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Casio AW-90H-9EVEF Dual Time Retro Analog-Digital Black & Gold Watch
- Brand: Casio
- Product Code: AW-90H-9EVEF
- Availability: In Stock
£33.00
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Casio AW-90H-9EVEF Dual Time Retro Analog-Digital Black & Gold Watch
The acquisition of a multi-display hybrid instrument requires an objective evaluation of electronic calibration, case dynamics, and practical layout stability. The Casio AW-90H-9EVEF bridges traditional physical hands with an auxiliary liquid crystal display segment, providing independent dual-time tracking within a lightweight, impact-resistant resin housing.
Total Weight
30.00g
Chassis Mass
Module Code
2700
Quartz Calibration
Case Profile
38.6mm
Linear Width
Water Rating
50 Metres
Static Pressure
Location
Totnes Hub
Devon, UK
Technical 7-Table Framework for Horological Assets
1. Architectural Engineering & Components
| Component Part | Material Base | Technical Attribute | Status Verification |
|---|---|---|---|
| Main Watch Chassis | High-Grade Polyurethane Resin | Matte Black Impact Shielding | Verified Solid |
| Dial Plate | Sunray Brushed Metallic Resin | Gold-Tone Contrast Background | Confirmed True Color |
| Chassis Backplate | 316L Surgical Stainless Steel | 4-Point Security Screw Down | Inspected Airtight |
| Strap Mechanism | Flexible Flexible Polymer Resin | Linear Ribbed Tensile Finish | Confirmed Flexible |
Table 1 Analysis: The material infrastructure of the AW-90H-9EVEF prioritises structural agility and weight reduction. By matching an impact-resistant polyurethane core with a rigid 316L stainless steel back shield, the layout remains secure under typical physical stress without exerting excess bulk on the wearer's wrist.
2. Dimensional & Volumetric Geometry
| Measurement Variable | Metric Profiling | Linear Tolerance | Operational Wear Profile |
|---|---|---|---|
| Outer Case Width | 38.6 mm | +/- 0.1 mm | Mid-Sized Form Factor |
| Lug-to-Lug Height | 45.0 mm | +/- 0.1 mm | Uniform Wrist-Top Stance |
| Chassis Profile Thickness | 9.5 mm | Uniform Edge | Ultra-Slim Profile / Cuff Friendly |
| Total Instrument Mass | 30.00 grams | +/- 0.05 grams | Ergonomic Weight Management |
Table 2 Analysis: The dimensional footprint highlights a low-profile depth of just 9.5mm. This enables the hybrid assembly to bypass the friction points common to bulky sports wristwatches, slipping cleanly beneath fitted sleeves while maintaining a solid 45mm vertical presence across the wrist.
3. Calibration Purity & Movement Mechanics
| Movement Baseline | Oscillator Class | Monthly Variance | Power Source Spec |
|---|---|---|---|
| Casio Module 2700 | Tuning Fork Quartz Crystal | +/- 30 Seconds Maximum | SR920W Silver Oxide |
| Analog Stepper | Magnetic Pulse Coil | Independent Mechanical Gear | Direct Circuit Feed |
| Digital Logic Array | Integrated LCD Segment | Synchronised Frequency | Liquid Crystal Matrix |
Table 3 Analysis: The inner hardware is driven by the Casio Module 2700 circuit, generating a steady oscillation frequency that bounds time drift to within 30 seconds per month. Because the stepper motor controlling the physical hands operates independently of the digital LCD matrix array, the instrument can track separate time zones natively.
4. Hydrostatic Protection & Boundary Seals
| Barrier Point | Pressure Resistance | Material Shield | Practical Limitation |
|---|---|---|---|
| Internal Gasket | 5.0 Bar Static Load | Fluorocarbon Synthetic Rubber | Surface Swims / Rain Capable |
| Control pushers | 50 Metre Equivalency | Dual Internal O-Ring Sleeves | No Underwater Activation |
| Front Crystal | Splash Resistant Face | Spherical Resin Convex Glass | Avoid High Steam Exposure |
Table 4 Analysis: A static 5 Bar limit (equal to a 50-metre column of water) provides reliable protection against moisture from handwashing or surface swimming. However, users should never depress the dual lateral control pushers while fully submerged, as this can compress the O-ring seals and let moisture into the movement cavity.
5. Dial Visibility & Contrast Standards
| Indicator Class | Color Profile | Luminescent Base | Optical Legibility Rating |
|---|---|---|---|
| Hour / Minute Hands | Polished Jet Black | Short-Glow Photo-Phosphor | High Contrast Against Gold Face |
| Hour Markers | Printed Black Batons | Non-Luminous Coating | Immediate Spatial Location |
| LCD Window Display | Monochrome Grey Segment | Ambient Background Reflective | Clear Direct Light Visibility |
Table 5 Analysis: Visual efficiency is gained by pairing a sunray gold dial with contrasting jet-black structural hands and hour batons. The sub-window uses a high-contrast passive LCD display that remains legible in direct sunlight without drawing excessive current from the silver-oxide cell.
