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Repair of an Allied Telesyn switch
Hi folks,
I have a very simple 100Mbit/s switch from Allied Telesyn (AT-FS716) laying next to me, which is
doing exactly nothing: Power supply defective.
I'd like to repair it, just for gaining experience with stuff like this and to get a (even 100MBit switch) back to work
The power supply has a model type printed on it: T99A019 REV 01.
I already replaced TOP234Y as it seemed to be the source of the problem but it did not help me in any way with it.
At the output I can messure 0V; 0A.
Here are some pictures:
If I forgot anything, please sent a reply, then I will try to add
it as soon as possible.
Thanks in advance :-)
Thanked by 1irm
Comments
Figure out the voltage output, if it's anything standard like 3.3 5 or 12V, covered by atx, just use atx power supply. Check the current too, don't use lower amperage than the factory supply on the rail you're using.
Take better pics of the capacitors (preferably from a slight angle) to see if they're bulging.
what's the point in learning how to fix a switch ? Would you put a self fixed switch back into production ?
Perhaps he'd just like to learn? Maybe the switch isn't for production?
Yeah, I agree. Fuck learning new skills. Especially ones that teach you how to repair things even as a hobby. I mean, who would want to take time out of their day to tinker with something that they might find interesting like repairing and/or repurposing electronics for personal use. What a loser!
/s...
That would be way too bulky and wouldn't count for a real fix (as it's unlikely you can fit even the bare ATX PSU board inside the switch case).
You could go for a laptop PSU though
Got a switch like this recently, and still unsure if it's a factory batch (ran out of proper PSUs?), or repaired/refurbished. Gives proper voltage, the connections look very quality made with heatshrink tubes over everything, etc.
Quite a bit of the Ubnt line of hardware has a PSU like that. Mostly orginal hardware and not the newer more “pro” hardware.
Hey Clouvider,
I thought better of you...
Who is using a 100MBit switch in DC production?! Many people here got the point, as they read even the second sentence. Sorry, thats simply ridiculous.
Gaining repair skills in 2017, where everyone is simply throwing away everything for a defective capacitor is a good thing.
Thanks, you got the point :-)
I talked to my ex teacher a few hours ago and we measured some components, he said, that the TOP234Y was definitely defective and that it was a good move to replace it. The last problem seems to be a blown fuse (brown round component, next to the 230V input)
I already bought a new fuse, I will replace it in 3 hours and will reply to the theme for completion.
Thanks to you guys
Ok, I think I was misunderstood : ).
I feel that there are many more useful skills to learn rather than fixing a damaged switch (any switch) since one wouldn't put it back into production anyway.
Just personal opinion on the subject, that was in no way an attack or anything on you.
Ok, then we're good. Sure thing, there are many different skills,
some more useful, some less useful.
I wouldn't wan't to gain skills just for repairing a switch. I'd like to
learn more as there aren't that many people, who are good at this
and it's fun to me, bringing devices back to life, which would be
recycled otherwise :-)
Thing is, I have one more of the exact same model of this switch, and that one uses a traditional PSU:
You can see the unused mounting stands for the board on the 1st photo as well.
The red tape looks not too factory default like :-P
Yeah it's not tape there, it's https://en.wikipedia.org/wiki/Heat-shrink_tubing
@rm_ Using laptop power supply goes by default on a MikroTik router board.
Back in the days in high school we used to have an atx psu connected to a, i think 26 port d-link, i'm not that sure, i forgot, anyhow it worked using the 12V rail, sitting on a shelf for solid 4 years. The legend says one can hear the psu buzzing even today, albeit i suspect the sleeve bearing of the psu fan can hold on for that long. Too bad i don't have pictures...
Anyhow, laptop or network gear supply, it's a power brick and your solution is a lot more elegant and even useful in the real world, nice.
There are tons of small PSUs made (rackmount, ITX, etc), so I suspect you could find something without resorting to a laptop PSU.
MEMORIES THRED!
Did the same with a D-Link switch, and also powered a CD-ROM that was so old that it had eject/play/ffd buttons. Then, it also powered that and speakers.
As far as I know it's still used in the repair shop I haven't been for decades. I do know that it became an "internal network switch" when they started thinking they could learn IOS and failed horribly.
Pretty sure that PSU is similar to the logic board I posted to awhile ago about.. maybe even here? It's not precisely a fuse, but it will pop when your voltage spikes.
Anything's a fuse if you put enough power through it...
There are several youtube videos about switch mode power supply repairs, see as example the Mr. Carlson's lab channel. There are dangerous voltages at the mains side of the power supply board and on the filter capacitor, be careful.
The circuit on most cheap/standard PSU is pretty simple and you may be wery well able to repair it. A common newbie mistake is to replace the power mosfet and fuse, see that the circuit is working again, and put the device in operation. This may lead to a new failure after a short time, because the underlining issue is often a faulty or degraded capacitor on the secondary side of the transformer, with increased ESR or a electrical leak. If the power supply is old, I suggest to exchange the capacitors with low-ESR ones. This is not required on industrial or high quality devices, they use high-grade capacitors.
At the office, when I fix a production device and the power supply has a standard output, I usually exchange the PSU board with a new one with same or better specifications, this will be ultimately cheaper and more reliable. On this fact, I agree with @Clouvider. But the skill to diagnose and repair a faulty switch mode PSU is useful. Sometimes it is the fastest way to restart the device while waiting for a spare, or the spare may cost a disproportionate amount of money and a complete replacement of the device is needed as long-term solution, but cannot be done in a hurry - exchanging a faulty electronic component will fix the issue for the time being at a very low cost. Almost any modern device has a switch mode PSU inside, and knowing how to fix them is useful.
My take: you don't repair at all. At least not to put it back into that switch.
Reason 1: switched PSs usually are trick beasts and there is a myriad of design variants ranging from "just implementing the chip producers example circuit" (more often done than one would expect) to serious wizardry. Sure, pretty much everything can be examined and studied but is it worth the effort and are you stricing for that kind of specialist knowledge?
Reason 2: As is the nature of a switch it is electrically connected to many another, often costly devices...
But if you go for it anyway:
what's the plug on the "main" board right next to the PS (second image)? Is it where you disconnected the PS? Or was/is it unused?
replacing a not customer replacable (Not reachable from the outside of the box) fuse (of any kind! ... and there usually are funny ones in switching PSs)) is absolutely not a good idea! Plain fuses, overvoltage protectors, spike protectors, overcurrent protectors, overheating protectors, etc, etc, normally "blow" for good reason - and unless you know that reason with some certainty you risk that next time it's not the "fuse" but some core part that breaks or blows or glows.
find out what that yellow wire on the PS output side is. It might be a 2nd voltage but it might also be some kind of sensor or control. And don't look on the PS side only but also on the other side.
@WSS The cd rom and the speakers were at home hooked to another atx psu.
No mp3s allowed.
LG cd player and Matroxx speakers. Nowadays the speakers are still working and the cd player has dented case from a cd that exploded inside and is buried somewhere in the rubble.