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- HP Community
- Printers
- DesignJet, Large Format Printers and Digital Press
- DesignJet T790 printhead replacement

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09-18-2019 01:26 PM
I haven't used my printer in a few years. Had to replace all the ink cartridges. Then it said I had a bad printhead (MK-Y, C9384A). Bought a new one. Pulled out the old one and installed the new one, just as the instructions specified. Then it told me I had "not completed the installation". No other explanation of HOW I "had not completed the installation" or what further actions I needed to take. Printer still will not work. Cannot get through to a live person at HP to help. Can anyone help me?
09-19-2019 05:18 AM
Is this the 24" or 44" size printer?
I had a 24" T790 with the exact same issue. Unused for sometime when I got it. I think I tracked it down to a bad service station. Couldn't get it to take a printhead or ink cartridge. Then it started throwing crazy errors about the ink cartridges being out of date and showing dates of 1968. Firmware updates didn't help.
Good luck. Let us know updates.
09-19-2019 05:25 AM
found something but don't know if it helps...
09-19-2019 05:31 AM - edited 09-19-2019 05:39 AM
Sorry, forgot to include link to service manual:
http://www.partshere.com/models/hpmanuals.asp?model=CR649A
It will show you how to use a torx driver to release the carriage so you can access the printheads. Or you can let the carriage move towards center and use the power switch to turn it off. Either way, you'll need to access the carriage and remove all the printheads and use the syringe priming tool to try to draw ink through the lines. Tool can be purchased here: https://www.lpscomputer.com/collections/designjet-t1300-t2300-parts-page
Inserting the syringe too far can accidently damage the valve.