Bad caps in US Robotics 24-port switch

[linker3000]

Hi, I have just dismantled a US Robotics 24-port switch (997924) that had completely died. The unit has a 3.3V 6A SMPSU boad made by Achme Corp and there were two bulging Teapo caps (1000uF and 2200uF at 10V) on the output side. I replaced these and the unit worked for about 30 mins and then died again - not even a whistle this time. There is also a Teapo HV electrolytic which I have not replaced yet (all I have done is a basic low voltage check with an ohmmeter for an open/short) but any other suggestions are welcome - I guess something else has been stressed by the faulty caps or one of the new ones has failed early?

[Tom41]

Re: Bad caps in US Robotics 24-port switch

Did you just replace the caps that looked bulged? Teapo are notorious for failing without physical signs, so it's possible that other caps on the board have failed. Replacing the bulging caps would have sorted your problem temporarily, but these new caps would get stressed by the already failed caps and the unit would die again.

If you have an ESR meter, check all the other Teapo caps for ESR. If not, it's probably best to replace all the caps that have a visible vent pattern on the top - even if they're not bulging.