Computer Hope
Hardware => Hardware => Topic started by: tabosko on January 28, 2012, 01:25:46 AM
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Hey everyone....I had a issue with my compaq presario SR1000 desktop not powering up. I ran thru the normal checklist (cleaning dusk from fans, checking components, wires, etc). still nothing. I visited the tech support section online for compaq...i followed the guide there and managed to get the green power supply light to come on with the powercord was connected but soon as you hit the power button the green light would go off. according to the guide this means the power supply is fine and the problem is elsewhere. However for some reason (I know i prolly shouldn't have done it LOL) when I switch the voltage toggle (red switch) to 220v the tower boots right up! (I AM LOCATED IN THE US) everything runs fine, nothing appears to be out of place. so I have two questions:
1) Should this even be possible? I know the US doesn't run 220v. I'm not a expert on the subject but I would assume since we run a lesser voltage that this shouldn't even be possible...so maybe the power supply is defective and the 220 switch position correcting what was thrown off??
AND
2) Should I continue to run at this setting...or get a new power supply?
Thanks in advance for any help :)
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The power supply voltage input switch will not matter which is somehow unlikely to cause such behavior. If everything is fine, I would stick with the current PSU if there are no problem. It would have gone the other way around when you have switch to a 220 volt output knowing that US standard voltage output is 110 V. Perhaps you could give the problem before this weird situation you are having.
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Possibly the voltage changeover switch is damaged. Or you are using a 220 volt power lead and a 220 volt outlet (they do exist) or the house wiring needs checking.
You can get 220v outlets in US houses - put simply the power coming in has 3 wires
Hot ------- 110 v
Neutral ------- 0 v
Hot ------- 110 v
From the middle (neutral) wire to either hot wire you get the normal 110 volts for lights, wall outlets etc but between the two hot wires is double that (220 volts) for large appliances like stoves, air conditioners, some clothes dryers etc.
The US standard is 120 volts / 240 volts but in fact you may see anything from about 107 to slightly over 120 on the hots depending on distance from the transformer feeding your house or group of houses.
One type of US 220 volt outlet
(http://www.220outlet.com/pictures/220_outlet.jpg)
READ THIS
Another possibility is a fault in the house wiring that has led to a 110 volt outlet getting 220 volts (sometimes the middle wire becomes disconnected somewhere, on the power pole or inside the house) but you would know this because any 110 volt appliance plugged into that outlet would go BANG and if the whole house was affected you would surely know. Anyhow if there is a fault this is dangerous and you should get an electrician to check your wiring out. If you are aware of a problem in your wiring and you do not get it fixed this could void your fire insurance, and if anybody got injured or killed you could get prosecuted.
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You should probably replace that PSU. Such a radical change in operation could lead to a fire hazard... And sparks. I love sparks.
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And sparks. I love sparks.
This adds to the discussion how, exactly?
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This adds to the discussion how, exactly?
Oh, are you starting now as well? You better be trolling. Or did you perhaps fail to read the sentence that came before it?
You should probably replace that PSU. Such a radical change in operation could lead to a fire hazard..
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Possibly the voltage changeover switch is damaged. Or you are using a 220 volt power lead and a 220 volt outlet (they do exist) or the house wiring needs checking.
You can get 220v outlets in US houses - put simply the power coming in has 3 wires
Hot ------- 110 v
Neutral ------- 0 v
Hot ------- 110 v
From the middle (neutral) wire to either hot wire you get the normal 110 volts for lights, wall outlets etc but between the two hot wires is double that (220 volts) for large appliances like stoves, air conditioners, some clothes dryers etc.
The US standard is 120 volts / 240 volts but in fact you may see anything from about 107 to slightly over 120 on the hots depending on distance from the transformer feeding your house or group of houses.
One type of US 220 volt outlet
(http://www.220outlet.com/pictures/220_outlet.jpg)
READ THIS
Another possibility is a fault in the house wiring that has led to a 110 volt outlet getting 220 volts (sometimes the middle wire becomes disconnected somewhere, on the power pole or inside the house) but you would know this because any 110 volt appliance plugged into that outlet would go BANG and if the whole house was affected you would surely know. Anyhow if there is a fault this is dangerous and you should get an electrician to check your wiring out. If you are aware of a problem in your wiring and you do not get it fixed this could void your fire insurance, and if anybody got injured or killed you could get prosecuted.
I'm pretty sure everything in my apartment besides the washer and dryer are at 120v. I pulled a few sockets out and didn't see any evidence of what you mentioned so I'm good there. so it maybe a faulty switch. I changed the setting to 115v and it didn't work at all.... So just for my understanding....If there's a outlet running at 120v and you plug a 220v device/appliance to it, its shouldn't work at all because the outlet doesn't provide enough electricity??
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If you undervolt something it is likely to not work. If you overvolt something, it's likely to burn up.
You can measure the voltage on your outlet with the use of a multimeter.
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Replace the PSU...
Don't get a cheapo Chinese unit for 25 Bucks.
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The Power Supply is OK.
The house wiring is OK.
Just leave it alone.
Trust me this one time.
Explanation upon request.
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I disagree the PSU is OK so i'll request the explanation...
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Explanation upon request.
Why do this? Why not just give the explanation?
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Is it a secret, Geek?
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He could tell us.
But then he would have to taser our *censored*.
It's complicated. Something to do with a typo in an NDA.
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Well, if the PC is operating correctly on 110 V (nominal) with the selector switch in the 220 V position then clearly I wouldn't go connectiing it to a genuine 220 V supply. The problem could just be the switch.
(http://i124.photobucket.com/albums/p29/badoit/115-230.jpg)
(http://i124.photobucket.com/albums/p29/badoit/2-115-230.jpg)
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Thank you Salmon Trout. That is the right answer.
During assembly the switch was mounted upside down.
Later, it was wired correctly as seen from the inside of the PSU.
It would have taken me hours to find the diagrams. Or to take photos of how the switch looks when it is upside down. You would hardly notice the difference. As seen from the diagram. the switch just closes one circuit, not two. The PSU operates from 220 volts if the switch is not coded. Close the switch and you have a classic voltage doubler, used in TV sets may, many years ago when vacuum tubes needed voltages over 150 volts to perform economically.
The use of the simple analog voltage couple provides a simple way to switch from 220 to 110 operation. The 300 volt DC output goes staring to the converter, where it becomes pules reacting near 1000 volts and drives the primary of a *high-frequency transformer that isolates the power from direct connection to the mains. Secondary windings provide the requires low-voltages needed by the motherboard and other devices.
* Actually low-frequency, but well above audio.
Some newer power supplies use a different technique.
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I still think you're wrong. Judging from the story the guy his machine was running fine with the switch set to 110V.
If it suddenly starts working only at 220V, that means there's a problem somewhere.
Too bad the OP pulled a hit 'n run so I guess we'll never get any clarification.
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Again if it were me i'd replace the PSU...
Doesn't matter if it works that way or not...
But that's just me.