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Old 01-08-2019, 05:02 PM   #1
disorder
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Default Lenovo z51 : no display, fan spin and stop looping

hello,

i have an issue with a lenovo z51 laptop
when plugged in leds are ok
when pressing power button with only the battey : leds shine, the cpu starts spinning but no display and after 1 or 2 seconds, lights and fan go off.

after 2 seconds, leds appear and fan start for 1 seconds and then and then

no display

i have tried bios reset : remove cmos battery, no fix
i have tried start directly by bios button (novo button) : exactly the same cycle as power button
i removed all the connectors except power button flex cable
i try another ram

no fix

can anyone help me : this could be caused by short ??? thank you all !
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Old 01-08-2019, 05:53 PM   #2
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Default Re: Lenovo z51 : no display, fan spin and stop looping

Check if you have CPU VCore.
Clean the RAM slot with some contact cleaner.
Try the motherboard outside the chassis.
If everything good, next step is to try to flash the BIOS.
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Old 01-09-2019, 01:17 PM   #3
disorder
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Default Re: Lenovo z51 : no display, fan spin and stop looping

hello, thanks for help
don't know exactly where to find all vcore lines but i have tested this ones :
-laptop off plugged to ac power : 20V, 5V, 3.3V ok
-when pressing power button : 1.4v 1.7v Ok
i have none coil with 0V

the lines that appears after pressing power button, disappear when the lights go off

i have clean ram slots, try all slots with two different ram

but the MB outside the chassis, the same

how to flah bios if i can't access bios ?

Visiblement tu es francais, ce sera plus simple.
donc le pc affiche les differentes leds : batterie, allumage sans probleme.
quand j'appui sur on, le bouton on s'eclaire, la led disque dur aussi, le ventilo cpu commence a tourner. puis au bout de 2 secondes, le ventilo ralenti, les leds s'eteignent et le ventilo s'arrete. puis sans que je fasse rien ca recommence en boucle.
on attend le hdd s'amorcer mais comme le 5V se coupe, il s'arrete.
j'ai bien essayé en retirant toutes les nappes de la MB , ca fait pareils.
ce probleme est arrivé apres une periode de 15 jours sans s'en servir. pas de liquide, pas de surtension ou quoique ce soit
merci a toi !!
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Old 01-11-2019, 12:58 PM   #4
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Default Re: Lenovo z51 : no display, fan spin and stop looping

up

can i flash bios with usbkey ?
i have only found .exe file, don't know how to extract .bin
i search on myself
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Old 01-11-2019, 01:35 PM   #5
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Default Re: Lenovo z51 : no display, fan spin and stop looping

Il Faudra dissoudre le Pouce Bios et après le reprogrammer, Mais pour cela on a besoin d'un Programmer Bios. Cela ne coûte pas cher sur eBay
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Old 01-11-2019, 01:43 PM   #6
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Default Re: Lenovo z51 : no display, fan spin and stop looping

Quote:
Originally Posted by piernov View Post
Check if you have CPU VCore.
Clean the RAM slot with some contact cleaner.
Try the motherboard outside the chassis.
If everything good, next step is to try to flash the BIOS.
(piernov]Check if you have CPU VCore)
Prends une photo de la carte mère et dans la photo, marque la tension de chaque inducteur (Gray Coils) a côté de ceux-ci. Il y en aussi à côté du processeur.

Last edited by techtiger; 01-11-2019 at 01:47 PM..
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Old 01-11-2019, 04:02 PM   #7
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Default Re: Lenovo z51 : no display, fan spin and stop looping

ok je ferai ca demain, merci

ce que je peux dire deja c'est que pour les coils :
-pres de la batterie : 0.228 ou 16v si la bat est branchée
-pres des rams 1.3V que apres avoir appuyer sur power
-pres du cpu : 1.7V que apres avoir appuyer sur power sinon 0V
-entre les prises usb et les rams : 5V et 3.3V pc eteint ou pas
-sur le bios : 3.3V toutes les pates

il n'y a que ces 5 coils
merci
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Old 01-12-2019, 12:55 AM   #8
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Default Re: Lenovo z51 : no display, fan spin and stop looping

Quote:
Originally Posted by disorder View Post
ok je ferai ca demain, merci

ce que je peux dire deja c'est que pour les coils :
-pres de la batterie : 0.228 ou 16v si la bat est branchée
-pres des rams 1.3V que apres avoir appuyer sur power
-pres du cpu : 1.7V que apres avoir appuyer sur power sinon 0V
-entre les prises usb et les rams : 5V et 3.3V pc eteint ou pas
-sur le bios : 3.3V toutes les pates

il n'y a que ces 5 coils
merci
is this you Mob & the PL Coils Voltages are correct ?
Attached Images
File Type: jpg Lenovo-Z51-70-Z51-70-Mainboard-AIWZ0-Z1-LA-C287P-Intel.jpg (605.6 KB, 22 views)
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Old 01-12-2019, 03:06 AM   #9
disorder
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Default Re: Lenovo z51 : no display, fan spin and stop looping

hello

yes this is the mob i have
and yes i have all this voltages, 1.3 and 1.7 are presents only when i push power button (i think it's normal : voltages for cpu and rams ?)
i have no shorts on coils
but when the laptop have done multiple loop, the coil of the cpu is a little hot.

