When is a printhead dead?

[JJ_Holland]

Hello,

Yesterday I replaced 12 dampers on my Roland SC-545EX for the first time by myself. I took the time and did everything very clean and carefully. When I was ready I did a test print and many of the LightCyan nozzles didn't print.
I did a cleaning on the C group and got some nozzles back, when doing another testprint, directly after that, there were more nozzles back, however some were gone again. Ater this I used a swap soaked in cleaning liquid and put that against the head, the first testprint was bad but the second was better. I printed a photo with lots of light blue and it printed terrible. Finally I decided to do a powerfull cleaning on the C group and after that all nozzles were back again. About 20 minutes after that I tried to print the photos again but again some nozzles didn't fire.

So to make it short, all nozzles CAN fire but after a while they decide not to fire. After a cleaning (from the menu) they are back for a short while. The nozzles that are not always working are mainly in the center of the head.
I also replaced the captops, wipers (and cleaned the small thing that scrapes the wipers).

Some additional info:
Because there were problems with the machine and the Roland tech did not fix it yet I decided to search for the problem myself and that is why I replaced the dampers. The problem I had with the machine was that when printing a dark blue/green (something in between) colour it did not print even. When looking at the print from distance you could see some parts were lighter than others. That problem now seems to be fixed, so it looks like replacing the dampers was the solution.

Anyone got any ideas what to do?

Thank you!

Kind regards,
JJ

 

[Jack Knight1979]

How did you prime the dampers? You probably have air in the lines. When I do a damper swap I hook up a syringe to the reaplced damper and suck air until the damper bladder is half full of ink. I drop it on the head and do a normal cleaning good to go.

Some times an air bubble is located at the nut area of the ink line. After a cleaning you print great. Then the air moves into the damper, then the head. Nozzle drop out.

 

[JJ_Holland]

Jack that sounds logical but what to do about it?

I replaced the dampers one at a time. I removed the damper from the head, removed it from the tube. Put the tube on the new damper, put a syringe on it and sucked until the ink ran into the syringe. After that I carefully put it back on the same place on the head.

 

[Jack Knight1979]

Okay. You installed the damper correctly. Some folks twist on a new damper and then do several cleanings to try and run the ink back into the head. Not a good way to go.

You probably have air in there. Did you crack the manifold when putting on the new damper? I've done it before. PITA.

You may want to run a squirt of flush through the head via the manifold. Then put the damper back one and do a cleaning to purge the solution. It is a very bad idea to leave flush in the head for more than a short period. Push some flush through the head and then do one to two cleanings. That should get you back.

How many shots are on the head? Any head strikes in the last month?

 

[JJ_Holland]

Okay Jack, thank you very much for your help.
Unfortunately I have totally lost you, I do not understand what you are advising. What is the "manifold" (is this the black top with the two connectors on top of the printhead? I don't think I have damaged that) and what do you mean by "a squirt of flush"?
I haven't had a big head strike, I did have the head touching the media in the beginning of a roll a couple of times a while ago, but there were no problems after that.
How can I find out the number of shots for a printhead?

I also bought this (link) last week but have not used it because I don't know how ;-) Would this be of any use here, or am I totally missing what your advising?

Thank you!
JJ

 

[Jack Knight1979]

The manifold is the black thing the damper sits on. If you don't know what I'm talking about. It's probably not a good idea to attempt any of the fixed I've suggested. You may want to get a tech out there to flush the head. After you see them do it once, you should be fine.

 

[JJ_Holland]

That is a bit disappointing, I hoped I could do things without the need of a tech guy. By doing things myself I learn how the machines is build and know better what to do when the printers has problems - unfortunately that's always in the weekend or evening with tight deadlines
Have had many tech guys in trough the years, never have seen any of them doing any such thing to the printhead, they always replaced them when they saw manual cleaning
did not have much effect.

I can imagine that manually running cleaning liquid trough the printhead with my cleaning kit isn't going to work?

 

[FrankW]

Try to pull the ink with a syringe through the tube of the cap top, not through the damper.

