<h3>Unless you know what you're doing, do not remove the covers from a PSU. The components can store a lethal charge long after power is removed, even if the fuse is blown.</h3>
<p>My guess is something loose (now vapourised) in the PSU. Electronics have a tendancy of failing either quite soon after manufacture, or lasting reasonably well. This is described with the <a href="https://en.wikipedia.org/wiki/Bathtub_curve" rel="nofollow noreferrer">Bathtub Curve</a>.</p>
<p>Looking at the failure, there was a significant short circuit somewhere - quite likely within the PSU itself. This doesn't mean you can be sure that the RAMPS board survived, but it has a reasonable chance of not being harmed.</p>
<p>There is no significant chance of the PSU failing like that simply due to an excessive load in its output - unless it was overloaded for a significant period of time. Generally these PSUs will have some degree of overload protection even if they are not explicitly designed to survive an overload.</p>

CC BY-SA 4.0
2019-02-12T09:32:27.740Z
No, completely wrong (unless your image is misleading, but I doubt it). This is common technique to increase the current carrying capability of the copper track. It goes without saying that you are not experienced enough to safely work on this with the covers removed.
Sean Houlihane
CC BY-SA 4.0
2019-02-11T16:08:56.373Z
2019-02-12T09:34:20.047Z
2020-06-18T08:29:41.667Z
Sean Houlihane
<p>You need to closely look at how to connect to the output connectors. In this case it appears that you have wired it correctly according to the stamped in markings above the connectors. You have chosen not to connect the earth, this is strongly advised.</p>

<p>Did you check if the power switch matches the voltage of your country? If you are in Europe the switch should be set to 230&nbsp;V, not 115&nbsp;V (which is used in America).</p>

<p>E.g. for the following power supply you see such a switch on the side:
<a href="https://i.sstatic.net/cIUcA.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/cIUcA.png" alt="PSU voltage setting"></a></p>

<p>If a PSU is connected without load and works, and short circuits when externals are connected there are a few options:</p>

<ul>
<li>there is a short in the connected printer board,</li>
<li>the load that the board takes is too large for the PSU,</li>
<li>the PSU cannot deliver the load,</li>
<li>the PSU was faulty to begin with.</li>
</ul>

CC BY-SA 4.0
2019-02-10T15:48:54.383Z
Hello! I just found this youtube video after i blew it, finding out he used the same method of connecting it as me. The voltage switch is on 230V, which is correct. I looked at charts which told me to connect it this way.
wessel dijkstra
CC BY-SA 4.0
2019-02-10T16:30:23.303Z
Dear oscar, the board is a ramps 1.4 board that doesn't short when i connect it to my laptop via a usb cable. the lights all flash nominal.

