820-2849-A no chime PPBUS_G3H intermittent 8.33v/1.9v

protocold

Member
i tried unplug magsafe and replug it, and the fan now remain dead, I think i have just created another problem.

Do i need to go back to the drawing board?

I have already undo the R8911 shorting. PP5V_S3 now missing, along with some of others.

And now even if I get PPBUS_G3H to start at 8.35v, it seems like it will drop to 1.8v after like 10 mins. I am trying to reproduce this.
 
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protocold

Member
ok.dont know how to reproduce.. sometime it take a lot longer to go low.

Can you guys please advise of what should I do now?

PPBUS_G3H 8.33V
PP5V_S5 5V
PP5V_S3 0V
PP5V_S0 0.33V

PP3V3_S5 3.3V
PP3V3_S3 0.5-3.3v jumping
PP3V3_S0 1.22v
PP1V8_S0 0V
 
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2informaticos

Administrator
Staff member
"Also some of these boards do need a battery connected or PPBUS will intermittently not come up."
Did you read that?

Check if PPBUS_G3H is steady in such case.

If someone already messed up with GPU, you waste the time with this board...
 

protocold

Member
Yes, i read it, i was going to try to plug in the battery to test, but the fan is now not working. I am trying to trace down why PP3V3_S3 is jumping and now I am on Q7812 and pin 6 is jumping. Probably PM_SLP_S4_L problem?

I messed up when I re-enable R8911.

I bought this machine on ebay and trying to learn something from this. Is there a way that i can at least go back to where I were before?
 
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dukefawks

Administrator
Yes, remove R8911 and see if it comes back. But how does the GPU look? Does it still have the glue around the corners?
 

protocold

Member
i removed R8911 already. Fan dont spin anymore.

Now PM_SLP_S4_L is pulsing, making P3V3S3_EN_L pulsing which in turn make PP3V3_S3 jumping. Do I have a screwed up U1800? Am I even looking at the right things here?

GPU still have glue around the corners.
 
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protocold

Member
I also desoldered the BIOS chip and did a dump, I see that the gpu-power-prefs was set to intel, thus confirming your earlier guess.
 
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protocold

Member
I am very confused.

As this is my first time. I felt like I am going in circles.

I was trying to figure out why 3.3V S3 is pulsing, I ended up looking at Q7810 which lead me to trace down to PM_SLP_S4_L which is pulsing and I thought it come out from U1800, which i am not sure what's next.

I then try to look for 3.3V S0 which is also pulsing, this lead to Q7830 and onto PM_SLP_S3_L which again pulsing and also come out from U1800.

What's next?
 

2informaticos

Administrator
Staff member
Then all S3 and S0 voltages should pulse too; maybe not CPU ones.

I don't recommend to waste more time on this board, already messed with GPU.
 

protocold

Member
You are correct, I re-measure all S3, S0:

PP5V_S3 5V pulsing
PP5V_S0 5V pulsing

PP3V3_S3 3.3V pulsing
PP3V3_S0 3.3V pulsing

PP1V8_S0 1.8V pulsing


Could you continue to help me out on this please? this is my first board and I bought this for learning. I understand what you said about wasting time. But I bought this for this purpose. The GPU is messed up, but i hope i can at least make some progression?
 
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protocold

Member
I just saw ONCE that PP5V_S0 at the fan was 5V but fan wasnt spinning. Then suddenly the fan come on for a few seconds and now it died again, PP5V_S0 go back to pulsing.
 

protocold

Member
ok, I decided to take the gpu off since there is nothing to loose here, since there is still the intel one in the CPU.

I dont know what else I did but somehow I get back PP5V_S0 and PP3V3_S0, ALL_SYS_PWRGD is 3.3v.

PPVCORE_S0_CPU was 0.1v, compared resistance value across C7414 with donor board seems strange, took C7414 from donor board now give me 1.46v

But

PPVCORE_S0_GFX 0.874V (should be 1.05V?)
PPVCORE_S0_CPU_VCAP0 0.35V (should be 1.25V?)
PPVCORE_S0_CPU_VCAP1 0.35V (should be 1.25V?)
PPVCORE_S0_CPU_VCAP2 1.03V (should be 1.25V?)

Still no chime. what else should I look?
 
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dukefawks

Administrator
Without a GPU this board will never display video as the GPU is needed for bootscreen until OSX is loaded and switches to Intel GFX.

I'm not even sure if these board will boot/chime without CPU, my guess is yes but not sure. Does the board beep now without RAM? Beep comes from speaker that is mounted on the board so make sure that is connected.
 

protocold

Member
I think you meant to say GPU on the 2nd line?... Does it make a difference when a GPU is phyiscally absent vs R8911 is removed? In both cases GPU is disabled?

I have the speaker mounted, but there is no beep when I took the ram out.

In what condtion/state would the board check for ram and beep? Where should I look now? What happen after vcore came on?
 
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dukefawks

Administrator
Yes I meant GPU there.
There are lots of more voltages going to the GPU besides the core voltages, so just removing R8911 would not prove the GPU is not at fault. Of course the GPU will not work when R8911 is removed. The thing is that R8911 was removed by someone that kind of knew what they were doing so the GPU is suspect.
If CPU Vcore is present that means that all the rest of the power rails that are important are good. From this point on I do not know if these 17" boards require the GPU to be present to at least give a "no RAM" beep. Stick 1 stick of RAM in the first slot and connect a USB mouse. Does the mouse light up? Boot is slow on these boards so give it a minute. These boards take PC8500 RAM.
 

protocold

Member
Thank you so much for your time and help, really appreciated. I know I could be looking at a dead crap here but i believe i am learning something.

The intermittent issue come back, fan dont spin but all S0 rails are present except 1.05v. Tracing through U7971 suggested PPCPUVTT_S0 is missing, intermittently.

I found your earlier post about similar symtoms: https://boards.rossmanngroup.com/for...er-gpu-replace

I also replaced U7600 and also Q7630, Q7636 and I still have intermittent PPCPUVTT_S0. When PPCPUVTT_S0 is 1.05v, DRVH is 1.63v and DRVL is 4.22v. When PPCPUVTT_S0 is 0v, both DRVH and DRVL is 0v.

What does it take for U7600 to properly generate the DRVH and DRVL signal so Q7630 and Q7636 can work to produce the 1.05v?
 
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