Electronic – Whats this white stuff on the board


I'm not an engineer, but my monitor stopped working yesterday (it just wouldn't display anything but still gets power) so I figured I'd like to take it apart and see what went wrong. At the very least I'd get to see what the inside of a monitor looks like :). Anyway, I took it apart, and also read around about my issue and it seems the capacitors have gone bad, at least some of them. However, I also noticed some white elastic stuff all over the board. Some of them are sticking two capacitors together and to the board, but I also see some from where power socket connects to the board.

My question is, what is the white stuff? Should I replace all capacitors that have white stuff around it, and should I also replace the power socket part? Or should I just replace the bulging capacitors and leave it at that?

white stuff

Best Answer

It's very likely to be fastening material for bigger components. Does it look very close to whats on the big capacitor in the middle of this photo, and also at the bottom of this picture, on the blue components. Edit: yes that very clearly looks like fixating material to me. They may have used it as a strain relief in this case for the mains wiring.

This is used to prevent any vibrations getting bad for the solder joints. The big component has a relative large weight and must therefore be fixated down more properly.

If you want to try and fix the monitor you could look for:

  • Dodgy capacitors, their tops are bulged. Replace with equal or higher voltage and preferably same capacitance (amount of uF's). Try to keep it as 'original' as possible, a capacitor that has a much higher voltage is larger, and less likely to fit (also consider the height, monitors are space constrained).
  • Burnt components.. well you should smell and see them. Usually black, toasted and not good. If so you may need to google around a bit to see if there is any information on what the component was (like forums, schematics..)

  • Dodgy transistors or soldering joints. I've fixed a monitor 2 years ago that had dodgy solder joints on the transformers (I just reheated them and added some new solder, didn't even had to remove anything at all) and 4 broken transistors. I was able to get 4 replacement transistors for 5-10$ and it worked for another 1.5 years.. it finally died, this time probably the video controller board (couldn't be bothered now, it's an old 17" slow monitor)

Usually I look for forums and other 'fix guides' on the internet to see what they are attempting and see if there is anything I haven't done yet. Usually one or a combination of these three faults are the most likely ones.