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#1
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HP 940 Strangeness
I'm noticing a strange phenomenon about my HP 940C printer and color
cartridges, type 78. My last color cartridge was replaced early because I got a "bad cartridge" failure. Today, I got the message on-screen that my color cartridge is low on ink. Within only a couple of hours, with no printing, the printer now indicated that the cartridge is bad. I cleaned the cartridge contacts and printer contacts with alcohol; cleaned the print head area. I ran a test print (the butterfly), which printed nicely. I cleaned the cartridge and print carriage contacts with a good-quality classic electronic contact cleaner/preserver that's leaves a very light oil film. The printer is still running the carriage over to the "bad color cartridge" indicator. But the lights don't indicate any problem. No messages are coming from the software. The next thing for me to try, I guess, would be to place these two cartridges into another HP printer that takes the #78 and see if these printers give the same indication. I haven't done this yet. What is going on? Richard |
#2
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HP 940 Strangeness
"Richard Steinfeld" wrote in
message ... I'm noticing a strange phenomenon about my HP 940C printer and color cartridges, type 78. My last color cartridge was replaced early because I got a "bad cartridge" failure. Today, I got the message on-screen that my color cartridge is low on ink. Within only a couple of hours, with no printing, the printer now indicated that the cartridge is bad. Try the diagnostic test as follows: turn on the printer. Press and hold the power button, then press the X button 8 times, then press the formfeed button 4 times, then release the power button. This will print a nozzle diagnostic page. These nozzle patterns should be ramps with a roughly rectangular shape. If a large block of color is missing, or if regular repeating patterns are missing from each color it indicates an electrical issue. Since you have scrubbed the contacts it is probably not an interconnect issue. It *is* possible the cartridge has failed. If the nozzle pattern is OK and the printer will print I would ignore the error position. Regards, Bob Headrick, MS MVP Printing/Imaging |
#3
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HP 940 Strangeness
I agree that the next step is to try the same cartridges in another
printer. That might help to determine if the problem is the cartridges or the printer circuitry. It might be a bad sensor. All to often, sensors to detect failures of other components fail themselves. Art Richard Steinfeld wrote: I'm noticing a strange phenomenon about my HP 940C printer and color cartridges, type 78. My last color cartridge was replaced early because I got a "bad cartridge" failure. Today, I got the message on-screen that my color cartridge is low on ink. Within only a couple of hours, with no printing, the printer now indicated that the cartridge is bad. I cleaned the cartridge contacts and printer contacts with alcohol; cleaned the print head area. I ran a test print (the butterfly), which printed nicely. I cleaned the cartridge and print carriage contacts with a good-quality classic electronic contact cleaner/preserver that's leaves a very light oil film. The printer is still running the carriage over to the "bad color cartridge" indicator. But the lights don't indicate any problem. No messages are coming from the software. The next thing for me to try, I guess, would be to place these two cartridges into another HP printer that takes the #78 and see if these printers give the same indication. I haven't done this yet. What is going on? Richard |
#4
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HP 940 Strangeness
I tried this cartridge in a different printer. It passed the simple
self-test. I'll try your diagnistic now. Thanks, Bob! Richard Bob Headrick wrote: "Richard Steinfeld" wrote in message ... I'm noticing a strange phenomenon about my HP 940C printer and color cartridges, type 78. My last color cartridge was replaced early because I got a "bad cartridge" failure. Today, I got the message on-screen that my color cartridge is low on ink. Within only a couple of hours, with no printing, the printer now indicated that the cartridge is bad. Try the diagnostic test as follows: turn on the printer. Press and hold the power button, then press the X button 8 times, then press the formfeed button 4 times, then release the power button. This will print a nozzle diagnostic page. These nozzle patterns should be ramps with a roughly rectangular shape. If a large block of color is missing, or if regular repeating patterns are missing from each color it indicates an electrical issue. Since you have scrubbed the contacts it is probably not an interconnect issue. It *is* possible the cartridge has failed. If the nozzle pattern is OK and the printer will print I would ignore the error position. Regards, Bob Headrick, MS MVP Printing/Imaging |
#5
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HP 940 Strangeness
Bob Headrick wrote:
Try the diagnostic test as follows: turn on the printer. Press and hold the power button, then press the X button 8 times, then press the formfeed button 4 times, then release the power button. This will print a nozzle diagnostic page. These nozzle patterns should be ramps with a roughly rectangular shape. If a large block of color is missing, or if regular repeating patterns are missing from each color it indicates an electrical issue. Since you have scrubbed the contacts it is probably not an interconnect issue. It *is* possible the cartridge has failed. If the nozzle pattern is OK and the printer will print I would ignore the error position. Nozzle pattern came out as follows: Magenta: a few dropped lines. Cyan: more dropped lines Yellow: I could only see the first strong bar; couldn't see any further lines. With the earlier cartridge for which I received a failure notice, only the magenta was present (I didn't try the pattern test with this one). What I'm assuming is that I just go through more yellow and cyan ink than red. Is this a reasonable assumption? Thanks again. Richard |
#6
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HP 940 Strangeness; another question for Bob
From my experience with this printer and the two cartridges reported "bad," I'm beginning to think that the cartridge can report to the printer when an individual firing chamber is fried. In other words, since the HP process is thermal, each chamber has a heater, and the heater presents normally presents a resistance in the circuit. I'm assuming that the printer looks for that resistance when it fires a nozzle. If there's no resistance (open circuit) or a short circuit, the printer will report a bad cartridge. Do I have this right? The Photosmart 1115 does not report these cartridges as "bad," as far as I can tell (I don't have this printer installed yet; just running self-tests). But the 940 does report them. Richard |
#7
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HP 940 Strangeness; another question for Bob
"Richard Steinfeld" wrote in
message ... From my experience with this printer and the two cartridges reported "bad," I'm beginning to think that the cartridge can report to the printer when an individual firing chamber is fried. In other words, since the HP process is thermal, each chamber has a heater, and the heater presents normally presents a resistance in the circuit. I'm assuming that the printer looks for that resistance when it fires a nozzle. If there's no resistance (open circuit) or a short circuit, the printer will report a bad cartridge. Do I have this right? [My first reply seems to have been lost in the ether....] You are mostly correct. Single nozzles shorted or open do not cause the cartridge to be rejected. Typically before each print job and at power on the printer does a check of the cartridges and will "complain" if too many are open or shorted. How many is too many will vary depending on the model and what the past history of warranty calls had been. (A too aggressive algorithm results in more calls for cartridge issues but less damaged printers. A too lax policy results in less cartridge calls but more printer damage.) My recollection is that about 20-30% of the nozzles can be reported bad before the printer will refuse to print but it has been a long time since I worked on the 78 cartridge. Regards, Bob Headrick, MS MVP Printing/Imaging |
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