abs 5-port gigabit ethernet switch, bad caps in power supply

[brianl703]

This switch died on me last week. According to the logs on my Linux machine, I discovered the problem just 12 minutes after the Linux machine lost the link to the switch. The power light on the switch lights up but the "alive" light doesn't blink.

I took it apart and I found a Seasonic 3.3V 2A power supply inside of it with a bulging cap. This is a 120/240 input supply.

The bulging cap is a Nichicon HD(M) 6.3v 1500uF.

I thought Nichicon were good capacitors?

I tried supplying 3.3V from an ATX power supply to the power supply input on the switch's main board, the "alive" light started blinking but I still got no link.

All I can think of is that the way I supplied 3.3V to the board is a little too sketchy to make it work--I used 24 awg solid wires jammed into the ATX power supply connector connected with alligator clip leads to the banana plug ends of the test leads from my multimeter, then used the test leads to input power to the board.

Apparently this switch draws pretty high current off the 3.3V power supply since there's two ground and two 3.3V wires going to the switch's main board.

Really I want to confirm that this switch still works before I go through the trouble of replacing the capacitor in the power supply.

I just checked and I got this switch back in February of 2006 so it lasted not quite 2 years. Interestingly, the price of 5-port Gigabit switches haven't dropped any since then.

[kc8adu]

Re: abs 5-port gigabit ethernet switch, bad caps in power supply

the extra leads may be remote sense.
is this psu that hard to work on?
i would have spent my time recapping asap.hd are ok but any can fail if overheated.

[brianl703]

Re: abs 5-port gigabit ethernet switch, bad caps in power supply

I'd have to order these replacement caps. I didn't think to order any extras when I replaced all the caps in my DVD player a couple of years ago. Or maybe I did and I've long since misplaced them.

[PCBONEZ]

Re: abs 5-port gigabit ethernet switch, bad caps in power supply

Nichicon are good capacitors.
Even good capactors fail once and a while.
.

[Krankshaft]

Re: abs 5-port gigabit ethernet switch, bad caps in power supply

The test probes you tried applying the power through probably were making intermittant contact. Its always best to solder directly onto the traces when testing.

In any case did you check the 3.3 volt current draw for the swtich and compare it to the maximum current of the 3.3V rail on the power supply?

If the supply's output current was too low all kinds of things can happen.

Also if the original supply had dual 3.3 Volt outputs you will need 2 3.3 Volt outputs at the proper current to test it.

[brianl703]

Re: abs 5-port gigabit ethernet switch, bad caps in power supply

The ATX power supply claims something upwards of 10 amps on the 3.3V rail (I don't recall the exact figure), of course it's entirely possible that the ATX power supply I used doesn't even work right, since I never tested it in a PC. (All I did was measure the 3.3V output with no load).

[davmax]

Re: abs 5-port gigabit ethernet switch, bad caps in power supply

Hope you are planning to replace all similar caps. If heat made one bulge, any others will be stressed and near end of life.


Good luck.