Lenovo 320s no power no led

[Jeroentje]

I have a lenovo 320s 13ikb mainboard type 1701A_05_01 REV: SVT 320S-13 hsb j mv-6 94v-0 e89382 with sr3la cpu.
no led no power not charge, when inject power the on light flashes ones, no power consumption, maybe a protection?
I attached a photo, the 0v seems to be ground.
Battery plus line is goning on /off to 3,6v

What would some steps I could take to find the defect

thx

[mon2]

Re: Lenovo 320s no power no led

Place your meter in resistance mode (ohms), remove all power and then read the resistance to ground for each coil on this board (large grey 2 leg parts).

If you have a low resistance reading on the coil then you may have a shorted cap causing this issue.

Do check for any blown fuses / traces near where the power enters.

[Jeroentje]

Re: Lenovo 320s no power no led

and what is low ?

I have got

274k
9.3
6.3
6.1
26
62
50m
3k
54

[mon2]

Re: Lenovo 320s no power no led

Please clarify the units of each reading:

274k
9.3
6.3
6.1
26
62
50m
3k
54

9.3 ohms? kohms?

and the rest...

[Jeroentje]

Re: Lenovo 320s no power no led

k is kilo ohms
m is mega ohms
9.3 = 9.3 ohm

this are all 9 coils

[mon2]

Re: Lenovo 320s no power no led

Do you have the schematic and boardview files for this exact logic board?

If you do, can you post them here ? I do not believe I am referencing the same logic board in my database. For example, D5902 is missing on my schematic.

never mind...I think I just found it

1) Confirm that DCIN receives the external power supply rail ok @ pins 3&4 of CN5802. This is DCIN.

2) Post the values for the attached pix.

[Jeroentje]

Re: Lenovo 320s no power no led

cool ! I did not find anything, i will get into it

thx for youre time

[Jeroentje]

Re: Lenovo 320s no power no led

pict 1
20v in

pict 2
1. 20v
2. 3,6v
3. 3,6

pict 3
unable to find correct pin, please look at my mbzoom.jpg, there is q5904 labeled

pict 4
6. 20v
7. 18v

ps where did you find this schema ?

[mon2]

Re: Lenovo 320s no power no led

hi. sent you a PM as well.

From pict2, points 2 & 3 should follow DCIN if the logic board is ON. At point 3, the DCIN value must be present to power the logic board.

Please confirm the values from pict4. Point 6 is ok and is DCIN value. However, Point 7 should be the same since the resistor between these 2 locations is only 4R7 = about 5 ohms. Something is wrong here. After this check, power down and check the resistor value with a meter in resistance mode. It should be about 5 ohms here.

Post your results.

Update - yes, Q5904 is present in your logic board picture. Please confirm the voltage readings on the SOT-23 mosfet (3 legs). The "S" value is what voltage ?

Review page 59 of the "320S" schematic, your issue is with this part of the schematic.

See and review the attached locations of R5932 & R5933.

[Jeroentje]

Re: Lenovo 320s no power no led

thx !
the board has no bios battery connected so I assume it tries to power on, also with keyboard does not make any diffrent.
Only when I user lab psu and from 0 to 12v slowly on battery pin around 5v the power led does turn on for a 1 ms.

I have checked those to resistors and the lower one on youre pict is 40k ohm and the one above 48k ohm, fluke meter is in auto range and a random other 2r2 resistor meassure 2,7ohm

on sot-23 pin 1=20,39v and 3=20,09v after resitor 16,07v

[mon2]

Re: Lenovo 320s no power no led

hi.

1) The resistors values @ R5932 & R5933 do not match the values in the schematic. For now, let us ignore this but they are a suspect. In theory, if these resistors were blown, this will imply that the surge current went through the dual diodes @ D5902 which appears to be working. Perhaps you can check this.

With the power removed, place your meter in diode mode.

The apply your red lead on D5902, pin # 2 & black on 3 - should conduct @ 0.6 volts (or close to this value). Reverse the leads and there should be no flow (OL).

Repeat with red on pin # 1 and black on 3 - should conduct. Reverse should block.

2) Can you apply your DC power supply onto the DCIN of this logic board? That is more practical to mimic your external power supply / adapter. Actually, you could even use the original power adapter but the benefit of the power supply is that you can current limit the power rail in case of some surge event.

With the power supply attached at DCIN, the power rail should continue downstream if ISL95521 (U5901) allows for this path.

