[SOLVED][820-3115] PPBUS_G3H trolling me, System not going further then S5 & voltage drops

[smiba]

[SOLVED][820-3115] PPBUS_G3H trolling me, System not going further then S5 & voltage drops

Customer came in with this laptop which suppositiously have been peed on "a little" (Eww!!!!), the customer already cleaned the motherboard them selfs with pure alcohol in a hope to fix it them selfs but no luck.

The motherboard itself looks alright, it has some heavily green(?) corroded parts. But most parts are untouched or looking almost like new, the only few corroded parts are related to thunderbolt. I even tried to replace some of the really corroded parts but obviously that didn't fix anything.

When powering the system on PPBUS_G3H drops from 13.3V quickly to ~3.4V and then slowly starts dropping until it hits 1.6-1.9V and goes back to 13.3V. At this moment trying to press the power button (or shorting the power_on test point) will drop the voltage again to less then 3.4V. This is exactly the same result you'd get by disconnecting the charger.


All the S5 power lines are up, it does not have any S3 power lines and if I remember correctly only 1 of the two S4 power lines.

The system has no fan spin (and obviously no chime). The charger has a green light, but only when you connected it before PPBUS_G3H started dropping, if this happened you'd need to wait 10-30 seconds before you can connect it with a green light. Connecting the power on a cold start it will always give a green light

My guess is that the charger's protection circuit is working and disables the power output because something is shorting. I have no idea what though, I've tested some of the major power lines and there is no short to ground.

Any idea where to look?

These were the power lines by the way in a state where the voltage on PPBUS_G3H isn't dropping:

PPBUS_G3H: 13.3v
PPBUS_S5_HS_COMPUTING_ISNS: 13.3v
PPBUS_S5_HS_OTHER_ISNS: 13.3v
PP3V42_G3H: 3.48v
PPVRTC_G3H 3.31v
PP5V_S5: 4.97v
PP5V_SUS: 0v
PP5V_S3: 0v
PP3V3_S5: 3.31v

 

[smiba]

PPVCORE_S0_CPU: 2Ohm to ground
PPVCORE_S0_AXG: 1.6Ohm to ground

Normal or dead CPU?

EDIT: Tested known working motherboard and it came back with the same values, alright. No short to ground, time to go back to the multimeter

Results off all the power lines I measured because why not, they're all in in diode mode

PP5V_SUS: >2000 (OK)
PP5V_S3: >900 (OK)
PP5V_S0: 1010 (OK)
PP3V3_SUS: 463 (OK)
PP3V3_S4 >1000 (OK)
PP3V3_S3: ~950 (OK)
PP3V3_S0: 491 (OK)
PP1V8_S0: 285 (OK)
PP1V5_S3: 253 (OK)
PP1V5_S0: 729 (OK)
PPVTTDDRS3: 588 (OK)
PP0V75_S0_DDRVTT: 191 (OK)
PPVCCSA_S0_CPU: 5 (OK?)
PPVP_FW >2000 (OK)
PP3V3_FW_FWPHY: 598 (OK)
PP1V05_S0_PCJ_VCCADPLL: 250 (OK)
PPVCORE_S0_CPU: 0 (OK, 2Ohm)
PPVCORE_S0_AXG: 0 (OK, 1.6Ohm)
PP1V5_S3_CPU_VCCDQ: 145 (OK)

 

[dukefawks]

Issues in 6259 circuit. Check R7021/22/51/52 and traces. Does the system work when a charged battery is connected?
Best to use a fake Chinese charger for trouble shooting this one as it won't shut down.

 

[smiba]

R7051 and R7013 missing... I hate working on devices that someone has touched before

I'll replace R7013 from a donor board, is it safe to just short the two pins of R7051 with solder since the resistor is set for 0Ohms anyways? If not I'll just replace it as well

EDIT: Ah whatever, I'll just move R7051 over as well, maybe that will make this motherboard be nice to me haha

EDIT2: Using a 820-2936 as donor board there is no R7013 on all of them, even though its in the schematic. (Pads are clean, no solder) Is this a case where they forgot to note it as NOSTUFF?

 

[smiba]

Alright just placing R7051 on there seems to have made it less angry, PPBUS is 12.8V and it doesn't seem to be dropping / shorting the charger so definitely something changed. Its still not booting however.