I don't think it really takes such a big load, since most 3d printers use it, and i didn't connect any motors to it yet. If it's broken, then how do i prove to Banggood (ironic name) that it wasn't my fault?
wessel dijkstra
CC BY-SA 4.0
2019-02-11T08:35:32.860Z
@wesseldijkstra "If it works over USB" has no relation to powering it with 12 V.
0scar
CC BY-SA 4.0
2019-02-10T15:44:46.337Z
2019-02-11T08:33:26.023Z
2019-02-11T08:33:26.023Z
0scar
<p>So yesterday I got my power supply in the mail and I thought, let's check it out!</p>
<p>I put all the wires in correctly (as shown in this YouTube video, <a href="https://www.youtube.com/watch?v=X8GhVKG2Nno" rel="nofollow noreferrer">Anet A8 power supply unit fuse blown</a>, I just searched really quickly, this person has the same problem as me) and &quot;BANG&quot;, it blew.</p>
<p><a href="https://i.sstatic.net/kBCjk.png" rel="nofollow noreferrer" title="Image from YouTube video"><img src="https://i.sstatic.net/kBCjk.png" alt="Image from YouTube video" title="Image from YouTube video" /></a></p>
<p>Luckily the only thing broken on it is the fuse, for which I can get a new one, but my main question is .. why? why did it blow out? Did I wire it up wrong? The 12 V output goes to a RAMPS 1.4 board which is working correctly.</p>
<p>It worked the first time I plugged it in; the little green light went on. The second time a nice &quot;big bang&quot;. When I tested it the first time, I didn't add the 12 V wires to the RAMPS board yet. When I did, the fuse of the PSU blew out.</p>
<p>The board is a RepRap RAMPS 1.4, which works fine when connected via USB to laptop.</p>
<p>Upon closer inspection I found a burned out resistor in the circuit of the power supply, maybe this caused the bang?</p>
<h3>BIG update!</h3>
<p>I opened it up and flipped the board, and noticed that there was a big ol' blob of tin connected to one of the pins I connected my wires to. I am very sure that this blob shouldn't connect to that pin at all, hence shorting my board.</p>
<p>Is this the cause?</p>
<p><a href="https://i.sstatic.net/lGGSF.jpg" rel="nofollow noreferrer" title="Close up of PCB"><img src="https://i.sstatic.net/lGGSF.jpg" alt="Close up of PCB" title="Close up of PCB" /></a></p>
<p><a href="https://i.sstatic.net/lKdWI.jpg" rel="nofollow noreferrer" title="Close up of PCB - Highlighted potential short circuit"><img src="https://i.sstatic.net/lKdWI.jpg" alt="Close up of PCB - Highlighted potential short circuit" title="Close up of PCB - Highlighted potential short circuit" /></a></p>
<p>Here is a link to the webpage I bought it from: <a href="https://m.banggood.com/nl/12V-20A-240W-Anet-Power-Supply-Dual-input-Centralized-Power-Monitoring-For-3D-Printer-p-1108988.html" rel="nofollow noreferrer">Anet® 12 V 20 A 240 W Power Supply Dual-input Centralized Power Monitoring For 3D Printer</a></p>
<p>Here is how I wired it up at the PSU side:</p>
<p><a href="https://i.sstatic.net/yHZxm.png" rel="nofollow noreferrer" title="Power supply connections"><img src="https://i.sstatic.net/yHZxm.png" alt="Power supply connections" title="Power supply connections" /></a></p>
<p>At the RAMPS side:</p>
<p><a href="https://i.sstatic.net/Od4en.jpg" rel="nofollow noreferrer" title="RAMPS board connections"><img src="https://i.sstatic.net/Od4en.jpg" alt="RAMPS board connections" title="RAMPS board connections" /></a></p>
<p>This shows the internals of the PSU, it clearly shows burn marks:</p>
<p><a href="https://i.sstatic.net/EuSfm.jpg" rel="nofollow noreferrer" title="Overview of the failed electronic component in the PSU"><img src="https://i.sstatic.net/EuSfm.jpg" alt="Overview of the failed electronic component in the PSU" title="Overview of the failed electronic component in the PSU" /></a></p>

CC BY-SA 4.0
2019-02-10T18:47:09.570Z
I think we also need to see how things are connected on the other end before we can help you see where you went astray or if there indeed is something wrong with the power supply. It appears from the picture you have up you installed the wiring correctly (except for the missing ground as 0scar pointed out in his answer). The controller end of the equation is important, because if you've crossed something up on that end, you're most likely in for an issue as well.
Pᴀᴜʟsᴛᴇʀ2
CC BY-SA 4.0
2019-02-10T19:26:33.080Z
Added images from your imgur link ... it looks like your board is fried to me, but I'm not an electrician. Disconnect the power from the supply to the board, replace the fuse, then plug it in and check the voltages coming from the power supply to verify it's still good. If it is, the main board is going to need replacement is my bet.
Pᴀᴜʟsᴛᴇʀ2
CC BY-SA 4.0
2019-02-10T19:28:52.297Z
@Pᴀᴜʟsᴛᴇʀ2 i think it is most certainly dead. the metal is scorched from the heat from the flash.. i  think i might as well throw it away. Thank god my ramps board is still okay. I sent a message to banggood and they will investigate it within 24 hours.
wessel dijkstra
CC BY-SA 4.0
2019-02-10T19:32:19.543Z
The "burned" image is from the power supply? Sorry, that wasn't made clear, but if so, yah, power supply no good! ;-)
Pᴀᴜʟsᴛᴇʀ2
CC BY-SA 4.0
2019-02-11T08:30:03.610Z
@Pᴀᴜʟsᴛᴇʀ2 Always nice to see people have the hammer close by in case of emergency! ;) Please try to keep the workspace clear when using electronics, metal screwdrivers laying around is not optimal.
0scar
CC BY-SA 4.0
2019-02-11T08:49:31.640Z
The resistor shows burn marks, but these are residues from the other component next to it (4-way diode?). I think this question is best asked in the [Electrical Engineering Stack](https://electronics.stackexchange.com/). In reaction to ` Thank god my ramps board is still okay!`; what makes you say that? You have no reason to assume that from this experiment. Is this your second PSU, as the Anet A8 comes with a board and PSU as it is a complete kit, you need to add more information. What kind of PSU did you buy? (make and model or link/image of info plate)
0scar
CC BY-SA 4.0
2019-02-11T17:20:05.737Z
Hello 0scar, thanks for your help so far. I tested it via the cura program,  clicking the axis buttons and looking for a flashing light when i did. That did work, so that's why i thought it wasn't toasted yet. But i am no expert so i just hope it still works on 12v
wessel dijkstra
CC BY-SA 4.0
2019-02-11T22:03:19.263Z
The lump of solder might just be a result of overheating. If it was the problem for the short, the solder would have vaporized, in your case the rectifier has blown out. I think it is best to ask this at EE.SE.
0scar
<ramps-1.4><anet-a8><power-supply>
Why did my power supply fuse blew out on my Anet A8?
wessel dijkstra
# Why did my power supply fuse blew out on my Anet A8?

