820-00281 A1707 No sound from speakers after liquid spill repair.

[thetech]

820-00281 board was liquid damaged. Corrosion around U7650 and U6400. Would not power on. Replaced a few damaged components around U7650 fixed the power problem. Now no audio through speakers. Audio through headphone jack works. U6400 had corrosion underneath it. Replaced U6400, problem persists. Can change volume, switches from headphones to internal speakers when headphones unplugged.

I have traced everything I can think of following schematic and all components around U6400 seem fine.

Don't know where to go from here, any help is appreciated!

 

[2informaticos]

Check power rails for U6400 and U6500/50.
Also check AUD_SPKRAMP_RESET_L level; must be high.

 

[thetech]

Power rails seem fine, PP1V8_S0 is 1.8v and PPBUS is 12.59 at all 4 amp chips.

AUD_SPKRAMP_RESET_L is 1.8v.

One thing I noticed is. VREF_AMP_WL is 2v while booting and drops to 0 when booted up. Can't find datasheet on MAX98706, any idea what VREF_AMP_WL, VREF_AMP_TL etc do?

I'm really lost on this one

 

[2informaticos]

Remove U6400 and check for sound on the other channels.

 

[thetech]

Removed U6400, still nothing on speakers.

 

[2informaticos]

Try known good speakers...

 

[thetech]

Don't have speakers for this. I did test them and all 4 are 4 ohms. Also tried just the right speaker and just the left. I feel like I'm missing something stupidly obvious.

 

[2informaticos]

I remember someone else thread where tried new non-working chinese speakers.
That's the reason I asked to test with known good working speakers.

 

[thetech]

Customer didn't want to wait any more, took it as is. Guess we'll never know what the problem was.