Dead network switch repair

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Dead network switch repair

Postposted on Wed Sep 15, 2010 12:09 am

About a year ago we had a couple of Netgear GS108 8-port switches at work that died and were being thrown out. I took one home; it's been sitting in my junk pile ever since. Finally popped the case open this evening to have a look, and lo and behold there were two obviously failed capacitors on the circuit board (tops of the caps were bulging). The failed caps were TEAPO 1000uF 6.3V units, which were one of the type of caps which were infamous back in the days of the motherboard capacitor plague. I'm kinda disappointed that Netgear was apparently still using these dodgy caps up until about 5 years ago (my guesstimate is that this switch is 4-5 years old).

I still have a sizeable stock of spare caps from several years ago when I was recapping a lot of dead mobos; I rummaged through the pile and found a bag of United Chemi-Con 1000uF 6.3V -- exact same electrical specs as the failed ones. They're also exactly the same diameter, but slightly taller (but still short enough to fit inside the case when it is reassembled). I swapped out the two bulging caps, and put the switch it back together; it seems to be working! I just tested it by transferring a 4GB file through each port (in both directions), and verifying that it was transferred error-free.

Looks like I can move this one from the junk pile to the spares pile now... :wink:
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Re: Dead network switch repair

Postposted on Wed Sep 15, 2010 7:14 am

Yup, I had the same thing with an old 100Mb/s switch a few years ago. I recapped it and it was working fine. It's now on my spares pile after I upgraded to GigE. I believe the bad caps plague affected an awful lot of stuff, not just motherboards.
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Re: Dead network switch repair

Postposted on Wed Sep 15, 2010 7:49 am

This one will likely move from the spares pile to active duty in the very near future, since it is a gigabit switch. My home network is still a mix of 100 mbit and gigabit, and I'm working on phasing out all of the 100 mbit stuff. As soon as I get around to running some Cat6 to the crawlspace I plan to move a couple of servers there... the crawlspace also feeds wired Ethernet to the family room above it, so I'll definitely want a decent switch.
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Re: Dead network switch repair

Postposted on Wed Sep 15, 2010 1:13 pm

Hmmmm I have a GS105 at home that's flaking out a little lately. How hard is it to recap these things? I'm still somewhat of a novice with soldering on machine assembled hardware, although I have a good bit of time under my belt working with a bread board.
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Re: Dead network switch repair

Postposted on Wed Sep 15, 2010 1:42 pm

Nice, wish I hadn't thrown out my old switch now, after years of leaving it sitting in the cupboard =X.
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Re: Dead network switch repair

Postposted on Wed Sep 15, 2010 2:38 pm

SuperSpy wrote:Hmmmm I have a GS105 at home that's flaking out a little lately. How hard is it to recap these things? I'm still somewhat of a novice with soldering on machine assembled hardware, although I have a good bit of time under my belt working with a bread board.

Piece of cake, since the caps that need replacing are "old school" through-hole devices (not surface mount), and large enough that you don't need tweezers and a magnifying glass to work with them.

On the GS108 (I assume the GS105 is similar) there are six screws (two holding the case together and four holding the board in place). There are 5 electrolytic caps in there -- 2 1000uF ones and 3 330uF ones. I only replaced the 1000uF ones as the 330s were not bulging and I didn't have any suitable replacements for those anyway.

I used a 25 watt pencil-style soldering iron; a slightly higher wattage one would've probably worked better, as the power planes of the PCB act as heat sinks and make it somewhat difficult to melt the old solder.

Removing the old caps --

Electrolytic caps have a "+" and "-" side. Note the orientation of the old caps before removing them, as the replacements will need to be installed with the same polarity.

Apply heat to one of the capacitor leads from the underside of the board, while gently pushing on the top of the capacitor can on the same side of the can as the lead you're heating. When the solder softens, the other lead will bend and the one you're heating will pull partway out of the hole. Switch to the other lead, and repeat. After 2 or 3 cycles of this you'll have "walked" the capacitor out of the mounting holes.

Clear the holes of old solder using your soldering iron and a solder-sucker type tool.

Installing the new caps --

Put the leads through the holes, observing proper polarity. Push the leads all the way through so that the cap is flush with the PCB, and bend the leads apart slightly on the underside of the board to hold the cap in place while you solder.

Solder the new caps in place, trim the leads.

That's about it...
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Re: Dead network switch repair

Postposted on Wed Sep 15, 2010 3:34 pm

just brew it! wrote:That's about it...

You forgot the part about inhaling the lovely fumes given off by hot solder. 8)

Yeah, I built WAY too many Heathkits back in the day.
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Re: Dead network switch repair

Postposted on Wed Sep 15, 2010 6:43 pm

If any one is starting now then they are going to be getting the lead-free solder. They will only get the joys of burning flux fumes and not the heavy metal poisoning. I'm still going on my big old roll of proper solder with lead and it hasn't affected me yet! 8)
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Re: Dead network switch repair

Postposted on Wed Sep 15, 2010 8:43 pm

notfred wrote:If any one is starting now then they are going to be getting the lead-free solder. They will only get the joys of burning flux fumes and not the heavy metal poisoning. I'm still going on my big old roll of proper solder with lead and it hasn't affected me yet! 8)

You can still get tin/lead solder at Ace Hardware or Radio Shack. Digi-Key (my online electronic parts vendor of choice) also still stocks it.

I imagine if you live in Europe it is probably difficult/impossible to find though.
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