Canon MP620 not printing black

[markbatey]

I'm having a problem with my Canon MP620. I did my first refill using Octoink's kit last week, using the top fill method which seemed to go well at the time. Now the black pigment ink isn't working. All four other colours are fine.

I would post a link to a test pattern, but this site won't let me stick up a link to a webpage. To describe it verbally, the test pattern has nothing where it should say PGBK followed by a grid of black lines, but it has three stripes of C, three of M, one of Y and one of BK - I've compared it to a print I found on google images of a MP620 test pattern, and it's just missing the PGBK bit.

I've done a clean and a deep clean of the nozzles, to no effect. I've also taken out the silicon plug and put it back in again, no joy. I'm getting by in the meantime by telling the printer to use matte paper, which forces it to use the dye black, but it's very slow.

Any idea what my next step should be?

Cheers

Mark

 

[PeterBJ]

There is a 24 hour waiting period before new members can upload pictures and post links. Instructions are here: http://www.nifty-stuff.com/forum/viewtopic.php?id=36 , so tomorrow you can upload a nozzle check, but I think your description is accurate.

Is the PGBK nozzle check pattern totally missing, with not even a few faint traces of black? And did it fail abruptly instead of gradually getting fainter? This usually means that the printhead and possibly also the logic board has failed. Normally the only thing that might help is a new printhead, but you could try to clean the contacts on the back of the printhead and in the printhead carriage with isopropyl alcohol or an electronics contact cleaner.

I have had a PGBK cartridge fail when installed to replace an empty cartridge. I had sealed the vent with a piece of aluminium tape to prevent evaporation from the cartridge. When I did a nozzle check some lines of the PGBK nozzle check were missing, and printhead cleaning from the printer maintenance only made matters worse. I then discovered that I had forgotten to remove the tape sealing the vent. After removal and one or two PGBK nozzle cleanings everything was fine. But this fail was gradual, not abrupt.

The problem could also be caused by the PGBK cartridge not delivering ink, but if that is the case the PGBK should fail gradually. If you have another PGBK cartridge you could try using that. You can test the PGBK cartridge by holding it over a sink and blow gently into the vent by mouth. If the cartridge is OK some ink should exit the ink outlet. For comparison you can try the same test with one of the dye cartridges, which are working, so you get a feel for how hard you should blow, actually a gentle blow into the vent is sufficient.

Canon printheads can fail in this manner for no apparent reason. If that is the case the error is likely caused by an open circuit in the printhead electronics, so chances are good that nothing else was damaged, and a new printhead should solve the problems.

But if the failure was caused by a leaking cartridge, there is a risk that a short circuit caused by ink creeping under the conductors at the bottom of the printhead. In that case the logic board might be damaged as well. A damaged printhead might ruin a logic board and a damaged logic board might damage a new printhead.

So replacing the printhead is a gamble. I would not buy a new printhead if leaking was the likely cause of the failure, but if I were certain no leaking occurred I would likely buy a new printhead.

When using the topfill method it is very important that the cartridge is sealed completely airtight after refill. Else the cartridge will leak.

 

[turbguy]

Another potential cause is a bad/misfunctioning/clogged purge system. This is the system below the purge or parking pads where the print head rests when idle. It's purpose is to cap the discharge of the nozzles to retard ink drying in the nozzles, and provide a light vacuum to the print head during cleaning cycles. The typical symptom is that it doesn't show up until immediately after a cart change, and printing of the ink may stop suddenly. You printer has two parking pads, one for the dye color nozzles, and one for the PGBK nozzles.

It is "easy" to test the system for proper operation. Do you know how?

Wayne

 

[markbatey]

Thanks very much for the detailed help here. The failure was abrupt, there was no gradual loss of print quality, and there is no sign of any black on the test pattern where the PGBK should be.
I've lifted the lid of the printer and had a look where the print heads normally park. There seems to be a fair bit of leakage in there, particularly below where the large hole in the bottom of the cartridge sits. I've stuck a bit of tissue paper in there and soaked up quite a bit of black ink. I guess that means some ink may have got onto circuit boards? Which would explain the failure.
If that's right then it looks like my first attempt at refilling has cost me a printer, which is a bit annoying. Mind you, it's about three years old now so that's not bad I suppose.
Look out for a follow-up post from me on recommendations for my next printer....

