Hi,
I've rescued an old Dell LCD monitor from work which blew up a few weeks ago. I decided to dredge up my old (OLD) hardware skills and have a go at fixing it up.
It had gone flash/bang, so I assumed a capacitor had just given up the ghost. which would leave me with a cheap and easy fix and a free monitor, however after opening it up, I found what looks like a charred resistor.
https://goo.gl/photos/s8GQskGb1sxEQPwt9

The markings on there aren't what I'm used to, it's pink-ish and has F0 written on the visible side and an E after the charred section (visible in the photo). After removing it, I can see it says F1J on the other side, and 0.2(charred section), so I'm guessing it's a 0.2ohm resistor. I just want to work what it is and track down a replacement part (actually a couple as I suspect that the cause of the problem is not the resistor, and if that's the case it'll likely blow up again and I'll have to try to track down whatever else is wrong on that board.

The board looks like it's the main power board for the monitor.

Any help would be greatly appreciated.
If it's relevant, I've got a degree in electronics so I'm not and complete noob and not likely to blow myself up, but I only just scraped a pass and I've not used it practically in over 15 years, so I'm not really up to speed on this these days (these days I'm all about the software).
Thanks
Chris.


Moderators Note:
Please upload your image files to our forum and compress them to as 800x600 or 1024x768 jpg files, above two files already uploaded, thank you.

 

Oh, and if it helps, the monitor is a Dell U2410, and the part number is R850 as marked on the PCB.
I've tried tracking down the Service manual, and all the results so far have been virus laden or insisting that I create an account before they'll show me the document (which makes me very suspicious).

 

If, when you measure its resistance it comes up open circuit then it is a fusible resistor or "resistor fuse".

Rarely do resistors themselves cause failures like that. Most likely there are one or more defective parts that caused the damage to the resistor.

 

Thanks, yeah, I was leaning that way, and had suggestions from a friend in that direction as well. Yes, the resistor shows as being open circuit, everything else looks OK, but that doesn't mean much. I'm hoping that maybe it was just a temporary power spike that caused it to fail, or it just failed due to age, otherwise it's probably out of my reach to fix it myself.
Looking at the underside of the PCB, the old solder flux around a number of the transistors in the vicinity of the blown resistor is dark brown, suggesting that they've got a bit hot over time, but being that it's the main power board, that's not necessarily an indication of a problem right?

 

You will probably find one or two power transistors on a heatsink between the mains input and the transformer and one or both will be short circuit. When this happens they generally take out some other components and you have to find all the faulty parts or it will likely do the same again when you power it up. This is, to say the least, difficult even with the schematic.

 

Here is an article describing how you can check those transistors with a multimeter.
http://www.allaboutcircuits.com/textbook/semiconductors/chpt-4/meter-check-transistor-bjt/
Or, if you prefer to watch a video lesson...

Just in case the transistors are MOSFETs...