Epson ET-16500 Disassembly: How to Retrieve and Reinstall a Dropped Timing Belt Torsion Spring

Question

I have an Epson ET-16500 and was following your timing belt and CR encoder tutorial. While cleaning the timing belt, I accidentally dropped the torsion spring down inside the printer.

I tried removing the scanner assembly so I could get inside the machine and retrieve the spring, but I cannot figure out how to disconnect the scanner's electrical cables. I also cannot find clear instructions showing how to remove the ET-16500 case.

How do I take the Epson ET-16500 apart, remove the scanner and casing, locate the dropped spring, and reinstall it correctly?

Answer

The ET-16500 Is Similar to the WF-76xx Family

For this particular repair, the good news is that the Epson ET-16500 follows a disassembly arrangement similar to some of Epson's older wide-format WorkForce machines, especially the WF-7610/WF-7620 style chassis. The ET-16500 service documentation specifically includes procedures for removing the scanner unit/printer cover and other major assemblies. (Manual Machine)

Therefore, if you cannot find a video specifically titled "ET-16500 disassembly," I would look at our WF-7610/WF-7620 case-removal procedure as a reference. We have a video specifically covering removal of the case and scanner on those WorkForce models. (YouTube)

The exact screw locations and cable routing can differ, so don't assume that every individual screw or connector will be identical. However, the general strategy for removing the scanner and gaining access to the printer mechanism is very similar.

Before You Start Taking the Printer Apart

First, turn the printer off normally and unplug the power cable. I would also disconnect USB, Ethernet, telephone/fax cables, and anything else attached to the machine.

Because you have a loose metal spring somewhere inside the printer, I would not power the printer on until you retrieve it. A loose spring can fall into a gear train, carriage mechanism, paper path, or electronic area. Even if it appears that the printer can still operate, it is better to find the spring first.

Also, do not aggressively shake or turn the entire printer upside down to get the spring out. That can move the spring into an even less accessible location and may also cause other mechanical problems.

Why the Scanner Can Be Difficult to Remove

The scanner assembly is not simply held on by screws. You also have electrical connections running between the scanner/ADF assembly and the printer's electronics.

This is probably the part that is stopping you.

When you start lifting the scanner assembly, do not pull upward forcefully if the cables are still connected. Some of the scanner connections use ribbon-style flat flexible cables, while others may use conventional wire harness connectors.

With ribbon cables, there is usually some type of locking mechanism at the connector. Depending on the connector, the locking tab may lift, flip, or slide slightly. You need to release the lock before attempting to pull the ribbon cable out.

Do not pull directly on the ribbon cable without checking the connector first. Those cables are relatively easy to crease, tear, or damage at the contacts.

I recommend taking several close-up photographs before disconnecting anything. Photograph:

• Which connector each cable plugs into

• Which direction the ribbon cable contacts face

• How the cables pass through guides and openings

• Where tape, clips, or cable retainers are located

• How much slack each cable has before disassembly

This will make reassembly considerably easier.

Removing the Scanner and Upper Case

Once you have access to the scanner cable connections, disconnect the necessary cables and release them from their routing guides.

As you remove screws, keep them organized according to their location. Epson often uses screws that look almost identical but have different lengths. Putting a longer screw into a location designed for a short screw can sometimes damage plastic components or nearby mechanisms.

You will generally need to work your way through the scanner/upper housing rather than trying to pull the entire assembly off immediately.

A useful approach is:

1. Open the scanner unit and inspect the hinge and rear areas carefully.

2. Identify the scanner/ADF wiring and where it enters the main printer body.

3. Remove the necessary covers that prevent access to those connectors.

4. Photograph and label the cable locations.

5. Release any locking tabs before removing ribbon cables.

6. Disconnect the wire harnesses by their connector bodies rather than pulling on the wires.

7. Remove the scanner mounting screws and hinge-related fasteners.

8. Support the scanner assembly as the final screws are removed.

9. Lift the scanner assembly slowly while checking for any cable, ground wire, or harness that may still be attached.

10. Continue removing the upper housing panels until you have sufficient access to the carriage and timing-belt area.

Do not force a plastic cover that seems stuck. If a panel will not release, there is usually another screw, hidden clip, or overlapping piece of plastic holding it.

Finding the Dropped Torsion Spring

Once the scanner and upper casing are out of the way, use a strong flashlight and inspect the bottom of the chassis carefully.

Pay particular attention to:

• Beneath the carriage path

• Around the timing belt

• Near the right and left frame walls

• Underneath the paper-feed mechanism

• Around wiring channels

• Near the maintenance station

• Along the bottom of the printer frame

A small spring can bounce much farther than expected after being dropped.

If you can see it, long tweezers, hemostats, or a narrow mechanical pickup tool can be very useful. Try to retrieve it directly rather than pushing it around inside the chassis.

Before reinstalling the spring, I would also confirm that you have the correct spring and that nothing else was dislodged during cleaning.

