3.3V voltage regulator damaged / DUET2 WIFI

[gcorthey]

DUET2 WiFi is not responding, 3.3V LED is OFF, so I followed instructions here and replaced the 3.3V voltage regulator for a new one. However the problem persisted. I removed the regulator and measured it outside and it got damaged, I measure 5.0V at V_out. Could it be a short between 3.3V and ground? What do you suggest checking? Please, I need some help !

[alankilian]

@gcorthey To find out if you have a short between 3.3 Volts and ground, disconnect EVERYTHING from the Duet and then measure the resistance between a 3.3 Volt pin and a ground pin.

Then use Ohm's law to figure out how much current that resistance would draw at 3.3 Volts.

I'm not sure, but I'd say anything more than 0.5 Amps is too much. I would expect more like 0.1 Amps would be typical.

Take a shot and let us know what your measurements are.

[gcorthey]

@alankilian thanks for your reply. I checked and this is a short between 3.3 and GND (0 resistivity !). I forgot to mention that 1A fuse was blown.

Would it be possible to recover this board? What else can I check?

[droftarts]

@gcorthey Post a good, focused, high resolution picture of your board, and we'll see if there's any component that is obviously blown.

Ian

[gcorthey]

@droftarts thanks. I upladed a photo in 2 parts here.

[droftarts]

@gcorthey looks like there might be a burn hole in the 5V regulator (U3) as well:

Ian

[gcorthey]

@droftarts I send you a bigger picture with microscope. Could you show me where you see the burn hole?

[Phaedrux]

From that photo you can see that it's a dot from the stencil on the chip. It looks ok.