Diode shorted on duet 3 expansion 3HC

Chrisac5348

Hello,

Recently I got a duet 3 expansion 3HC from my friend, when I tried to install it I found a little component (D34) was shorted between pin 1 and 6 with a multimeter. I also found it was a diode IC according to the schemtic. Maybe the board hit the static accidentally or any other related electrionic device in my room.
Can someone tell me the type of this component? I think I can buy it from my local store or Digikey.

Thanks in advance.

T3P3Tony

Hi Chris its a BAT40V-7 dual diode, is it only D34 that is shorted? Do you have a USB microscope to look to see if there is anything shorting between the pins?

Chrisac5348

@T3P3Tony Thanks for the type information, I will try to find the diode in my local store in my spare time. Yes I checked the all little diode blocks on the board then found this one and D33 was shorted for the moment. I am sorry I has no microscope on my room, maybe I can get one from my local store too.

I also found the 2 bigger blocks above the diode block maybe happened the issue, I tested them with a multimeter with buzzer mode, sometime it beeps and sometimes it doesn't beep. It seems that the 2 bigger blocks are the MOSFET with special package. Is it normal? Can you also tell me the type of these MOSFET?

dc42

It's unlikely that the diode has shorted, but not impossible I guess. It has a 150R resistor in parallel with it. Can you see any markings on the resistors? I have very occasionally seen a wrong value resistor fitted, although not on production boards; so I guess it's not totally impossible that a 0R resistor has been fitted instead.

How did you come to be measuring the diodes with a multimeter?

The dual mosfet part number is DMT6018LDR.

Chrisac5348

@dc42 Hello,
My friend told me he got the board from an American reseller, my friend has some experience on duet 2 series and duet 3 board, but I am a newer on duet products, I also don't know if the board will produce any negative influence for the printer or firmware. So finally I decided to send the board back to him. He also says he will try to contact the reseller for help in next days.
Thanks for your professional and nice help.

I just tested the pin 1 and 6 with the buzzer mode in multimeter (D33 and D34), it beeped in most time.
Sometimes the pin 3 and 4 also produced the beep at that time. (D33 only, I didn't tested the D34, I am sorry for that)
I also didn't see any strange marks on resistors around the diode and the MOSFET block, I remenbered the package of resistors around them are the pure black 0402. The board was sent back to my friend, so I cannot test the value of the resistors directly, maybe the resistor was 0R like your guess or any other a very low value.

dc42

Were you testing the diodes because that driver isn't working?

Chrisac5348

@dc42 No, the board was not installed completely, I just found a bit of dust around the drivers when I received the board then cleaned them with a little brush. In order to avoid the danger, I started to test some components around the diode and MOSFET blocks.