(Asked by: username_0 on 2019-02-10)

So yesterday I got my power supply in the mail and I thought, let's check it out!

I put all the wires in correctly (as shown in this YouTube video, [Anet A8 power supply unit fuse blown](https://www.youtube.com/watch?v=X8GhVKG2Nno), I just searched really quickly, this person has the same problem as me) and "BANG", it blew.

[![Image from YouTube video](https://i.sstatic.net/kBCjk.png "Image from YouTube video")](https://i.sstatic.net/kBCjk.png "Image from YouTube video")

Luckily the only thing broken on it is the fuse, for which I can get a new one, but my main question is .. why? why did it blow out? Did I wire it up wrong? The 12 V output goes to a RAMPS 1.4 board which is working correctly.

It worked the first time I plugged it in; the little green light went on. The second time a nice "big bang". When I tested it the first time, I didn't add the 12 V wires to the RAMPS board yet. When I did, the fuse of the PSU blew out.

The board is a RepRap RAMPS 1.4, which works fine when connected via USB to laptop.

Upon closer inspection I found a burned out resistor in the circuit of the power supply, maybe this caused the bang?

### BIG update!

I opened it up and flipped the board, and noticed that there was a big ol' blob of tin connected to one of the pins I connected my wires to. I am very sure that this blob shouldn't connect to that pin at all, hence shorting my board.

Is this the cause?

[![Close up of PCB](https://i.sstatic.net/lGGSF.jpg "Close up of PCB")](https://i.sstatic.net/lGGSF.jpg "Close up of PCB")

[![Close up of PCB - Highlighted potential short circuit](https://i.sstatic.net/lKdWI.jpg "Close up of PCB - Highlighted potential short circuit")](https://i.sstatic.net/lKdWI.jpg "Close up of PCB - Highlighted potential short circuit")

Here is a link to the webpage I bought it from: [Anet® 12 V 20 A 240 W Power Supply Dual-input Centralized Power Monitoring For 3D Printer](https://m.banggood.com/nl/12V-20A-240W-Anet-Power-Supply-Dual-input-Centralized-Power-Monitoring-For-3D-Printer-p-1108988.html)

Here is how I wired it up at the PSU side:

[![Power supply connections](https://i.sstatic.net/yHZxm.png "Power supply connections")](https://i.sstatic.net/yHZxm.png "Power supply connections")

At the RAMPS side:

[![RAMPS board connections](https://i.sstatic.net/Od4en.jpg "RAMPS board connections")](https://i.sstatic.net/Od4en.jpg "RAMPS board connections")

This shows the internals of the PSU, it clearly shows burn marks:

[![Overview of the failed electronic component in the PSU](https://i.sstatic.net/EuSfm.jpg "Overview of the failed electronic component in the PSU")](https://i.sstatic.net/EuSfm.jpg "Overview of the failed electronic component in the PSU")

