Trying to Save the Scitex Printheads

It’s been a while since I made a post, work as been busy.

Anyway about a week before Christmas I was walking by our HP Scitex FB-500 and I saw that the white ink was empty.

Our Scitex FB-500 has the optional Roll-to-Roll accessory and the White Ink option. Our FB-750 has neither. Though now that we have the Latex 360 (and have it running correctly again) We rarely use the FB’s for roll to roll. An exception would be for black and clear stocks, since for black we need white ink, and clear the Latex can’t see it. We have rigged up the 750 a few times to run 96″ Wide banner material.. that’s always fun.

But anyway, the white ink was empty. It’s never good to have the printheads go dry, ink can dry on the thermistors in the ink reservoirs, causing the printer to think that the reservoirs have in when they really don’t, so no ink will pump in to the reservoir, causing no printing. That’s a fairly easy fix. There’s also the chance of ink drying in the printheads themselves. It’s a bad enough problem with the other colors, but white is thicker and has the tendency to skin over more than the other colors. In fact, if you have the white ink option you get a little vibrating table, the Homogenizer, to vibrate the ink at intervals to keep the pigments suspended. And the printheads get serviced a lot more often to keep the ink flowing through the printheads. Generally, since it wastes so much ink with all the extra servicing, most places save the white ink jobs for a specific day, like every other Friday or whatever to switch the ink from Light Magenta/Light Cyan to White. That, however, also wastes a lot of ink in clearing the lines, so you have some decisions to make. Waste a little ink many times every day, or waste a bunch once every few weeks.

We used to run a lot of White Ink jobs and it wasn’t worth switching over to LM/LC. However, right before we got the FB-750 our biggest white ink customer changed the format of their signage, so we no longer needed the white ink for them, and we are actually able to run on the Latex now. We do have a few jobs here and there that require the White Ink, but nothing like it used to be. We tried once to switch it over and do the “once every couple of weeks” thing, but as I had predicted, the second I switched over a “RUSH-Gotta go!” white ink job came down and had to switch over again.

The printer shows a running tab of how much ink is left in the ink boxes via the profilers. They’re generally pretty good, the idea is to change the box when it says 0%, but you can actually run quite a while past 0% – there’s extra in the box. However, the white ink was never that accurate. I suspect it doesn’t accurately take into account all the servicing it does to the printheads. So, even when we constantly ran that printer the white would be empty at 20%. Now that we rarely use it it can say 40%-50% and be empty. That’s what happened here. I, personally, liked to have an extra box of each color ink at all times. Use a Black, order a Black. Use a Yellow, order a Yellow. The decision was made to wait until the ink was at 40% to order a new box after we got the FB-750 since the FB-500 would be used less.

So anyway, the week before Christmas I walk by the FB-500 and it says it can’t refill the ink reservoirs for white. I check the ink box – empty. Go to change the box – no box. The screen is showing we should still have 55% of the ink left. Lesson: It wastes a ton of ink if you don’t use the printer. Which, to be fair, they recommend you use the printer. I try to get them to rush a box of white ink in since I know it will definitely have issues with the printheads if we wait too long.

Well apparently and invoice didn’t get paid on time and instead of getting a box of ink in quickly it took about 2 extra weeks.

In those 2 weeks I was planning on what I was going to do. I knew the ink would be drying in the printheads. And trying to flush it out would probably be difficult to impossible. Luckily, I thought, we have a Service Contract on these machines. And we get a yearly allotment of 4 printheads. That’s important because the printheads for these printers are about $1700 a piece. And there are 12 of them in the printer, 2 for each color: Black, Cyan, Yellow, Magenta, Light Cyan, Light Magenta. The White Ink takes takes the place of the Light colors, so 4 are used for the White. The contract had always been up at the end of January, and generally at the beginning of January we would call up to use our allotment and replace any bad heads, provided we didn’t have to during the year. I had 2 printheads left over from last year that the HP tech didn’t feel the need to install, so they sit on the shelf. I know how to install the heads, but you have a service contract might as well use it.

Thinking I have everything planned out, I get called about errors on the FB-750. Thinking that the errors were caused by a dirty encoder strip I have to operator clean it. However, due to a brain fart, he cleaned the bottom side, with the wrong chemical, and cleaned off the encoder lines. Con: There’s no way it’ll print now. Pro: It won’t pop that error anymore?

So I have him call HP, as the supervisor wants him to get used to calling them, and come to find out: we don’t have a service contract on that machine. When we first got it it had a warranty with it, but after the warranty expired apparently it was never put on a service contract.

Luckily, I happened to have a new encoder strip that we previously got in that another HP Tech didn’t feel needed to be installed, so it sat on the shelf. I’ve done a couple encoder strips in my day, so it wasn’t that big of a deal.

A few days later I get a call that the FB-750 wasn’t printing correctly, that the image had lines, and “There wasn’t a head strike.” It was quite obviously a head strike. A piece of aluminum that was being printed had a bent corner and it scraped against the heads.

I map out the printheads and most of the heads have quite a few damaged jets. Each printhead has 192 jets by the way. The most bad was 23 in a head. It doesn’t sound like much, but it’ll affect the print. Knowing I didn’t have an allotment for this printer, and only 2 on the shelf, but possibly needing 4 for the other printer with IT’S allotment, I say we can change up to 2 on this printer. But which ones? I cleaned, and purged, and mapped, and cleaned, and mapped, and purged. They were getting better, but not perfect. I call up HP to get my 4 heads from my FB-500 allotment.

We have 1 in our allotment. ONE. How? We’ve always had 4, and we didn’t use any the past year. Apparently the contract was changed, presumably to save money, and it left us with one per year. Although, no one at work seems to know anything about it and the HP tech I’ve talked to has never heard of anyone having a contract with only an allotment of 1. So, I don’t know. They send me the one I definitely had available.

So now I have 3 printheads in my possession, and 4 probably going to be bad on the FB-500, and about 6 that could use a changing in the FB-750. After many, many cleanings, the FB-750 got to a “good enough to run” state. Most of the jets came back, some were still iffy, but at a high enough print quality you couldn’t tell.

Finally the white ink came in. I install the box and it’s doesn’t recognize the ink filling the reservoir. I do a couple purges and it finally recognizes it. I print a test pattern: No jets are printing. ZERO. All 768 White jets are dead. I decided to try anything I could before changing printheads, especially not that I didn’t have enough.

I cleaned them multiple times to no avail. Next step was to soak some link free cloths with Head Flush and let the carriage sit on it, hoping the head flush would soak up into the jets and soften it up. After the first time I got 17 jets on one head to print. Multiple times later I got up to 60 on one head to print. The other 3 wouldn’t print at all.

I had one other idea, and I ran it by HP first. I emptied the printheads: filled with air, shut down the printer, and took the tops off the 2 white in reservoirs. Filled them with head flush, put the tops back on, and let it sit overnight. The next morning I “Filled the Printheads with Air” again, and I could see the jets squirting on all the heads. A couple cleanings and map out later all of the jets were firing again on all of the printheads, even ones that were mapped as bad a year ago. So there you go, save $6800 in printheads and have more jets printing than before.

My plan was to try it on the FB-750 on the head strike affected printheads to see if I can get any back on that one, but they’ve been printing away on it in the mean time.