[Solved] RX 460 Blown Fuse

iRevert

Limp Gawd
Joined
Jun 7, 2012
Messages
487
Just out of curiosity what hot air station have you been for this project?

I've been trying to talk myself into picking one up.
 

kodaf56

n00b
Joined
Mar 3, 2020
Messages
43
From what I found, 81161 is decreasing resistance of this resistor (without it resistance is 10K, just like after desoldering this resistor from the board). But on this phase even with a 81161 from the other phase it still has that 8.7K resistance.
Once again it was just one pin on 81161 that caused this. It wasn't soldered properly, because I really should use solder in paste or at least clean the old solder and not just reflow the solder that was there. I'm still learning hot air soldering. But anyway after making sure that every pin is soldered correctly that suspicious resistor has now 8K - which is I guess good. At least close enough to 7.8K-7.7K of other resistors.

So let's summarize what we learned now. It's not only a mosfet, not NCP81161 (that time gate to ground voltage was low I think I just killed the 81161 by running into the mosfet failure few times), nor the bootstrap capacitor. Also on my last try to run the card after fixing that resistor issue I once again checked the gate to ground voltage and it was the same as on the other phases, but it was hitting 13v more frequently. Which I think is normal, because this phase seems to be the main phase that is always used the most. Anyway card died when I was redoing my measurements - problem is still there.

In my free time I checked NCP81022 - VRM controller. And one pin made me suspicious. It's called CSREF and I have there like 2 ohms to ground. Pin description is in the image below. Should it be like that?

csref.png
 
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