Epson WF-7720 Not Printing Cyan After Printhead Replacement- Causes and Fixes

Question:
I own an Epson WF-7720 that suddenly stopped printing cyan. I cleaned the printhead thoroughly, but it still didn’t print. I even replaced the printhead after watching a repair video, and while the replacement was successful, the printer still won’t print blue. What should I try next?

Answer:

1. Air in the Ink Lines or Dampers

When a new printhead is installed, air often gets trapped in the ink system. Air bubbles prevent ink from flowing into the nozzles, and this frequently shows up as one missing color channel (in your case, cyan).

• Try running a cleaning cycle or two, but avoid excessive cycles, as they can stress the printhead.

• A more reliable method is to use a syringe and tube to draw ink through the capping station gently. This helps prime the cyan channel with ink and ensures it’s ready for firing.

2. Clogged or Defective Dampers

The WF-7720 uses dampers between the cartridge system and the printhead. If the cyan damper is clogged or defective, no amount of cleaning will restore flow.

• Inspect the damper assembly, and if needed, replace the cyan damper or the entire damper set.

• In some cases, carefully flushing the damper can also help, but replacement is generally the more reliable option.

3. Cartridge or Chip Recognition Issues

Epson printers are notoriously picky about cartridges and their chips.

• If the printer doesn’t properly recognize the cyan cartridge, it may not deliver ink even if it shows “installed.”

• Try reseating the cyan cartridge, cleaning the chip contacts, or swapping in a new compatible cartridge.

• If you’re using third-party cartridges, ensure they are fully compatible with the WF-7720 firmware.

4. Printhead Alignment and Ink Delivery Problems

Even after a new printhead is installed, it must be properly primed and aligned.

• Perform a head alignment after running a priming or cleaning cycle.

• Make sure the ink delivery system is not blocked and that the capping station is sealing properly.

5. Mainboard or Electrical Issues

If none of the above resolves the issue, the root cause may be electrical. The printer’s mainboard sends firing signals to each nozzle channel. If the cyan channel’s signal path is damaged, the printhead won’t fire, no matter how new or clean it is.

• Unfortunately, diagnosing this requires specialized tools and usually professional service.

• In such cases, replacing the mainboard or having the unit evaluated in a repair shop may be necessary.

Practical Priming Method (Syringe and Capping Station)

Here’s a more advanced approach you can try if you’re comfortable with hands-on maintenance:

1. Power on the printer so the printhead parks naturally on the capping station.

2. Connect a syringe and tube to the waste line of the capping station.

3. Slowly draw about 1.5 ml of air. You should feel slight resistance—this indicates that the nozzles are opening.

   • If you only pull air, the head may not be sealing correctly on the station, or there could be a leak.

   • If you can’t draw anything at all, the capping station might be clogged.

4. Continue drawing up to 2 ml, holding it for about 10 seconds. You may hear the membrane on the damper crinkle, which is a good sign of ink flow.

5. Afterward, run the printer’s built-in cleaning cycle. Avoid back-to-back “strong cleans,” and let the printer rest at least 12 hours between deep cleanings to prevent damage.

Addressing printer issues can be complicated because of the hands-on nature of the repairs. For this reason, we’re unable to provide remote troubleshooting or one-on-one support. However, we do offer in-person evaluation and repair services at our local diagnostic facility (https://bchtechnologies.com/printer-repair-service). Please note that our service operates on a first-come, first-served basis, and it may take a few weeks before your printer can be evaluated. While our rates are not the lowest, our services cover both full-printer repairs and targeted part replacements with clear instructions on how to proceed.

We also encourage you to explore self-help options through online resources. A great place to start is our YouTube channel homepage (https://youtube.com/@bchtechnologies). Use the search icon next to “About” to locate videos on specific problems. Since we’ve created hundreds of videos over the past nine years, searching directly is often the fastest way to find what you need—and YouTube may also suggest other helpful videos from the wider repair community.

Thank you again for your question and your trust in BCH Technologies. We appreciate your support and hope this guidance helps you get your Epson WF-7720 back up and running.