Reinstalling the Timing Belt Torsion Spring

The spring involved in the timing-belt arrangement provides the mechanical tension needed to keep the carriage timing belt properly tensioned.

On this style of wide-format Epson mechanism, the timing-belt spring arrangement is on the right-hand side in the belt installation procedure. The spring is attached and tension is then applied so that the corresponding hook/tensioning mechanism can be engaged. Our timing-belt tutorial discusses this arrangement as part of the ET-16500/WF-77xx procedure. (BCH Technologies)

This is one place where I strongly recommend returning to the original BCH Technologies timing belt video [https://www.youtube.com/watch?v=6yRUerGqjz0] and carefully comparing the position and orientation of the spring with your printer.

Pay attention not only to where the spring attaches but also to its orientation. A torsion/tension spring installed in the wrong direction may physically fit while providing incorrect tension.

Check the Timing Belt Before Reassembling Everything

Since you were already working around the timing belt, take this opportunity to inspect the entire carriage-drive system before putting the scanner and casing back on.

Make sure:

• The timing belt is seated correctly on its pulleys.

• The belt is not twisted.

• The belt teeth are not damaged or missing.

• The spring/tensioning mechanism is seated correctly.

• Nothing is rubbing against the belt.

• The carriage path is free of loose screws, springs, pieces of plastic, or tools.

• The CR encoder strip is still correctly positioned through the carriage's encoder sensor.

• The encoder strip has not been pulled out of its mounting points.

• No ribbon cable is trapped in the carriage path.

The encoder strip is especially important. If it gets dirty, scratched, disconnected, or routed outside the carriage sensor, the printer may lose track of carriage position.

If you cleaned around that area, avoid putting grease, oil, or other lubricant on the encoder strip. It needs to remain clean so the carriage encoder sensor can read it properly.

Test the Carriage Mechanism Carefully

With the printer unplugged, inspect the carriage and timing-belt area before reconnecting power.

You are mainly looking for anything obviously binding or incorrectly positioned.

Do not force the carriage against the maintenance station or try to overcome resistance with excessive pressure. The objective is simply to identify an obvious obstruction, incorrectly installed belt, misplaced spring, or cable caught in the mechanism.

Once everything looks correct, reinstall the scanner cables and covers carefully.

Ribbon cables should be inserted straight into their connectors and fully seated before the connector locks are closed. A ribbon that is inserted only partially can cause scanner, control-panel, ADF, or communication problems after reassembly.

Take Pictures During Reassembly Too

One technique that helps enormously with a complicated printer like the ET-16500 is taking photographs at every stage of disassembly.

If you have not already done that, start now.

When you eventually put the machine back together, compare each stage with your earlier photographs. Check cable routing carefully because a cable routed on the wrong side of a frame or screw post can become pinched when the scanner housing is reinstalled.

Do not install every screw and exterior panel immediately after reconnecting the scanner. First make sure that all essential connections and mechanical components are where they belong.

What About Error Codes?

You did not mention a specific printer error code in your question, so there is no particular error code for me to interpret at this stage.

If the printer produces an error after the spring is recovered and the machine is reassembled, make a note of the exact message or error code before taking it apart again. That information can help distinguish a carriage/encoder problem from a scanner connection, paper-feed, or other mechanical problem.

For example, if a problem appears immediately after this repair, the first things I would recheck are the timing belt and tensioner, the CR encoder strip, the carriage movement, and every scanner/control-panel cable that was disconnected during disassembly.

Printer repairs like this can become complicated very quickly because diagnosing mechanical problems usually requires hands-on inspection. For that reason, we're not able to provide remote troubleshooting, individualized repair suggestions, or ongoing remote support for printer repairs. We do offer in-person evaluation and repair through our local printer diagnostic and repair facility [https://bchtechnologies.com/printer-repair-service]. Because demand is high, the service operates on a first-come, first-served basis, and it may take a few weeks before an appointment or drop-off is available. Our services can address either a complete printer or certain individual components, and the service page provides instructions on how to proceed. We also recognize that professional repair is not always the most economical option, so we strongly encourage self-help and online research when appropriate. A good place to begin is YouTube or the homepage of our BCH Technologies YouTube channel [https://youtube.com/@bchtechnologies]. On our channel, use the search icon located near the "About" area of the menu to search for the specific printer model or repair topic. I receive dozens of questions every day asking whether we have a video covering a particular problem. After creating videos for more than nine years, it is difficult for me to remember every video we have published, so using YouTube's search function is usually the fastest way to locate the appropriate tutorial. YouTube may also recommend useful repair videos from other creators that cover the same mechanism.

Thank you again for watching our tutorials and for supporting BCH Technologies. I hope the WF-76xx-style disassembly procedure helps you get the ET-16500 opened far enough to locate that spring. Work slowly around the scanner cables and plastic clips, take plenty of photographs, and make sure the spring, timing belt, and encoder system are correctly positioned before applying power again.