Msi B550M PRO-VDH Identified Missing Components

[Rabit]

Hi I get cheap boards to repair ,missing I assume 1 to 3 SMD and 2 pads
Anyone know what SMD missing ?

Right Down Corner next to screw hole

Zoom

Closer Zoom on PAD A I not see any additional connection I can assume dead end ?

Closer Zoom on PAD B

[Rabit]

Re: Msi B550M PRO-VDH Identified Missing Components

I bought open box motherboard to clearly see what is missing and later return.

resistor show on multimeter 10kohm in circuit measurement

second smd I believe is capacitor can anyone identified it ?

[DynaxSC]

Re: Msi B550M PRO-VDH Identified Missing Components

It's a MLCC cap, but to measure its capacitance, you need to take if off the board.
Also power the board, and look what voltage is standing on the cap, then use a cap with at least higher nominal voltage, but to go sure use the highest voltage you can find in this case and capacity available.

[Rabit]

Re: Msi B550M PRO-VDH Identified Missing Components

I cannot take it of board without risk that board will not be accepted after return.
Max V on board can be 12V I go with random 16V capacitance I try my luck
Previous owner manage to power this board without of this smd but he have reboots.

Edit:
First I try ask MSI support to provide me with values of this missing SMD, before I try my luck with random value

Edit 2:
Missing Capacitor looks like (X7R, X5R ceramics) light brown microfarads range.

[Lisa Su]

Re: Msi B550M PRO-VDH Identified Missing Components

I am pretty noob to the game so not sure if it's possible to identify these missing components from the schematic. I hope it helps.

[Rabit]

Re: Msi B550M PRO-VDH Identified Missing Components

I am pretty noob to the game so not sure if it's possible to identify these missing components from the schematic. I hope it helps.

Sadly no if this was board-view, this will be different.

[Rabit]

Re: Msi B550M PRO-VDH Identified Missing Components

MSI respond that they cannot provided any info , crappy company practices.
My last solution is to visit Rusian hackers forum and buy board-view and schematic of this board that they steal from MSI.

[DynaxSC]

Re: Msi B550M PRO-VDH Identified Missing Components

Hi, I woud give it a try with the schematics. The chip near the missing cap is 99% a NCT3933U. There are 4 of them on page 57 in the schematics, called "Over Voltage Control IC". The marking in the datasheet meets the one on the good board. The other chip on your board will be the same, but different make.



If there is a connection on the board between the cap and this chip, you might be able to deduct which cap this is on the schematics, also comparing the resistor values, which can be measured in circuit in most of the cases.

If you attach a picture showing a slighly bigger area, I could have a look on this too. Also one pad of the cap goes somewhere to the "north", it would be helpful to check where it is connected to, eg to identify a part with marking/type, which can be found on the schematics easily.

[Rabit]

Re: Msi B550M PRO-VDH Identified Missing Components

Checked on this chip what leg is connected to resistor pad and this lock like pin2 sense and in block diagram I see one with 10kohm 1% resistor this equal to my results from multimeter.


I make close up oh chip connected to capacitor pad

[Rabit]

Re: Msi B550M PRO-VDH Identified Missing Components

Resistor from first pin second chip show 93ohm on my multimeter on block diagram I find only one 11 pin chip that have resistor 0ohm + capacitor on first pin and no GND on pin 1-10 like this chip
page 55 RT8125E

[DynaxSC]

Re: Msi B550M PRO-VDH Identified Missing Components

The chip with the marking MK=7K is a Richtek RT9553B, its the U9 on page 60 of the schematics. Pin one of this chip is 12VN_CS_N_R signal, and it is connected in the schematics (only by the signal name) just below to R34 (93.1R 1%), so what you measure.



So the the resistor just below the cap (on picture with the S83P) could be R34 and your missing cap is most probably C46 (10u 6.3V) as there is no other cap connected directly to pin 1 of U9 and the signal 12VN_CS_N_R is to be found only twice and only on page 60. The other resistor to the left and down is probably R33 / 93,1R1%. Pls measure this resistor to confirm.

To confirm this 1000% it would be interesting, where the pad marked "2" of the cap is connected. I suspect it goes through the "north" going track to one of the pins of CHOKE1 which is most probably just aside to the 12V 8pin CPU power connector.

BTW, the Richtek marking, only the two first letters are meaningful, "=" is always there, and the two final characters are only manufacturing date codes.

[DynaxSC]

Re: Msi B550M PRO-VDH Identified Missing Components

& Lisa Su, thanks for the schematics, one never knows when it can be needed.

[Rabit]

Re: Msi B550M PRO-VDH Identified Missing Components

Left and down 93ohm confirms

last question about resistor 10kohm for NCT3933U what wattage use ?
I see in schematic 1%4 this will be 250mW ?

Thank you all for help

[DynaxSC]

Re: Msi B550M PRO-VDH Identified Missing Components

4 means probably case 0402, as far as I remember in this case max. wattage is 0,125W. As this is 10kohms it does not play a role, as max. wattage lost on this resistor will be P = U x U / R, so 12x12/10000 = 0,0144 W, so a range lower than the standard wattage of 0402 resistor case.

[Rabit]

Re: Msi B550M PRO-VDH Identified Missing Components

I ordered already 250mW they will be fine ?

[DynaxSC]

Re: Msi B550M PRO-VDH Identified Missing Components

Sure.

[anikin73]

Re: Msi B550M PRO-VDH Identified Missing Components

you can get grab another capacitor from another board . but same size and colour. the capacitor should be fine. its your copper thread broken and not connected. even if you dun fix the cap, it will still works.

[Rabit]

Re: Msi B550M PRO-VDH Identified Missing Components

lol my 250mW resistor are so large that I not see pads, time to buy smaller one ;0
Capacitor soldered with coper wires, my work results do not look neat at all, my soldering skills are not top notch

[Rabit]

Re: Msi B550M PRO-VDH Identified Missing Components

Sure.

After my fix board booting to bios I check full load stability tomorrow.
And buy something to cover exposed traces.



Once more thanks.

[DynaxSC]

Re: Msi B550M PRO-VDH Identified Missing Components

To cover the best solution is liquid soldermask (polish: soldermaska - easy to buy) you can paint it, and then harden with UV light. It also can act as kind of additional protective glue and is non-conductive. Apply only thin layers at one time, otherwise the UV light may not harden the liquid which is deeper beneeth the surface. Apply 2-3 layers to make is robust. You can use any type of UV light source, the stronger the better (but do not expose your eyes to UV light !!!!), so the hardening time will be lower. Even exposing to sunlight can harden this after a long time. The soldering looks not good but will most probably do its job, you should use more or better flux, maybe temperature is too high. Hotair gun would be better, but for one repair does not make sense to buy one. Also it is more difficult to use hotair gun, you need some practise to do it right, in order not to blow out the parts or overheat and destroy the PCB. Check the resistance of the resistor after soldering, it might happen that too long soldering or bad flux will decalibrate them, they are sensitive to chemical and temperature influence.