3) From page 58, what is the voltage value @ VSYS, to the right of R5903, pin 2?

Voltage value to the LEFT of R5903, pin 1 ?

4) Can you confirm which LED turns on for you and then quickly turns off ? Which label on the LED ?

[Jeroentje]

Re: Lenovo 320s no power no led

1) understand
When check the D5902 red on 2 black on 3: 0.295v, indeed OL when reverse. 1 and 3 the same.

2) yes !

3) 3,578v on both sides (20v in @ q5901), when not powered you see 3v 2,5 and from 1,5 slowly to very low on R5903. ( my basic knowledge thinks that the porblem is a bit further otherwise it was instant 0 and consumes power, right?)

4) led3 (red) at charging cable, it sparks and psu enters amp protection for also a few ms, I use 11v on main rail and battery + same behave.

maybe irrelevant but on the look a like diode on the right of the chip s=3,6v d=17v and other 4,7v, straight below R7027 (empty)

[mon2]

Re: Lenovo 320s no power no led

Not liking the resistor values @ R5932 & R5933. Would you please check again?

You are reporting these values to be in Kohms ?? The parts should be 4R7 (about 5 ohms). This rail is required to power the switch regulator from Intersil / Renesas and is a LDO. That is, it is this rail that powers the switching regulator so that it can do its work as a switching regulator.

If I understand correctly and the resistors are @ 47Kohms, then there is not enough current passed through these parts to power the regulator.

I = E/R = 20v/47000

vs.

I = E/R = 20v / 4.7 = much higher current to power this component.

I do not think it is harmful to just short these resistor with a piece of wire.

So you are applying a direct short across any of these parts to feed the voltage directly from the common cathode of the SOT-23 dual diode to power the ISL part.

If you feel comfortable with this, please attempt the short. I know that in working with past ISL based designs, the ref schematic was simply the dual diode and then this Vin pin. You can check the ISL9241 full schematic / ref kit schematic for similar details. The ISL onboard this logic board is censored - never will understand why they do this...

[Jeroentje]

Re: Lenovo 320s no power no led

yes I am sure about the kohms, checked more then once and also on other parts to confirm meter is not crazy

sure I could try to short them on my own risk, would it make sense to put lab psu at 20v after the resietor with normal power connected.

as you may understand now I am not fully expert on those diagrams, this is very helpful for me.
laptop was on battery and then died, that is what is told me.

what is youre expierence with protection chips ? based on current?

[mon2]

Re: Lenovo 320s no power no led

Hi. No.

If you are comfortable, you can bridge the 47k SMD resistor with a piece of wire. Do this with soldering and with all power OFF; battery removed so the logic board is without all power rails.

What I think is happening here is that the 47k resistance is too high, leading to very small amount of current being passed through to power the ISL regulator. Respectively, the ISL is not being powered. From memory, pretty sure that the dual diode is fed directly into the ISL regulator on more recent reference designs. I will try to validate this understanding but 47k is too high.

Cannot explain how and why this high resistance value is on the logic board.

Welcome feedback from other techs but fairly confident this 47k resistor reading is a show stopper.

Update - found my frame of reference. Not losing my mind...yet. Please see attached and the value for R7.

We had designed a power bank for the travel industry just before Covid-19 hit. Of course had to halt the development but we used the ISL9241 in our product design so the dual diode rang a bell. The reference design has a 10 ohm resistor. 47K is just not right.



1) First measure the voltage output from your Lenovo adapter with your meter.

2) Then use your lab power supply and set it for this same voltage value.

3) You can also set the power supply to a limited current (as marked on your adapter). Probably 3A or so.

4) Then apply this power supply feed to the same location as the DCIN.

5) By the flow of the logic board, this voltage will enter the dual diode -> then the 47k resistor (which should be 4R7) -> this then powers the ISL switching power supply.

Do not attach a battery for these tests. The battery is not required. The DCIN will be the primary and sole power source.

[piernov]

Re: Lenovo 320s no power no led

https://www.badcaps.net/forum/showpo...02&postcount=2

2.6. Never randomly bridge MOSFETs/fuse/components
Bridging components can easily lead to the destruction of the board without any way to repair it.
If it's a fuse, replace it with a matching fuse. If you don't, it will not be able to protect the board and if the source of the problem is still there, some other component will go up in flames.
If it's a MOSFET, its purpose is to stop current from flowing through it when turned off, and allow current to flow through it when turned on. It's not necessarily always turned on, otherwise it wouldn't be there. If it's turned off when it shouldn't be, then there is an issue elsewhere in the circuit, bridging the MOSFET won't solve it.

