I purchased a Canon MP730 Multi Function Printer January 30th, 2004. Since then I have printed 11,700 pages, a lot of them full page colored pictures. I have reset the ink counter 2 times without replacing or emptying the waste ink tank and have replaced the print head twice. I refill the ink cartridges myself. In August 2008 the printer started printing solid areas with white space smears and then the colors stopped entirely. The PDF document accessed by the link below explains what I think the problem was and shows how I disassembled the MP730 to assess the damage and fix the problem. The documents here are copyright and may be downloaded for personnal use but may not be copied to another site or sold for profit in any form.
Canon MP730 Printer Waste Ink Tank Full ResolutionNote: this is a 21 mega byte file and takes about 1 minute to download over a high speed connection.
Those who use the document do so at their own risk and I will not be responsible for any damage to them, the printer, their house(ink spilling, etc.) or any other problem that arises.
Also be sure to follow the safety precautions in the document
NOTE: Before I took the printer apart I had tried 1) using the Canon software to deep clean the print heads multiple times, 2) taken out and cleaned the print head manually, 3) changed the ink cartridges, 4) put in a whole new Canon print head (QY6-0064) with new Canon ink cartridges (NOTE: As of October 2013 print heads for the mp730 are no longer available from Canon however there are new and refurbished printheads available on ebay). When these efforts didn't work I took the more drastic action of taking the printer apart and replacing the purge unit (QG4-0279-000) with one ordered via overnight mail from Canon (1-800-828-4040 9-7pm M-F as of 10/28/13 (NOTE: When I checked in October 2013 this part was no longer available from Canon). Thus you should follow the instructions below for the Purge Unit Disassembly and Assembly.) Before you start this project make sure you have done 1-4 above.
Oh yes, there is really no "ink tank", it would be easier if there were.
At the the time I wrote the document above I had not taken the purge unit apart. Since then I took my old unit apart, cleaned it and put it back together and have written a document describing that. November 2013 update. I recently had a problem with the ink carriage not retracting into its home position. This caused an error and the machine would not print but continually asked to be reset. I took the printer apart and found that the mechanism in the purge unit which covers the print nozzels when the carriage is in the home position and when it purges ink to clean the heads was not retracting as expected. Taking things apart further I found that the spring that helps retract the mechanism had broken. Thus I needed a new purge unit. Canon no longer sells the part. Thus I put in the one I had cleaned and rebuilt. I put in a new print head and got no ink coming through. This indicates the purge unit is not working properly or the head is really clogged. Since it was a new head I suspected the purge unit I had rebuilt. I had a second MP730 I bought to use for parts and so I took the purge unit out of it and put it in my production printer and now the printer works fine. I will have to go back and check how I rebuilt my previous unit. One thing I need to look at is how the purge unit decides to purge black, color, or both. Apparently there is some selection mechanism which somehow switches between color and black and I may not have calibrated that correctly. More later.
Canon MP730 Printer Purge Unit Disassembly and Assembly. (7 megabytes)
Canon MP730 Printer Paper Feed Unit Replacement/Alignment. (11 megabytes)
In 2011 my MP730 print head was slightly clogged but normal procedures didn't clean it. I took the print head out tried my normal procedure with soaking it for an hour in alcohol and then cleaning it with sterile wipes. No luck, so I soaked it overnight in alcohol. When I put it back in and plugged the MP730 back in the printer started to come to life and then died. I couldn't turn it on or off, it was dead. Since I have a backup MP730 I put the print head in that one (it also was good except for the print head) and the same thing happened. It then dawned on me that something must have happened to the print head during the alcohol soak that caused the problem. I then ordered a new SPCNT board from Canon (HM1-0604-000) which cost about $181. and print head (QY6-0064-000) which cost about $50. I put the new SPCNT board and the new print head in the first printer and it now works like new. The lesson is when you are soaking a print head don't leave it overnight or perhaps if you do only soak a little way up the bottom. I had the alcohol over the pads on the inside of the print head and it must have done something to damage the print head which then fried the SPCNT electronics.
This section records some problems people had with following the documents and some tips.
1. After putting everything together only some colors printed.
Possible Solution - While the printer is apart the ink in the print head may dry up. Soak the bottom of the print head, just over the circular input areas in denatured alcohol to get out the dried ink and blow out gently with compressed air.
2. After putting everything together I got the message "Put In Your Cartridges".
Possible solution - One of the ribbon cables came loose or was not put back properly so the printer does not recognize that the ink cartridges are there. Go back and make sure the ribbon cables are all tightly connected.
3. After putting everything together I get a few lines of print and then the ink fades away.
Possible Solution - When you cleaned the purge unit the rubber tubes going to the suction unit (see second document) came loose so when the purge unit tries to suction in more ink there is no suction and thus no ink.
3. After putting everything together the phone does not work. The phone wires are the white wires running to the lower left back area and must be unplugged there to disassemble the unit. Perhaps the white wires were not clipped back together.
4. After putting everything together I get some print pixel errors. The ribbon cables going to the printer have gold connections on the end. If you don't take them out and put them in carefully one of the gold connections may bend up or even break off. As you work with the ribbon cables always check that all the gold connections are there.
5. When working with the pinned connections a pin may get bent. If, during reassembly, the pin connector does not start easily don't force it. Check for a bent pin.
6. When putting the printing unit/page feeder assembly back, the tab on the right front of the assembly must slide under a notch in the plactic case. If it doesn't the middle frame unit will never seat correctly. This is made clear in the document but you can waste a lot of time trying to seat the middle frame unit if you don't get the print/page feeder in correctly. Similarly the SPCNT cover slips under ledges at the back of the unit and if not slipped under, the SPCNT cover can't close. It usually takes some careful wiggiling to get the cover back under the case.
7. Some people leave out the fourth screw which holds the middle frame to the case when doing the reassemble. This makes future dissasembly easier since you don't have to take off the SPCNT electronics board and the SPCNT shield. So far I have not heard that this causes later problems.
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(11/04/13)