Solved Duet 2 wifi - 3.3v failure

[espenbor]

I experience a 3.3v failure on my Duet2 wifi (v1.04)
There is no light in the +3v LED, and when measuring the voltage on a 3.3v pin it shows only about 0.5v.

The failure is however (for me) a bit strange. The board might start up normally, but after short time use it freezes and the 3.3v drops. (down to about 0.5v).

I suspect the 5v to 3.3v regulator (U2) being the "problem-child" ... but I'm not shure.

In a desperate attemt to come around the problem, I tried to supply 3.3v from an external source (via one of the 3.3v pins) - but the effect is the same. The voltage is drawn down to about 0.5v. So someting is shorting - with some resistance - to GND.

Has anyone experienced similar failure?

[Phaedrux]

When and where did you purchase your product?

Is this a new board? Did it ever work?

Can you post some close up photos of the board, particularly the U2 chip?

Is it the same when powered via USB as when powered by VIN?

[espenbor]

The board is bauht on ebay, and is most likely a clone i'm affraid. .... and probably with low-quality components.
It has been working perfectly for about a year.
It's all the same when powered via USB.

[kb58]

An easy test is to unplug everything except power, power up the board, and see if the 3.3V rail drops again. If it stays good, start plugging in things one at a time (except steppers) until you find the troublemaker. If it remains bad, then yes, it's something on the board itself.

[dc42]

@espenbor it's also worth checking whether any components are getting hot, in particular the 3.3V regulator chip, the SD card and the WiFi module.

[espenbor]

@kb58 Thanks for your simple, yet brilliant, advice!
Pulled out everything, and the board worked fine. Put back one plug at the time and tested ..... and there it was - the X-Stop
Turned out to be the small end-switchboard with only a couple of resistors and caps. Replaced the board and everything works perfectly

[kb58]

@espenbor said in Duet 2 wifi - 3.3v failure:

@kb58 Thanks for your simple, yet brilliant, advice!
Pulled out everything, and the board worked fine. Put back one plug at the time and tested ..... and there it was - the X-Stop
Turned out to be the small end-switchboard with only a couple of resistors and caps. Replaced the board and everything works perfectly

Glad that I could help. So I'm half way there; I'm already considered simple, now I just have to work on the brilliant part...

[espenbor]

@dc42 Thank you for your quick response and your advice - it's really appreciated
As you se it turned out to be an end-switch board causing the problem .