820-3115 sound problem

[Kyle93]

Have a 820-3115 that had liquid damage. Replaced u7000 and all corroded components which achieved a fan spin. After ultrasonic cleaning everything works but I have no sound. I also have no chime when powering it up

have 4.25V on pin 24,25 of u6201 and 4.25V on pin 1 of u6200

Not sure what to check next.

 

[dukefawks]

4.25V on pin 1? That should be 3V3!

Voltage on pin 46, 9 and 3?

Audio device recognized in OSX?

 

[Kyle93]

pin 46 4.82V

pin 9 0v

pin 3 0v

internal speakers are recognized in OSX

 

[dukefawks]

Have you looked at the diagram and checked what pin 9 and 3 should be? What about pin 1? Are you measuring the correct pins, as all measurements seem weird to me. Chime will only come through the 4 pin case speaker, not the one on the board.

Can you adjust volume in OSX?

 

[Kyle93]

pin 9 1.42V pin 1 3.13V pin 3 1.42V pin 46 4.83V

All I have is schematic and cant find where it says what they are suppose to be but I measured a second time, yes measuring the correct pins.

yes can adjust volume in OSX

what to try next?

 

[dukefawks]

Then the audio chip is working so it is an analog problem. Does the headphone output work?

 

[Kyle93]

Headphone output also does not work. What to try next??

 

[Kyle93]

headphone output also does not work. what to try next?

 

[dukefawks]

Was there any corrosion around U6201? CS4206_VREF_ADC present?

 

[Kyle93]

no corrosion around u6201 and

CS4206_VREF_ADC ​

is present but only .5V and flucuating

 

[dukefawks]

If you are 100% sure the 4.5V is making it to the chip then at this point I would say the chip is dead.

 

[Kyle93]

getting 5.12V on pin 46, just finished replacing chip but no change. What to try next?

 

[dukefawks]

Pin 24/25 carry the 4.5V for the analog part of the chip. Is it still recognized under OSX and can change the volume after replacing it?

 

[Kyle93]

yes still recognized in osx and can adjust volume after replacing chip but still no sound.

Are you suggesting running a jumper from pin 24 to 25? Not sure what carry the 4.5V means.

 

[dukefawks]

Is there really 4.5V on pin 24/25?

 

[Kyle93]

Yes have exactly 4.51v on pin 24 and 25

 

[dukefawks]

There is just not much more to this. Check pin 46 again and CS4206_VREF_ADC and HPAMP_REF

 

[Kyle93]

I have 0V on CS4206_VREF_ADC Replaced it but still 0V and HPAMO_REF is 0.305V

 

[dukefawks]

Checked on a known good and it is also 0V.

I am out of ideas on this one now. Last ditch is to diode mode all pins of U6200 and compare to a working board.