Duet3 6HC main board (ver0.6) is in short circuit state.
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Team,
Please, help me.Duet3 6HC board is in short circuit state.
A short occurred during IO port operation by mistake.
I think 3.3V or 5V is shorted to GND. (not sure)
After that, the power is not turned on. It is not a problem of fuse.
The external power supply(24V) detects short circuit and shuts down.
The resistance of the board's 24V Vin is around 190 ohms.I want to fix this board.
Which part should I check? -
@psyblue said in Duet3 6HC main board (ver0.6) is in short circuit state.:
Which part should I check?
U10 is responsible for 5V
U4 is responsible for 3.3V -
This post is deleted! -
@bearer
First of all, thank you for your reply.
yes, of course
But the resistance of the board's 24V Vin is around 190 ohms.
Even in this case, Can U10, U18 (not U4) are suspected?Any way, I'll take the two parts off and test them right away.
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@psyblue said in Duet3 6HC main board (ver0.6) is in short circuit state.:
Any way, I'll take the two parts off and test them right away.
Hold off on that please; take the one that get warm when you apply power to the board? Or do some proper troubleshooting
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@bearer
Team,
As a result, U10(24V to 5V buck controler) was dead.
First of all, I checked out U10 problem by removing D3 and connecting an external 5V power supply.
Despite I have a hot blower for SMD rework, removing the U10 was very difficult because of the pad-heat-dispersion.
I couldn't remove it, just cut off the pins.
Fortunately, it is possible to use an external 5V power supply, so the board can be used.In my experience, source-drain short of FET is rarely happen, but happens.
I hope the board's short symptoms and repairs will be shared.Good luck!
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@psyblue, thanks for sharing that. I did some 5V short-circuit tests on a V0.6 Duet 3 and found that L4 overheated and started smoking fairly quickly. I did this several times, but for no more than about a minute at any time. No components failed.
The problem was that the actual internal current limit of U10 turned out to be much higher than its rated output current. As a result of these tests, we added a 3A PTC fuse feeding 5V_EXT on the latest Duet 3 revision, and increased the rating of L4.
I am still surprised that U10 failed on your board, and I suspect that the flyback diode may have failed first.
