U.S.ROBOTICS 1000 SWITCH Mod USR7930

[LEMO]

Delta Electronics ADP-30JP Powersupply ADP-30JP used in Netgear FS308
After Powerdown no OUT voltage
Found def CAP 47uF 25V has 4,8uF ESR =>20.0ohm


Helpful was:
https://groups.google.com/forum/#!to...-y/q7Zg4eESXEE

A very common failure mode in SMPS's is an electrolytic cap in the startup circuit, causing the PSU
to fail to restart after a power interruption. This is often mis-attributed to mains problems/spikes
etc. as the fault only exhibits after a switch-off, when it then fails to re-start - the problem may
actually have been there unnoticed for years if it has never been switched off.
Look for a small, low-voltage (<=63V) electrolytic on the mains side of the supply - there will
typically only be one, and replace it ( ensure the replacement has a 105 deg.C temp rating).
And be careful - the main HV reservoir cap on a non-starting PSU can really hurt for many minutes
after disconnecting from mains...!

[kasfamily]

Re: U.S.ROBOTICS 1000 SWITCH Mod USR7930

Yeah a lot of money on this raised

[budm]

Re: U.S.ROBOTICS 1000 SWITCH Mod USR7930

Very common startup cap failure for the Vcc of the SMPS IC. If you heat up the cap with hair dryer, you will see the ESR goes down if the cap is not too far gone.