 

[JJ_Holland]

Hello Frank, thanks for your advise.
Do you mean I should put a syringe on the tube of the LightCyan captop and pull ink into the syringe? I just tried this (after reading it somewhere on this forum) and the testprint for the LightCyan printhead was perfect, after doing another testprint after 5 minutes some weren't firing again, after doing another testprint 5 minutes later some of the nozzles that didn't fire worked again and some + some extra didn't.

Does this still sound like an air problem? It would be a logic explanation as air can move in the tube and cause problems at different places, but that's my unexperienced view.

Do you pull ink whith machine on or off? How much ink should you pull?

Thanks again!

 

[Jack Knight1979]

You have an air leak. I've been there. It's very hard to find them, but you've got one. Swap the dampers from another dead and see if the problem follows the head or the dampers.

 

[JJ_Holland]

Thank you Jack.
Just to be sure, I should swap the dampers of the LightCyan with, for example, the dampers of the LigtMagenta?

 

[FrankW]

Sometimes using a syringe to pull directly from the dampers damages the connector of the damper to the print head. But sometimes too when disconnecting or connecting a damper to the head the pin on the head where the damper is plugged onto breaks.

 

[Jack Knight1979]

Right JJ. Swap with the neighboring head. If the drop out follows the damper your problem is the ink train. If it stays at the head. It's manifold/head.

 

[JJ_Holland]

Okay I now did the following:

1st I connected my syringe to the tube om the LightCyan cap top and pulled ink to see if it would run in nicely without bubbles. Did a testprint after that and it was perfect, printed some photos with lotst of LightCyan and did a testprint directly after that, some nozzles weren't fired again, did a new testprint and .... same problem still there.

2nd I did something that might not be the normal way but I just wanted to see what it would do. I took the dampers of the LightCyan of and switched them with the dampers of LightMagenta, I did not remove the tubes so I swapped LightCyan and LightMagenta completely. I did a testprint and it was perfect again, did a print of some photos and although it looked weird (because of the mixed colours) it printed okay, after that the testprints stayed perfect. Switched eveything back again and after some testprints the problem was there again.

Because this was not logical to me I switched them again to do some more testing, everything stayed okay.

Finally I now also swapped the tubes so ink would run to the correct head again and until now (fingers crossed) I have not had any nozzles not firing.
Basically the only thing I did was switch the LightMagenta and LightCyan dampers.

Does anyone see any logic in this?

Will let you now how the printer works in printing real work

 

[Jack Knight1979]

It doesn't seem logical, but I had this problem once.

My magenta head would not print magenta, but it printed cyan fine.
I ended taking my cyan and magenta heads out and swapping them. It's been printing fine for two years. For whatever reason the head that I bought to replace a bad head, didn't like magenta ink, but printed cyan fine.

I would switch the LM and LC dampers. It's probably something like an o-ring that isn't secure enough on the manifold, but is snug enough on the other head manifold. The nipple diameter could be a little but larger due to manufacturing tolerances.

So take the dampers off and switch the colors. Make sure you suck the ink out of them before you swap them to the other lines.

That should take care of it.

 

[JJ_Holland]

Thank you Jack, that sounds like the most logic explanation.
In the end the dampers were switched. When the problem comes back again it should come back at the other printhead (LightMagenta) if it comes back at the LightCyan there must be a problem with the manifold and than I will replace it with a new one.

 

[Jack Knight1979]

Sounds like you've got it sorted. You can buy manifolds for about 15-30 dollars. I've cracked two over the years.

 

[JJ_Holland]

A week further now and all that has been replaced still works. Thanks to you guys I have kept money in the pocket and have learned a lot about my Roland.
I am still having some problems with the machine but will make a new thread for that.

Thanks again!

 

[Jack Knight1979]

Awesome! I'm glad it's sorted. My machines are acting up a bit right now. they get a little more finicky during change of seasons. Partly because my shop environmentals are bad and take a little time to get dialed in.

 

[JJ_Holland]

Environmental conditions and seasons don't always get the attention they need. I have heard a lot of stories about machines with weird problems that were caused by low humidity. Before you find out thats the reason you have probably allready spend much time on double checking every part.
Good luck!