Performance of stored PC SMPS for several years

Thread Starter

Willen

Joined Nov 13, 2015
291
I have $35 biostar mainboard facilitated desktop computer. Was working fine. Today I replaced a SMPS which was used few years andvthen stored almost 3 to 4 years. To avoid capacitor explosion, I powered the SMPS with no load, and left ON a day. Then used in desktop. Looked like worked but I keyboard started to behave strange. If I just long pressed a key, computer used to get multiple clicks. Sometime clicked twice at one and sometime not even a click. Hard to type.

Then changed previous working SMPS, keyboard worked well and was stable. Again used the stored SMPS, keyboard started unstabilizing the performance. Again now, used previous working SMPS.

But how? Because the stored has poor capacitor condition and unable to smooth the supply, which causing effect in keyboard? Interesting
 

roadey_carl

Joined Jun 5, 2009
132
But how? Because the stored has poor capacitor condition and unable to smooth the supply, which causing effect in keyboard? Interesting
Yup, you're exactly right. Once the electrolyte dry's / starts drying out in a electrolytic capacitor, the ESR increases and it's capacitance decreases. They let all sorts of noise and frequency though which causes chaos. I had a very similar problem with an old laptop power supply recently. When it was plugged in I was unable to use the touch pad. I tested the filter caps and they were all out of spec by a mile. I replaced them and it worked fine.
 

Thread Starter

Willen

Joined Nov 13, 2015
291
Are you sure Willem, it was stored in a dry place?
I had found the SMPS stored in rough condition. Sometime sunlight and wet in rainy day.

Yup, you're exactly right. Once the electrolyte dry's / starts drying out in a electrolytic capacitor, the ESR increases and it's capacitance decreases. They let all sorts of noise and frequency though which causes chaos. I had a very similar problem with an old laptop power supply recently. When it was plugged in I was unable to use the touch pad. I tested the filter caps and they were all out of spec by a mile. I replaced them and it worked fine.
YES! I was expecting to hear this type of experience. Did you changed output low voltage high uF filter capacitor or changed input low uF high voltage capacitor?
 

roadey_carl

Joined Jun 5, 2009
132
I had found the SMPS stored in rough condition. Sometime sunlight and wet in rainy day.


YES! I was expecting to hear this type of experience. Did you changed output low voltage high uF filter capacitor or changed input low uF high voltage capacitor?
I changed the output capacitors. I'll be honest, I didn't even check the input one!
 
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