Clevo n870hc / No boot

[cdgold3]

Hi Guys,

I looking for some advice.

I have a Clevo n870hc that's has stopped working. Plugging the power adaptor in and displays a amber light on front. (No Battery installed)
If power button is pressed that the led turns green for a few seconds and go back to amber.

With battery attached the changing circuit seems to be fine and laptop was displays amber and when battery is
changed it goes green as it should so i'm guessing the ITE is working.

On the odd occasion when pressing the power button, the power button led stays on and both the CPU and GPU fans kick in but after a few seconds they
shuts down and wont restart. On that occasion the screen stays blank and displays nothing, not even a back light.

Where would the best place for me to start?

Thanks

[cdgold3]

Re: Clevo n870hc / No boot

Doing some basic testing:

AC Port = 19.30v
Bios u43 = Ground + pin 8 = 2.84v (Pin 1 + 8 = 2.84v)

Will update when i get more

[Duranitron]

Re: Clevo n870hc / No boot

did you do all the basics. substitute with known working memory module.. check the rtc cmos battery, check all the ALW voltages the 3.3ALW and 5vALW.. try to reflash bios with known working bios dump. be sure to save your original bios for backup. look for burnt parts or overheating parts... gud luck

[cdgold3]

Re: Clevo n870hc / No boot

Thanks Duranitron

I have started doing a cap test and found shorts in:

Page 66 - Gpu
c587, c616, c618, c619, c621

Page 55 - Processor 5/6
c594, c595

Page 56 - Processor 6/6
c596, c579

Before i start changing the caps, i cant seem to find what may have caused the issue. Possable GPU/CPU Temp?

[cdgold3]

Re: Clevo n870hc / No boot

It also seem to be around the bottom of the board as well, in the cpu and gpu area.

Unless i am doing something wrong?

[Duranitron]

Re: Clevo n870hc / No boot

do diode mode test and test it again.. remember the processor or gpu only uses 1.2v or less a low resistance like 10 to 3 ohms are good or maybe a cap is fried.

[Duranitron]

Re: Clevo n870hc / No boot

have you check the processor fan for gummed or clogged dirt in side.. that maybe the cause.. an over heating processor or a toasted gpu...do you own this laptop if so.. before a gpu die it displays symptoms like sudden hung.. blue screen of death or screen freezes but the mouse pointer moves.. that kind of thing.. try to look for shorted cap and hoping to find shorted one or if not.. the gpu is toasted..

[cdgold3]

Re: Clevo n870hc / No boot

I removed cap c578, tested on bench and works fine removed

[cdgold3]

Re: Clevo n870hc / No boot

have you check the processor fan for gummed or clogged dirt in side.. that maybe the cause.. an over heating processor or a toasted gpu...do you own this laptop if so.. before a gpu die it displays symptoms like sudden hung.. blue screen of death or screen freezes but the mouse pointer moves.. that kind of thing.. try to look for shorted cap and hoping to find shorted one or if not.. the gpu is toasted..

Checked and could not see anything in the fan. Its my unit and did not see anything.

[cdgold3]

Re: Clevo n870hc / No boot

I removed cap c578, tested on bench and works fine removed

So I'm guessing I have a short on the gpu and cpu side as I get a connection to ground even on the CPU points on top.

What's the best way to test faulty caps without removing one side? Or is there no way without proper equipment?

I am just working my may thought the diagrams if anyone can point me to something else that may be causing it?

Would a dead gpu/CPU cause everything to ground?

[piernov]

Re: Clevo n870hc / No boot

Measure exact resistance to ground. 6 ohms to ground on CPU VCore for Kaby Lake is perfectly fine. GPU VCore may be similar or even lower.

[cdgold3]

Re: Clevo n870hc / No boot

Measure exact resistance to ground. 6 ohms to ground on CPU VCore for Kaby Lake is perfectly fine. GPU VCore may be similar or even lower.

Hi piernov,

Is that with no power attached?

[cdgold3]

Re: Clevo n870hc / No boot

I have been working on finding 19v and 3.3v and they seem to be fine but i cant find the 5v rail.

Can anyone tell me if on page 84 the type-c, 5v should that be always live with ac connected?

[Techtiger]

Re: Clevo n870hc / No boot

Check page 90 5V, 5VS, 3.3V, 3.3VS, 3.3VA if all voltage are available then follow the power sequence page 107 & feedback what’s missing

[cdgold3]

Re: Clevo n870hc / No boot

Check page 90 5V, 5VS, 3.3V, 3.3VS, 3.3VA if all voltage are available then follow the power sequence page 107 & feedback what’s missing

Thanks tachtiger

v3.3
u31
--------
pin 1,2,6,7 - vdd3 - v3.3
pin 8,9 - 3.3vs - v0.00
pin 13,14 - 3.3v - v0.00

v5
u30
--------
pin 1,2,6,7 vdd5 - v0.00
pin 8,9 - 5vs - v0.00
pin 13,14 - 5v - v0.00

u26 - VA
--------
1 - 19.28v

So it does look like i have 5v is rail down. I have been looking at the type-c/usb 3.0 area as i can see a bit of what looks like liquid damage as U14 looks a bit crusty.

[Techtiger]

Re: Clevo n870hc / No boot

Thanks tachtiger

v3.3
u31
--------
pin 1,2,6,7 - vdd3 - v3.3
pin 8,9 - 3.3vs - v0.00
pin 13,14 - 3.3v - v0.00

v5
u30
--------
pin 1,2,6,7 vdd5 - v0.00
pin 8,9 - 5vs - v0.00
pin 13,14 - 5v - v0.00

u26 - VA
--------
1 - 19.28v

So it does look like i have 5v is rail down. I have been looking at the type-c/usb 3.0 area as i can see a bit of what looks like liquid damage as U14 looks a bit crusty.

DD_ON# SUSB# missing trace it back U31 pin 8.9 5VS not 3VS

[cdgold3]

Re: Clevo n870hc / No boot

Thanks tachtiger for all your help

Getting there slowly

Nothing from pin 4 on PQ42. just tracing DD_ON# & SUSB# now.

[Techtiger]

Re: Clevo n870hc / No boot

find out PJ501 jumper if its' soldered remove it & see if 5V is there or not if not check the resistance to gnd of both pads

[cdgold3]

Re: Clevo n870hc / No boot

find out PJ501 jumper if its' soldered remove it & see if 5V is there or not if not check the resistance to gnd of both pads

Removed and got about 0.65v and then it started to slowly drop on pins 1,2,6,7 - u31

[cdgold3]

Re: Clevo n870hc / No boot

Pad on side of U31 - no resistance

Pad other side - 1.191