Urgent help Canon ip4920

[The Hat]

I was one of those who maintained that continued deep cleaning could damage a vulnerable print head when it has obvious signs of clogged nozzles because of the stress that it can cause leading to overheating.

I strongly suggested limiting the deep cleans to just two and if that doesn’t visibly work then removal of the print head is necessary for better cleaning outside the printer by overnight soaking. (But be sure it’s not the carts first)

Every time you run a cleaning cycle that counts as a print cycle because the heads have to fire to push ink through the nozzles, so the less you do the longer the print head will last, not to mention your ink and where it all goes..

 

[PeterBJ]

I have tried to find out if the nozzles are fired during a purge, using the temperature info from the EEPROM info from service mode on a MP970. My test was inconclusive.

When turning on a Canon printer both in user mode and service mode the printer goes through a startup routine including a purge. The EEPROM info printed using only pigment black showed these temperature values:"Head TempBK=29.0 Head TempC=28.0 Env Temp=24.5" This could indicate that the nozzles are fired during the startup, as no dye ink was used printing the EEPROM info, and the dye ink nozzles are also a higher temperature than the printer environment. But how accurate are these temperature sensors?

I then switched off the printer and switched it on in user mode and did an extended nozzle cleaning from the printer driver, but only for the dye inks. A new temperature info from service mode was confusing:"Head TempBK=28.5 HeadTempC=26.5 Env Temp=24.5" So head temperatures seems to have dropped? Maybe the startup routine is harder than an extended nozzle check? or what ? The switch from service to user mode and vice versa also takes some time allowing the print head to cool.

I haven't got the print outs mixed up, the D-value proves that. The first printout shows D=30.8, the second printout shows D=31.0.

 

[martin0reg]

In very simple terms. Canon printers basically heat the head up before they print...

I know this. Actually a "bubble jet" printhead does not heat up before printing - but the ink jet / droplets are made by a heating element at each nozzle (unlike the cold piezo process)
While printing the nozzles need ink to not overheat...
...my question: Cleaning = Printing???

It has been reported in other threads that the print head IS fired during purge cycles...

That is the point: the cleaning / purging unit is working with a pump under the capping station. Every time you make a cleaning cycle (in the printer menu with the PH installed) ink is pulled into the cleaning unit (comparable to soaking the PH external on paper towels - but with a pump underneath)
While this is a passive and cold process, without danger of over-heating, and effective against slightly clogged or dry PH -
- why should canon let the nozzles activ "fire", with possible over-heating of the clogged nozzles...??..

(edit) @The Hat @PeterBJ
I have just read your answers - after writing the above to make my question clearer..

@The Hat: I agree that several cleaning cycles are useless if the nozzle checks are not getting better ... question remains, wether a cleaning cycle means "active firing" or "passive ink pulling"...
@PeterBJ: thank you for testing the temperatures...so we have no real proof for the one or for the other... While the passive "ink pulling/sucking" (with that peristaltic pump under the purge pads) definitely will be done..

 

[The Hat]

Look at the possible implication if say for instance the print head didn’t fire during a standard nozzle cleaning exercise and ink was instead just pumped or sucked out unaccounted for.

The EPROM chip must keep a very accrete record of the remaining ink that is left inside a cartridge after the low ink warning appears and by all accounts it does an excellent job of it.

There is no possibility whatsoever of overheating the nozzles if you follow Canons' own advise when confronted by a clog, nowhere in there does it say to run continues deep head cleaning cycles one after the other till clear.

Because we here are dealing with the use of refilled cartridges in just about every printer that is used, and 98% of them are directly the cause of every suspected head clog. (Ink Starvation)

 

[martin0reg]

Look at the possible implication if say for instance the print head didn’t fire during a standard nozzle cleaning exercise and ink was instead just pumped or sucked out unaccounted for.
The EPROM chip must keep a very accrete record of the remaining ink that is left inside a cartridge after the low ink warning appears and by all accounts it does an excellent job of it....

A possible answer may lie herein...

...Also, the Canon Service Manual reports the amount of ink wasted in maintenance cycles...

...because this means the amount is fixed and can be taken in account without counting single droplets...

Certainly multiple cleaning cycles can be ineffective or even conterproductive, e.g. when it sucks the PH empty because of a bad cartridge..
.. but I am not convinced yet that it means active firing = possible overheating ..

 

[turbguy]

I know this. Actually a "bubble jet" printhead does not heat up before printing - but the ink jet / droplets are made by a heating element at each nozzle (unlike the cold piezo process)
While printing the nozzles need ink to not overheat...
...my question: Cleaning = Printing???

