Epson WF-7710 Not Printing All Colors After Mainboard Replacement - Cyan, Magenta, and Yellow Missing or Intermittent

Question

After replacing the mainboard on an Epson WF-7710, the printer powers up and functions, but the printhead is still not producing all colors. Initially, only cyan printed, while yellow and magenta were missing. After cleaning the printhead, magenta began printing, but now cyan and yellow are not printing.

The printhead has been removed multiple times and flushed with warm distilled water and a mixture of distilled water and window cleaner. Fluid passes through easily with a syringe, and no visible clog is present. Reverse suction has also been attempted while the printhead was submerged. The printhead was fully dried before reinstalling.

Are there additional troubleshooting steps? Is it possible to purchase a new Epson WF-7710 printhead from BCH Technologies? Do we repair printheads? Where can a reliable brand-new printhead be purchased?

Answer

1. The Printhead May Be Electrically Damaged (Even If It Flushes Fine)

The most important thing to understand is that a printhead can pass fluid perfectly and still be electronically defective.

When you flush with a syringe and fluid flows easily, that only confirms:

• The ink channels are physically open

• There is no hardened clog inside the nozzles

However, printing requires two things:

1. Open ink channels

2. Proper electrical firing of piezo elements

If certain colors (cyan, yellow, magenta) print intermittently or switch after cleaning, that strongly suggests:

• Partial internal electrical failure

• Burned nozzle firing circuits

• Internal shorting in the printhead

This is extremely common with used or "refurbished" eBay printheads. Many are harvested from damaged machines and resold without proper electrical testing.

2. Color Switching After Cleaning Is a Red Flag

You mentioned:

• Initially only cyan printed

• After cleaning, magenta printed

• Now cyan and yellow are missing

That behavior is not typical of clogging.

True clogs usually:

• Affect one color consistently

• Improve gradually with cleaning

• Do not cause other colors to stop working

When colors come and go after flushing, that typically indicates:

• Internal electrical instability

• Moisture contamination of internal circuits

• Shorting caused by liquid exposure

Even if you dried the printhead before reinstalling, moisture can remain trapped inside the electrical plate area.

3. Important: Mainboard and Printhead Compatibility

Since you replaced the mainboard, here's something critical:

If the previous mainboard failed due to a shorted printhead, installing a used or questionable printhead onto a new board can:

• Damage the new board

• Cause erratic color firing

• Lead to partial channel failure

Epson WF-7710 printheads are very sensitive to electrical faults.

If you have access to the printer's maintenance mode, check for error codes such as:

• 0x97 - Printhead internal error

• 0xEA - Carriage or printhead issue

• 0xF1 - CR motor or carriage lock

• 0x10 / 0x9A series errors - Firmware or head communication errors

Even if no error code appears, partial firing failure can still exist.

4. Ink System Possibilities

Before concluding it is definitely the printhead, check:

A. Ink Supply and Dampers

• Are all ink lines fully primed?

• Are dampers properly filled?

• Any air bubbles in the yellow or cyan channels?

Air bubbles can prevent firing even if fluid passes manually.

B. Capping Station Seal

If the capping station is not sealing correctly:

• Cleaning cycles won't properly prime ink

• Certain colors won't draw ink

You can test this by:

• Parking the head

• Applying gentle suction from the waste tube

• Seeing if ink flows evenly from all channels

5. Why Flushing with Window Cleaner Is Risky

Many window cleaners contain ammonia or additives that:

• Attack adhesive seals

• Damage internal membrane layers

• Cause delamination of piezo layers

Even if diluted, repeated flushing can weaken an already fragile used head.

For Epson piezo heads, we recommend specialized cleaning solution rather than household cleaners.

6. Can You Purchase a Brand-New WF-7710 Printhead?

Here is the honest truth:

• Epson does not widely distribute brand-new WF-7710 printheads directly to the public.

• Most printheads online are:

  • Pulled from donor printers

  • "Cleaned and tested" (but rarely electrically stress-tested)

  • Previously used

True brand-new units are extremely difficult to source reliably.

At this time, we typically do not stock brand-new WF-7710 printheads because of supply inconsistency and quality concerns.

7. Do We Repair Printheads?

Unfortunately, printheads themselves are not repairable in most cases.

Reasons:

• The piezo elements are microscopic

• Internal circuit layers are sealed

• Once electrically damaged, they cannot be rebuilt

Printhead repair is generally not feasible-even at manufacturer level.

8. Most Likely Scenario in Your Case

Given your description:

• Mainboard replaced successfully

• Multiple printheads tried

• Colors shifting after cleaning

• No physical clog during syringe testing

The most probable cause is:

The eBay printhead is electrically unstable or partially damaged.

The fact that different colors work at different times suggests internal firing channel failure rather than ink blockage.

9. Recommended Next Steps

1. Inspect FFC cables carefully for:

   • Bent pins

   • Burn marks

   • Uneven insertion

2. Ensure the printhead contact plate is:

   • Completely dry

   • Free from cleaning residue

3. Try one more controlled test:

   • Install the head

   • Perform one cleaning cycle only

   • Print a nozzle check

   • Do not repeatedly flush

If colors remain inconsistent, replacement is the only realistic solution.

Addressing printer issues can be a complicated affair due to the hands-on nature of the problems. Because of that, we're not able to provide remote troubleshooting, step-by-step repair guidance, or detailed live repair support. However, we do offer an in-person evaluation and repair service through our local diagnostic facility (BCH Printer Repair Service: https://bchtechnologies.com/printer-repair-service). Due to high demand, we operate on a first-come, first-served basis, and it may take several weeks before we can schedule a drop-off. Our services are structured to repair either complete printers or specific components, with clear instructions on how to proceed. That said, we understand our rates may not be the most economical option. Therefore, we strongly recommend self-guided research. You may start by exploring YouTube or visiting our YouTube channel homepage (BCH Technologies YouTube Channel: https://youtube.com/@bchtechnologies). Use the search icon next to "About" on the right-hand side of the menu bar to locate specific topics. I receive dozens of video requests daily, and after creating content for over nine years, it's impossible to remember every video. Using YouTube's search function is the most efficient method-and it may also suggest helpful content from other creators.

Thank you again for your continued support and for taking the time to reach out. We truly appreciate your engagement and wish you the best in getting your WF-7710 fully restored.