounds like an issue with the ink tube assembly. Really expensive. CQ869-67037. What has probably happened is the nipple where you are inserting the syringe to draw the ink is broken at the bottom and that is where the ink is leaking when under pressure. Remove the assembly at the carriage and there will be plenty of ink below.

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currentcreation
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I replaced them. I wanted to be sure that the connections weren't the bad part, so I replaced all 12 nozzles and couplers. On the LC couplers, I added a small touch of silicone glue to be sure that they were not the weak point. The ink is definately coming from the top of the nozzle, but it doen't look like it is due to them leaking where the nozzles connect at. It is just that much pressure pushing on the LC line that it is working its way through the rubber seal at the top.

 

I have pulled the lines all apart and inspected them. And yes, the ink is collecting in the bottom of the carriage. There must be something causing the pressure on that one ink line though.

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davidzuts
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My experience is that nipple fitting that the pin from the printehad goes into has an issue. It is not a pressure issue as if it was then all the printheads would have an issue since the pressure is the same to all printheads since the air is supplied by the unit. Also a tip that you have an issue is you can not draw ink when you use the syringe which means the needle of the syringe can not draw. One thing I have seen when using a syringe is the type of needle. Most of the needles available on line are not suited for these devices as they are to long and the opening is at the bottom of the needle. I have used a syringe I received a long time ago that was designed for designjet printers. The hole the draws the ink is in the middle of the needle and the needle is shorter then the ones on the net so you will not damage the fittings. Below is a link to the company where I got the syringe when we ordered a 1050C tube assembly. I have received 2 other needles from this firm for other purchases so maybe you can contact them to see if they will sell you just the syringe.

 

https://www.lpscomputer.com/products/c6074-60342r-designjet-1050c-ink-tube-system-199-w-exchange

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currentcreation
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Thanks.
I use a disassembled printhead with a 1/8" hose and syringe. Works perfectly and with an OEM needle.
I will try a different nozzle, but as I mentioned before, these nozzles are all brand new, so it seems like they should be fine.

Good point about the pressure being the same on all of them.

So, when I manually push ink through the line, it seems to flow fine. I need to try another ink cartridge too.
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currentcreation
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Another thought, looking at that link, I wonder if the seals at the valve are shot, the O-rings.
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davidzuts
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The first thing you need to solve is the LEAK. Until you do so everything else is mute. Forget about the seals since the leak is at the carriage side.

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currentcreation
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Thanks again David.

I am hoping I found the culprit now. The ink tube end piece has a small chunk missing from the flat base rim, where the coupler would rest. Going to try to glue the coupler on and hope that fixes it.

It would explain the minor ink starvation issues and constant printhead cleaning that needs to be done, ever since I purchased it...
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currentcreation
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Still having issues with this..

The problem is just with the LC apparently.

I have now replaced all of the nozzle pieces and replaced the broken base -to- tube piece, new printheads, new ink cartridge. Feeling pretty confident that any leaks are fixed.

So..
When it was initizing the ink system, the LC was leaking into the print head carriage, so I cut the power.
I began removing the printheads to clean up the mess yet again and one of the LC nozzles started spraying ink straight up and wasn't quitting, so I pulled the cartridge and found that it was inflated like a balloon.

What would cause this?
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