Motherboard W26361-W84-X-02 - Black Screen

[Stanley1843]

Hello to everyone.
My W26361-W84-X-02 motherboard starts but don't show image (no logo screen neither bios). Because, I have two of them I desoldered the bios chip from the no working motherboard and I soldered it to the working motherboard and the motherboard works OK, so the bios firmware isn't the problem. Below I took some measurements from the no working motherboard when is power on. Also, I replaced the RAM and didn't work again (maybe some pins from the RAM slot don't have the right voltage?). I replaced and the bios battery, and I made reset on the bios and again the problem didn't solved.
Finally I replaced the two leak capacitors where are in the red circle on the below image.
Do you know what could be the source of the problem or do you know where can I find a schematic?


Motherboard when is power on:
RAM decoupling capacitors - 1,84V
CPU inductors - 1,48V
Bios flash memory - 3,23V

[rogfanther]

Start by checking cpu socket pins. Also, check in the board´s manual in which slot it needs to have RAM ( or try with one stick in all combinations ) .

[Stanley1843]

Hello and thanks for your reply.
I check the CPU pins and are OK. Also I check all the combinations in the RAM slots and didn't work again. Any idea?

[rogfanther]

What were the caps that were in it before ( brand, series, capacitance, voltage ) and with what did you replace them ?

[Stanley1843]

The original Caps was OST (Brand) 2200uF / 6.3V / 105Celcius and I replace them with Panasonic (Brand) 2200uF / 6.3V / 105Celcius Low ESR (Part Number: EEUFM0J222L).

[rogfanther]

If some OST´s are bulged, chances are that a lot of the other OST on the board are bad too. Do you have a post car ? Could try replacing all the 820uF or greater OST.

Is this from a Fujitsu computer ? Also, seems the board doesn´t have a speaker soldered. If you connect on the the front panel pins, and power the board without RAM, does it beep ?

[Stanley1843]

First of all many thanks for your time to reply me. What do you mean by "Do you have a post car"?
This mainboard is from an old PC that controls a CNC laser router.
It doesn't have a speaker solder on the PCB neither have in the panel. I started without a RAM but doesn't beep and makes the same thing again. Do you know if can I connect a buzzer (how can I find the pins - if it has pins for speaker/buzzer)?
Do you suggest me to change all the capacitors?

One thing that I remebered. I had the same motherboard before some years where was working fine and I replaced preventively these two capacitors that I changed at this time and the motherboard made the same exact problem like this one that I am trying to repair now. Back then I have checked all the voltages and I re-program the BIOS and all these movements that I made this time but I couldn't make it to work again. How do you explain this; just from the preventively changing of these two capacitors a working motherboard stop working?

[rogfanther]

Oops, sorry. I meant a "Post Card", to insert in the pci slot and see bios debug codes.

Without a buzzer connected, you won´t hear the beeps. Yes, you can connect one, it should be in those pins near the atx connector. The photo doesn´t show if there is something written around them, so maybe you need the manual to see that.


Can you take a better picture of it? Cannot read the markings on you picture.

[Stanley1843]

Could you suggest me to buy a "Post Card" (part number or brand or link)? I always want to buy one and now I think it is the time.
For this motherboard I couldn't find a manual and I found a manual from another model of motherboard where it seems that is the same from what I check in my motherboeard (I don't know if you know a site that I could find it).

[rogfanther]

If the other pins/connections correspond to the way the motherboars was connected to the front buttons, then I believe the buzzer is connected to those yellow points, yes.

[Stanley1843]

Do you know any trusted "Post Card" (part number or brand or link) to suggest me to buy?

[rogfanther]

Just a couple from Aliexpress, no specific recommendation. They are useful to know if the board is at least a little alive, or if nothing is working.

Alsi, please post pictures of your board, both sides.


https://www.aliexpress.com/item/1005006053395173.html

https://www.aliexpress.com/item/32832307293.html

https://www.aliexpress.com/item/1005006338028041.html

https://www.aliexpress.com/item/1005006757438677.html

[piernov]

I would recommend getting one that can be hooked up to LPC bus through TPM header or manual soldering, more modern desktop boards don't have PCI slots and neither do laptops, so all you have left is LPC bus. (if you are lucky enough there's a debug connector but not always)

[Stanley1843]

I would recommend getting one that can be hooked up to LPC bus through TPM header or manual soldering, more modern desktop boards don't have PCI slots and neither do laptops, so all you have left is LPC bus. (if you are lucky enough there's a debug connector but not always)

Thanks for your reply. You mean something like this?
https://vi.aliexpress.com/item/10050...yAdapt=glo2vnm

[Stanley1843]

Just a couple from Aliexpress, no specific recommendation. They are useful to know if the board is at least a little alive, or if nothing is working.

Alsi, please post pictures of your board, both sides.


https://www.aliexpress.com/item/1005006053395173.html

https://www.aliexpress.com/item/32832307293.html

https://www.aliexpress.com/item/1005006338028041.html

https://www.aliexpress.com/item/1005006757438677.html

Thanks again for your help.

[Stanley1843]

If the other pins/connections correspond to the way the motherboars was connected to the front buttons, then I believe the buzzer is connected to those yellow points, yes.

Hello,
I received the PCI tester cards from the alliexpress and I attached on the motherboard.
The one of them show nothing "--".
The second show "0000".
The third show "FF".

As I saw in a "PC Analyzer Users Guide" pdf that I found on the internet:
The "00" means "Code copyng to specific areas is done. Passing control to INT 19h boot loader next.
The "FF" means "Flash ROM programming was succesful. Next restarting the system BIOS."

Do you know what these codes means?


Tests where I have do until now:
I have replace the RAM with a same and functional one (from a same second PC that I have).
I have replace the CPU with a same and functional one (from a same second PC that I have).
I check the CPU socket for bend pins and all are ok.
I have replace the BIOS chip with a same and functional one (from a same second PC that I have).
I have replace all the caps in the yellow circles with brand new capacitors.
I place a buzzer on the motherboard and no beep even when I remove the RAM.

I can't understand what is the problem at all.

[Stanley1843]

New update:
I check the voltage with oscilloscope on the CPU coils and the CPU don't have the proper voltage. If touch the CPU when the fan spins is slightly hot.
I measure the pulses from the 15,18,19 pins of ISL6565BCRZ (Multi-Phase PWM Controller) and looks OK. Also, these pulses arrive at the pin 3 of each ISL6612ECB-T (Advanced Synchronous Rectified Buck MOSFET Driver) respectively.
The problem in my opinion is at the output pin 1 that drives the high side mosfet. And in three chips ISL6612ECB-T the pulses are weak and seems like a noise.
I checked for shorts but I didn't find anything and I replace the electrolytic caps.
Any idea of what is going on?


https://www.renesas.com/us/en/docume...6613-datasheet

https://rocelec.widen.net/view/pdf/t...=true&u=5oefqw

[Aliencomputres]

put a single memory stick in each slot.