new thing : once, when the laptop began to loop (when the light was on 1 second), i have touched the area near 3+5V cols , then the light stay on but fan was off , no display, no sign of life but this light.

i think i will buy a new chip bios and switch it.
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Old 01-12-2019, 04:34 AM   #10
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Default Re: Lenovo z51 : no display, fan spin and stop looping

Quote:
Originally Posted by disorder View Post
hello

yes this is the mob i have
and yes i have all this voltages, 1.3 and 1.7 are presents only when i push power button (i think it's normal : voltages for cpu and rams ?)
i have no shorts on coils
but when the laptop have done multiple loop, the coil of the cpu is a little hot.

new thing : once, when the laptop began to loop (when the light was on 1 second), i have touched the area near 3+5V cols , then the light stay on but fan was off , no display, no sign of life but this light.

i think i will buy a new chip bios and switch it.
If you have a hotair gun reheat PU401/PU402 and see if any changes
yes it' normal voltage in CPU & RAM those are not ALWS VIN only comes after presing the power button PL1102 getting hot or worm ?
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Old 01-12-2019, 05:20 AM   #11
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Default Re: Lenovo z51 : no display, fan spin and stop looping

ok, i have reflow pu401 and 402, it does the same
effectivly pl1102 is worm, not hot
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Old 01-25-2019, 10:53 AM   #12
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Default Re: Lenovo z51 : no display, fan spin and stop looping

hello,
some news...bad news
i have changed the bios chip with a programmed one
the laptop is always dead
exactly same symptoms : led on, fan spin and stop. no backligh no display.
the sequence repeats itself many times and always same issue

pl1102 is hot progressively, in diode mode it is at 136, don't know if it is a good value
with power supply, 1V2Amp, consumption on pl1102 is 7mamp, and consumption on pu803 0.50
i think it is a short somewhere no ??
does somebody knows wich line it is ?

and if it is normal to have consumption current ?

tjank you
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Old 01-25-2019, 03:34 PM   #13
techtiger
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Default Re: Lenovo z51 : no display, fan spin and stop looping

need the Schematic to help you out give some time i made a reqest for the Schematic,
once you press the power button the sequence repeats itself many times ? send a snap of the motherboard both sides
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Old 02-02-2019, 07:44 AM   #14
disorder
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Default Re: Lenovo z51 : no display, fan spin and stop looping

hello, here some pictures, not enough time to do it before, thanx
Attached Images
File Type: jpg IMG_20190202_153459.jpg (541.6 KB, 5 views)
File Type: jpg IMG_20190202_153542.jpg (533.7 KB, 3 views)
File Type: jpg IMG_20190202_153537.jpg (564.3 KB, 4 views)
File Type: jpg IMG_20190202_153447.jpg (634.9 KB, 3 views)
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Old 02-02-2019, 01:36 PM   #15
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Default Re: Lenovo z51 : no display, fan spin and stop looping

this is your Schematic
Attached Files
File Type: pdf Lenove G50-45 Lenovo Z41-70, Z51-70 LA-C287P.pdf (1.70 MB, 22 views)
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Old 02-02-2019, 01:42 PM   #16
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Default Re: Lenovo z51 : no display, fan spin and stop looping

test PJ501 PJ503 PJ602 PJ704 PJ801 PL902 PL903 PL1102 all voltages
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Old 02-06-2019, 04:58 PM   #17
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Default Re: Lenovo z51 : no display, fan spin and stop looping

hello, there it is the mesures i could do.
all are only present when power button is push
PJ501 : 1.368
PJ503 : .400 but sometimes 0.683, when the laptop boot loop this voltage rise to 0.683 and then 0v when the laptop switch off. when the laptop on and off without bootloop it only rise to 0.400 and the 0V
PJ 704 : 1.500v
PJ 801 : 1.04v but it is no soldered,
PL 1102 : 1.701

i don't find PJ602, PL902 and PL903.

thank you for help
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Old 02-07-2019, 05:25 AM   #18
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Default Re: Lenovo z51 : no display, fan spin and stop looping

I had the same problem in the past and when I tried everything possible, I found short on lvds cable! So try to start the board up with no lvds cable connected, what if..

Have you tried reprogramm KBC EC rom already?
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Old 02-07-2019, 02:03 PM   #19
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Default Re: Lenovo z51 : no display, fan spin and stop looping

find out if your Mob have U13 IC if so test pin 10 & 6 +5VS +3VS stable, test PJ802 PJ803 for Voltage ?
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Old 02-07-2019, 05:14 PM   #20
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Default Re: Lenovo z51 : no display, fan spin and stop looping

hello, i tried without any cable except power line and power button flex :
U13 : pin 10 J5=5.050V ; pin 6 J4=3.358V stable
pj 802 : 3.350V (laptop off) 3.347V on
pj803 : 0.016V off, and 1.046V on

thanks
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