M

 

[PeterBJ]

There is a risk that the printhead and possibly also the logic board was damaged by the leakage. But a risk doesn't necessarily mean that the printhead was actually damaged. A coating of ink on the underside of the PGBK nozzles could also prevent the nozzles from firing and cause the same symptoms.

So before giving up on the printer try to clean the underside of the printhead by gently touching it on a piece of moistened soft tissue paper. Do not rub the printhead. This could damage nozzles or force dirt into the nozzles. Continue the cleaning with new pieces of paper until the underside of the printhead is clean.

Also continue to soak up black ink from what is the purge unit. When most ink has been removed, drip on a little water and continue so soak up ink using kitchen paper and Q-tips. This might bring the PGBK back to work.

But turbguy knows much more about purge systems than I, so I think you should wait for his instructions before doing the cleaning of the printhead and purge unit, and subsequent testing the the function of the the purge unit.

 

[markbatey]

Well I've taken the printer head out and given it a gentle clean with damp tissue paper, but it's still not doing what it should. I've had a google of testing/fixing the purge unit but I couldn't find anything that looked reliable.

M

 

[turbguy]

Testing:

1. Do the PGBK nozzles have ink available when ready to print? After performing a single deep cleaning cycle, remove and blot the printhead nozzles ONCE, against white tissue carefully and see if there is a black line transferred from the PGBK nozzles to the tissue. If none, there's no ink at the nozzles.

2. Reinstall print head and inks and power down the printer by pulling the plug (don't use the on-off button). Locate the PGBK parking pad (probably larger than the color pad) and apply a Milliliter or two of Original Windex (contains ammonia-D) to the parking pad with a syringe. The intent is to build up a standing puddle of Windex atop the pad that will stay there for a minute without draining away. Use more Windex as required but don't exceed 5 ML. If the standing puddle cannot be built and stay for a minute, this is evidence of a leak in the purge system (small hoses becoming disconnected somewhere is most likely). With this leak, the vacuum pump (a small peristaltic pump) will not pull a vacuum on the print head during cleaning.

3. IF the puddle on the parking pad remains for a minute, plug in the printer, close the cover, do a regular clean cycle. Re-open the cover and examine the PGBK purge pad. It should appear completly drained of the puddle, revealing the texture of the ceramic insert that fills the space within the rubber rectangular gasket. If there is still evidence of a puddle, then this is indicative of a clogged purge system. If the purge system is clogged, then, again, the small vacuum pump will not pull a vacuum on te print head during cleaning.

Please advise us of the results of the three tests above. Don't bother with #3 if you can't pass #2.

Wayne.

 

[markbatey]

Thanks turbguy,

Test 1 - passed
Test 2 - failed. Windex (well, Mr Muscle glass cleaner, but apparently it contains the same ammonia stuff) disappears almost as fast as I can tip it onto the pad. None remains. So looks like a leak in the purge system? And is it fixable? Looks like a right faff to get the printer to bits enough to get under those pads.

Mark

 

[PeterBJ]

It looks like turbguy's diagnosis was spot on, and the purge unit is the cause of the problem.

When checking a Canon website, the MP620 and MP640 appear very similar, they are also of the same PGI-x20/CLI-x21 cartridge generation, so I think the MP640 service manual could be useful for instructions for disassembly and service mode operations. Link here: http://www.bendata.de/Downloads/Canon/mp640_e.pdf .

I think you should download the manual, but wait for further instructions before starting to take the printer apart.

 

[turbguy]

Typically, if you can blot ink from the nozzles (passing test #1), there should be something printing.

I don't have familiarity with what it takes to reach the purge unit on an MP620. Typically it's a lot. The cause for leakage could be anywhere between the pad outlet(s) (there may be more than one) to the discharge from the purge pump. I have had tubes come off their nipples within the pump. It's a real dig to get to the pump, and snap it apart to investigate the internals, but it can be done.

If it is any relief, using refilled carts did not cause the purge system to fail in this manner...

One further test. I assume you dripped solution onto the PGBK purge pad only. try the same test #2 and #3 on the color pad as well and report back. You should be passing both tests on the color pad. I you already tried it on the color pad, please report that result.

Wayne