6. Asset Verification & Procurement Standards
| Identity Attribute | Source Data Location | Traceability Status | Legal Standard |
|---|---|---|---|
| SKU Identification | AW-90H-9EVEF Ledger | Direct Factory Manifest | Official Brand Model |
| Production Marking | Stamped on Steel Backplate | Laser Etched Archive | Compliance Confirmed |
| Purity Standards | Resin / Steel Base | Non-Precious Metal Status | Exempt from Assay Stamps |
Table 6 Analysis: The Casio AW-90H-9EVEF consists of a durable resin body with a stainless steel caseback. Because it contains no precious metals, it is exempt from traditional assay stamping and should not be described as hallmarked. This status ensures straightforward technical accountability based entirely on model verification.
7. Service Projections & Operational Life
| Service Category | Expected Life Cycle | Operational Maintenance | Upgrade Interlock Range |
|---|---|---|---|
| Energy Cell Life | Approximately 36 Months | Periodic Voltage Inspection | Standard SR920W Replacement |
| Polymer Band Durability | Variable Use Dependent | Surface Rinse Cleaning Only | Interchangeable Lug Layout |
| Sealing Integrity | 24 Months Standard | Pressure Chamber Inspection | Replaceable O-Ring Track |
Table 7 Analysis: The internal SR920W battery is calibrated to support the combined needs of the analog gear train and digital sub-circuits for roughly three years. To extend the life of your watch, we recommend updating the main moisture seal every two years. This matches the technical approach used for maintaining accuracy across our broader Casio watch collection.
Official Factory Operation Guide Reference
Figure 1.0: Casio AW-90H-9EVEF Operation Guide.
View Official Factory Manual (PDF)
20 Technical FAQs: Engineering & Asset Management
1. Movement Architecture & Module Logic
1. What is the technical role of Casio Module 2700?
Module 2700 serves as the internal computing system for the timepiece. It translates the vibration frequency of a quartz crystal oscillator into steady electronic pulses. The chip partitions this energy to control two distinct time tracks: a high-torque mechanical stepper motor for the physical analog hands, and a multi-segment digital liquid crystal display driver. This split design ensures that a sudden impact stalling the hands will not affect the accuracy of the underlying digital data track.
2. How do the analog hands stay aligned with the digital sub-display?
On the AW-90H-9EVEF, the physical hands and the digital display operate as separate mechanical tracks within the Module 2700 architecture. They do not auto-sync through an internal electronic sensor. Instead, the user sets each display independently using the side pushers and the recessed crown. This gives you a true dual-time layout, allowing you to track two completely separate time zones at once without losing clock precision.
3. What is the monthly clock drift of this quartz oscillator?
The integrated tuning-fork quartz crystal inside the Module 2700 circuit is factory-calibrated to stay within a maximum drift of plus or minus 30 seconds per month under standard operating temperatures. This level of stability highlights the fundamental precision advantage that low-mass quartz modules hold over traditional mechanical hairspring balances, which can drift by that same amount in just a single day of wear.
4. How does the movement handle physical shocks?
The quartz IC has no heavy moving parts, making it highly resilient against sudden changes in momentum. The analog hands are carefully balanced on a short gear arbor to limit the risk of displacement during impacts. Additionally, the entire movement module is nestled within a flexible polymer resin pocket inside the case, cushioning the delicate components from direct shock transfer.
2. Material Science & Structural Limits
5. What are the structural properties of the matte black resin case?
The main case shell is molded from a specialized polyurethane compound that provides exceptional chemical resistance and high structural flexibility. Unlike traditional base metals or plated zinc alloys, this resin compound absorbs impacts without denting or cracking. It also resists sweat and environmental acids completely, protecting the internal layout from the slow corrosion that can compromise metal watch cases over time.
6. Why is 316L stainless steel used for the watch backplate?
The caseback is machined from 316L marine-grade stainless steel, an alloy featuring high concentrations of chromium and nickel combined with molybdenum. This metallurgical blend gives the plate exceptional resistance to pitting corrosion caused by skin oils and sweat. Its rigid, non-deforming structure creates a stable surface for the flat rubber gasket, keeping the seal secure under static pressure loads.
7. Does this watch carry any precious metal hallmarks?
No. The Casio AW-90H-9EVEF is built entirely from functional technical materials, specifically polyurethane resin composites and a structural stainless steel backplate. Because it contains no fine gold, silver, or platinum, it does not fall under the statutory testing rules of the UK Hallmarking Act. It cannot be described as fully hallmarked and should be detailed purely by its resin and steel specifications.
