Need Help FB700 LC head not filling, not holding ink

[FulSnygg]

Problems started with LC suddenly not printing due to no ink in head/reservoir. Heads filled if we did fill and/or purge trough maintenance menu but didn't fill by itself during printing. Tech was here last week, changed the thermistor(-s) without result. He couldn´t find out what was wrong.
Now problem has worsened, and LC heads doesn't seem to hold the ink either. It splurts all of it out when we try to print a primebar. Other heads are ok. What is this?!

Edit: the LC heads are losing ink even when just parked at the carrige station. I se droplets hanging from under the heads.

 

[Turnergraphics]

Maybe the ribbon cable to that head has a tear in the cable.

 

[FulSnygg]

Maybe the ribbon cable to that head has a tear in the cable.

The problem has gradually gotten worse during the last two weeks, is this likely if there is an electrical problem (with cabels or a board)?

 

[FrankW]

I had an issue like that, was a blocked ink filter.

 

[FulSnygg]

I had an issue like that, was a blocked ink filter.

Thanks for your input, where is that filter located?

 

[FrankW]

The filter is located behind the ink box rack, near the ink pumps. Will not give a specific error.

It is no possibility to check that filters visually, but there is a possibility to loose the tubes and let the ink pump work ... if no ink comes out of the tubes while the pump is working, the filter is clogged. Check the ink pump too.

We had that issue on a machine with white ink option.

 

[FulSnygg]

The filter is located behind the ink box rack, near the ink pumps. Will not give a specific error.

It is no possibility to check that filters visually, but there is a possibility to loose the tubes and let the ink pump work ... if no ink comes out of the tubes while the pump is working, the filter is clogged. Check the ink pump too.

We had that issue on a machine with white ink option.

It's not only problem with the heads not getting any ink, they can't keep it either when filled. Seem to be something fishy with the vacuum. Or did you experience this too?Tech comes here again tomorrow, will test if another motherboard will do the trick.

 

[papabud]

could even be a bad o-ring letting air into the system. or a crack somewhere. pretty much anything that will allow air to enter the system

 

[FulSnygg]

could even be a bad o-ring letting air into the system. or a crack somewhere. pretty much anything that will allow air to enter the system

That was my theory but the tech seems awfully sure about the mother board. Tomorrow we will know (I hope)!

 

[papabud]

well lets hope this tech is right then.

 

[FrankW]

If the ink is really dropping out of the nozzles, then you can be shure that air gets into the system somewhere.

 

[FulSnygg]

IMG_20180207_181244

• FulSnygg
• Feb 8, 2018

LC heads not printing after a while

Tech was here for 8 h yesterday (plus he has a 2 h drive just to get here!). We don’t yet know what is wrong. Think we have had techs here for 25 h the last couple of weeks, uuh.


The drop out of the LC printheads seems to be a secondary problem. After the replacement of the thermistors, by some reason neither we or the tech understands, the reservoir had overfilled, and ink went up all the way through the air tubes, filter and to the manifold – which now also must be replaced. After using a compressor to blow out the worst of the ink from the tubes, the dropping stopped.


So now we’re back to heads not printing after a short while (see attached image).


Tech replaced headboard – no difference.


Tech will come back later to switch back headboard (he didn’t have the time yesterday so currently we have a board from one of their machines) and replace manifold + tubes and filter. He will contact HP again to see if they have any ideas. They were sure about the headboard-thing so at the moment we don’t know what’s next.

Why does the printhead print while recently filled, and then just run dry? The thermistors still indicate ink in the reservoir (the thermistors are checked and checked again, indication is correct). Might it be the ink not running freely from the reservoir to the head (partly blocked tubes?)? Or is it pulling air rather than ink when not filled “by force”? Why does it affect both heads at almost the same time?! Something wrong with the vac/air pressure (in manifold or solenoid valve)? I have tried to bring my ideas forth to the techs but they are just “Naah...”. One thing we noted is that when emptying heads, ink from LC are not dripping as fast as the other heads. Does this indicate anything special?

 

[Ron the Sign Man]

We had a similar problem and found that it was caramelized ink inside the reservoir cap around the glass sensors (not sure of terminology here). Cleaned them and works fine again.

