Failure

makerdise

Hello,

one of our customers who purchased a Duet Wifi 1.04 (in november 2018) did contact us cause his board doesn't work anymore. We asked him how this happened and if it ever worked. Here are the facts he wrote us:

Did work normal after delivery, so no case of damage through shipping
Used as a replacement for the Anet A8 board
Started a print, after one hour the print was interrupted by itself...
From this point no connection to the board is possible
The 3.3V circuit seems to be broken!
We asked the customer to measure if there's a short circuit between the heaters cartridge and the thermistor, but he didn't measure it
I did talked to Roland, he redirect me to the forum

Here's an image with only USB connected...

alt text

Our first intention was that some faulty cable did create a short in the 3.3V circuit. We all know about the quality of the A8, especially the low quality electronics.

Should we replace the board @T3P3Tony?

Greetings
Jan

makerdise

Update: The customer informed us a few minutes ago, that he's working with the original Anet A8 board again, without having failures. He also did measure all cables and detected no cable breaks.

dc42

I am happy to approve a warranty replacement.

makerdise

@dc42 - thanks! What do you think did happen?

dc42

@makerdise said in Failure:

@dc42 - thanks! What do you think did happen?

Either a component on the Duet has failed, or there has been a short between either +3.3V or +5V and a fan, heater or motor circuit. On an A8 I think that's quite unlikely, so I'm prepared to give the customer the benefit of the doubt without further investigation. Also I can't see any damage to the 3.3V regulator, which is typically visible when there has been that kind of short.

Shorts between +3.3V and ground don't normally cause any damage, because the regulator is designed to cope with those.

makerdise

@dc42 - Hello again

We replaced the board and finaly received the broken with a clear blister mark on U2 I think I know what did happen.

BR
Jan

dc42

U2 is the 3.3V regulator. The only known reason why it fails is that either the +3.3v rail or the +5v rail was shorted to a high voltage.

Wiring endstop switches incorrectly will short +3.3v to ground, but that doesn't normally cause the regulator to fail because its short circuit protection kicks in.