Have one of those common brick type switching power supplies. Typical 12vdc 3A output. Is still working fine, but I have narrowed this supply down to putting noise back onto the AC line which is affecting the control of some X10 equipment. The issue recently started so i suspect one of the internal components is failing, anything in particular I should look for, the electro caps physically appear fine, but will pull them tonight and check their ESR.?
Thanks Nigel. Just ordered a ESR meter off EBAY. Seems to have favorable reviews on various sites. Did have a DIY ESR I made but broke the analog meter and can't be bothered to fix.
Turns out 1 dead 33uf 400v cap on the board. Easy find with my new ESR meter that arrived from Ebay the other day. Going to replace it along with all the others.
Turns out 1 dead 33uf 400v cap on the board. Easy find with my new ESR meter that arrived from Ebay the other day. Going to replace it along with all the others.
Presumably that's the reservoir capacitor? - amazing how some SMPSU's still work with that completely O/C, and yet some 'explode' if it is
It would explain the huge increase in RFI, that's a common symptom of it's failure.
However, one point to bear in mind, such capacitors don't test well on ESR meters - even good ones tend to have a far higher ESR than you would expect - but in this case it's likely to be so bad that it's obviously duff.
Presumably that's the reservoir capacitor? - amazing how some SMPSU's still work with that completely O/C, and yet some 'explode' if it is
It would explain the huge increase in RFI, that's a common symptom of it's failure.
However, one point to bear in mind, such capacitors don't test well on ESR meters - even good ones tend to have a far higher ESR than you would expect - but in this case it's likely to be so bad that it's obviously duff.
Another way to find bad DC filter caps in power supplies is to set your meter on AC to measure the ripple voltage when the supply is running under load.
There will always be some ripple, but not too much. Unfortunately there is industry standard number for how much is too much, but I'll throw out a target of < 10% of the DC value.
I'll start measuring those values on good and bad supplies to gather some statistics.
Another way to find bad DC filter caps in power supplies is to set your meter on AC to measure the ripple voltage when the supply is running under load.