Purpose

The purpose of this article is to outline the process to replace an existing Verifone UX410 reader with a Castles S1U2-M4 reader on supported MM6 and MM6 Mini kiosks. The S1U2-M4 must be installed with the retrofit kit assigned to the exact kiosk chassis, processor, and region being serviced.

Supported Configurations

• MM6 kiosk with the matching MM6 S1U2-M4 retrofit kit.
• MM6 Mini kiosk with the matching MM6 Mini S1U2-M4 retrofit kit.
• Processor-specific, region-specific, and network-specific harnesses as identified by the work order or kit packing slip.
  • Please Note: Other kiosk chassis require a chassis-specific retrofit kit and should not be converted using MM6 or MM6 Mini mounting parts.
     

Quick Ordering Process

1. Confirm the kiosk model, processor type, region, and currently installed reader before ordering parts.
    
2. For a UX410 replacement, order the complete S1U2-M4 retrofit kit for the kiosk in front of you.
   • Do not order a reader-only unit unless the work order explicitly confirms that all required mounting and interface parts are already onsite.
      
3. Verify that the kit includes the S1U2-M4 reader, adapter plate or spacer, kiosk-specific mounting hardware, primary power/I-O harness, and any required Ethernet, COM, USB, MDB, antenna, or interface-board components.
    
4. Check the packing slip against the work order before dispatch. Hold the job if the kit revision, harness labels, processor, or region does not match the work order.
    
5. Record the S1U2-M4 serial number from the reader label before installation so it can be attached to the service ticket without reopening the kiosk.
    

S1U2-M4 Port Reference

The S1U2-M4 includes several labeled ports and controls on the rear and side of the terminal. Not every port is used on every 365 retrofit kit, so follow the kit labels and work order first.

• If a kit packing slip, regional work order, or support instruction conflicts with this guide, follow the kit-specific document for the build you are servicing

S1U2-M4 Reader Kit

The standard S1U2-M4 Reader Kit will contain:
 

• S1U2-M4 reader
• MM6-specific (or MM6 Mini-specific) adapter plate or spacer
• MM6-specific (or MM6 Mini-specific) mounting hardware
• Primary power / I-O harness
• Ethernet jumper and or antenna lead if included by the kit
• Any kit-supplied interface board or bracket
   

Process

Clear the following prerequisite list before starting on-site hardware disassembly:

• Verify the kiosk model is an MM6 or MM6 Mini and confirm the currently installed reader is a Verifone UX410.
   
• Confirm that all retrofit kit components are present and undamaged, then compare the new hardware to the production build before removing anything.
   
• Photograph the existing UX410 cable routing, controller location, fastener locations, and hinge clearance before disconnecting anything. 
  • Record the S1U2-M4 serial number or serial numbers before installation.
  • If working with a support team during this process, sending the support member the pictures is a good backup that they can keep in internal support notes.
     
• Power down the kiosk and disconnect AC power before opening the chassis or touching payment hardware.
  • Wear an ESD strap or follow local static-control practice when handling the reader, controller, or interface board.
     
• Have a credit card or mobile wallet available for final testing.
   
• Do not reuse the UX410 controller with the S1U2-M4.
  • Keep removed UX410 parts separate from S1U2-M4 parts so legacy hardware is not accidentally reinstalled.
     

Tools Needed

• Phillips screwdriver.
• Small socket or ratchet set; 5/16 in or 8 mm is commonly used on legacy UX410 hardware.
• 9/32 in socket or nut driver when required by reader standoffs.
• Side cutters or flush cutters for cable ties.
• Flashlight for verifying rear fasteners and cable routing.
• ESD strap or approved static-control method.
• Kiosk key for the service door or front door.
• Replacement cable ties.
• Test credit card or mobile wallet
  

Kit Content Verification and Fit Test

Lay out the kit on a clean surface before removing the UX410. The exact contents can change by build, but each field kit should provide the parts needed to mount, connect, and test the S1U2-M4 without reusing the UX410 controller.

S1U2-M4 Mounting Hardware Reference

Use this reference before placing the reader in the kiosk. The screws in the kit are not painted; the red and blue overlays below are guide annotations only. Red identifies the larger screw set and its matching holes. Blue identifies the smaller screw set and its matching holes. Keep the two screw sizes separate, start each screw by hand, and tighten only after all screws in that set have started cleanly

• Adapter frame, contactless harness, and S1U2-M4 reader laid out before assembly.
  
• Red Set - Larger Screws and the corresponding hole positions.
  
• Blue Set - Smaller Screws and the corresponding hole positions.
  

MM6 Kiosk

Please Note: The MM6 uses a front-opening chassis for service access. Bracket position, spacer thickness, and cable lengths can vary slightly by production run, so compare the retrofit kit against the existing hardware before removing anything.

Removing the Old Reader

1. Power down the kiosk and disconnect AC power before opening the chassis. Open the front chassis fully.
   • Support the open front assembly as needed while you work.
      
2. Locate the UX410 reader assembly behind the payment opening and identify the legacy controller or harness associated with the reader.
   • Photograph or label the cable routing before disconnecting anything.
      
3. Disconnect the UX410 power lead first. Then disconnect Ethernet, COM, USB, serial, antenna, coax, or other reader harnesses from the controller and reader as applicable.
   • Cut only the cable ties required to free the UX410 harness. Do not cut nearby kiosk harnesses.
      
