Hello,
I'm trying to repair a Nest thermostat at the moment mostly for fun. This is the newer version released in 2020 which is called simply "Nest Thermostat" no to be confused with the several other similar Nest thermostat naming scheme.... thanks google...
At first glance when inserting batteries the unit is completely dead. Nothing on the screen. I then powered it via a power supply with 3V and it was getting current limited at 0.5A. Using a thermal camera I discovered that U35 was getting super hot. I removed it and now the thermostat draws still around 200mA.
The circuit is really quite complex for such a simple device and uses crazy small package all over the place. So without any schematic It's alot of guessing.
Anyone got a similar unit and would be willing to get some of the expected test points value on a working unit? There is about 90 testpoints on that thing
One thing I know is I do have a steady 3.3V rail so there is a boost converter doing it's job somewhere
Another thing that doesn't help is that a bunch of the IC I can't find any info on. I know some are most likely regulators for different voltage rails but so far apart from the 3v3 rail I have'nt found any other standard voltage rails
Anyway I'll leave some pictures of the main board for the curious as it is quite interesting design.
If you have already worked on these or know where I could get a schematic/service manual it would certainly help.
I already checked all the fuses and did a visual inspection and probed pretty much every testpoints.
I'll probably need to reverse engineer the whole thing to get it working
Home
Help
Search
Login
Register
