K cartridge

[cabinetry]

I have 2 7740's and both have the same problem at the same time ,code K cartridge are bad . I have 2 new cartridge's and the y have the same code

[VikramTheGreat]

Hi @cabinetry,

Welcome to the HP Support Community.
 

Thank you for posting your query. I will be glad to help you.

It’s understandably concerning to have both OfficeJet Pro 7740 printers show “Cartridge K are bad” simultaneously, even with brand-new cartridges. Let's carefully work through this together to restore reliable printing:

What “Cartridge K are bad” Typically Means

This message often indicates the printer is unable to recognize or trust the cartridge chip, even genuine new ones. A firmware or communication error is often at the root.

Steps to Fix the Issue

1. Remove & Clean Cartridge Contacts

• Turn off the printer.
• Remove the K (black) cartridge.
• Use a lint-free cloth lightly moistened with distilled water to gently wipe: 
  • The cartridge’s gold contacts.
  • The corresponding printer carriage contacts.
• Reinstall firmly and close the carriage, then power on.
• Clean contacts on the other cartridges (CMYK) while you’re at it.

2. Reset the Printer

• With the printer on, unplug the power cord.
• Wait 60 seconds, then plug it back in and power up.
• This forces the printer to reinitialize cartridge data and often clears errors.

3. Try New Genuine HP Cartridges

• If the error persists after cleaning and resetting, the new cartridges may be defective or mis-chipped; this can happen occasionally.
• Replace the K cartridge with another genuine HP cartridge of the same model number, install it while the printer is off, then power on.

4. Update Printer Firmware

• Make sure your OfficeJet's firmware is the latest version: HP OfficeJet Pro 7740 Wide Format All-in-One Printer series | HP® Support.
• Updated firmware can resolve compatibility issues with cartridge detection.

I hope this helps.

Take care and have an amazing day!
 

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Regards,

VikramTheGreat