820-4924 No wifi detected

Sykulski

Member
I've got this one that isn't detecting wifi most of the time. Eventually on some boot-ups it is working. Something like 1 of 50 times it is discovering the wlan card and working. But after reboot and for the next many many reboots says "no wifi hardware installed"

No liquid and no corrosion to be seen anywhere. I have tried:

- checked for software issue, it's not as it does the same in both known good os and is also not detected in the boot manager
- known good wlan card
- known good rio board
- known good rio flex cable
- power 3 and 5 V are going to rio power connector
- J9501 looks beautiful
- L9501 looks and measures ok

What's the next thing to check?

Thanks
 

Sykulski

Member
Also audio isn't working on this machine. I just realized now (customer didn't mention it). Could it be related? I just had a couple of start ups where wifi came to life but sound wasn't working. Says "no output devices" in audio output settings. Also no chime when turning it on. Now wifi is back to not working and no sound also.
 

Sykulski

Member
Yeah. It was one of the first things I even checked

J9500:
p3: 3.339V
p4: 5.151V

J9501:
p40/42: 1.505V
 

dukefawks

Administrator
So when wifi is working the sound is still dead? Maybe a power sequence issue. Measure if the 1V5 drops off when machine is put in sleep.
 

Sykulski

Member
Yes.

Wifi sometimes working.
Sound never working.

I'll check 1.5V in sleep later and get back with the result.
 

Sykulski

Member
PP1V5_S0 is still present after putting the computer to sleep. Not changing at all. Rock steady 1.505V
 

Sykulski

Member
Yes. Wakes ok from sleep but wifi and sound still not detected. In the rare occasions where wifi is working then it is still working after wake from sleep but still without sound.

Wifi rarely work in boot menu and I can press the hard drive icon and it boots up with wifi working. But mostly no wifi in boot menu.

Chime never comes also after PRAM reset there is no chime.
 

dukefawks

Administrator
Have you looked around the codec and checked voltages? Is an audio device recognized in OSX? It is very likely these issues have a common cause.
 

Sykulski

Member
Yes i checked 3V3 and 4V5. Both going into codec. I was also thinking the issues are related to same culprit but i couldn't manage to find out what is causing it :-(

No audio devices are recognised
 

dukefawks

Administrator
I can only think of cracked pads under the CPU. Measure PCI lines to the Airport card on diode mode. Without flat cable attached measure on pin 2 of C9532/33 and pins 1,3,7,9 of J9510.

Any history on this thing, was it dropped or slammed on?
 

Sykulski

Member
Diode mode with no flat cable:

C9532/p2: 0.348
C9533/p2: 0.348

J9510/p1: 0.255
J9510/p3: 0.255
J9510/p7: 0.348
J9510/p9: 0.348

Was never dropped, slammed or liquid spilled. WIFI just one day did not work (and also the sound apparently but customer did not even discover the sound-problem)
 
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