HP DesignJet 500PS Black Ink Not Printing: Checking the #11 Printhead, Cartridge, and Ink Delivery System

Question

I have an older HP DesignJet 500PS plotter that has worked well with refill kits and ink assortments in the past, but I recently ran into a new issue. During a long spreadsheet print job, the black ink suddenly faded out and then disappeared completely. The print continued with bluish-looking characters, while yellow and magenta areas still printed normally.

The printer's ink level indicator showed the black cartridge was about two-thirds full, but when I removed it, it looked like it might have been empty. I replaced it with a freshly filled black cartridge, and the printer then showed the black cartridge as about three-quarters full. I ran the printhead alignment, but black still would not print at all.

I also replaced the installed #11 black printhead with another #11 black printhead I had on hand, although it may have been used. That did not change the diagnostic test results. The advanced diagnostics reported that the cyan/magenta and yellow printheads were out of date, which makes sense because those HP parts have been unavailable for years, and the last ones I bought were expired. However, they still seem to work. The printer reports the black printhead as worn out rather than just out of date.

Is there anything else I can check in the ink delivery system? Also, does BCH Technologies sell HP #11 printheads? If not, is there a known good source for them? I like this old 42-inch plotter, but I am wondering if it may finally be time to replace it.

Answer

For the HP DesignJet 500PS, the symptoms you described point most strongly toward a black ink delivery or black printhead-related issue. Since yellow and magenta continued printing, the printer's electronics, carriage movement, and general printing process are still functioning. The problem appears isolated to the black channel.

The first important detail is that the printer's "fuel gauge" or ink level reading should not be treated as a reliable physical measurement of the ink left inside the cartridge. On older HP cartridges, especially refilled ones, the displayed level may be based on chip memory, estimated ink usage, or previous cartridge data rather than the actual amount of ink still present. So it is very possible for the printer to report that the black cartridge is partly full while the cartridge is actually empty, starved, or unable to deliver ink properly.

If the black faded out gradually and then disappeared completely during a long print job, that often suggests ink starvation. In other words, the black printhead may have continued firing until the available ink in the printhead or supply path was depleted. Once air enters the line or the printhead runs dry, simply installing a refilled cartridge may not always restore black printing immediately.

The next issue is the #11 black printhead. If the advanced diagnostics say the black printhead is "worn out," that is different from saying it is merely "out of date." An expired or out-of-date printhead may still work if the nozzles and electronics are healthy. A worn-out black printhead, however, may have excessive nozzle failure, internal clogging, electrical failure, or a damaged firing system. In that case, cleaning cycles and alignment procedures may not bring it back.

Replacing the black printhead with another #11 printhead was a reasonable test. However, if the replacement printhead was used, stored for a long time, dry, or already partially failed, it may not prove much. These older HP #11 printheads can dry out internally, and the black pigment channel is especially prone to clogging or starvation-related failure. A used printhead sitting on a bench can easily be bad even if it looks physically fine.

There are several things you can still check before deciding the printer is finished.

First, confirm that the black cartridge is truly supplying ink. Remove the black cartridge and check whether ink is present at the outlet. Be careful not to spill ink, but you want to confirm that the cartridge is not only "filled," but also capable of feeding ink. A cartridge can contain ink and still fail to deliver it if the outlet, sponge, internal bag, venting path, or valve area is restricted.

Second, inspect the black cartridge bay and ink receiver area inside the printer. Look for dried black ink, debris, damaged seals, or anything that would prevent the cartridge from seating correctly. If the cartridge does not seal properly, the printer may not be able to maintain proper ink flow.

Third, check for air in the black ink path. On some DesignJet systems, once the printhead or supply path takes in air, the black channel may remain starved even after a good cartridge is installed. The printer may need several proper servicing cycles to re-prime the channel, but repeated cleanings should be used carefully because they can waste ink and may not help if the printhead itself is electrically or mechanically failed.

Fourth, inspect the printhead contacts. Remove the black printhead and look at the gold contacts on both the printhead and the carriage. Dirty, oxidized, ink-contaminated, or bent contacts can cause the printer to misread the printhead or fail to fire it correctly. Clean only with appropriate care, using lint-free material and a small amount of isopropyl alcohol if needed. Let everything dry completely before reinstalling.

Fifth, check the carriage area where the black printhead sits. If black ink has leaked, dried, or built up around the printhead station, it can interfere with seating or ink flow. The printhead must lock down firmly and make proper electrical and fluid contact.