[Jeroentje]

Re: Lenovo 320s no power no led

Hi. No.

If you are comfortable, you can bridge the 47k SMD resistor with a piece of wire. Do this with soldering and with all power OFF; battery removed so the logic board is without all power rails.

What I think is happening here is that the 47k resistance is too high, leading to very small amount of current being passed through to power the ISL regulator. Respectively, the ISL is not being powered. From memory, pretty sure that the dual diode is fed directly into the ISL regulator on more recent reference designs. I will try to validate this understanding but 47k is too high.

Cannot explain how and why this high resistance value is on the logic board.

Welcome feedback from other techs but fairly confident this 47k resistor reading is a show stopper.

Update - found my frame of reference. Not losing my mind...yet. Please see attached and the value for R7.

We had designed a power bank for the travel industry just before Covid-19 hit. Of course had to halt the development but we used the ISL9241 in our product design so the dual diode rang a bell. The reference design has a 10 ohm resistor. 47K is just not right.



1) First measure the voltage output from your Lenovo adapter with your meter.

2) Then use your lab power supply and set it for this same voltage value.

3) You can also set the power supply to a limited current (as marked on your adapter). Probably 3A or so.

4) Then apply this power supply feed to the same location as the DCIN.

5) By the flow of the logic board, this voltage will enter the dual diode -> then the 47k resistor (which should be 4R7) -> this then powers the ISL switching power supply.

Do not attach a battery for these tests. The battery is not required. The DCIN will be the primary and sole power source.

ok ok I did some things, it seems I burned the diode berfore the resistor (see picture), maybe I did make a mistake. no problem.
BUT I was checking the battery and tried to charge it with the lab psu, it was taking power and did charge, on lucky shot I did press the bios reset/enter bios button, and it turned on! So connected a hdmi screen and did it again, and yes picture. Also only on battery same, then no battery and only 20v ( with the sinlge flash) and also picture. Only power from lab psu on battery in does show led but no boot.

so pretty cool progress agian thanks mon2, I realy like to hear youre next advise steps or conclusion.

So I guess it could be the first mosfet ? and proberly the (burned) diode, all tho is seems to charge when all connected via lab psu.
and maybe I also can change the resistors from donor board, kind off happy now this is some result!

[mon2]

Re: Lenovo 320s no power no led

Ok. No panic.

1) The dual diode is cheaper than dirt - about $0.05 USD. Will investigate in a few minutes.

2) Thanks for the resistor close up. 100% the markings = 4R7 = 4.7 ohms. If they are reading as 47k, something is not correct.

This value agrees with the ISL9241 reference design where they recommend a 10 ohm resistor in series.

So for this repair, you will need:

SMD Dual diode in SOT-23 package with common CATHODE.
2 * 4R7 SMD resistors @ 0603 size (according to the schematic)

3) At this time, best to wait for the replacement dual SMD diode and also suggest some 0603 4R7 resistors to replace the ones in your picture.

Where are you located ? Do you have a local electronic parts supplier ? If not, I think we can send some parts to you from Arrow Electronics through free shipping. Want to test out this service. Shoot me your details in a PM and will see if we can receive free shipping. If it works, you will have the parts in the next few days. Arrow has warehouses worldwide. Our company account has free shipping - regardless of the value of the purchase.

Getting closer...

update:

https://www.arrow.com/en/products/ba...s-incorporated
* dual diode will work here just fine.


https://www.arrow.com/en/products/cr...-4r7elf/bourns
* will work for the 4R7 part

[Jeroentje]

Re: Lenovo 320s no power no led

thx for the do and don't tips, read the article.

Ok thanks for the links, I have found the resistors on donor board.
I have serveral mosfets but not exact match, how critical is that ?
I am talking about q5901 with type 6366E.
I have some on boards: 6372, 6414A and nikos pk5e6ba
The diodes I checked do all have diffrent labels. I will check local first.

I am in the netherlands (in europe )

[Jeroentje]

Re: Lenovo 320s no power no led

replaced the 4R7, tested at 5.2 ohm the peace, in the system 2.6 ohm so thay are parralel.
The old ones had value of 19 and 2,7 mohm.
due to the dual diode it does not provide 20v to, but no fire also