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‎08-25-2023 02:36 PM - edited ‎08-25-2023 02:37 PM

HP Recommended

My HP DesignJet T790 threw the error code 79:04 which instructs the user to restart the printer and if that does not clear it to contact HP Support. At this point, the controls are frozen. Not even the power button works. I restarted the machine several times and it failed to 79:04 each time.

Rebooting did not clear it. HP no longer supports this machine (firmware updates) and recommends replacing the machine.

The solution: 

Powered down (unplugged and removed network cable).
Removed main ink cartridges.

Removed paper from feed.

Plugged in power and network and followed instructions to feed the paper and install the ink cartridges (I installed them one at a time from right to left).

Miraculously, all became normal. Never had to replace any ink cartridges or printheads. (Your results may vary).

Printed a job… All is well.

I’m goin’ to Moe’s!

2 REPLIES 2

‎08-25-2023 04:31 PM

HP Recommended

You should buy a lottery ticket on the way!  That error is usually the hardest to diagnose because the printer is essentially saying "Hey, I'm lost and don't know what to do!"  Your solution is one of the first things to try.  Glad you got it going again.

I don't work for HP....I just repair their printers.
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‎08-28-2023 07:36 AM

HP Recommended

Hi, D Hook. I spent a lot of time looking it up on the internet with no luck. Then I went back to a fix I found for a different problem (during startup it only initializes to 94% and then freezes) as posted by Davidzuts at  https://h30434.www3.hp.com/t5/Printers-Archive-Read-Only/HP-Designjet-T790-stuck-at-94-initializing/...

Apparently, his fix is some kind of workaround method of jumpstarting these old things.

 

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