820-00840 5v not turning on

Yoel Ren

Member
i got 5v, on ppdcin, drawing 0.17 amp,
ppbus and pp3v3_g3h cycling, found that pp3v3 is shorted to ground,
I saw a tiny hole on cd3215, so I remove the chip but pp3v3 still shorted, is my only way to inject voltage ? if yes can I go over 3,3v ? thanks.
 

2informaticos

Administrator
Staff member
Which is the exact ohm value of that short?
Do not exceed 3.8V if you inject voltage.

Probably the other CD3215 chip is bad too.
 

Yoel Ren

Member
14,4 ohm.., should I inject ? im a bit more careful because Im not too familiar with newer board thanks.., ordering cd3215 too
 

2informaticos

Administrator
Staff member
You can try, but current could be to low to heat something.
May need to wait few minutes and use alcohol method to detect if something heats a little bit more than other thing.
Lucky scenario if some chip enters in avalanche process and gets really hot...
 

2informaticos

Administrator
Staff member
"Probably the other CD3215 chip is bad too."
Remove it and check again diode mode value to ground.

On the other side, next to U2800 is the redriver chip; many times dead with small hole on it.
Be aware, it is not present on schematic/boardview...
 

Yoel Ren

Member
removing both cd3215 doesnt remove the short, still 30ohm resistance to ground..
u2800 looks fine, I tried removing u7000 to see if the short is gone, but still the same, injeting 3.8v make the board at the right side near usb c side just a a very bit bit of warm
 

TCRScircuit

Super Moderator
Staff member
You replaced the redriver and both CD3215s correct?

What does it pull without the battery plugged in? Both voltage and amps?
 

Yoel Ren

Member
Yeah i replaced redriver chip and both cd3215c00 , without battery it pull about 0.05Amp
, ppbus 0.5v, but not shorted to ground, without battery, and i only get 5v on dcin, does this mean my cd3215 is defected ? but the macbook still can be turn on, so..
 
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Yoel Ren

Member
i notice when running on battery, the cpu is extremely hot, and I checked ppbus_g3h_cpu is shorted, can I inject to this line or should I remove caps 1 by1 ?
and does this ppbus_g3h_cpu has anything to do with me not getting 20v ?
 
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TCRScircuit

Super Moderator
Staff member
OK, let's slow down here.

You said it worked with a battery, and now you say PPBUS G3H is shorted.

Does it turn on?

If PPBUS is shorted and the CPU is getting hot then this is done for.

If it turns on and you get image you are getting trolled by your meter.
 

2informaticos

Administrator
Staff member
Please post accurate information.

Do you mean turns on with battery alone and battery plus charger, but not on charger alone?
Also turning on means working (image, USB activity), or just fan spins?

BTW, do not check diode mode on PPBUS_G3H with battery, or charger, connected.
Allow 10-15s for this kind of test, after ANY power is removed.
 

Yoel Ren

Member
It Turns on means i get an image, the trackpad click, and I can login and use it for youtube etc.. but when i touch the heatsink its extremely hot.., i thought something must he shorted.., any chance that ppbus_cpu is shorted without affecting ppbus_g3h?

If only by charger, macbook cannot turn on, but with battery, It can turn on.., I check the ppbus is shorted or not when its not connected to batt / anything
 

TCRScircuit

Super Moderator
Staff member
It's normal. Of course it's going to get hot. Nothing is shorted.

If you still have 5v when plugged in, plug in the USB C the other direction. Does it work? Something is likely messed up with the CD3215 replacement or the redriver replacement.
 

2informaticos

Administrator
Staff member
If board works, you cannot have any short!!!

Let the battery out and start repair process on charger only.
Post R7020, L6995 and F7000 voltages.
Do you get only 5V at USB-C meter, or it switches to 20V?
 

SMMRepair

Member
Guys, he's obviously checking for a short IMMEDIATELY after powering off the board. OP, let the board discharge for 2-3 minutes and then check for short on ppbus. It will show a short if you check it immediately after removing power. If it shows a short, then check again after 30 seconds. Keep checking and I guarantee the "short" will go away.
 
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