HP Officejet Pro 8500A - trying to recover from bad pigment ink refill

[Pcarsba]

I am still trying to recover my 8500A from what I believe was very poor quality pigment ink. I ran into severe issues soon after the refill. It started as some bad quality prints and went on to complete blockage of all four colors. During my experiements I noticed that pure Windex (the Amonia in there) is the only thing I found that is able to dissolves dried ink again. IPA did notthing. I also tried more agressive solvents (mineral spirits, flux remover, brake cleanr, etc.) but none would do anything usefull. In Windex I could see solid clumps dissolving. I did this to a solid big particle under a high-powered microscope. Next I might try and source pure Amonia solution.

At this point I have cleaned and flushed the black/yellow head and installed another used magenta/cyan head (lost the cyan/magenta head to some overzealous microwave treatment ). Note to myself: embedded chips don't like microwaves, not even for 10 seconds. oh well, good data point.

I now run dye ink in all four carts and flushed the lines, too. And I have the printer back to where it passes a pen alignment, yeah . The nozzle pattern shows "hope". I still have some issues to work out. My next steps are to flush out a used cyan/magenta head, fill it with dye ink and then see where that gets me. I got multiple used heads to play with thanks to evil bay. Right now I like to better understand the nozzle patterns and what it wants to tell me?

The printer has four ink colors (black & yellow in head #1, cyan & magenta in head #2). From left to right the blocks are pure black, pure cyan, pure magenta, yellow+magenta (red) and yellow+cyan (green). In a perfect world the two rows would look identical like the second row sans the streaks. See here for my latest status:

I'd like to understand why the printer does two rows that are acting very different. Could each row of blocks come from a different set of nozzles on the head?. When I look at a print head under a stereo microcope I believe I see a double-row of ink nozzles for each color. Maybe someone can confirm that's why there are two rows of blocks.

I know that black has still some individual nozzles that are still blocked. Looks like the patterns in boht rows are very similar. Remember the black/yellow had a complete blockage. I cleaned it out, flushed it and refilled everything with dye ink for black and yellow. My current assumption is that I still have some partial blockage in that head.

I don't understand what's going on with magenta: In the first row it looks like magenta is OK for the solid block and then starves to nothing in the forth block. For the most part only the yellow shows and next to no magenta. The second row looks almost normal. When I re-run the test over and over it looks exactly the same.

 

[The Hat]

Pcarsba

The cartridges in the 8500 are not that easy to refill so I would suggest you
concentrate your problem searching to them instead of the print head.

I would also suggest you perform an autopsy on one of the cartridges to get a better
understanding of them and how to refill them correctly.

Ink starvation looks just like a blocked print head so its much easier to blame the head rather than the ink cartridge.

Another way to problem solve your poor ink flow would be to install all new cartridges
and print a few test patterns and see if that improves or correct the problem for you..

 

[websnail]

I would suspect more than there's residual particulate matter still blocking the nozzles in the printhead and it's forming a constriction as it continues through.

Also possible the nozzles are now damaged due to overheating as it's still a bubble (read: boil!) jet process...

Don't forget that your ink itself may be part of the problem, possibly high concentrations of pigment in the cartridge/flow system and/or printhead itself...

 

[Pcarsba]

@The Hat: I think I got a pretty good handle at how to refill the carts by now. I have disected one to be absolutely clear on how the pump and the internals look like. I can refill them and ensure zero air bubles in the pump and a nice hard pump. So I am 99.9% certain it is not an ink starvation problem due to improper refilling techinques.

Further to that the problem is consistent with the print head. If I chose another head out of my pool of 13 I get a different, yet constant pattern. This confirms the problem is 100% located in the print head and not the carts. When I got the batch of 13 heads (per color) I put each on a scale and the weight ranges anywhere from 59 grams to 48 grams. That tells you some of them are nearly empty. I will get exact figure of a clean dry empty head and a fully filled head soon and post here.

What is harder to assertain is whether the ink starvation is due to blockage in the feed line passage between the nozzles or the feed capilar line to the individual nozzle and how much damage that starvation has already caused to the nozzle structure.


@websnail: I agree that ink was the inital problem since the issue started soon after the refilled ink made it to the nozzle area. What is funny is that when I had the black (first cart I refilled) hit the nozzles I first saw that prints started to look funny at the left edge of the page. Upon closer inspection with a microscope you could see certain nozzles spraying into the wrong direction before clearing up enough to produce a nice line. This is what makes me believe that the refill ink was leaving reside in the nozzle that cleared within the first fraction of an inc when the print started.

This is the main reason that I am switching to dye for the time being. Maybe once I get a head clean enough to where it prints nice and stable with the dye ink I start experiementing with a 50:50 mix of dye and pigment. I am mainly concerned with the black where dye doesn't produce the same dark black as the pigment.