Reply 40 of 41, by Jepael
You must check two things about those traces with scratch marks on them:
1) Are there any shortcuts between the different traces and remove them by scratching them away with some sharp object
2) Are there any cuts in the traces and if there is figure out a way to reconnect them (conductive lacquer, reconnect them with a wire or something)
There is no way to measure if caps are bad while they are mounted on board, you must remove a cap and measure it if you want to measure them. There are multimeters that can measure capacitance, or special tools like LCR meters that can for example measure capacitance at certain frequency and effective series resistance (ESR).
Please note that most likely you don't want to remove them just for measuring, as most likely a worn-out electrolytic capacitor does not cause the whole card to fail suddenly.
I have to repeat that I have never had to replace any capacitors on sound cards. Besides, some electrolytic caps are there to provide local bulk power supply reservoir, while others are there to pass audio signals through them, so it makes no sense to change them all to good power supply capacitos or good audio grade capacitors. Modern general purpose electrolytics are better than the old general purpose electrolytics that were originally put on the card. If you put too good capacitors there to filter power for example, in an old system the best and lowest ESR capacitors on your sound card start to filter out the power supply ripple current for the whole system which may even cause more noise on the sound.
