[HELP] 820-3437 SEMI DEAD!

[phantomEVO]

i! i don't know the history of ths motherboard...i need help.

PP3V42_G3H present 3,42v

i have green light as soon as i connect power supply, that become orange

diode mode on ppbus_g3h is ok
pp5v / 3v _s5 present

I'm pretty sure that smc was changed before trying to fix the problem

spirom_use_mlb and pm_pwrbtn are 0v also pm_bat_low_l.

SMC_BATLOW_L still low in bypass mode
3V3_SUS not present

AT THE MOMENT, I'M USING BY-3200S

[mon2]

SMC_BATLOW_L should not be low. If low, logic board does not like your power adapter. Test with the official one for this box.

[phantomEVO]

tried with another smc

tried with original magsafe 2 60w...still the same

[mon2]

What is the voltage to ground of PPBUS_G3H? Is it stable or cycling?

pp5v / 3v _s5 present

Stable or cycling?

[phantomEVO]

stable

[mon2]

What is the voltage to ground of PPBUS_G3H?

[phantomEVO]

after changing smc, i have ppbus_g3h at 8,58...SMC_BATLOW_L stiill 0v

[mon2]

If you have a stable ppbus_G3H = 8v58 then the SMC is working since the voltage on ppbus_G3H has been boosted.

Reference:

https://logi.wiki/index.php/PPBus_G3H

In my schematic, there is no SMC_BATLOW_L but there is a PM_BATLOW_L.

For PM_BATLOW_L, confirm the presence of the pull-up resistor. Confirm the high side voltage of the resistor @ R1410.

[phantomEVO]

thank you8 for your reply! what do you mean with high side

[mon2]

Test the voltage on resistor R1410 but the pin that mates with PP3V3_S5. There must be a stable voltage of 3v3 here for this signal to be parked to the logic '1' state. Easier to test both sides of R1410 for a voltage.

[phantomEVO]

0v on both sides

[phantomEVO]

i've made a big mistake!!! pp3v3_s5 is not present at all!!! pp3v3_s5 amref smc is present! i've made a big mistake!!! pp3v3_s5 is not present at all!!! pp3v3_s5 amref smc is present!

[phantomEVO]

By U7501 i have P3V3S5_EN_R- 3.42v; SMC_PM_G2_EN - 3.42v; PP3V3_S5_REG_R- 0v; P3V3_S5_REG_L - 0v; pin24;25;27 on U7501 also 0v

[phantomEVO]

changed u7501, still the same

[phantomEVO]

u7501:
VREG3: 3.3 volts
VREG5: 5 volts
VREF: (I'm assuming pin 13) 2v
EN S4RS3: 0
EN2 3v3S5_EN_R: 3,42 volts
SMC_PM_G2_EN 1v

[mon2]

What is the voltage to ground on each side of L5001?

Remove all power. Measure the resistance to ground of PP3V3_S5_REG_R rail @ L7560. Something is wrong with this rail since the enable for the power rail is OK and this rail should enable.

[phantomEVO]

3,42 on both sides of l5001

0,35k on l7560

[phantomEVO]

SOLVEEEED! it was a broken trace on P3V3_S5_CSN2

[mon2]

0,35k on l7560

350 ohms to ground resistance for L7560 is too low.

reference:

post #6

https://www.badcaps.net/forum/troubl...ssing-pp3v3_s5


Attempt to measure the voltage on this same rail @ L7560 but on immediate power up. Also, is P3V3S5_EN_R always enabled and is stable?


Flowchart suitable for this model:

https://logi.wiki/index.php/G3_to_S3..._and_Broadwell

[mon2]

Just saw your post - excellent!!

So the current loop circuit was broken and this half of the regulator was powering OFF because it felt the voltage was being created but tanked to 0v (due to the missing loop voltage) = assumed the load was too much so power it off.