Samsung NP750QFG-KA3DE does not turn on , Blue LED flashes 3 times

[Egidio85]

Hi everyone, I have a Samsung NP750QFG-KA3DE , MainBoard VESTA3-15 BA92-24515A

the battery is charged. pressing the power button the blue LED flashes 3 times and then stays blue. then the sequence repeats.
the fan does not start.

I noticed that I have no power on the processor and it does not heat up. could it depend on the bios?

any advice on what to check?

[mon2]

the battery is charged.

?? The motherboard is able to charge the battery or the battery is pre-charged?

Which battery charger is onboard? Schematics available?

Remove all power. Meter in resistance mode. Measure the resistance to ground of each inductor on the board. Each inductor is linked to a power rail and we are hunting for a shorted part. What is the history of the unit?

[Egidio85]

?? The motherboard is able to charge the battery or the battery is pre-charged?

Which battery charger is onboard? Schematics available?

Remove all power. Meter in resistance mode. Measure the resistance to ground of each inductor on the board. Each inductor is linked to a power rail and we are hunting for a shorted part. What is the history of the unit?

yes, the motherboard is able to charge the battery.
in the attached photo the values of the coils.
the only anomalous values seem to me to be those in the 2 coils in the video area 00,4ohm , where the monitor is connected.
the component where the coils go is SM3201B but I can't find the datasheet

[mon2]

the only anomalous values seem to me to be those in the 2 coils in the video area 00,4ohm , where the monitor is connected.

This is your sore spot. You have a short here. Suggest to carefully flux and remove each capacitor. After you remove a capacitor or 2, test this resistance to ground again. Do not lose track of the capacitor location for each. Take close pics. If the short is not removed, place the capacitor(s) back.

[Sephir0th]

Remove each capacitor? What sort of advise is that?! Are datasheets not supplied and bench top power supplies not sold anymore these days?

I am seriously confused about you my friend. Sometimes you are sharing great stuff and ideas and it appears like you know what you are doing and in the next moment it appears like there is a second guy using your account who either doesn't read the request in full or comes with a completely random or pointless approach.

However, i strongly assume that this is a converter for a AMOLED panel and therefore this circuit is exactly like supposed to be present.

Egidio85 Add present voltages in the picture instead since there is nothing suspicious to see in this picture if my guess is true.

[mcplslg123]

Those coils with 0.4 Ohms seems suspect but that depends on the circuit its intended for. can you write the name of the controller there. It does seems like screen related controller.

[Egidio85]

Remove each capacitor? What sort of advise is that?! Are datasheets not supplied and bench top power supplies not sold anymore these days?

I am seriously confused about you my friend. Sometimes you are sharing great stuff and ideas and it appears like you know what you are doing and in the next moment it appears like there is a second guy using your account who either doesn't read the request in full or comes with a completely random or pointless approach.

However, i strongly assume that this is a converter for a AMOLED panel and therefore this circuit is exactly like supposed to be present.

Egidio85 Add present voltages in the picture instead since there is nothing suspicious to see in this picture if my guess is true.

yes exactly, I have no shorts on the capacitors around the controller, so I think it is useless to remove the capacitors.
yes it is a converter for amoled panel marked SM3201B.

I removed the coils, on one side I have 00.4ohm so I think it is the ground. on the component side I have no shorts. if I turn on the pc with the coils removed I have 0.5v. reading other posts I saw that those who had problems with SM3201B amoled converter the pc starts but displays only with an external monitor.

my problem is that the led flashes 3 times blue and 1 fixed, the keyboard lights up for a moment and then repeats until I unplug the battery. the battery charges regularly. when the pc is on I have no power on the processor coils.

I have other voltages like 16v, 3.3v and 5v. could this behavior depend on a corrupted bios?

[mon2]

Are datasheets not supplied and bench top power supplies not sold anymore these days?

where the coils go is SM3201B but I can't find the datasheet

Please post the datasheet. OP already stated he does not have one.

[Sephir0th]

Touché, no datasheet available for this one...

However, this doesn't change anything about that there is no point to inspect it since a) the Main power rail isn't shorted and b) it is not clear whether the board does even reach the point where all power rails are present and the SM3201B is actually being enabled. Because from a logical point of view there is no reason for the AMOLED panel being enabled before the board is fully powered, including CPU Core and everything else.

tl;dr Basic measurements are still missing to determine where to dig in.

[mon2]

The OP stated the power supply is shorted that drives the LCD. Granted this is an OLED / AMOLED so yes, there will be inductors to ground for the bipolar rails. The linked surrounding caps for this controller in the witness protection program has a few caps nearby. If indeed there are shorted caps, the whole process is 5-10 minutes of pluck a cap process. Have done this a few times with success.

The mfr of this chip is Silicon Mitus.

https://www.siliconmitus.com/m_e/index.asp

BTW - the same power supply series is used on the HP products (OLED):

https://www.badcaps.net/forum/troubl...g0#post1807911

You can get a general feel for how the SM3201B may be operating from this public diagram.

PS: I will bury the hatchet after this but cool it with your comments. The advice that was given was 'free'. Use at your own risk. Personally do not need to be here and am certainly not using it to promote my non-existent YT channel. Keep it up and will seriously unleash my only fans channel. Recently left eevblog on a similar bitch fest. The web-owner has since apologized a few times after claiming I am a paid Chinese spammer. On the contrary. Most of the 'engineers' there will not go across the street nor leave their parent's basement let alone visit China. Been there many times and wanted to share my personal experience of importing high volumes of electronic goods. Irony is that we have bumped into the buyers from DK / Mouser in China at the same venues. They can continue to pay 10x the price of the direct China pricing.

[Sephir0th]

See, this is the mon2 I wanted to see, not the other one. So this is how I can summon you?

Touché again, and good evening.

PS: awaiting measurements from the OP like described in Post #9

PPS: I'm not doing anything on YT for almost one year. I like the "direct" contact in the various discord communities and forums more and it helps the people more, when they get immediate feedback.

[mcplslg123]

I request all members not to indulge in personal comments.We all are here to help fellow members and not to promote ourselves.

Ofcourse, the suggestions given are free and sometimes we'll err on comments.So should'nt be a big fuss.

I've my own PAID channels where i teach my students online and i dont even refer it here. I earn more as trainer then by repairing.