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Introduction

Your Polar M400 won’t charge anymore? The micro-USB connector has corroded? You don’t want to pay a whopping 20€ (+ shipping) for a new connector from Polar? Not afraid of soldering and heat guns? If so, you have come to the right place!

  1. Polar M400 Watch micro-USB connector Replacement, Disconnecting the flex PCB: step 1, image 1 of 3 Polar M400 Watch micro-USB connector Replacement, Disconnecting the flex PCB: step 1, image 2 of 3 Polar M400 Watch micro-USB connector Replacement, Disconnecting the flex PCB: step 1, image 3 of 3
    • Follow the screen replacement tutorial to dismantle the watch.

    • Carefully lift the screen from the board.

    • Disconnect the USB's flex PCB from the main board. Save the red rubber seal of the USB connector for later.

    • Use a tool like a helping hand to hold the USB connector part.

    • Using a heat gun, blow hot air underneath the PCB.

    • Once the solder is melting give the connector a good tap in order to make the PCB fall loose.

  2. Polar M400 Watch micro-USB connector Replacement, Soldering a new USB connector: step 3, image 1 of 2 Polar M400 Watch micro-USB connector Replacement, Soldering a new USB connector: step 3, image 2 of 2
    • Place the new USB connector on a flat surface with its pins pointing upwards.

    • Place the PCB on top on the pins, the exposed copper traces on the flex PCB facing the flat surface.

    • Using an iron, solder the PCB by heating all the pads at the same time (as much as possible) and apply pressure so that the pins of the USB connector come through.

  3. Polar M400 Watch micro-USB connector Replacement, Sealing the USB connector: step 4, image 1 of 2 Polar M400 Watch micro-USB connector Replacement, Sealing the USB connector: step 4, image 2 of 2
    • Connect the flex PCB back to the main board.

    • Reassemble the watch stopping before screwing the lid back.

    • Add hot glue to the base of the USB connector filling the watch case's cavity. Be careful not to put hot glue inside the connector.

    • While the glue is still hot, put the red rubber seal back on top.

    • Screw the lid back.

    Warning update : In my case hot glue wasn’t so good at waterproofing… The watch steamed up after long activities, which eventually led to corrosion… Maybe silicon would have been better.

    Benjamin Freeman - Reply

Conclusion

To reassemble your device, follow these instructions in reverse order.

5 other people completed this guide.

Benjamin Freeman

Member since: 01/16/2020

259 Reputation

1 Guide authored

7 Comments

Sehr gute Beschreibung,

aber ich finde keine USB-Buchse für die M400 zu kaufen

Wo gibt's die Teile?

martinmartinez644 - Reply

Danke schön. Für den Konnektor allein habe ich auf Aliexpress gekauft : https://www.aliexpress.com/item/32960430...

Benjamin Freeman -

From where do I order usb connector?

Pankaj Singh - Reply

Thanks for posting this guide. Very helpful.

Leon Joubert - Reply

Ich habe die Reparatur noch etwas verfeinert. Die Uhr ist danach auch wieder dicht, der Stecker stabil.

- Die feinen Bohrungen auf der Flex-Leiterplatte bekommt man gut mit Pressluft frei, während man die Pads erhitzt

- Man kann den defekten Stecker von unten soweit freikratzen, dass sich der Metallteil aus der Hülse herausziehen lässt

- wenn man die Hülse etwas ausarbeitet, kann man den neuen Stecker von oben einschieben (nicht kleben für nächste Reparatur ;o))

- Stecker dann einlöten

- Der Ersatz ist wie das Original und sitzt auch ohne Heißkleber fest.

Klaus Neumann - Reply

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