Graphics Cards

[Gabethebabe]

Hello everyone, I'm troubleshooting a dead R9 290(reference PCB) that won't power up.  I have very limited technical knowledge, but I have another (working) R9 290, a multimeter and I can read numbers

https://i.imgur.com/8QdlVDF.jpg

The U300 converter requires 12V input on its upper-left pin and 5V on the red marked pin. As a matter of fact, on my bad card, this 5V does not materialize. It's like 0.25V. We have a short here, because the resistance to ground is only 25 Ohms, and it should be like 50k Ohm.

I also note some (significant) differences in the resistances of the green marked capacitators, The green side = ground. The 8 ones on the right have 34 ohms on my bad card and 285 on the good one. The C102-C104-C305 have 1.8k ohm on the bad card and 4k on the good card. I have no clue if this is significant and if it  significant, if is a cause or an effect of the short.

From here, I have no clue how to further troubleshoot and find the bad component. Any help is much appreciated. Cheers.

[BNITRO]

Hey Bud, 

First thing relax take ur time, and LEARN... 

NITROs NERP guide "Nitro Electronic Repair & Parts"

LOOK AT the card, 

CHECK PCI SLOT PINS on the CARD FOR CORROSION 

CHECK VRM FOR CRACKS or DAMAGE such as warped surface...

CHECK the SOLDER for super greyed out solder balls meaning oxidization.

CHECK for any parts that may have been damaged or ripped off..

IF ALL CHECKS OUT, DUMMIE tried to flash a custom mining bios... 

CHECK THE BIOS CRC I've had to reflash A lot of 500 series parts of the bios just would disappear,,

R9 290, prob just a main fuse... GO TO THE 8PIN power connector and follow the connections.. BLACK dot surface mounted part is resistor, white or grey fuse, Black dot with a direction dot or line is a diode, bit metal tubes are capacitors, metal boxes are coils/chokes , little squares with all the little pins around the edge are power controllers, rectangles with 3 pins can be a filter or a rectifier, the metal boxes with 1 big tab and 2 to 3 pins is a mosfets, most of the time its just same part different size and output...