Home Assistant Yellow Not Powering On

I received my Home Assistant Yellow (pre-assembled) this past week, but sadly it won’t power on. AC adapter plugged into known working 120V outlet, barrel connector into Yellow, but no LEDs and it doesn’t show up on the network.

The AC adapter seems to be supplying power. The CM4 board is aligned with the white outline and I’ve tried to press it in with reasonable force, but no help.

Is there anything else I can try? Is there an RMA process if nothing works?

Do you have access to a multimeter to probe the PSU barrel jack for 12V DC to avoid an RMA delay for something you might be able to source locally? The UK kit came with a 2A PSU, centre +12V, barrel GND.

I should probably should repeat the usual “only use the PSU that came with the device”, however the circuit also shows polarity reversal protection and a 3A fuse.

Sadly, the circuit diagram suggests all of the PCB LEDs are run by the CM4 or logic controlled by the CM4 - e.g. a bad CM4 could mean no blinky lights. Do the two buttons do anything at all?

Your reference to checking the CM4 is seated suggests you’ve already read my-home-assistant-yellow-appears-broken. The CM4 2Gb on my kit looks pretty well attached via the heatsink bolts.

a bad CM4 could mean no blinky lights. Do the two buttons do anything at all?

They do not.

Do you have access to a multimeter to probe the PSU barrel jack for 12V DC

I do, which is the last thing I plan to check (barring clever or obvious-but-overlooked suggestions here) before deeply sighing and figuring out the RMA process.

Sorry I can’t think any subtle tricks to help more - the disappointment must be rather terrible. :frowning:

There are a few threads looking more deeply at M.2 SSD or CM4 NVMe flash issues, but this sounds a bit more basic. The docs show how to remove the CM4 and heatsink which might be worth a try after proving the PSU. Other stuff requires another CM4 carrier board, or using the circuit to probe test points for the various power supply rails on the Yellow PCB.

I would suggest to try and remove and refit the CM4 board completely if you havn’t already,
you stated that you have pressed it with resonable force but just to be on the safe side remove and refit it. This has helped a couple of people in the Discord channel who has had issues as well.
For some reason the pre-fitted CM:s don’t always connect it seems like.

Yep, as expected, that did it.

For anyone else who might be interested and who has the pre-assembled Yellow:

  • Undo the thumbscrews on the bottom of the case and remove the top
  • The bottom cover plate is attached by a push-in in each corner. Undo these and remove the board from the bottom plate.
  • Locate the heatsink push-pins. They’re at two corners of the heatsink covering the CM4 board, with spring push buttons.
  • Turn the board over, and push the pins back through the board to remove the heatsink. This may require a small flat-blade screwdriver inserted and turned in the opening in the bottom of each push pin. (Obviously, don’t use too much force or try to pry the heatsink off the board.)
  • In my case, the CM4 board was already disconnected from the board. Ease it up and out of the sockets if it isn’t.
  • Look for any obvious damage on the connectors or sockets.
  • Reconnect the CM4 to the main Yellow board. Thanks Yellow devs for including outlines that make it obvious what the correct orientation is!
  • Replace the thermal paste (something I probably should do!)
  • Reattach the heatsink.
  • Reattach the bottom plate of the case to the board.
  • Plug the power cable into the barrel jack and watch the LED lights activate like the never did before.
  • Optional: Put the case back on and shove it to the side of your desk so you can get some real damn work done today.

:grin: Thanks for your help folks!

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Glad to hear you got it sorted!
Welcome to Team Yellow :wink:

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Thanks for sharing this. I had the exact same issue. Now up and running.

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