capacitor's in a power supply

Thread Starter

Rogerbrownbrown

Joined Jan 28, 2019
2
In the output stage of a power supply what would changing one electrolytic capacitor for a different value do. I have a D-Link DSL-2640B wireless router that stopped working and after taking the lid off of the power supply I see one of the electrolytic capacitors right next to the outlet cables has blown, it is a 300uf electrolytic, and I was wondering if I don't have a spare 300uf in my junk pile what will it alter if I replace it with the next nearest capacitor I can find give or take a few Uf.

This one is very strange as the power supply is still outputting the correct amount of voltage and powering up the router I.e all lights on the router light up however the said cap seems to have something to do with amperage as the supply is outputting 0 amps under load and is making the power light on the router stay red and not change into ready mode (green) so my assumption is the supply is not giving enough amps to kick something in due to the blown cap.

so again my question is will replacing the cap with either a smaller or larger Uf rated cap harm anything, I am assuming as I have narrowed this down to controlling output amperage that it will alter the amount of amps outputted with different values of cap.
 

ericgibbs

Joined Jan 29, 2010
9,136
hi Roger,
A close value cap of the same working voltage should be OK.
A problem could arise if the power supply is a switched mode [SMPS] this type of SMPS requires low ESR type caps [ low equivalent series resistance].
Which type of power supply do you have?
E
 

mvas

Joined Jun 19, 2017
538
In the output stage of a power supply what would changing one electrolytic capacitor for a different value do. I have a D-Link DSL-2640B wireless router that stopped working and after taking the lid off of the power supply I see one of the electrolytic capacitors right next to the outlet cables has blown, it is a 300uf electrolytic, and I was wondering if I don't have a spare 300uf in my junk pile what will it alter if I replace it with the next nearest capacitor I can find give or take a few Uf.

This one is very strange as the power supply is still outputting the correct amount of voltage and powering up the router I.e all lights on the router light up however the said cap seems to have something to do with amperage as the supply is outputting 0 amps under load and is making the power light on the router stay red and not change into ready mode (green) so my assumption is the supply is not giving enough amps to kick something in due to the blown cap.

so again my question is will replacing the cap with either a smaller or larger Uf rated cap harm anything, I am assuming as I have narrowed this down to controlling output amperage that it will alter the amount of amps outputted with different values of cap.
The replacement capacitor MUST must have the exact same voltage rating, or higher.
Make 100% sure you align + and - pins properly.
A cap with a slightly different uf might work, give it a try.

Measure the Voltage from the AC-to-DC adapter, is it pure 12 Volts DC ?
 
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