Dell A940 prints black but doesn't print in color. I installed a new color cartrige and the 50c error went away, but still doesn't print in color...

Hi there Error 50c
This is for yours.
Regarding the Dell A940 "Error 50c"....the user guide doesn't seem to mention "Error 50c". They do, however, mention a "Cartridge Error" on page 52 of the manual. They claim this means that the printer has detected a short circuit (fuse/resister) in the cartridge. As you may or may not have noticed in the manual, this is what they recommend doing about it:

1) Press Power to turn the printer off.

2) Lift the printer cover/lid (scanner unit) until the scanner support holds it open.

3) Turn the printer on.
The ink cartridge carrier moves and stops at the loading position unless the printer is busy.

4) Remove the color ink cartridge.

5) Lower the printer (scanner unit) until it is completely closed.
If the error message displays again, replace the black cartridge with a new black cartridge.

If the error message does not display, repeat steps 1–3 and then go to step 6.

6) Reinstall the color cartridge and remove the black ink cartridge.

7) Lower the printer (scanner unit) until it is completely closed.

If the error message displays again, replace the color cartridge with a new
color cartridge.
If there is no error message (indicated by flashing lights), repeat steps 1–3 and then reinstall both ink cartridges.
8) Lower the printer (scanner unit) until it is completely closed.

If you get the error message again, while both cartridges are installed, replace both of the cartridges.

Basically, what they want you to determine is,....if the short circuit is with the "black ink" cartridge or the "color ink" cartridge and then replace the cartridge that has the problem.

You may have to buy a new cartrige.
Please all I ask is call back and just gave a vote, it will gave me some satisfaction to know am helping some one, so I will keep on helping.
All The Best: Pineworks