Sixth, review the printer's diagnostic pattern carefully. If there is absolutely no black at all, not even broken lines or faint marks, the problem may be a completely failed printhead, no ink reaching the printhead, an electrical contact issue, or a carriage-side failure. If there are a few black marks or partial nozzle patterns, then the black printhead may be clogged, starved, or partially worn rather than completely dead.

Seventh, consider the service station. The service station caps, wipes, and primes the printheads. If the black printhead is not being capped properly, it can dry out. If the wiper is damaged or the cap is clogged with dried ink, the printhead may not recover even after cleaning. On an older plotter, a failing service station can cause repeated printhead drying and black dropout.

The fact that cyan/magenta and yellow are reported as out of date is not surprising on a printer of this age. HP #11 printheads have become difficult to find in dependable condition, and many available units are old stock, expired, counterfeit, refurbished, or clone parts. If those colors are still printing acceptably, I would not focus on them first. The black channel is the immediate failure.

Unfortunately, BCH Technologies does not sell HP printheads in any regular or reliable way. We are essentially out of the HP printhead business. If you happen to see an HP printhead on our site, it would likely be an odd leftover item we found in the warehouse, not something we routinely stock or can consistently support. The HP #11 printhead is also used in some industrial and specialty equipment, including certain 3D-printing or inkjet-based systems, so it remains in demand even though the printers that originally used it are quite old.

Because of that demand, genuine HP #11 printheads can be expensive and difficult to verify. I would be cautious with low-cost listings, unknown marketplace sellers, and "compatible" or clone printheads. Some may work, but quality is inconsistent. At $100 or more per printhead, it is understandable that you do not want to keep buying parts blindly.

If you decide to purchase another #11 black printhead, I would look for a seller that clearly states whether the part is genuine HP, sealed, returnable, and compatible with the DesignJet 500PS. A return policy is very important because even a new-old-stock printhead can be expired, dried, or electronically rejected. I would avoid any listing that has vague photos, no expiration information, no return option, or wording that suggests it is only "replacement," "compatible," or "for HP" without confirming it is genuine HP.

At this point, your most practical troubleshooting path would be:

1. Verify the black cartridge is physically delivering ink.

2. Inspect and clean the cartridge bay and printhead contacts.

3. Confirm that the black printhead is seated correctly.

4. Check the service station and capping area for dried ink or poor sealing.

5. Try a known-good black #11 printhead only if you can obtain one from a seller with a reliable return policy.

6. Avoid replacing multiple expensive parts unless you are confident the printer itself is still worth repairing.

Your comment about the plotter being a "dinosaur" is very understandable. The HP DesignJet 500PS was a solid machine, and many users still like them because of the build quality and the wider 42-inch format. However, once printheads, service station parts, carriage components, and ink delivery parts become scarce, repairs can become less about technical possibility and more about parts availability and cost. If you rely on this plotter for regular work, it may be worth comparing the cost of a risky printhead purchase against the cost and availability of a newer wide-format printer.

Addressing printer issues can be a complicated process because many of these problems require hands-on inspection. For that reason, we are not able to provide remote troubleshooting, suggestions, or support for printer repairs beyond general guidance. We do offer in-person evaluation and repair through our local diagnostic facility, which you can review here: BCH Technologies Printer Repair Service [https://bchtechnologies.com/printer-repair-service]. Because demand is high, service is handled on a first-come, first-served basis, so it may take a few weeks before we can schedule a printer drop-off. Our repair service is structured to work on either a whole printer or specific printer parts, with instructions provided for how to proceed. However, we also understand that our repair rates are not always the most economical option. For that reason, we strongly recommend self-help research when possible. You can start with YouTube or visit our channel homepage at BCH Technologies on YouTube [https://youtube.com/@bchtechnologies]. Once there, use the search icon next to "About" on the right-hand side of the menu bar to search for specific repair topics. I receive many questions every day asking for videos on particular problems, and after creating videos for the past nine years, it is difficult to remember every single one. YouTube's search function is usually the fastest way to locate the most relevant video, and it may also suggest helpful videos from other channels.

Thank you again for contacting us and for your continued support. I am glad the refill products worked for you in the past, and I understand why you would want to keep a reliable 42-inch plotter running as long as possible. In this case, I would focus first on confirming whether the black ink supply is reaching the printhead and whether the black #11 printhead is truly functional before investing in more expensive parts.