MP500 again - purge problem?

[Robert the Bruce]

ok, here are the shots I took when disassembling the print head.
The one of the bottom of the head was taken before wiping off - lots of cleaning cycles had produced rather a mess here!



I have inserted the images as thumbnails here. If anyone wants more detailed ones I can attach them to another message.
You should be able to see the two screws that have to be removed to take off the nozzle plate. This is then only attached with the brownish (mylar?) ribbon cable. It seems to be fairly robust, but obviously if you damage it by letting the nozzle plate flap around you've wasted your time!
I haven't shown the elastomer gasket in place, but it goes between the little protrusions on the underside of the plastic part of the head and the holes in the top of the nozzle plate. The latter seems to be ceramic on top, with a metal plate bonded to it underneath in which the nozzles are actually located.
You'll notice that, in addition to the slot for the PGBK, there are six little holes in the ceramic, corresponding to the rows of colour nozzles - two magenta, two cyan, one yellow and one photo black. There are *seven* protrusions and corresponding holes in the gasket. I have no idea what the 7th one is for, as it doesn't seem to match up with anything on the ceramic block. Perhaps this is intended for a higher end model with a six-colour ink system?

 

[Robert the Bruce]

After having no success with this advanced cleaning, I tried to rule out printer problems by replacing the head with the original (which had functioning PGBK but faulty colour nozzles). Unfortunately I got the dreaded 'the type of print head is incorrect' message after installing all the cartridges - curiously, not before - followed by an 'error 5110' when I switched the printer off and back on again. So I still don't know whether the fault is in the replacement head or the printer itself :-/

 

[Robert the Bruce]

I am reluctant to get yet another replacement print head in case that also fails - at £40 a time it is an expensive experiment! I would like to be able to rule out other possibilities first

 

[turbguy]

Disassembling the print head is always VERY risky. Even thoughyou thnk you did not disturb anything, things still go wrong. Apparently you don't get ANY PGBK with a nozzle check with the re-assembled prin head? If that's so, either the internal gasket is not sealing perfectly, or the PGBK section of the print head or logic board is bad. I would suggest you remove the print head, force some dye black ink into the PGBK passage until it seeps out the PGBK nozzles, re-install the head and all carts, and try another nozzle check. Report what you see on the first nozzle check.

 

[Łukasz]

You'll notice that, in addition to the slot for the PGBK, there are six little holes in the ceramic, corresponding to the rows of colour nozzles - two magenta, two cyan, one yellow and one photo black. There are *seven* protrusions and corresponding holes in the gasket. I have no idea what the 7th one is for, as it doesn't seem to match up with anything on the ceramic block.

Hi,

some time ago i have dismantled QY6-0080 printhead and found same thing. That "7th element" is linked with PGBK ink "pipe" with no output. It has no printing function, except it is "collecting" any PGBK ink used (plus heat from ceramic insert), finally ensuring clog of PGBK pipe.

 

[Robert the Bruce]

Hi,

some time ago i have dismantled QY6-0080 printhead and found same thing. That "7th element" is linked with PGBK ink "pipe" with no output. It has no printing function, except it is "collecting" any PGBK ink used (plus heat from ceramic insert), finally ensuring clog of PGBK pipe.

Hi, I'm back after a notable absence....
I don't quite understand what you mean here. How can that 7th hole collect/transmit anything when it doesn't match up with anything on the ceramic block? I could just about understand it sinking heat (although don't know how effective that would be unless it were a very good thermal contact), but ink?

 

[Robert the Bruce]

Disassembling the print head is always VERY risky. Even thoughyou thnk you did not disturb anything, things still go wrong. Apparently you don't get ANY PGBK with a nozzle check with the re-assembled prin head? If that's so, either the internal gasket is not sealing perfectly, or the PGBK section of the print head or logic board is bad. I would suggest you remove the print head, force some dye black ink into the PGBK passage until it seeps out the PGBK nozzles, re-install the head and all carts, and try another nozzle check. Report what you see on the first nozzle check.

I finally got around to doing this!
After priming the PGBK nozzles by squirting some ink through, I managed to get a patchy nozzle check pattern, which improved somewhat upon several cleaning cycles. This is positive, because previously the pattern was getting worse on each cleaning after priming. There are still quite a lot of missing segments, but I will try more cleaning and see if it improves further.
Meanwhile, I have managed to work out how to force the printer (using software on the computer) to use the photoblack instead of PGBK by specifying 'Glossy Photo Paper Plus' in the default settings (I'm on Ubuntu Linux, and this is done from the printer administration menu). It's not perfect, as can be seen by doing a test print from Linux (slight feathering around letters when printing text, presumably due to some nozzles not quite lining up) but it looks OK at a distance. I still wouldn't want to use it for anything high quality, like music printing for archival purposes, but could just about make do with it for the moment.

 

[The Hat]

Pulling the print head apart is not something I would never recommend except when you know for certain that the head is definitely banjacks.

If you need to print and your PGBK is out of action then set your printer to use Matte paper media and it will print using the CMBY dye inks and the only difference is it prints a bit slower and your text won’t be water or highlighter proof.

 

[Sherden]

@Robert the Bruce : Hi, I am experiencing the same issue as your with my IP4300. Just wondering if you were able to recover completely the PGBK issue and how.

Thank you in advance

 

[turbguy]

One thing I notice from your print head photos in post #21 above that I didn't think of. The photo showing the assembled head "prior to wiping off" shows two black rectangles, an almost square one around the color nozzles, and a narrower rectangle around the PGBK nozzles. The rectangles appear to be imprints from the soft sealing gasket of the purge pads, and really should not intersect, as this could disturb the sealing "quality" during purging...

Any condition that disturbs this seal will degrade the already meager vacuum that the purge pump is capable of...causing ink supply issues, particularly after a cart change.