Defeated by an HP Latex 570 – calling all HP Latex experts

[Morten CHristensen]

I have been servicing our own Latex printers for years and have encountered a lot of strange errors over time, but this specific one has me completely defeated for now.

We are currently running four HP Latex 570s in production. One of them suddenly started horizontal banding—and strangely enough, it’s happening across all six colors. The printhead test plot shows that the nozzles look fine, but there is very noticeable horizontal banding in the color blocks.

I ran an OMAS calibration, and everything checked out OK. I then tried disabling the OMAS entirely, but the issue persisted. So, it doesn't seem to have anything to do with media transport.

Next, I focused on the Drop Detector.

• Reset calibration flag: OK
• Drop detector calibration: OK

However, when I forced a Drop Detection, it reported exactly zero nozzles out across the board. Even with brand-new printheads, I never get zero on all heads, which led me to conclude that the drop detector was dead—even though it passes calibration and doesn't throw any error codes.

To test this, I tried a spare drop detector I had lying around. Same result. I then pulled a verified, working drop detector from one of our active production machines. Same result. So, it's safe to assume the drop detector isn't the problem either—but why on earth is it reporting zero nozzles out?

I decided to compare one of the working machines directly with the offending unit. I quickly realized that during a forced drop detection, the faulty machine doesn’t actually move the carriage over to the drop detector at all; it just stays parked over the cleaning cartridge. The cleaning cartridge makes all the right noises and moves correctly, but the carriage doesn't budge.

At this point, I figured it had to be a bizarre software glitch. I went ahead and performed a factory reset—no change. Getting increasingly desperate, I did a full hard disk recovery—still the exact same behavior.

According to the service manual, the next line of attack is the Interconnect PCA. I swapped it out with one from a working machine, but it made no difference whatsoever. Still absolutely no error messages, nothing.

What would you guys do next?

 

[balstestrat]

Clean the drive roller encoder and sensor.

 

[ToTo]

I would start with IQ testplot from menu. This provides a suitable point of view. Send pictures of obvious IQ problems. Next step would be to have a look at service informations. This would be a good starting point.

 

[cornholio]

Delete all profiles sometimes helps(i think it's in diagnostic mode). Or EEPROM reset maybe.

 

[FyphonSilter]

Does it sometimes complain about the cartridges not being HP original, even though they are?

 

[Morten CHristensen]

Does it sometimes complain about the cartridges not being HP original, even though they are?

Yes it does! We only use original HP products and exactly on this printer we get that warning, do you think it could be linked to it ignoring the drop detector?

 

[Morten CHristensen]

Our original banding problem has been solved - it turned out to be more simple then i first realized.. one of the optimizer printhead was going bad and causing the banding in all colors.

But the problem with this printer ignoring the Drop detector still persists!

 

[balstestrat]

Yes it does! We only use original HP products and exactly on this printer we get that warning, do you think it could be linked to it ignoring the drop detector?

I think he's onto something. It probably doesn't use it at all when you have "non-genuine" flag on the unit.

 

[FyphonSilter]

I've seen this on 570's only, it still eludes me...

 

[Morten CHristensen]

I've seen this on 570's only, it still eludes me...

I guess HP was so hyped on blocking third party inks, that they even exclude their own ink and cribble their printers Never used anything other than original inks heads and cleaning cartridges.