A1989 820-00850 no power

[hgoncalves]

Hi.

I have an A1989 820-00850 with no power.

It had CB300 and CB308 burnt, and so I've replaced them and UB300 (wich I realize after it was also a bit burnt in the pads) and now I've 3.3V on both.

DBZ500/503 were broken (maybe I've broke them removing the board) and so I've replace them.

PPBUS_G3H = 12.27V w/o battery

PP20V_USBC_TA_VBUS has 0V and 0.181 on diode reading.

PPDCIN_G3H only has 5.150V and 0.518 on diode reading.

FB200 also has 0V and seams ok.

Only have 5V on ampmeter.

Should I replace QB300?

Can you help?

 

[2informaticos]

Did you get 0V on mentioned points with charger connected to UB300's port?

 

[hgoncalves]

Yes

 

[2informaticos]

Check traces between JB500 and UB300.
Also check diode mode to ground on CC1/2 lines.

 

[hgoncalves]

UPC_TA_R_OSC was the culprit.

Replacing UB300 fixed it.

However, now, with the battery screw in place, the mac wont't power on. Without the screw attached, it powers on normally.

I have already tested it with anknown good battery and I have the same behavior.

Any idea?

 

[2informaticos]

Did you connect battery data cable in correct way?

 

[hgoncalves]

Yes, but even with the data cable disconnected (just screwed) the Mac won't power on

 

[2informaticos]

What is PPBUS_G3H voltage, w/ and w/o battery connected?

Check resistance over C7020/23 (ohm scale).
Be sure Q7065 isn't shorted D-S.