Lenovo cg516 nm-a741 no power

[mon2]

Re: Lenovo cg516 nm-a741 no power

After the above confirmation,

1) if the +1v8VS rail is not present, check the source of this rail @ coil PL702, pin # 2. Is the root +1v8ALW rail producing this voltage value ?

2) Assuming yes, this +1v8ALW value is then fed into a mosfet @ Q39. Then Q39 offers the +1v8VS that feeds the referenced UC3 bios and other such labelled rails. Please confirm you are seeing each of the above rails on your logic board.

3) while you are on PU701 region, confirm that the other rails are also correct. That is, PL701 with +0v95. Is this working ?

[Spider1211]

Re: Lenovo 310-15abr no power

From schematic and your attached picture, it seems the BIOS is powered by +1.8VS via RC246. There is no physical part for it, the PCB trace itself (where you wrote "No parts" on the picture) acts as the 'component' (DO NOT apply 3.3V to the BIOS chip, you might damage it).

Measure resistance to ground on pin8 of UC3. Try removing CC204 and measure voltage/resistance again. If you still do not have +1.8VS, check Q39 and if +1.8VALW is present or not. Report back your findings.

[mon2]

Re: Lenovo 310-15abr no power

hi. Just realized you have 2 threads open. Replied earlier to the other thread:

https://www.badcaps.net/forum/showthread.php?t=95203

[Spider1211]

Re: Lenovo 310-15abr no power

Yikes, thanks for the redirect. Maybe one of the moderators can merge the threads.

[SMDFlea]

Re: Lenovo 310-15abr no power

Yikes, thanks for the redirect. Maybe one of the moderators can merge the threads.

Both threads merged .

[NConstantinou]

Re: Lenovo cg516 nm-a741 no power

OK
on PL702 i have 1.4v but on caps pc720 and pc721 i have .325v by disconnecting pj704.
PC722 AND PC723 ARE MISSING FROM THE BOARD
PC720 AND PC721 ARE NOT SHOWN SHORT.

[mon2]

Re: Lenovo cg516 nm-a741 no power

1) Reflow / resolder PL702 to be sure there is a solid connection to the SMD pads. Have seen hairline cracks on ROHS solder that can raise such issues.

This rail @ +1v4 is too low.

2) After the above, place your meter in ohms mode and check that you have a solid connection from PL702, pin # 2 onto the caps downstream but before PJ704.

3) Remove PC720 and PC721 and confirm that they are not damaged. With these caps removed, confirm the resistance from PL702, pin # 2 to these pads. The reading should be close to 0 ohms = solid traces from PL702, pin # 2. After this confirmation, place each cap back and test this rail again. The voltage output should be very close to +1v8.


4) If the rail is still not +1v8 (or close to); review that the input to this rail @ PJ703 is @ +3v3 = pin 19 of PU701.


PS: Will check back later today - being yelled at to do some gardening

[NConstantinou]

Re: Lenovo cg516 nm-a741 no power

Hi Mon2
after resoldering PL702 area.
i have removed PL702 and i checked pin1 was 0v and pin2 0.332v.
this tells me that it is an input to the ic PU701 correct!
then i removed PC721 and 722 and there is connection to pin2 of PL702 and caps are ok.
by disconnecting pj704 on the side of PL702 i still get 0v and on the other side 0.332v.
Now on pin 5 of PU701 if i disconect PJ705 on cap i PC727 i get 3.3v.
this i believe is the output of the ic for 1.8v.
if i solder PJ705 i get .332v.
i solder everything back and i checked Q39 pin5 without the mosfet and i got 0.332v.
Q31 has 20vsb and also +5valw.
Qv2 i have only on pin1 .332v and on the other 2 pins 0v. testing transistor shown ok.
Also .775valw is missing.
could be the ic PU701!

[mon2]

Re: Lenovo cg516 nm-a741 no power

Hi. PU701 may be defective...

1) PU701 is a multi-rail switching power supply controller. The INPUT to this controller IC is on the LEFT side of the schematic; the RIGHT side are the outputs.

2) For each rail that is a switching power supply, the local coil and charge caps are required to build that rail to the referenced values.

3) Try the following:

a) What is the value @ PJ705 ? PJ705 should be shorted as drawn in the schematic - solder blob? It should be +1v8 and this is an INPUT to PU701 controller. This input rail then builds the rail on the left side via pin # 6 @ +0.775V.

Do you see this relationship?

b) Same idea for PJ707. INPUT = +3v3. OUTPUT on pin # 3 = +2v5.

Do you see this relationship?


c) PJ701 should be @ INPUT = +5v0. OUTPUT on pin # PL701, pin # 2 @ +0v95 (just shy of 1V).

d) PJ703 should be @ INPUT = +3V. OUTPUT on pin # PL702, pin # 2 @ +1v8.

[NConstantinou]

Re: Lenovo cg516 nm-a741 no power

thanks for the reply

yes i have seen the relationship but i wasn't sure because i try to google the ic pu701 but didn't find datasheet.

if i dis solder pj705 on pin 5 of pu701 i have 0.33v.
i will try to find the ic then.

i have one question.
on pl601 pin1 i get 3v and on pin2 1.9v is that correct!

thanks

[mon2]

Re: Lenovo cg516 nm-a741 no power

there is a Pizza place in Pelissier street between Wyandotte str west and Elliott.

Cyprus Pizza ??

[NConstantinou]

Re: Lenovo cg516 nm-a741 no power

You got it. CYPRUS PIZZA

That place was an old house and we renovated it.
It paid for my studies plus I save some money also.
Next to that there was a parking lot which I was renting and collecting money from people
Across the street there was a Binco place. Within 3 years I made 60,000.
Unfortunately I had to leave because my mother had cancer and I had to return.
Canada was a gold mine for me but a was working very hard too many hours of work.

I will never forget that country.
Nice people, no presure no stress everything was running smoothly besides the weather.
Here everyday we are under stress, more competition, margins are down but we have a very nice weather. The coldest time for us is 10 degrees celcius.
Today's temperature 30 degrees but out problem is the Turks. That took half of the island since 1974.

Are you Canadian!
How is your business!
Describe something about you


By the way i order lv5075 from China it will take 15-20 days to arrive.
Unfortunately we have no other way for supplies