**Tags:** ramps-1.4, anet-a8, power-supply
> **Comments:**
> **username_1**: I think we also need to see how things are connected on the other end before we can help you see where you went astray or if there indeed is something wrong with the power supply. It appears from the picture you have up you installed the wiring correctly (except for the missing ground as 0scar pointed out in his answer). The controller end of the equation is important, because if you've crossed something up on that end, you're most likely in for an issue as well.  
> **username_1**: Added images from your imgur link ... it looks like your board is fried to me, but I'm not an electrician. Disconnect the power from the supply to the board, replace the fuse, then plug it in and check the voltages coming from the power supply to verify it's still good. If it is, the main board is going to need replacement is my bet.  
> **username_0**: @Pᴀᴜʟsᴛᴇʀ2 i think it is most certainly dead. the metal is scorched from the heat from the flash.. i  think i might as well throw it away. Thank god my ramps board is still okay. I sent a message to banggood and they will investigate it within 24 hours.  
> **username_1**: The "burned" image is from the power supply? Sorry, that wasn't made clear, but if so, yah, power supply no good! ;-)  
> **username_2**: @Pᴀᴜʟsᴛᴇʀ2 Always nice to see people have the hammer close by in case of emergency! ;) Please try to keep the workspace clear when using electronics, metal screwdrivers laying around is not optimal.  
> **username_2**: The resistor shows burn marks, but these are residues from the other component next to it (4-way diode?). I think this question is best asked in the [Electrical Engineering Stack](https://electronics.stackexchange.com/). In reaction to ` Thank god my ramps board is still okay!`; what makes you say that? You have no reason to assume that from this experiment. Is this your second PSU, as the Anet A8 comes with a board and PSU as it is a complete kit, you need to add more information. What kind of PSU did you buy? (make and model or link/image of info plate)  
> **username_0**: Hello 0scar, thanks for your help so far. I tested it via the cura program,  clicking the axis buttons and looking for a flashing light when i did. That did work, so that's why i thought it wasn't toasted yet. But i am no expert so i just hope it still works on 12v  
> **username_2**: The lump of solder might just be a result of overheating. If it was the problem for the short, the solder would have vaporized, in your case the rectifier has blown out. I think it is best to ask this at EE.SE.  

---

## 2 answers

### Answer by username_2 on 2019-02-10. Score: 4 | Accepted answer

You need to closely look at how to connect to the output connectors. In this case it appears that you have wired it correctly according to the stamped in markings above the connectors. You have chosen not to connect the earth, this is strongly advised.

Did you check if the power switch matches the voltage of your country? If you are in Europe the switch should be set to 230 V, not 115 V (which is used in America).

E.g. for the following power supply you see such a switch on the side:
[![PSU voltage setting](https://i.sstatic.net/cIUcA.png)](https://i.sstatic.net/cIUcA.png)

If a PSU is connected without load and works, and short circuits when externals are connected there are a few options:

* there is a short in the connected printer board,
* the load that the board takes is too large for the PSU,
* the PSU cannot deliver the load,
* the PSU was faulty to begin with.

> **Comments:**
> **username_0**: Hello! I just found this youtube video after i blew it, finding out he used the same method of connecting it as me. The voltage switch is on 230V, which is correct. I looked at charts which told me to connect it this way.  
> **username_0**: Dear oscar, the board is a ramps 1.4 board that doesn't short when i connect it to my laptop via a usb cable. the lights all flash nominal.  I don't think it really takes such a big load, since most 3d printers use it, and i didn't connect any motors to it yet. If it's broken, then how do i prove to Banggood (ironic name) that it wasn't my fault?  
> **username_2**: @wesseldijkstra "If it works over USB" has no relation to powering it with 12 V.  

---

### Answer by username_3 on 2019-02-11. Score: 2

### Unless you know what you're doing, do not remove the covers from a PSU. The components can store a lethal charge long after power is removed, even if the fuse is blown.

My guess is something loose (now vapourised) in the PSU. Electronics have a tendancy of failing either quite soon after manufacture, or lasting reasonably well. This is described with the [Bathtub Curve](https://en.wikipedia.org/wiki/Bathtub_curve).

Looking at the failure, there was a significant short circuit somewhere - quite likely within the PSU itself. This doesn't mean you can be sure that the RAMPS board survived, but it has a reasonable chance of not being harmed.

There is no significant chance of the PSU failing like that simply due to an excessive load in its output - unless it was overloaded for a significant period of time. Generally these PSUs will have some degree of overload protection even if they are not explicitly designed to survive an overload.

> **Comments:**
> **username_3**: No, completely wrong (unless your image is misleading, but I doubt it). This is common technique to increase the current carrying capability of the copper track. It goes without saying that you are not experienced enough to safely work on this with the covers removed.  

---

