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A7 (3-Pin SMD) Identity?

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Trurl:
I've run into another mystery part on the HP server PSU(HSTNS-PD43) I'm analyzing, and would be grateful for any advice.

Device(A7) as it sits on the auxiliary(side) PCB.
*Measured Body Dimensions: 2.1(L) x 1.25(W)mm


Surrounding Schematic
Notes:
1. Two BAS40 diodes were used in the schematic for the time being to show the A7's inner diodes' orientations according the multimeter tested results -> "common anode"(pin-2) diode pair with pins 1 & 3 being cathodes.
2. Cap values are unknown so they are all marked by "default" to 1uF.


As shown in the schematic above, my tests of the A7 (in circuit) using a multimeter in diode setting(& Ohm setting) revealed the following;
(PL=Positive Lead, NL=Negative Lead)

1. PL on Pin2 / NL on Pin1 = 0.508V (Resistance 1.336k) - (Seems like a good diode)
2. PL on Pin2 / NL on Pin3 = 0.508V (Resistance 1.336k) - (Seems like a good diode)
3. Pin1 & Pin3 connected to GROUND.
 
But I noticed the following as well ...
4. NL on Pin2 / PL on Pin1 = 0.188V* (Resistance 515 Ohm) - (What the hell is goin' on here?)
5. NL on Pin2 / PL on Pin3 = 0.188V* (Resistance 515 Ohm) - (What the hell is goin' on here?)
*not showing as "OL" in the multimeter diode check(leads in reverse)  :-//

I've searched literally hundreds of  diode arrays and noticed that the following types are available.


The closest type from the image above would be the one in "Fig.33 - SERIES(Rev)" as pins 1 and 3 are connected to cathodes, but as the diodes are in series it would not explain the fact that the resistance between pins 1+2 and 2+3 are both 1.336k - same.

I'm wondering if this A7 device is not a diode array and perhaps something entirely different?

Any pointers would be appreciated. Cheers~

MLXXXp:
Probably a BAV99

https://www.mouser.ca/datasheet/2/308/BAV99-1118535.pdf

Trurl:
BAV99 (Nexperia) was actually the first device I suspected as its datasheet indicates;
https://assets.nexperia.com/documents/data-sheet/BAV99.pdf

"Marking code: A7* (* = placeholder for manufacturing site code)"
This explains the rotated "3" next to the "A7" in the top photo.

But my diode/resistance tests (in-circuit) with a multimeter(mentioned above) threw me off.

(Please do correct me if I'm wrong but) The multimeter diode tests suggests a "common anode"(on Pin2) diode pair with pins 1 & 3 being cathodes (as I've shown in my adjusted schematic above).

Could it be that testing in-circuit (and the ground connection of pins 1 and 3) is causing false readings on the multimeter?  :-//
 

MLXXXp:

--- Quote from: Trurl on May 04, 2024, 07:40:23 pm ---BAV99 (Nexperia) was actually the first device I suspected as its datasheet indicates;
https://assets.nexperia.com/documents/data-sheet/BAV99.pdf

"Marking code: A7* (* = placeholder for manufacturing site code)"
This explains the rotated "3" next to the "A7" in the top photo.

--- End quote ---

It's hard to believe that it's not a BAV99 when compared to a photo like the second one on this page (even though they call it a transistor):
https://www.alibaba.com/product-detail/THJ-Power-Transistor-BAV99-A7W-Smd_1600998341493.html


--- Quote from: Trurl on May 04, 2024, 07:40:23 pm ---Could it be that testing in-circuit (and the ground connection of pins 1 and 3) is causing false readings on the multimeter?

--- End quote ---

It's possible. It would be best if you could remove it and test it alone, assuming it's still good.

Trurl:
Thank you for your support!

I also do think it's a BAV99 and it was the initial part I had in my schematic for simulation. It resulted in oscillations of the voltages nearby. This made sense as one of the horizontal traces connects to the PIC's pin 27 "TCK"(Test Clock Input). The current schematic representation of the A7 on the other hand doesn't do anything of interest during simulation.

Fortunately, I've found an amusing YouTube video demonstrating how to make "Y" shaped 'SMD Desoldering Tips'(from thick gauge copper electrical wire) so I may give it a try (Note: at about 7:05 into the video, Morrisey's alter ego  ;D demonstrates desoldering a 3-pin SMD device:
"How I desolder and process SMD components ..."

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