what diode is this ?

[nashkato]

is there anyone familiar with SMD codes who could tell me if this is just a "regular" diode ?

 

[CJ]

Measure the fwd drop


.5 to .7 is normal

.4 to 5 is abnormal (shockme or ge)

 

[Khron]

SMB package?



https://www.s-manuals.com/smd/mt
SMBJ43A or 1SMB43AT3 possibly?

 

[nashkato]

most likely smb , yes .
zener protection diode could fit
it measures a little over .5

 

[nashkato]

i need to come back to this.
this diode is part of lm2586 regulator powersupply.
its a metric halo uln2 .
symetrical voltage for analog path
and 48v are each regulated via a small transformer with the lm2586.
i already ditched 48v but now +/- supply went dead , too.
can anyone more familiar with switch mode supplies tell me what this diode‘s supposed to be before i waste an expensive part ?
it goes from pin 5 of the lm2586 to ground.

 

[Khron]

What're the odds the feedback is taken from the 48v rail? If you "ditched" that... No surprise if the rest of the supplies are down as well.

https://z3d9b7u8.stackpathcdn.com/pdfhtml/0441/61842/page-000001.png
That example schematic on the first page of the datasheet could easily be the +/- supplies for the analog circuitry; a third secondary winding would be providing the phantom power voltage. The value of that is a bit more critical than the absolute voltages powering opamps.

 

[zamproject]

Have a look at LM2586 datasheet (TI version), it show a schottky from pin5 to ground at page 28 fig 48
If that help...

 

[nashkato]

What're the odds the feedback is taken from the 48v rail? If you "ditched" that... No surprise if the rest of the supplies are down as well.

it‘s two separate circuits , each with its own regulator and its own transformer.
only thing in common is the external supply voltage of 24V

Have a look at LM2586 datasheet (TI version), it show a schottky from pin5 to ground at page 28 fig 48
If that help...

thanks , i saw that
but there‘s also the transient voltage suppressor diode that got me confused .