Canon MP 780 Won't Print Black

[Bongo44]

Hello all;

I'm a newbie to this forum and am impressed with all the good info. Here's my MP780 story. I've had the printer for about 2.5 yrs & about 8 months ago the printhead went out. Well, I got suckered by Cannon & upgraded with a coupon to the MP830. Anyway, the 780 went into storage for about 2 months before I got stationed overseas & took it with me. I purchased a new printhead & cartridges & everything worked great until it was time to replace the BCI3-EBK cartridge. Then, yup you guessed it, it quit printing black. I performed the purge tube cleaning procedure trigger 37 described--no luck. I then soaked the printhead in windex overnight & thoroughly cleaned that. Still no luck. I even tried a new cartridge but to no avail. I'm not getting any other errors except that the top part of the nozzle check pattern refuses to print, and of course I can't print black. Everything else appears to be OK. Is it time to buy yet another print head?

I'm open to any suggestions folks. Thanks for the assistance.

 

[talstails]

I have the same problem too! My black won't print. Please help me too. Thanks.

 

[ocular]

You need to work out if this is a printhead blockage or if if the purge mechanism is blocked.

My experience of this problem is gained from IP3000 and MP730 Canon Printers so bare with me - I don't know the exact setup of the MP830. If the printer has had lots of use and then is left for some time, black pigment ink can cause blockages either in the printhead or the purge tubing.


Make up a 1/2 a cup of windex/water 50 /50 solution

Take out the print out and soak it in a few mm of windex /water solution.

Find some clean paper towel and fold it into several layers. Place the printhead so the face is flat on the paper towel. The ink/fluid in the printhead will wick onto the paper towel. Place a few drops of solution on the ports that ride into the ink cartridges and watch to see if the fluid is wicked away. If the the fluid disappears down thru the printhead then the printhead is unlikely to be blocked.


To check if the purge mechanism is blocked with everything reinstalled open the lid so the printhead moves to centre , ( you can disconnect power lead and move the printhead even further away). Now looking at the pad in the rubber cup that covers the black area of the printhead - see if it looks dry or moist. Drop some windex solution onto the black pad and then do a head refresh and if the pad is still floodded then the purge tubing is blocked and the printer is unable to suck the black ink into the cartridge to prime it.

The best success I have had at un blocking purge lines is by removing the pad from the rubber well to reveal two drainage holes. Only one of the two holes in the black ink well seems to be connected to the purge lines. I use a piece of nylon fishing line to thread it down the small port. Then with some soft silastic tubing connected to a syringe I flush out the purge line to check that it is patent. Access to the MP730 is far more difficult than the IP3000 but can be done with some tweezers and a headlamp without dismantling, not sure about the MP830.

Don't always right off the printhead when it could be the purge mechanism.

 

[leo8088]

Dave at Hobbicolors once gave me a suggestion about this "black won't print" problem. I found it kind of interesting to try. The suggestion is to first purge your BCI-3ebk cartridge thoroughly. Then refill it with dye based black ink. You need to clean the print head with water to some extend before using the cartridge. This probably means soaking the print head for 10 or 20 minutes. One the bci-3ebk is plugged in you can first do a few cleaning cycles along with nozzle checks. If the grid pattern begins to appear you can print a black purge 4x6 block in draft quality mode once or twice.

According to Dave this uses the dye black ink to blast off the clogs in the print head by the pigment black ink. My mp780 print head had a fairly nasty clog before. I tried his method and my print head completely recovered. I really thought it was hopeless to savage my print head but this dye black ink procedure restored the print head. I now keep a BCI-3ebk filled with dye black in only. But I never get to use it again. The print head remains in perfect working condition.

If your printer has a problem in the purge unit you will have problems with all the colors of the print head, not just black. You can try Dave's suggestion and see if it can unclog yours.

 

[Bongo44]

OK all, thanks for all the great tips, but still no joy. I tried cleaning the print head by soaking it in windex solution (for the 2nd time) and used the paper towel trick to check if fluid was flowing through the head. It appears to be fine as I thought it would be because the printhead is almost brand new (purchased it 4 months ago & ran 1 set of cartridges thru it w/out problems). That leaves the purge unit.

I removed the pads from both sections of the purge unit & used windex solution to try and clean them. I also used fishing line to try and unblock the purge tubes, one under each pad. The line went in each about 3-5 inches & the fluid eventually disappeared. I don't know if that means they're clear or not, but anyway I did multiple head rereshes, cleaning cycles & black page primer attempts. I still can't get even a faint hint of black ink when I print although the other colors are still fine. Does anyone have any other suggestions? A dissassembly procedure for the MP780 perhaps? I really do suspect the purge unit, but I don't have a good way to get at it without trying to take the printer apart.

Any other tips or suggestions would be greatly appreciated. Thanks to all for their help thus far.

 

[CartersPoppie]

Possibly the print head has shorted out, I know that the colors are working but it is possible that the contacts for the black are done. I know the probability of knowing someone with the same printer is small but if you can find one (repair shop perhaps) try the print head inside their printer. One trick I have used to clear the print head that was plugged was to place it in a dish with windex, using a slip syringe with suction hose placed over the tip draw some windex up through the print head.

Good luck