My Photosmart C4780 makes a loud clacking noise before printing

SOURCE: Hp Photosmart C4780 won't recognize

Switch off the printer and switch on again,Unclip the cartridges one by one and clip back in again this sometimes cleans out the connector pins.This has happened to me.

SOURCE: c4780 printer cartridge problem cannot fix problem

Ok. As per your statement , the power cable is working properly. So , the problem is with your printer only. If you are using the original cartridges and still having the priblem , it is only the defualt printer. If you are having the extended warnty for (3) years , you are adviced to contact ' HP Authorised Service Partner'. they will replace your old printer with new one. Generally the HP company is giving 1 OR 2 years warranty for replacement.If have paid extra amount for extended warranty , your printer may have warranty up to (3) years. So, within the period of (3), the HP Authorised Service Center will replace your printer. They will give reciept for your old printer, and replace your prionter within a (15) days to (25) days with new one. If the printer is not having warranty or extended warranty , the printer is assumed to be as damaged. So, you have to purchage the new one. Be, cuacious the HP printers are not repairable. Please don't try to approach the local repairer.They will eat your money and also don't try to purchase very very very costly HP in cartridges. I think your problem may be solved.

SOURCE: My HP Photosmart C4780 makes the loud clicking

There could be something stuck inside. Look inside and inspect to make sure there's no paper or anything else clogging in