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AMD RX 480 BLOWER EDITION "VRM 2 phasses problem and +VDDCI"
https://vlab.su/viewtopic.php?f=48&t=138560
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PT-AH [ 24 ноя 2023, 17:47 ]
Заголовок сообщения:  AMD RX 480 BLOWER EDITION "VRM 2 phasses problem and +VDDCI"

I would like to ask for help, but I have an error in these areas that are marked in red in the image.
2 phases with lack of PWM when measuring with an oscilloscope.
At +vddci I only have 0.018v, sometimes at start-up I have a small boost but then it cuts off.
What can I do?

Image: https://ibb.co/Lk4pfhD

Изображение

ruzalit [ 24 ноя 2023, 22:07 ]
Заголовок сообщения:  Re: AMD RX 480 BLOWER EDITION "VRM 2 phasses problem and +VDDCI"

2 фазы без нагрузки на видеочип могут не работать. Смотрите в схеме условия для старта шим в цепи питания +vddci , напряжение для питания шим, сигнал для включения шим. Может в его обвязке керамический конденсатор неисправен и резистор низкоомный увеличил свое сопротивление.

PT-AH [ 25 ноя 2023, 15:55 ]
Заголовок сообщения:  Re: AMD RX 480 BLOWER EDITION "VRM 2 phasses problem and +VDDCI"  [РЕШЕНО]

I'll look for that capacitor.
The graphics had oxidation, I cleaned it and replaced some components.
It turns on the second gpu but doesn't show video and installing the driver freezes the pc almost at the end of the installation.
thanks

Posted after 4 hours 8 minutes 19 seconds:
I had a capacitor that was measured at 1 ohm but in the multimeter it was 1uf. However, I replaced it and it was starting up but with a lot of noise to check on the oscilloscope.
However, I replaced the GS7256 with APW8722A and it seems to be working.
I finally understood what you said to me:
The last 2 phases of the VRM only do PWM when effort is required and this +VDDCI too.
I will test the gpu

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