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How do I check out power supply?
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Original Message
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Name: Coos Bay Lumber
Date: June 12, 2004 at 12:36:59 Pacific
Subject: How do I check out power supply?OS: Win98CPU/Ram: P2/? |
Comment: How do I check out power supply? Recently was given an unknown brand of computer, and previous owner mentioned he throught a bad power supply. How can I check out the power supply for a computer without connecting it in? Found that you cannot connect it to wall and expect it to output voltage. There is usually some sort of connection through the motherboard to the switch on front face. I am questioning the functionality of the on/off switch in all this at present. How can I work around this and then measure the output?
Wm.
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Response Number 1
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Name: johnr
Date: June 12, 2004 at 13:08:12 Pacific
Subject: How do I check out power supply? |
Reply: (edit)If you short together the green and either of the black connectors which are on the same side as the retaining clip (they are actually pins 14 and 13or15) this will start your ATX PSU. A bent paper clip is the ideal tool for this. But if you're colour blind or not too sure, leave it to the experts!
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Response Number 2
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Name: name
Date: June 12, 2004 at 13:33:32 Pacific
Subject: How do I check out power supply? |
Reply: (edit)Above is not always true. Some power supplies will not "start" without a load or other connections hooked to them.
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Response Number 3
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Name: StuartS
Date: June 12, 2004 at 13:36:17 Pacific
Subject: How do I check out power supply? |
Reply: (edit)Even that won't work. Pins 15 and 14 will operate the switch. Switch mode power supplies need a load, otherwise they go into runaway mode and burn themselves out, consequently the power supply will cut the outputin the absence of a load. Even if you did apply a load sufficient to get the power supply running, there is no guarantee the voltages would be stable once the rated load was applied. To test the voltages from a power supply you need a low impedance voltmeter and that means a digital voltmeter. An analogue voltmeter will itself present a load to the power supply which will affect the voltage output. Getting a power supply tested properly is not worth the hassle, would cost more than a new one. I would just plug it in try it. If it works fine, if not then buy an new one. They are not expensive. Stuart
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Response Number 4
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Name: johnr
Date: June 12, 2004 at 13:38:50 Pacific
Subject: How do I check out power supply? |
Reply: (edit)Also, any decent techy has got a proper PSU test unit with which to do the test properly.
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Response Number 5
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Name: Coos Bay Lumber
Date: June 12, 2004 at 13:44:11 Pacific
Subject: How do I check out power supply? |
Reply: (edit)JOHNR..... There are no green wires coming out of the power supply at all. I have a PC fixum book, but it does not give a diagram of the plugs for the power supply.
There are twenty pin holes on the connector. One of which is blank. The label on the power supply also does not have a diagram as to what is relation for each wires coming out of box. How otherwise, do I count for pin numbers? Wm.
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Response Number 6
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Name: StuartS
Date: June 12, 2004 at 14:25:24 Pacific
Subject: How do I check out power supply? |
Reply: (edit)Pin 1 is the top right hand pin on the connector when looking at it with the connector key on the bottom. Both pin 1 and pin 2 should be orange. I would be very wary of a power supply that does not colour code its output cables to a recognised specification. Stuart
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Response Number 7
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Name: name
Date: June 12, 2004 at 16:10:29 Pacific
Subject: How do I check out power supply? |
Reply: (edit)"""To test the voltages from a power supply you need a low impedance voltmeter and that means a digital voltmeter. An analogue voltmeter will itself present a load to the power supply which will affect the voltage output."""
ABSOLUTELY, POSITIVELY, INCREDIBLY, UNTRUE, and INCORRECT.
ANY digital voltmeter I've ever seen or used was HIGH impedance. Not only that, but ANY analogue voltmeter I've ever seen or used, even some of the relatively "poor" old 1000 ohms per volt units made back in the '50s and '60s, would not load down a power supply designed to put out more than even a few milliamps. I will agree that most any digital voltmeter is probably more accurate that most any analogue voltmeter, but there could even be exceptions to that. I will also agree that spending much time on this is not worthwhile.
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Response Number 8
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Name: johnoh
Date: June 13, 2004 at 08:35:11 Pacific
Subject: How do I check out power supply? |
Reply: (edit)Don't even plug it into your motherboard if you think it might be bad. You put your mobo at risk.
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