Apple Watch Series 4teardown reveals major improvements in terms of the internals

Repair masters at iFixit earlier this morning published their detailed teardown analysis of a larger 44mm, cellular-equipped edition of the new Apple Watch Series 4 (model A2008).

“The original Apple Watch was revolutionary upon its release, but the yearly updates have been mostly minor—until now,” they noted.

Daring Fireball’s John Gruber has likened Series 4 to the leap in design brought by iPhone 4, prompting iFixit to actually call it Apple Watch’s iPhone 5 moment: “a device that knows its priorities, and wants to look elegant inside and out.”

Whereas the original Apple Watch model had the “awkwardly placed internals”, Apple’s engineers have “really painted the back of the fence” in terms of the component layout for the new Series 4.

The Crown with a secret

Cellular Series 4 models no longer feature a large red dot on the Digital Crown, which many people disliked. Now you get a far more subtle red ring outline that gives it an elegant feel. The completely reengineered 4 Digital Crown on the new apple Watch Series 4 also contains an electrode for a brand-new ECG function.

Apple Watch Series 4 teardown shows a much-improved Digital Crown

Series 4 has the most elaborate Digital Crown Apple’s create to date

The redesigned Crown takes advantage of an enhanced haptic feedback system to give the wearer a believable clicking sensation as they spin it, almost as if the Crown trips mechanical notches. Aside from the built-in ECG function and haptic feedback, Series 4’s new Digital Crown is also smaller and more compact.

A stronger battery & other tidbits

Even though it has a six percent slimmer case with less volume, Apple Watch Series 4 packs in a 1.113 watt-hour battery (291.8 mAh at 3.81 V) representing a four percent capacity increase over the 1.07 watt-hour battery powering the previous Apple Watch Series 3.

Apple Watch Series 4 teardown reveals a longer Taptic Engine than before

If only Apple found a way to miniaturize the Taptic Engine..

The Taptic Engine is now much thinner and a bit longer than before. I suspect a longer haptic feedback mechanism is needed for that faux spinning wheel feel afforded by the redesigned Crown. “Even this smaller engine takes up a lot of room in this tiny device—room that could have gone to a bigger battery, but Apple seems to feel physical feedback is very important,” iFixit notes. And whereas Series 3 has an unsightly hole in the case for its barometric censors, Series 4 cleverly uses the grille holes.

As you know, Series 4 also rocks a thinner, about 15% larger display.

Apple Watch Series 4 teardown reveals a new ECG sensor at the bottom and in the Crown

X-rays reveal optical sensor in the middle, surrounded by a new ECG electrode

According to iFixit, the 44 mm model’s display covers 977 square millimeters versus 740 square millimeters on the same-sized Series 3 model. The 40mm model of Apple Watch Series 4 spans 759 square millimeter compared to 563 square millimeters on the predecessor.

Apple Watch Series 4 teardown also has shown a streamlined antenna system

This golden ring is likely a streamlined antenna

From the conclusion:

  • The corners are noticeably rounder for more of that squircle look.
  • The side button now sits flush with the case.
  • Series 4 is a Lead I ECG: it only measures voltage between the right and left arms.
  • Battery replacements are pretty straightforward, once you’re inside.
  • Band replacements remain fast and simple, and are even backward-compatible with previous models.
  • Screen replacements are difficult but doable: it’s the first thing to come off, and detaches via simple ZIF connectors.

Like with previous Apple Watch processors, the new S4 chip is still a system-in-package solution that combines a tiny microcomputer with logic boards, microchips and other components crammed onto a single resin-protected component, a first in the smartwatch industry.

Apple Watch Series 4 teardown shows the resin-plated S4 chip

The S4 chip is secured only with screws, unlike the fiercely-glued chips of years past

iFixit notes that several component flex cables are mounted directly to the S4 package, requiring skilled micro-soldering to replace. The resin-encased housing, however, makes most board-level repairs impossible.

Series 4 repairability

“Where the first Watch was awkwardly layered together and used too much glue, the Series 4 feels much more thoughtfully laid out,” the iFixit team observed.

Series 4 has neared iPhone levels of repairability, but iFixit said that a sticky display remains a challenge. In terms of batter replacements, once you’ve actually managed to make your way inside the device, the battery is straightforward to replace.

The aforementioned architectural and engineering improvements have prompted the iFixit team to give Apple Watch Series 4 a solid 6 out of 10 on their repairability scale.

Thoughts about the teardown?

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