INTEL NUC BOXNUC8I5BEK2 - zwarcie na zasilaniu

Witam. Na stole INTEL NUC BOXNUC8I5BEK2 model NUC8BEK mb: NUC8BEB. Po podłączeniu zasilania zwarcie - element zaznaczony ewidentnie uszkodzony. Zdjęcia przedstawiają płytę przed i po wylutowaniu elementu. Po piktogramie można domniemywać , że był to jakiś rezystor .... Po jego zdjęciu zwarcie na zasilaniu ustaje - jednak na jednym z padów zwarcie nadal występuje. Próba zwarciowa na tym padzie powoduje nagrzewanie się układu zaznaczonego strzałką na zdjęciu - czyżby uszkodzona hybryda ?

Hello!

Measure the resistance between points "A" and "B" as marked in the following picture.

matic napisal/-a:Hello!

Measure the resistance between points "A" and "B" as marked in the following picture.
[ Obrazek ]

Resisance between A - B is 4,8 ohm.

Remove the MPxxx chip marked with an arrow from the board and remeasure the resistance between points "A" and "B".

pawel1978 napisal/-a:[ Obrazek ]

matic napisal/-a:Remove the MPxxx chip marked with an arrow from the board and remeasure the resistance between points "A" and "B".

pawel1978 napisal/-a:[ Obrazek ]

Now resistance is 2,5 ohm

Remove the coils L1, L2, L3 from the board (picture below) and measure the following resistances:

• Between point "A" and point "B".
• Between point "A" and point "C".
• Between point "A" and point "D".

matic napisal/-a:Remove the coils L1, L2, L3 from the board (picture below) and measure the following resistances:

• Between point "A" and point "B".
• Between point "A" and point "C".
• Between point "A" and point "D".

[ Obrazek ]

AB- 77kOhm
AC- no transition .. solder on MPxxx chip place?
AD- 110kOhm

On the other side of points C and D, the resistance to A is now 3.8ohm

pawel1978 napisal/-a:AC- no transition .. solder on MPxxx chip place?

Not for now.

Measure the resistance to ground on point "A".

matic napisal/-a:

pawel1978 napisal/-a:AC- no transition .. solder on MPxxx chip place?

Not for now.

Measure the resistance to ground on point "A".

A to ground - short circuit - 0.05ohm

Perform a short circuit test on point "A" with removed coils L1, L2, L3 and with removed MPxxx chip. For s short circuit test limit the voltage to 1V.

matic napisal/-a:Perform a short circuit test on point "A" with removed coils L1, L2, L3 and with removed MPxxx chip. For s short circuit test limit the voltage to 1V.

Founded damaged capacitor ...

Remeasure the resistance to ground at point "A" with a damaged capacitor removed from the board.

The short circuit is gone. I hurried up and re-soldered L1, L2, L3 and MPxxx. The resistance between A and ground is 40kOhm

Check the transistor between the DC socket and point "A".
If it's good, replace the damaged capacitor and replace the resistor at point "A". Then test the board.

The value of damaged capacitor is most likely 10µF/25V, package 0805.

matic napisal/-a:Check the transistor between the DC socket and point "A".
If it's good, replace the damaged capacitor and replace the resistor at point "A". Then test the board.

The value of damaged capacitor is most likely 10µF/25V, package 0805.

Mosfet marked SM3303 is damaged. What should be the value of the burned resistor?

pawel1978 napisal/-a:What should be the value of the burned resistor?

Are there any visible markings on old resistor?
It is most likely a low value resistor, probably with a value around 0,01 - 0,02Ω.

After replacing the damaged mosfet and resistor, the equipment started working properly. Thanks matic!