That is the point: the cleaning / purging unit is working with a pump under the capping station. Every time you make a cleaning cycle (in the printer menu with the PH installed) ink is pulled into the cleaning unit (comparable to soaking the PH external on paper towels - but with a pump underneath)
While this is a passive and cold process, without danger of over-heating, and effective against slightly clogged or dry PH -
- why should canon let the nozzles activ "fire", with possible over-heating of the clogged nozzles...??..

(edit) @The Hat @PeterBJ
I have just read your answers - after writing the above to make my question clearer..

@The Hat: I agree that several cleaning cycles are useless if the nozzle checks are not getting better ... question remains, wether a cleaning cycle means "active firing" or "passive ink pulling"...
@PeterBJ: thank you for testing the temperatures...so we have no real proof for the one or for the other... While the passive "ink pulling/sucking" (with that peristaltic pump under the purge pads) definitely will be done..

The level of vacuum (inches of water) generated by the peristaltic pump depends upon the rebound nature of the soft tubing used. I doubt the I could pull more than 10 inches of water without that soft tubing temporarily remaining collapsed (reaching the limit of vacuum capability). I SUSPECT that the nozzles fire to enhance the situation, but it would take measurement of the electrical pulses in the ribbon cable to confirm it.

I'm just going by what others have indicated here...

 

[CakeHole]

.. but I am not convinced yet that it means active firing = possible overheating ..

You can easily find out for all of us simply go run cleaning cycles over and over with empty carts installed, then fill them and tell us all if it burned out your print head. If no heat is being applied the head should be fine on the other hand if heat is applied then i expect you will soon find out.

Or short version does it really matter what is happening at power on? The idea is to avoid potential issues by NOT doing multi cleans, not to see if they occur.

Even if multi deep cleaning does not apply heat its still pointless. If any issue you have is not solved after ONE deep clean cycle and TWO at THE MOST further ones are not going to solve the issue because that is going to be either a serious clog which the printers cleaning functions will not clear or its a cart ink flow issue.

Under no circumstance is multi deep cleaning a good idea, at best it will just waste ink and not fix the issue, at worse its going to damage something. Im no expert but this seems common sense to me.

 

[stratman]

There are various amounts of ink (in grams) used during the various maintenance cycles of my printer as listed in the Service Manual. Is the purge pump accurate enough to provide these amounts - from 0.20 g to 2.25 g and "oddball" amounts such as 0.38 g, 0.57 g, 1.06 g or 1.27 g? Since there is no common denominator for these numbers, which would suggest an easier engineering/coding solution if only using the purge pump in a force over time type situation, then there is an increased potential that the print head is firing to obtain these variable amounts.

On the other hand, firing the print head increases risk for print head failure and the potential increased that this process is controlled primarily or wholly by the purge pump to prevent early print head failures (before warranty expires) requiring a reduction in profit by Canon in providing technical and warranty support.

 

[stratman]

Look at the possible implication if say for instance the print head didn’t fire during a standard nozzle cleaning exercise and ink was instead just pumped or sucked out unaccounted for.

The EPROM chip must keep a very accrete record of the remaining ink that is left inside a cartridge after the low ink warning appears and by all accounts it does an excellent job of it.

Canon determined the amount of ink wasted to be sufficient for the maintenance cycle required. This data could be easily incorporated into the ink monitoring function.

The question then becomes is there enough accuracy in how much ink is used if only the purge system is used in the maintenance cycle and not the firing of nozzles. Once the optical warning system has been triggered by no ink in the reservoir (spongeless) portion of the cartridge, how does Canon keep track of any maintenance cycles, manual or automated, in addition to ink usage from actual printing?

My gestalt at this point is it makes more sense for Canon to not fire the nozzles during a purge/cleaning, relying upon the purge pump to waste the predetermined amount of ink.

Framing this issue another way, have we ever had a report of a print head failure during a cleaning/purging event?

 

[stratman]

The level of vacuum (inches of water) generated by the peristaltic pump depends upon the rebound nature of the soft tubing used. I doubt the I could pull more than 10 inches of water without that soft tubing temporarily remaining collapsed (reaching the limit of vacuum capability). I SUSPECT that the nozzles fire to enhance the situation, but it would take measurement of the electrical pulses in the ribbon cable to confirm it.

Could this issue be avoided by using less pressure over a longer period of time to pull the same amount of ink?