I'll diagnose whats going wrong with those power lines tomorrow, thanks for your help so far

 

[jadao]

Hi Smiba I confirm R7013 should be marked "nostuff" at least on 820-2850 820-2936 and 820-3115 schematics.

I remember having a nightmare water damage 820-2850 where I had to replace all the ISL6259 region including resistors. Since I was following the schematic I soldered R7013...

It had the same issue you describe, it was droping all the way from 12,6 to near 0 and back again to 12.6v

I did everything, replaced ISL 4 times, did again the soldering and checked back all traces, 18v transistors, sensing circuits, compared diode mode values... Hours and hours.

I left the board 8 months on the shelf and one day when comparing another same working 820-2850, I discovered that R7013 was no stuff but not mentioned in the schematic.
I removed it and it worked!
The biggest ultimate maximum troll I had.

So don't solder 1k R7013 and good luck?

 

[smiba]

PM_SLP_S4_L is 0V, which is the reason why it never enters a S3 state, P5VS3_EN_L will stay high because of Q7911 not being activated thus not setting it to ground.

How to proceed? For me it seems PM_SLP_S4_L should be generated by the CPU, is this an issue where the CPU is broken or should there be another signal going into the CPU to tell it to go to a S3 state?

EDIT: PP3V3_S4 is <0.5V, P3V3S4_EN is 0v. I think part of the issue is the system not even going into a full S4 state, lets see if I can find out whats causing this

EDIT2: PM_SLP_S5_L is low, so there is no attempt going into a S4 state

EDIT3: PM_PCH_PWROK is low, SMC-DELAYED_PWRGD is low. Bad SMC? It looks good around so probably not, I'll keep on digging to see what might be wrong

So don't solder 1k R7013 and good luck?

Glad I didn't haha, thanks for confirming!

 

[G.Beard]

Look at the power management section of the PCH. It may help you figure out what signal has to go in before you get PM_SLP out

 

[G.Beard]

http://www.intel.com/content/dam/www...-datasheet.pdf

Above is the datasheet. Look at the power management parts....
This forum add link thing is bullshit! Add a link and you can't edit post and it links the wrong fucking page.

Anyway, this may help.

 

[smiba]

Thanks, do you have any idea why SMC_DELAYED_PWRGD is staying low which means PM_PCH_PWROK stays low too?

SMC related issue? Or issue with some signal going into the SMC?

 

[G.Beard]

Sorry, I don't have an answer for you. I just linked you to the datasheet because I asked the same question once.

 

[dukefawks]

Check voltages on R1800/1/2/3. Is PPBUS stable at 12.6V? It should now also be able to charge a battery.

 

[smiba]

All the PPVRTC_G3H (Pin 1) on R1800 to R1803 are 3.34V, their outputs ranging from 2.97V to 3.32V

I just tested and the system does change batteries with no issues at all, the light turns orange and the battery reports a higher %

PPBUS stays at a steady precise 12.60V

 

[dukefawks]

Check if 5V on L7260 is pulsing. Check voltages on Y2605. Was there corrosion around the clock chip?

 

[smiba]

Constant 0V on L7260 (Which is to be expected since its powered by an S3 rail), Clock signal exists on Y2605, although there is a 0.25V peak on its pins every ~2 seconds. I don't think this is supposed to happen as its at least 50 times more powerful in voltage then the clock signal is on my oscilloscope

There was some corrosion around the clock chip, I cleaned most of it off with some 2-Propanol and it looks very acceptable right now. However I'm slightly worried about possible corrosion underneath U1800 itself.

 

[dukefawks]

If the voltage on Y2605 is pulsing the machine is power cycling. If there was any corrosion at the clock chip replace it.

 

[smiba]

Replaced Y2605, still power cycling

Checked and replacement clock is working and looks stable for as far as I can see on my digital oscilloscope

Any idea what else might be causing it?

 

[dukefawks]

Uhm, you replace the chip not the Xtal.

 

[smiba]

Oh, uh. Whoops... Sorry

I replaced the Clock chip (Yes, chip this time haha) and it worked! There is a fan spin, thank you so much!

Lets see if it has video

 

[smiba]

Fully working, thanks a lot!

I'm really sorry for the mistakes I make sometimes, I'm still learning and hope I'll ever become as good as you.

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