4. Remove the controller or bracket hardware tied to the UX410 and set the legacy controller aside for return or disposal according to the work order.
    
5. From the rear of the payment opening, remove the nuts and washers securing the UX410.
   • Support the reader from the front so it does not fall as the final fastener is removed.
      
6. Slide the UX410 out through the front and remove any legacy gasket, spacer, adhesive, or plate that is specific to the old reader. 
   • Clean the mounting area before installing the new plate.
      

Installing the S1U2-M4 Reader

1. Compare the new adapter plate or spacer with the MM6 payment opening. Verify the orientation, stud pattern, gasket location, and cable exit path before placing the reader.
    
2. Feed the kit-supplied harness through the opening or adapter plate as directed by the kit. Do not pull on the connector shells or twist the harness.
    
3. Insert the S1U2-M4 from the front with the screen upright and the contactless target facing the customer.
    
4. From the rear, install the kit-supplied hardware. When the adapter frame includes both screw sizes, use the mounting hardware reference above: larger screws in the red positions and smaller screws in the blue positions. 
   • Start all fasteners by hand, then tighten evenly in a cross-pattern until the reader is secure and flush. 
     • Do not overtighten the housing.
        
5. Mount any kit-supplied interface board or bracket in the approved service location. Do not reinstall the UX410 controller.
    
6. Connect the kit-supplied harness to the S1U2-M4 using the printed port labels and harness tags. Populate only the ports called for by the kit or work order.
    
7. Connect Ethernet, COM, USB, MDB, or antenna leads only when the harness labels or work order require them.
    
8. Dress and re-tie the cable bundle. Leave enough service slack to reopen the chassis, and keep the bundle clear of hinges, latches, sharp edges, and the front chassis closing path.
    
9. Before applying power, close the front assembly slowly and reopen it once to confirm that no cable is pinched or stretched.
    
10. After installation, navigate ahead to the section: Testing the Reader.
     

MM6 Mini Kiosk

The MM6 Mini field flow mirrors the UX410 service procedure: open the front door, remove the legacy controller and reader, install the S1U2-M4 with the Mini-specific plate and harness, then validate reader power and host communication before closing the kiosk.

Removing the Old Reader

1. Unlock the kiosk and open the front door fully. 
   • Confirm that the door is stable and that the hinge path is visible.
     
2. Locate the legacy UX410 controller on the inside wall of the kiosk and identify each cable before removal.
   
3. Disconnect cabling from the legacy controller and reader. Remove the power lead first, then Ethernet, COM, USB, serial, antenna, coax, or any other reader connection used by the installed build.
    
4. Remove the controller mounting hardware and pull the controller away from the kiosk.
   • Keep the removed controller separate from the new S1U2-M4 components.
     
5. From the rear of the payment opening, remove the nuts and washers that secure the UX410.
   • Support the reader from the front while it is freed.
     
6. Slide the UX410 out through the front and remove any gasket, spacer, or mounting plate left in the opening.
    

Installing the S1U2-M4 Reader

1. Compare the MM6 Mini adapter frame or spacer with the payment opening and confirm the orientation before installation.
   • Lay out the larger and smaller screw sets separately before placing the reader in the opening.
      

2. Prior to installation of the bracket for the CC reader, install the ethernet adapter onto the reader as shown

   
3. Install the adapter plate with the cable from the ethernet adapter going under the lower rib and through the middle gap as shown.
   

4. When installing the CC reader and bracket onto the kiosk, first pull the MDB power connector through the opening on the kiosk and plug into the back of the reader.

   
5. Slide the ethernet adapter through the opening in the kiosk bezel and attach the CC reader with the 4 provided screws.
   
6. Connect Ethernet to LAN and connect COM, USB, or MDB only if specifically called for by the supplied harness labels or work order.
   
7. Route cables away from the hinge and door path, re-tie the bundle, verify service slack, and close the kiosk slowly while watching for cable movement.
   • Before applying power, close the front assembly slowly and reopen it once to confirm that no cable is pinched or stretched.
      
8. After installation, navigate ahead to the section: Testing the Reader.
    

Troubleshooting Quick Checks

Testing the Reader

1.  Restore AC power and allow the kiosk and S1U2-M4 to boot fully.
    
2. Confirm that the reader display powers on and that the kiosk service menu detects the reader without payment-device errors.
    
3. Run at least one supported payment test, such as tap, chip, or swipe as applicable to the kiosk configuration and processor.
    
4. Verify that the transaction reaches the host and that the kiosk returns to the ready screen.
   • Attach the installed reader serial number, final routing photos, and test result to the service ticket, then close and lock the kiosk.
      
5. Confirm the kiosk and terminal communicate cleanly.
   1. MM6: for builds that use receipts, include receipt-print validation in the post-retrofit test set.
       
   2. MM6 Mini: for wall mounted builds, complete a stability check so the mounted unit does not move during customer use.
       

Reader Startup and Functional Testing

After completing the Reader Test in Testing the Reader, use the below checklist to confirm proper installation readiness. If issues persist, see the Troubleshooting Quick Checks section. 

• Please Note: A reader swap is not complete until the S1U2-M4 powers on, is visible to the kiosk, and successfully completes a payment-path test.