Grandad35,.. Well it has been awhile but I finally got down to testing the "Reset the EEprom" solution. When I first saw this suggestion I felt that it would be "Logically Impossible" for the following reasons. 1. The EEpron in question is on the Main logic board and has nothing to do with the eeprom that is on the back of the printhead. The eeprom on the back of the printhead is probably not a prom at all but a EROM and the primary use is as a matrix decoder to convert the serial bitstream that de-serializes the bit stream, and to loads output registers, and drives the diode decoder matrix that selects which nozzles to fire.
Initializing the EEprom only clears all memory of what current data is stored there. None of this data has any effect on the decoding of signals to the printhead. Having said that,.. nothing is out of the realm of possibility when in comes to electronics. The logic card could read that data and decide to do what EVER it wanted to do.
However, there is NOTHING in that data that would provide any intelligence on what decision to make. How do I come to such a rational conclusion,... well I spent 33 years of my life in the design and development of complex integreated system and down to the level of design of integrated logic control system and the chips that did the final work. I also spent 15 years in the Management of these systems so I know what upper management would allow any engineer to do, "OR NOR TO DO".
I have examined each and every post since the original and I can find no evidence of anyone else being successful with this suggestion. My last resort was to test the suggestion myself, but I had to wait until I had a valid example. Below I have posted the image of my example prior to any testing.
As you can see, every other band of the nozzle test for Cyan is missing. As Grandad35 original suggested in this post, this looks so much like an electrical problem because it is so symetrical, and clogs don't have a mechanism to duplicate this effect. Reguardless of all of this imformation, I was excited to proceed with the testing, for I really hoped that "Somehow" this would be the answer.
This image is from a Canon S750 printer that I was given to repair. This is not a low cost throw awy printer as the spec's tend to surpass the i560 printer. So I did the test and the results made absolutely no change what so ever in the nozzle check. I have also scanned an loaded the Service test print to show that the rest of the eeprom data reset was totally successful.
This image shows that the upper nozzle matrix is not present at all. In the analysis that some of us have done this is the ODD band of the Matrix Nozzles. The first band that is printed in the nozzle check is the "0" band which is Even, and the 1,3,5, etc. bands are the odd bands in the printer code.
This is not the final word on this question, as it only concludes that "Resetting the eeprom" has no effect what so ever on the full band. Many times we have seen that the upper or lower part of either the ODD or EVEN band have been missing. I have not had the opportunity to test this, but I do have a defective printhead that has this occurance and I will test it as soon as I have the time. By the way, I did do this in a more "Engineering test mode" as I printed the Service test pattern before I made the reset, and then immediately after the reset I printed it again and that is the image above. Not one other change was made to the printer before each test.
I would love to have anyone that has different results with other heads post their results at this site. In the mean time, we continue the mystery of bad printheads.
