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Dead 820-00165-A. Orange light, no fan after U1900 replacement.

J

joshAU

Member
Hi all.
I have a dead 820-00165-A logic board, only an green then orange light, with everything including the battery disconnected.

When it arrived, with those symptoms, I found U1900 was getting to hot to touch.
Checking power to U1900,
PP3V42_G3H was correct at 3.40 volts
However, PP3V3_S5 was 5.96v, way too high, I assume?

Thinking that U1900 had an internal short, I replaced U1900 with one from a donor board.
The new U1900 is not getting hot, however PP3V3_S5 is still 5.96v.

I removed the new U1900, and with it removed, PP3V3_S5 is still 5.96v.

With or without U1900 connected, no part of the board seem to be getting hot at all.

So I guess the issue is with PP3V3_S5....
Any suggestions?
I cannot seem to work out what is generating PP3V3_S5?

other voltages (with replacement U1900 installed):
PPBUS_G3H 8.56v
PPDCIN_G3H 16.93v
PP3V42_G3H 3.41v
PPVRTC_G3H 6.01v ???
PP3V3_S5 5.96v
PP3V3_SUS 0.0v ?
 
2informaticos

2informaticos

Administrator
Staff member
PCH, even SMC, may be damaged with such high voltage on 3V3_S5.

Check feedback resistors R7560/61/63 and R/C network at pin 15 of U7501.
 
J

joshAU

Member
Hi 2infomaticos.
Thanks for you input and advice, once again.

R7560 4.2K Ohms (should be 23.2K Ohms)
Pin 1 5.96v
Pin 2 1.08v

R7561 3.9K Ohms (should be 10K Ohms)
Pin 1 1.08v
Pin 2 0v

R7563 10.2 Ohms (correct)
Pin 1 5.97v
Pin 2 5.97v

R/C network at pin 15 of U7501 shows 846 Ohms to ground.
It has 1.96 volts on pin 15.

Not sure those figures are what they should be...
 
2informaticos

2informaticos

Administrator
Staff member
I was expected ohm values for these resistors, removed from board.
Onboard reading do not reflect nominal value; only valid for R7563.
Also check their traces continuity.
 
J

joshAU

Member
oh, sorry 2informaticos.

Gee. they are tiny!

OK, Ohm values when removed:
R7560 23.2K
R7561 4.6K (less than 1/2 what it should be?)
R7563 10.5

Replace R7561?
 
J

joshAU

Member
OK I replaced R7561, and the PP3V3_S5 rail now reads 3.34v
Still only green then amber Magsafe light, and no fan spin though...

PPBUS_G3H 8.57v
PPDCIN_G3H 16.95v
PP3V42_G3H 3.41v
PPVRTC_G3H 3.33v
PP3V3_S5 3.33v

Which all look good, but:
PP3V3_SUS 0.0v ?
I'll have to look and see what createsPP3V3 I guess.
 
J

joshAU

Member
PM_DSW_PWRGD 3.34v
PCH_DSWVRMEN 3.22v
PM_BATLOW_L 3.34v
SMC_ADAPTER_EN 3.4v

RTC_RESET_L 3.31v
PCH_SRTCRST_L 3.30v
PCH_INTRUDER_L 3.03v
PCH_INTVRMEN 3.23v
 
J

joshAU

Member
OK.
PM_SLP_SUS_L 0.00v. :(
Oh well, at least I learnt a bit. :)

Thank you nonetheless for all your advice and suggestions 2 informaticos.
I appreciate it, once again.
 
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