 

[FulSnygg]

We had a similar problem and found that it was caramelized ink inside the reservoir cap around the glass sensors (not sure of terminology here). Cleaned them and works fine again.

Thanks, but we first cleaned them and then put in new ones - just to be sure - but no, it didn't work. They're the ones called thermistors

 

[theyllek]

I had this problem and it was a Bad O-Ring on the reservoir cap. I tested this theory by cutting a nitrile glove to fit the area in addition to the O-Ring that was already in there. It let me run the entire day with no problems. I got new O-Rings the next day at the store and haven't had a problem since.

 

[FulSnygg]

I had this problem and it was a Bad O-Ring on the reservoir cap. I tested this theory by cutting a nitrile glove to fit the area in addition to the O-Ring that was already in there. It let me run the entire day with no problems. I got new O-Rings the next day at the store and haven't had a problem since.

That's interesting, will try later today. The top of the reservoir is replaced by tech, but I don’t know if they replaced the o-ring.

 

[theyllek]

That's interesting, will try later today. The top of the reservoir is replaced by tech, but I don’t know if they replaced the o-ring.

They should have replaced the O-Ring with a new cap. but make sure it isn't kinked or anything. That's what ended up causing the leak in ours. Amazing that a tiny leak can cause the amount of issues that it does.

Make sure the thermistors clear the "glove o-ring" so they don't get broken for anything Use it in addition to the regular o-ring for the best seal.

If you are having ink drip out while it's sitting in the service station (we had this problem too) you can use clamps on the low vac lines to narrow down where the leak is happening.

Attached is a photo showing the clamps I've used. I don't remember the exact circumstances as to why I had 3 hemostats/kelly camps on the HP that day but these style clamps are fantastic. They sell them at the Harbor Freight if you don't have any from First Aid Kits, Medical Related Field Employed Friends or ER visits.

You can clamp the low vac line above the cap and it will tell you what side of the clamp the leak is happening. If you clamp it, and it still drips, it's between the clamp and the head. If it stops dripping, the leak is before the clamp.

If you get Ink in the low vac lines they are helpful to keep it from going to the manifold if you spot it in time that is. that's why I haven't put the carriage cover back on either of the presses I run.

 

[wunder]

1st change the Pressure/Vacuum Valve "Festo mini 2-way valve" change means.....use the LM Valve to LC place and LC Valve to LM Place and see if the issue now on LM.....

Festo Valve not close correctly think thats all.
Check and come back with result.

 

[czbhu]

I had this problem and it was a Bad O-Ring on the reservoir cap. I tested this theory by cutting a nitrile glove to fit the area in addition to the O-Ring that was already in there. It let me run the entire day with no problems. I got new O-Rings the next day at the store and haven't had a problem since.

I had a missing nozzles problem too. Almost as same as it has been described here. The LC and LM channel had a nice nozzle check, but after a few minutes the 10th and the 12th head started to drop out like this:

First I checked the vacuum. It was fine. Then I purged a little bit more. No change. Then I read your post, so I checked the O-Ring in the ink/air thermistor, and I cleaned it. I used the nitril glove trick also, since I had no O-Ring. And tadaaammm... it worked.
Thank you for your advice.

On Tuesday I go and buy a whole bunch of O-rings.

It is weird because I only changed the O-ring of the LM heads, and the dropping stopped on the LC too.

My first thought was that the problem is the O-ring of the printhead connection since I had a problem with only 1LC and 1 LM channel, not the both. And that is the first point where the ink can leak seperatly from the other channel. But since it is harder to reach I changed the o ring of the reservoir.

 

[FulSnygg]

Turned out to be the heads causing the problem! Both went bad att the same time.

Problems started with LC suddenly not printing due to no ink in head/reservoir. Heads filled if we did fill and/or purge trough maintenance menu but didn't fill by itself during printing. Tech was here last week, changed the thermistor(-s) without result. He couldn´t find out what was wrong.
Now problem has worsened, and LC heads doesn't seem to hold the ink either. It splurts all of it out when we try to print a primebar. Other heads are ok. What is this?!

Edit: the LC heads are losing ink even when just parked at the carrige station. I se droplets hanging from under the heads.