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Apple TV 4k Power Supply Test

WindburnWindburn Registered User regular
My Apple TV 4k died over the weekend. It's possible it suffered a power surge during a heavy rain storm, but it was connected to a surge protector. I tried connecting it to a different outlet with a different power cable (from another working ATV4k unit) without success. From my reading it sounds like it might be a bad power supply. Before I buy a new one, I would like to test the current power supply.

My plan is to connect the power cord and measure the VDC at the conductive posts (red circles in the picture below). If the power supply is bad, I shouldn't measure any voltage, correct?

Power Supply

Conductive Posts

Windburn on


  • ShadowfireShadowfire Vermont, in the middle of nowhereRegistered User regular
    Food for thought: if it died from a surge, there's a very real possibility that it's more than just the transformer that ate shit. You can check the voltage there but that will just tell you if it's pulling in volts from the wall which it probably is. I want to say ifixit has a breakdown that will tell you which rails to check for voltage and resistance but I'm not 100% sure on that.

    Also your surge protector needs to be replaced. Depending on where you live and how dirty your power is, you should plan on replacing them every 2-5 years.

    WiiU: Windrunner ; Guild Wars 2: Shadowfire.3940 ; PSN: Bradcopter
  • WindburnWindburn Registered User regular
    That’s good advice about the surge protector. I will replace it.

  • WindburnWindburn Registered User regular
    Project update:
    Tear down complete. Of course the power supply is the deepest component.
    Connected the power cable and I measure 120 VAC on the pins immediately adjacent to the power jack (confirming the problem isn’t there). When I measure at the output conductive posts, I get 0 VDC.

    I’ve ordered a replacement power supply off EBay. I’ll post an update once it has arrived and I test it. As Shadowfire said, it’s possible more than just the PSU was damaged.


  • WindburnWindburn Registered User regular
    edited February 2020
    The new power supply passed the initial test (produced 12 VDC). I put everything back together, new thermal paste, etc. and plugged it in. Light came on the unit (step up from before), but that was it. No signal to the TV. I tried a variety of different troubleshooting steps without success.

    This is not surprising given the amount of silver discoloration I could see on the chassis, power supply, and logic board (see pic below near the Ethernet jack). Looks like it was cooked pretty solidly.

    Unfortunately the last step is buying a new one. If anyone would like the Apple TV for parts or as a project, PM me and I’ll send it to you.


    Windburn on
  • kafuquakafuqua Registered User new member
    Do you still have this Apple TV 4k? I could use it for parts. Have one that seems to also have a bad power supply and no replacement power supplies are non existent.

  • WindburnWindburn Registered User regular
    Sure. PM your address.

  • FicklelifeFicklelife Registered User new member
    I’m about to covert a 4K 5th gen A1842 to 12v. Just wondering if you know for sure which one of the two internal posts on the power supply is positive 12v? I am assuming the right hand side (with boat posts on top of the board) as that’s what was in older generation Apple TV’s, but I’m not sure!

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