Diode id request (New Member)

[Detectorist]

Hi everyone,
Thank you for allowing me to join your group. I am having difficulty in identifying a surface mount diode. I hope someone can help. All it says is 933 TZ Picture included.

Thank you

 

[(*steve*)]

One option is a 1PMT5933B. This is a 22V 2.5W zener diode. the case for this is DO-216AA, and I'm not sure that looks like that.

What makes you think it is at fault?

Is it shorted?

Which end of the diode is more positive? (and what is the voltage drop across it)

 

[Detectorist]

Hi Steve, Thank you for your reply. Much appreciated. In circuit i am getting a reading of 32meg ohms and the other way i am getting 17meg so open circuit not short. With my smart meter i am getting no reading on the diode test.

 

[(*steve*)]

OK, one of the alternatives is that it is a TVS diode, and this would explain what you see.

Do you know what voltage exists across this diode with the unit powered on?

Diodes generally fail short circuit rather than open, so I'd tend not to suspect this unless you have a good reason to.

It might be useful to show us more of the board, as that may give some clues as to what this component does/is.

 

[Detectorist]

Hi Steve, TVS diodes did show up in my searches but was not sure. No sorry i can't power it up as it is a daughter board and you can't get to the board when the unit is assembled. I will get a picture sorted. Thank you again.

 

[(*steve*)]

It would also be useful if you can determine what the power rails are and where this diode sits in relation to them. (e.g. is it in series with one of them, across them, or tied at one end to one of them, or something else)