Uwatec D420 User Manual

D420 Service Manual
Use this manual at your own risk. It is not approved by Scubapro.
DIY service of scuba life support equipment may kill you.
This manual has been adapted from a copy of Version 1.0, March 2020
D420 SERVICE PROCEDURE, D420 SECOND STAGE GUIDELINES,
DISASSEMBLY, ASSEMBLY, ADJUSTING AND FINAL TEST,
published by Johnson Outdoors. As no copyright notice was observed on the
document, any use of copyrighted material is unintended and inadvertent.
The document had apparently been translated from the Italian, and text has
been modified for clarity where translated phrases were unclear.
The author has made additions and modifications based upon his experience,
which have not been approved by Scubapro.
Use this document at your own risk.

Uwatec D420 Specifications

General

Type	Dive Computer
Display	LCD
Nitrox Support	Yes
Modes	Air, Nitrox, Gauge
Wireless air integration	Yes
Digital compass	Yes
Battery Type	CR2450
Water Resistance	100m

Summary

Service Preparations and Components

General Notes

Provides essential guidelines for regulator use with Enriched Gas (Nitrox) and clean environments.

Cleaning Procedure

Details the process and requirements for cleaning regulator components, referencing a specific document.

Component Integrity Checks

Specifies requirements for seals, o-rings, plastic, rubber, and metallic components during service.

Service Tools

Cutting and Driving Tools

Essential tools including screwdrivers, knives, punches, and hex keys for disassembly and assembly.

Specialized Wrenches

Includes specific spanners and multi-tools required for adjusting components like the flow vane.

Handling and Gripping Tools

Fine-tipped tools such as picks, pliers, forceps, and tweezers for delicate part manipulation.

Measurement and Fixturing Tools

Tools for specific tasks like retaining ring removal, torque application, and hex drive extensions.

Disassembly Procedure

Initial Component Removal

Steps for removing the mouthpiece, cover pin, decal, purge button, and face plate.

Internal Part Extraction

Procedures for carefully lifting out the diaphragm, thrust washer, and flow vane plug.

Lever and Hose Inlet Removal

Instructions for removing the lever, decorative cap, case plug, and hose inlet with o-rings.

Flow Vane and Housing Disassembly

Steps to disassemble the flow vane assembly, housing support, and exhaust tee components.

Exhaust Valve Access

Final steps to access and inspect the exhaust valve for replacement or damage.

Reassembly Procedure

Exhaust Valve and Tee Installation

Guidance on fitting the exhaust valve, exhaust tee, and securing them with the pin.

O-Ring Lubrication and Placement

Instructions for lubricating and fitting o-rings onto the housing support, hose inlet, and case plug.

Housing and Support Assembly

Steps for inserting and securing the housing support and housing into the regulator case.

Lever and Flow Vane Assembly

Details on installing the lever, flow vane, adjustment screw, and related components.

Poppet and Spring Installation

Instructions for positioning the poppet, spring, spring support, and flow vane sub-assembly.

Final Component Fitting

Steps for fitting the flow vane washer, dive switch, o-ring, and flow vane plug.

Tuning and Final Testing

Initial Pressurization and Adjustment

Pressurizing the regulator and adjusting the screw for air leaks and cracking effort.

Diaphragm Seating and Lever Gap

Ensuring diaphragm seating and adjusting the lever height for optimal performance.

Faceplate and Purge Button Installation

Attaching the faceplate, thrust washer, and installing the purge button assembly.

Leak and Freeflow Testing

Performing leak tests without air supply and checking for freeflow in the Pre-Dive position.

Final Assembly and Checks

Applying decals, fitting safety pins, decorative caps, and completing reassembly.