| Electronics > Repair |
| Need some help with ATX psu repair! |
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| baitz:
Greetings! So I plan to build a cloud chamber using a peltier cooler and an atx psu. My problem is that the psu I have available is, as of recently, dead. I now need some help with repair. All the outputs are at 0V, standby and power_on are at around 5V and when I short power_on to gnd nothing changes. I'm very much a beginner so is repair even viable for me, since I don't know where to start. Before we go further I want to be sure the psu is even usable for my project. My cooler operates at 24V, so I was planing to use the two 12V rails on my psu in series. Would that work? They both provide enough current. Another unrelated question: Doing some initial testing of my psu I got a really nasty shock just from touching the plug. I measured the voltage on it and it was around 230V (mains) and dropping. This was all with the switch off. I then noticed a cap that was wired directly on the power cord connector. Is this standard, safe? Thank you for any help! |
| Bored@Work:
The cap is standard and it is reasonable save - if the PSU is build according to regulations. However many PSU's aren't build according to regulations. Our Chinese friends give a fucking fart if they kill someone or not. These PSUs work by rectifying mains. If you happen to live in a 240V area the result of the rectification is a 400V DC, charging a cap. If the cap has no bleeding resistor or it is broken the deadly 400V DC can be around for a long time. This is why it is in general recommended that laymen should not open these PSUs. They can kill you. Second, these PSUs are shit for everything but powering PCs. They are just capable of doing this, and are build with the idea in mind to save every cent possible. Used in other ways they are great fire starters. My recommendation: Throw it away and get a reasonable PSU for your project. |
| Short Circuit:
Trash it. Obviously, you don't have reasonable knowledge on electronics, and poking around in such power supplies can get you killed... - no, it's not normal to get nasty bite from an unplugged device, - no, you cannot connect the two 12V ouputs in series, you'd short circuit one of the two. |
| Rerouter:
the capacitor on the output is a normal thing yes, however it should rapidly discharge itself as for the power supply, was it working previously?, for unknown reasons some models of power supplier will not wake up with shorting those 2 pins, (maybe uses the 3.3V sense line as a safety check) though rare in my own experiences, as for the 12V rails, mainly its just a marketing term and they actually end up tied together on the same regulator 90% of the time, so no for series, so yeah, like the others have said, this wont do, there is a way to make an ATX supply float, but really, you wouldnt want to, |
| baitz:
Yeah the shock I got was before I opened the thing. China I guess.... The psu was in my pc up until a week ago when it died and this opportunity arose. Are there cheap alternatives for my requirements? |
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