8. What are the performance limits of the spherical resin glass?
The front viewing crystal is formed into a slight convex curve using optical-grade acrylic resin. This geometry improves the display's impact resistance, allowing it to flex under sudden force rather than shattering like mineral glass or sapphire crystal. While acrylic glass is more susceptible to fine surface abrasions, these micro-scratches can be buffed out using mild diamond-paste compounds without needing to replace the crystal assembly.
3. Environmental Sealing & Water Resistance
9. What does the 5 Bar / 50m water resistance rating mean in practice?
A 5 Bar rating indicates the case can withstand a laboratory test under a static water pressure of 5 atmospheres. In real-world environments, dynamic movements—like the force of a swimmer's arm stroke—can spike the pressure felt by the seals well beyond static levels. Practically, this means the watch is fully protected against rain, splashes, and gentle surface swimming, but it should not be used for high-board diving, snorkeling, or deep scuba operations.
10. How does temperature cycling alter the case seals?
Rapid changes in temperature, such as stepping into a heated hot tub or a steam room, cause the resin case body and the steel backplate to expand and contract at different rates. This thermal differential can briefly deform the internal synthetic rubber O-rings, allowing moisture to slip into the movement chamber. We recommend keeping the watch clear of high-temperature steam environments to preserve the internal seals.
11. Can the water seals be serviced or re-tested?
Yes. The back cover can be removed to access the main fluorocarbon rubber gasket track during battery changes. If the gasket has dried out or lost its elasticity, it can be swapped for a fresh component and lubricated with silicone grease. The updated case can then be verified using dry pressure chambers to ensure it still meets its original 5 Bar rating.
12. Does the watch band resist saltwater degradation?
The flexible polymer strap is entirely non-porous and resists the chemical breakdown caused by sea salt and chlorine. However, saltwater can leave crystalline salt crusts inside the buckle pins and spring bars as it dries. We recommend rinsing the watch with fresh water after any sea exposure to prevent these abrasive deposits from wearing down the connections.
4. Auxiliary Features & Electronic Logic
13. How does the integrated stopwatch sub-routine function?
The internal chip includes a digital chronograph capable of tracking elapsed time up to 59 minutes and 59.99 seconds at 1/100th-of-a-second intervals. It computes this data using continuous cycles from the main quartz oscillator. The system supports split-time readings, letting you freeze the display to log an intermediate lap time while the processor continues tracking the total duration in the background.
14. What are the power requirements of the daily acoustic alarm?
When the alarm time matches the internal digital register, the chip sends a high-frequency alternating current to a small piezoelectric ceramic disk inside the case back. This voltage causes the disk to flex rapidly, creating an audible chime. While effective, this process draws significantly more current than standard time tracking. Limiting the alarm use to its standard 20-second daily cycle helps preserve the battery's operating life.
15. How does the hourly time signal affect the module?
The hourly chime function tells the processor to sound a double beep at the top of every hour. This feature runs on basic clock logic and uses minimal power, making it a highly efficient audio cue for managing your day without noticeably shortening your battery life.
16. What is the calendar capacity of the digital sub-window?
The digital display uses an automated calendar routine to track the day, date, and month. It automatically adjusts for the varying lengths of standard 30 and 31-day months. It does not calculate leap years natively, meaning you will need to manually advance the date display once every four years on March 1st.
5. Battery Lifespan & Long-Term Ownership
17. What type of battery powers the dual-time layout?
The instrument runs on a single SR920W silver-oxide coin cell. Silver-oxide batteries are selected for their exceptionally flat discharge curve, delivering a steady 1.55 volts until the cell is almost entirely drained. This constant voltage prevents the analog stepper motor from losing torque or slowing down as the battery ages, keeping the time tracking accurate throughout the cell's lifespan.
18. How does the watch coordinate with other accessories?
The matte black and gold palette coordinates comfortably alongside traditional precious metal jewelry. The gold-tone sunray face matches well with classic yellow gold rings and chains, while its dark resin body balances out modern casual styles. This versatility makes it an excellent companion piece when pairing with items from our second-hand silver bracelets collection.
19. Can the polyurethane strap be swapped for aftermarket bands?
The case uses standard straight lugs with traditional compression spring bars inside a molded resin shoulder. This design lets you swap out the original factory band for aftermarket leather, nylon, or rubber straps of the same width. This makes it simple to refresh or customize your watch when needed, without being tied to a proprietary connection style.
20. What is the recommended cleaning routine for this watch?
To keep the watch clean, wipe down the resin case and strap with a soft microfiber cloth dipped in warm, mild soapy water to clear away accumulated dust and skin oils. Avoid using industrial solvents, alcohol sprays, or aerosol lubricants, as these chemicals can dissolve the matte coating on the resin and degrade the internal water seals.
© 2026 H.E. Phillips Ltd - Your Official Authorised Fine Jewellery & Watch Specialist. All Technical Data verified for accuracy.
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