ASUS K570U (X570UD) low resistance after EC change

[someonenotyou]

Hi.

I have a ASUS K570U (board model X570UD) which had a bad EC (IT8995E-128 DXS). I ordered 2 new EC chips on AliExpress.

After I changed first chip and powered it on, nothing happened, and I found out that there was a short on +3VA_EC. I desoldered the EC and checked +3VA_EC on board, it had kOhms (cant remember exact number). Then I checked the GND and +3VA_EC on the EC chip itself and they were shorted.

Now, I soldered on the second chip and made measurements on all the pins (I have not powered the board with the new chip yet). And I found these pins to be low on resistance:

+3VA_EC - 33ohm
+3VPLL - 33ohm
+3VACC - 33ohm
Pin 43 (KSO7) - 33ohm
Pin 41 (KSO5) - 10ohm
Pin 33 (OP_SD#) - 3.8ohm

Does this mean the EC chips were bad, or there are other issues on board? Or these measurements are how they are supposed to be?

Link to boardview - https://www.badcaps.net/forum/troubl...90#post1810890

Thank you.

[mon2]

To me, as long as the chip was soldered properly, the chip is the wrong type / pinout. You should not have such a low resistance to ground immediately upon soldering. Were the chips sourced from a trusted vendor? Perhaps a remarked chip? If repeating this process, do not power on after soldering. Test the same pins for the resistance before powering up.

[someonenotyou]

To me, as long as the chip was soldered properly, the chip is the wrong type / pinout. You should not have such a low resistance to ground immediately upon soldering. Were the chips sourced from a trusted vendor? Perhaps a remarked chip? If repeating this process, do not power on after soldering. Test the same pins for the resistance before powering up.

Thank you for the reply.
It was soldered properly, and I checked all the pins under microscope if they were solid and no bridges between pins.
I just desoldered the EC chip to check resistances without it (maybe some broken/shorted traces between layers), but everything seems fine.

+3VA_EC - 33ohm > 135kOhm
+3VPLL - 33ohm > 139kOhm
+3VACC - 33ohm > 142kOhm
Pin 43 (KSO7) - 33ohm > OL
Pin 41 (KSO5) - 10ohm > OL
Pin 33 (OP_SD#) - 3.8ohm > OL

This would indicate wrong/defective chips, correct?
I do not know how trusted the seller was, I was just making sure it was IT8995E-128 DXS, as there were 4 variants - CXA CXS DXA DXS.

Should I avoid ordering EC`s from AliExpress?
Any suggestion where would be the best place to buy in (or shipping to) Europe?

Thank you.

[mon2]

Can you confirm that the replacement EC was mounted with the proper pin #1 orientation?

The resistance without the chip looks good, otherwise, something is wrong. Wait on comments from others for guidance on EC vendors. Not sure but doubt that the suffix variations would cause such drastic low resistance readings. Not everyone on Aliexpress is evil. Just need to find a vendor with high ratings and experience with perhaps the logic board you are servicing. Definitely need to test with another vendor to confirm if the sourcing is the issue here (ie. remarked chips?).

[someonenotyou]

This should be pin 1, then it was soldered correctly.

[someonenotyou]

I made some measurements on the EC chip unsoldered.
All the low resistance is coming from the chip itself.

That would mean the chips are low quality, because the resistances are too low, correct?

[mon2]

I would agree. Does not sound correct to have such low measurements on a working chip.