Lenovo Ideapad 100-15ibd restarts every few seconds continuously.

[lawrenceptrini]

Lenovo Ideapad 100-15ibd
Laptop turns on and restarts every 7 seconds or so.
Power led and Webcam led turn on and goes off repeatedly.
Pressing the power button does absolutely nothing.
Same thing happens whether the bios battery is connected or not.
I tried resetting the bios, press power button to drain power etc.,
but no change same thing. I tried numerous ram modules but same result.
Using a desktop power supply I can see the amps going to zero and rebuilding,
same thing with multimeter. Doesn't matter if I plug in adapter or main battery,
it starts looping (with or without bios battery).

Can anyone please assist.....thanks!

[mcplslg123]

Mere description of symptoms cant help. Where are the measurements?
Is it booting? Are you getting display and then it loops?
If its not booting ,measure the voltage and resistance to GND on all coils.

[lawrenceptrini]

Thanks for your reply.
Initially it was giving display then looping, I was seeing the lenovo logo
then it was restarting but now there's no display but it's looping continuously.
I will take measurements and report tomorrow.
Thanks again.

[lawrenceptrini]

Hi,
With adapter and battery unplugged here are the measurements:-
Voltages:
PL303 - 3.388v
PL304 - 5.111v
PL501 - 1.363v
PL701 - 1.054v
PL302 - 0.003v
PL9 - 1.810v (goes to 0 then rebuilds repeatedly)
Bios chip:
PIN 1 - 3.388v
PIN 8 - 3.388v

Resistance to ground:-
Ohms:
PL303 - 3.041 K ohm
PL304 - 5.230 M ohm (goes to 0 then rebuilds repeatedly in sync with loop)
PL501 - 388.4 Ohm
PL701 - 171.3 Ohm
PL302 - 3.115 M Ohm
PL9 - 46.5 Ohm

[lawrenceptrini]

Here's the schematic for this motherboard:

Link to schematic - https://www.badcaps.net/forum/docume...ptop-schematic

[mcplslg123]

PL9 is for Vcore and even this tries to rise. The resistance readings seems fine to me.
The display went off suddenly or you did something?
I'll suggest to first flash clean me bios to see if you get display back.
Your mb is discrete or UMA?

[lawrenceptrini]

Hi, thanks for your reply.
The laptop had a damage hinge but was giving display. I disassembled to change the palmrest and bottom cover . I then noticed there was a white highlight around the screen suggesting screen going bad so I change the screen and since the problem arise....
I will try your suggestion of flashing the me bios......the motherboard is UMA.

[rogfanther]

Just in case, are you sure the battery was disconnected when you changed the screen ?

[lawrenceptrini]

Hi,
Yes, the battery was disconnected. Laptop was dismantled and was testing the screen.
At first the display came and I saw the logo, then it restarted and it was a continuous loop. Now there's no display but same fan spinning for a few seconds the repeating.