D19 on MS3 board

[onig]

I am assembling my board, MS3 V3.0 with the Xpander.
On D19 I have a reading of .670 one way and .604 the other way when testing.
This is the only diode that is reading both ways.
I am going to say that this diode is burnt/damaged - Correct???????

[onig]

So I took out the so called bad D19 diode from the board and the reading was normal after testing it.
I tested the new diode of the same value and it tested good, reading one way but not the other.
I installed the diode into the board and tested it before soldering it and I get these readings both ways.
It is a zener diode, what ever that is.
Could this be why I am getting a reading both ways with my meter because it is a zener diode?

[DaveEFI]

Any reading you get with a device in circuit can depend on the other things connected to it.

[onig]

Yes, I was thinking the same thing.
I know nothing about semi-conductors.
As the parts are assembled I am hoping to test to make sure that I didn't damage any of them with the heat.
I will continue to assemble my board and test what ever I can.

[DaveEFI]

The important thing when you first power it up is to use a PS with a maximum current of about 1 amp. If using a larger one, like a car battery, fit a 1 amp fuse. So that if there is a short or whatever, you don't burn the PCB. I'd also power up the bare PCB first, without the daughter card etc plugged in, and check the various voltages are correct.

[onig]

Do you mean to first test the board without the Xpander plugged in when using the power supply and JimStim?
Good advice.