Pc power supply as benchtop power supply - Page 1
Forum section: electronics / projects

author: mikerobertsn
author_rank: Newbie
timestamp: January 13, 2015, 09:07:12 am
content: Hi guys, i was converting an atx power supply to a benchtop one and I accidently short circuitred it. It says short circuit protected and there is still voltage on the cables but as soon as I put a load on it, it turns the power supply off. I opened it up I saw one little fuse that is in tact but other then that nothing was really obvious. Anyone have any Ideas what the problem is or how I couod fix it.

author: paulie
author_rank: Frequent Contributor
timestamp: January 13, 2015, 12:19:45 pm
content: PC supplies make great bench sources. I have blown a few though. Generally if you short to ground they are protected but one voltage to another (i.e. 12v to 5v or -12v) will often do in cheap chinese clones.ps. meoooowwwwww !!!

author: LaurenceW
author_rank: Frequent Contributor
timestamp: January 13, 2015, 12:45:45 pm
content: Hmm, I have to sound a note of caution with the often-heard mantra, "PC power supplies make great bench supplies!". Sometimes, they *can* be repurposed into bench supplies, but "great"? Not for me. Where are the meters? The terminals? The controls?Only with a lot of jiggery-pokery are anything other than the standard output voltages be available, and generally this will be at much larger potential currents (20-30 Amps not uncommon) than you really need, OR are able to control. So if you have a fault in your circuit, some uncontrolled big currents are going to flow. If you get lucky, you might just blow some silicon. If you get unlucky, you might start a fire. Short circuit protection in a PC power supply may well not be a bomb-proof as a custom-built bench supply, and, importantly, may not be available on all the output rails.Having said that, I did have a need for a high current (>40 amp) 12V only supply, and wasn't precious about meters and bling. A 575W second hand HP blade server power supply fitted my bill, exactly! and all for less than GBP £20.

author: paulie
author_rank: Frequent Contributor
timestamp: January 13, 2015, 01:10:02 pm
content: Quote from: LaurenceW on January 13, 2015, 12:45:45 pmOn Ebay. Some very cheap like this 5 digit meter for $4.70:http://www.ebay.com/itm/370966721056?_trksid=p2059210.m2749.l2649&var=640165395235&ssPageName=STRK%3AMEBIDX%3AITQuote from: LaurenceW on January 13, 2015, 12:45:45 pmAgain for less than a dollar some 3amp 36v adjustable jiggery:http://www.ebay.com/itm/111290462898?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AITor for a dollar and change some very nice 4amp buck/boost pokery:http://www.ebay.com/itm/311161462956?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

author: Evil Lurker
author_rank: Regular Contributor
timestamp: January 14, 2015, 01:22:48 am
content: ATX power supplies do have the potential to become "utility" power supplies, however they lack the precision, adjustability, and perhaps most importantly quality of a "real" bench PSU. If you do get one, please don't hack the case, chop off all the wires, and put all sorts of terminals on the housing... go ahead and get an ATX breakout board. And I agree with 3roomlab... the best route to go IMO is to get a laptop charger and hook one of them adjustable buck converter module(s) on it.

author: mikerobertsn
author_rank: Newbie
timestamp: January 14, 2015, 03:53:08 am
content: There isn't much to take a picture of the circuit board looks in tack. So no one know what is happening as there is a voltage but as soon as there is a load the thing turns off??