UniFi Switch 48 750W No power problem / dead unit fixed.
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- Опубликовано: 12 апр 2019
- UniFi Switch 48 750W No power problem fixed.
This video mostly for parts reference. Since there no service manual for it, this may help you to fix your set.
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Thank you very much. I couldn't have fixed mine without your video.
FYI for others:
R39 is 4.7Ohm
R33 is 22kOhm
R47 is 470Ohm (I also replaced this one additionally)
The big resistor is 240mOhm (5% tolerance) and I think 3W or 5W (I used a 7W)
The SMD resistors I replaced are all in the 0805 type.
Big Resistance value is 0.24 Ohm in 3 Watt
I’ve fixed three Ubiquiti switches so far with this fault, one each of 250, 500 and 750 watt supplies. Thank you for these great videos! Without them I would not have been able to figure out the component values and part numbers.
On the 500w power supply, R5 had exploded so badly that the PCB underneath was damaged. When I tried to power up the supply after replacing the components, it just clicked. It took me a long time to realize that the part of the PCB that was damaged actually connected the current sense lines of the TEA18363 to each leg of R5. One I jumped the two broken traces/vias, the power supply worked perfectly. Hopefully this might help someone else.
I know this is old but I have the same issue, R5 exploded, not too bad. Are you saying you jumpered the ends of R5 as a test? Or left it that way?
@@ChuckClaunch the 500W circuit board is a bit different than the one shown in the video. In the 750W supply in the video, the spot where R5 goes has some thick traces (0:55) underneath it. On my board, it had very thin traces that were destroyed when the resistor exploded. I had to rebuild those traces with jumper wires.
You'll definitely have to replace R5 with the proper resistor to get the power supply working. It's part of the current sensing circuit, so if it's not installed or if it's just jumpered/shorted, the supply won't start.
Hi. I like to fix broken equipment but I don't have enough knowledge for troubleshooting the bad parts. I have only two classes years a go about 3 credits each, for trouble shooting the soldered parts on PCBs. Is there any book or knowledge base video(s) available that I could watch or read the material to improve my troubleshooting skills?
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Can I send mine to you for repair. If it is more than a power supply, is it still within your realm to repair potential general board issues?
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I have a us-48-500w ubiquiti switch it powers on but think it is in a boot up loop and there are no link lights. I have tried the reset button and tried multiple Ethernet cords. I still can’t figure it out
What kind of resistor is R5?
How can this happen? Lightning?
Please, I need to know ID of U7, Q7 and Q8. Thank you
Hi, How much is repair? I have 500w power supply broken. Thx
For any repair questions, feel free to call us. Thank you
I HAVE BAD D9 , R27,R39, Q5, R5 AND U5
Mine starts blinking white, stabilizes in blue and blinks white again and no network port lights up when connecting anything.
That's similar to what I'm seeing. Except, having reset mine, it never gets to blue. If I'm watching the console cable, it loads until it gets to BusyBox. At that point, it just freezes. Seems more like a software issue than a hardware issue, but if resetting won't fix it and ethernet is dead (assumedly, BusyBox is necessary for ethernet to work), I need a way to reload the firmware over serial (console cable) or something else that isn't reliant on the ethernet.
Vc teria uma contato de WhatsApp?
Those Unifi switch tend to just die and not be very reliable...
There is an easier way to solve this issue. Step one, throw the piece of crap Ubiquiti switch in the trash. Step two, go to eBay and buy a used Cisco 3750G 48 port with PoE for a few hundred bucks. Even though the Cisco switch is much older, it will outperform the Ubiquiti switch. You're welcome.
Sure, that would likely be perfectly fine for a homelab, but still that's like comparing apples and kumquats for a number reasons. Here are some that come to mind:
1) The Cisco has reached end of life a few years ago, hence no more vulnerability patches.
2) Even with EOL aside, it takes a different skillset to config the Cisco, compared to the single pane of glass the owner might be used to with the UniFi. They could have a few other UniFi devices this neatly fits in with.
3) When new, the MSRP of the two were literally an order of magnitude apart, so naturally the target audience is likewise different. If the owners are bothering to fix the switch at component level, it would seem the budget is tight. If they had enough to get a supported Cisco, I doubt they would have gotten the UniFi to begin. Instead they're getting by with what I'm guessing is less than $30 worth of parts. Now, on the other hand, if this thing keeps blowing parts, the Cisco just might end up being cheaper in the long run.
4) The Cisco doesn't have 10 GB if that's at all important to the user
Anyhow, not trying to dump on Cisco. They're absolutely great and will withstand the apocalypse :-). I've purchased dozens and dozens of them in a my past lives, but now working with much less critical infrastructure type of an environment, the UniFi stuff has been performing fairly reliably, at a fraction of the cost.
@@lensherm I’m a network engineer and I’ve worked with Cisco, Juniper and a multitude of various cheap junk switches like HP etc. Ubiquiti is most definitely in the latter category. They have a really high failure rate. Not impressed. Ubiquiti support is atrocious. Just calling a spade a spade here.
@@coult45usmc come on. I mean no disrespect, yet that's just borderline trolling now. On many levels, chiefly of which is pricing, Ubiquiti as a brand is way closer to the Netgears, D-Links, TP-Links of the world than it ever was to Cisco, Juniper, Avaya, old Alcatel or Enterasys.
Of course Ubiquiti's support is literally nonexistent. Support is not even closely baked into the price of the damn thing and they're probably one of the more closed-lipped companies who even tries to play with the big boys. While when new, the switch being fixed in this video was priced in the sub $1,000 range, while the Cisco you brought up easily sold between 5 and 10 K USD, and that's before Cisco would tack on licensing and support. Let's also not forget that Cisco sounds like a mixture of a swarm of angry bees and a small jet engine, especially when pushed to its limits.
Of course one can recommend more bulletproof and better-performing hardware. Hard to say without knowing the full context, but at first glance, it seems this is someone penny-pinching, by soldering surface-mount resistors.
If you can name an in support Cisco, which would fit the bill sub $1,000 then maybe it would make sense to the authors of this video. If money is no object, may I recommend an $80,000 switch-router which I got blast and impact tested, even before putting a few dozen of them in a dev environment? Sure this was a beast and this was about 15 years ago, but it is almost literally bulletproof. :-)