Which Head is Bad - Or Are Any?

[rdm01]

We're running a HP 370, and have a reoccurring issue. This time we're printing a longer project that has a darker green on it. over the course of about 3 feet it lightens up and then is a slightly banded lighter green.

So a head must be going bad right?

Check the heads, none are above 3,000 ml. Typically we get at least 3,500 ml, but that doesn't necessarily mean one hasn't gone bad - maybe prematurely due to head strikes or something. We do a manual clean of all heads, and then print some head tests. All look good, but the solid areas have a little inconsistency, which makes me think optimizer, but not conclusively.

So next step - force drop test. Nothing above 20, which to me says all the heads should be firing fine?

How the heck do I find out which head needs replacing, or is there another issue plaguing our prints?

 

[Jayefkay531]

I had a head that was new with only 150ml put through it and 0 nozzles not firing on drop detector. However, the head that was shipped to me was already out of warranty and the tech deemed that the problem. I got a new printhead and it started printing great. Check if any are past their warranty date. Unfortunately, that's the only advice I can offer - I'm sure there's people WAY more qualified than me on here.

Side note, I have the HP360, but I'm assuming it's basically the same issues with heads/inks.

 

[rdm01]

Yeah 360 and even 560/70 would be basically the same.

We have a few heads out of warranty, but that has never before caused an issue. And at this point, I want to avoid the crap shoot of replacing heads until the problem is fixed. That turns a $100+ problem into a $300-$400+ dollar problem if your luck isn't great.

 

[Jayefkay531]

Yeah 360 and even 560/70 would be basically the same.

We have a few heads out of warranty, but that has never before caused an issue. And at this point, I want to avoid the crap shoot of replacing heads until the problem is fixed. That turns a $100+ problem into a $300-$400+ dollar problem if your luck isn't great.

I get what you're saying. I print until my heads are just about dead and doing cleanings/alignments won't fix it anymore. I've actually gotten over 10k ml on some heads (the tech laughed at me when I told him this but was still wow'd when he saw the print quality).

When the tech had me do some tests to find out if a head was going out, all the tests came back great and it would print well for the first 4-5feet, then start to get banding. Anything within warranty HP replaced, I had to pay for only 2 heads. Haven't had trouble since. I hope you can find a different solution and it's not all the heads, but that showed me that sometimes the heads can make a difference even when I thought they were only at half-life.

There is a test you can try - print vertical bars about 5' long x 6-8" wide of each 100% C, 100% M, 100% M, 100%K. This may help to narrow down which color is failing, if any. If you still see the same bad print across the board, it could be the optimizer or ALL the heads.

Good luck!

 

[rdm01]

Now to complicate matters, when I went to print a non-color critical banner I got the following out of the printer. It was printing fine, but I canceled to reposition the banner in the middle of the roll. When I restarted It started doing the zebra stripes. When I printed the test, I got the perfectly healthy looking test found in the second image.

 

[ikarasu]

You can take out a used head and let it sit for months and it’ll still work. It might require a few cleanings or a deeper water clean, but we've had some out of our system for 6 months... Pop it in and it's like a new head.

We keep 2-3 of each head on hand - we haven't run into your issue, but we had another... Swapped all heads, kept the old ones... And when the new heads died we replaced with the old ones as they died. The old heads still worked, minus one which we believe to be the one that caused our problem.


So I'd say get replacement heads a d throw them in - it isnt cheap, but in the long run it costs you nothing and is better than getting a tech out.


To me that doesn't look like a head issue though.

 

[rdm01]

It seems asinine that you have to guess what heads are bad, possibly waste heads, etc. It seems to be an ongoing issue with us, and I've never received a straight answer. I have a 570 that is now having an issue with print quality and I'm doing the same freaking thing. It's total guess work and a waste of time/money.

 

[Jayefkay531]

Now to complicate matters, when I went to print a non-color critical banner I got the following out of the printer. It was printing fine, but I canceled to reposition the banner in the middle of the roll. When I restarted It started doing the zebra stripes. When I printed the test, I got the perfectly healthy looking test found in the second image.

Yikes - try printing those solid bars much larger. Crop the image in Onyx if needed to just those bars, then make them 3-5ft in length. See if that duplicates the errors at all?

 

[rdm01]

So, after giving up and switching all of our printing to our 570, one of its heads takes a dump. Appears to be the #7 yellow/magenta. Put two different, brand new heads in it and still have the same issue (photo attached). So - clearly not a head problem - maybe cable connection? Has anyone seen anything like this?

 

[Sign Impressions]

Your issues don't seem to add up to this, but have you cleaned the encoder strip?