Designjet 1050 printheads

[fixthecopier]

This plotter spent 15 months in Iraq. It had a rough time. Just before the military police deployed again, they decided to have it serviced. I have had it for weeks and got it to print. While testing it I got a fault for the black printhead, so I replaced them all to solve future problems. In testing it I ran several large prints, about 4 or 5, and on number 6 it started banding and then told me the black printhead failed and needed to be replaced. I pulled it and checked it and then it came up as OK and I went to do another print and lost the yellow and magenta. I have tried reseating them over and over and running the alignment but I cannot get them to take. My question would be, is the problem most likely in the carriage or the ink tube system?

[fumblejack]

I would most definitely go for the tubes first. Then the air pressurization system.

[fixthecopier]

I thought I would post this to assist anybody else who works on plotters. I tested the system for leaks and it tested good. Somehow the tubes had got air in them that I did not detect. When I put the new heads in they had enough ink in them to do the 6 or 7 things I printed, then the air got in and they failed. Seeing as how I was putting in about $700 worth of heads on a machine that had just come out of a combat zone, I should have spent the extra $40 and put a set of set up heads in to bled the lines. The first thing that happened was "banding". Then the machine kept trying to recover the heads. I went to HP website and got advice on their forums that said to dip or soak the end of the heads in boiling water to bled them. This would work, but only for about half of a poster size print. I had to bite the bullet and change out the heads again. I changed them and printed about a dozen posters today with no problems. I plan to print about a dozen more in the morning. When in doubt bled the lines, it is cheaper than replacing the heads