HP DesignJet 755CM says to replace ink cartridges or missing cartridges

**yourownfree** · 09-03-2016

Customer has tried new refurb ink units approved for government use. I replaced the trailing cable (new)and carriage assy with a used one, still cost me 100 dollars for the carriage unit I am thinking of trying my own ink from another source, and the only thing left is the main board. I would still like input if someone has had this and resolved the issue. This is the first 755cm I have worked on but I have worked on similar models for the Forest Service and I am trained on Canon wide format printers. I surely thought the carriage assy was the fix. Now I think maybe the ink then the main board. Even though they say they had new ink and have tried new ink maybe three times, I tend to believe them up to 90 percent. Now I did not check all power supply voltages I suppose there could be a problem there as well. I do that sometimes, forget to check something just because it doesn't seem obvious. Had that bite me in the butt before. Felt pretty hurt after that. I welcome your comments, Thanks.

**Kiran Otter** · 09-03-2016

For $100 you could have probably bought an entire 755 off ebay that worked. These printers are OLD. (There actually is a 755 on ebay for $100.)

ALWAYS rule out the consumables before replacing other parts, unless it's something obvious like a belt. Start out with a set of HP cartridges and go from there. Put in each cartridge by itself and make sure it registers. Then put the others in together and watch what it does. If the black is OK by itself, but then starts flashing when the yellow is inserted, the yellow cartridge is probably bad. Never trust refilled or non-HP cartridges.

Look really closely at the flex cables in the carriage, make sure they're not wrinkled, torn or deformed. If you changed out the carriage, and the same cartridges still didn't work, it's likely the cartridges. Again, get a set of HP cartridges to start with. If the customer wants to monkey with 3rd party inks, that's their responsibility.

Even having a set of HP cartridges isn't a guarantee that they're all OK. I can't count the number of times I took a new cartridge out of the box and it didn't work.

I personally never had to replace the trailing cable or main PCA on one of these.. but I suppose they're possible candidates. But by the time you get these parts (if you can find them) and invest the time to replace them, you would have easily exceeded the value of the machine. Tell them they need to get a new printer. Find a 500 for them for $500-800.. they'll be much happier.

Kiran

**theengel** · 09-05-2016

Originally Posted by yourownfree

Customer has tried new refurb ink units approved for government use.

I'm not even sure what that means. If it's the US government, it doesn't say very much for the ctgs. If you want to rule out the ctgs, you gotta use 'HP approved'.