Vogelek23
Member
Hello,
Currently working on the one from topic title with no audio device issue (originally won't boot).
First of all, tried known working OS - no luck. Checked MLB under microscope and found that U6400 looks strange - measured it and power bus was shorted to ground so I have removed U6400. I spotted underneath that someone has attempted to make some "unsuccessful" work here, found ripped off C5 pad (NC) and a bit corroded D5 pad (AUD_SPKRAMP_INT_L). Removed the signs of corrosion and tested MLB - still no audio device present. Replaced U6200 and R6228 (this resistor looked like overheated and had only 20 Ohms despite it is 33 Ohms). Neext I found AUD_SPKRAMP_RESET_L and HDA_RST_L to be High, power rails for U6200 correct. R6203 - 0V and no oscillograms on both pins, value 33 Ohm, 540mV on diode test (red probe to resistor, black to GND), shouldn't be some data visible over here?
My main question: should U6400 be assembled to get the audio device visible in the OS? If not, what is the next step in diagnosing of such problem?
Currently working on the one from topic title with no audio device issue (originally won't boot).
First of all, tried known working OS - no luck. Checked MLB under microscope and found that U6400 looks strange - measured it and power bus was shorted to ground so I have removed U6400. I spotted underneath that someone has attempted to make some "unsuccessful" work here, found ripped off C5 pad (NC) and a bit corroded D5 pad (AUD_SPKRAMP_INT_L). Removed the signs of corrosion and tested MLB - still no audio device present. Replaced U6200 and R6228 (this resistor looked like overheated and had only 20 Ohms despite it is 33 Ohms). Neext I found AUD_SPKRAMP_RESET_L and HDA_RST_L to be High, power rails for U6200 correct. R6203 - 0V and no oscillograms on both pins, value 33 Ohm, 540mV on diode test (red probe to resistor, black to GND), shouldn't be some data visible over here?
My main question: should U6400 be assembled to get the audio device visible in the OS? If not, what is the next step in diagnosing of such problem?
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