What diode is this...

Thread Starter

VUK

Joined Oct 20, 2009
5
I am not an expert lol

I have been trying to find out what kind of diode this is.

SMD diode, silver ends, 2 bands = white and purple

CAR application off 2001 BMW m5 variable valve timing (vanos)

circuit board powers 4 solenoids

Schematic attached

Thanks! :D
 

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Last edited:

Wendy

Joined Mar 24, 2008
23,408
Don't know. Was is across the coil of the solernoid perhaps? If it was it is there to prevent the coils from making a high voltage spike, which can damage other electronics. If not, I have no idea.
 

ELECTRONERD

Joined May 26, 2009
1,147
It could be an inductor, perhaps 97μH (according to the bands). Diodes don't have the color bands on them and if it is a diode they usually just have one band to note the cathode. If you have a meter you can check if it's a diode or not. It should have a high resistance one direction and a lower resistance the other direction. If it doesn't, I can almost guarantee it's a inductor. Just to make sure, though, measure the inductance with a meter also.
 

Thread Starter

VUK

Joined Oct 20, 2009
5
Thanks for yours help

I measured with a multimeter that I have laying around, I got a reading ONLY 1 WAY and here is what I got.
 

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ELECTRONERD

Joined May 26, 2009
1,147
If you get 0.800 for the diode measurement then it definitely is a diode. But try measuring the resistance the opposite way and record the difference between the two.
 

Thread Starter

VUK

Joined Oct 20, 2009
5
If you get 0.800 for the diode measurement then it definitely is a diode. But try measuring the resistance the opposite way and record the difference between the two.

Thats the thing, I get no reading the opposite way. I tired all OHM functions on the meter and the dioide test, none work the opposite way.

:confused:
 

Thread Starter

VUK

Joined Oct 20, 2009
5
All I want to know is what kind of diode I need that will take care of the inductive flyback on the solenoids, any ideas?
 

CDRIVE

Joined Jul 1, 2008
2,219
Did the empty pads next to this Diode contain a fried one? I ask because there's no need to replace a Diode that tests good, as this one did.
 

ELECTRONERD

Joined May 26, 2009
1,147
Indeed, the diode looks fine. Did you intentionally disconnect the diode yourself as shown in the picture due to the measurements? Or, what it like that when you saw it? Maybe you could just solder it back on.
 
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