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Old 10-02-2011, 01:21 PM   #1 (permalink)
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Default bad power supply

Have an old Dell desktop that won't turn on at all. Just wondering if there is anything else I should check before I order a new power supply? Any ideas appreciated.


Thanks,
Nate
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Old 10-02-2011, 03:05 PM   #2 (permalink)
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Default Re: bad power supply

I would check the mobo for faulty capacitors, if any of them are swelled up or leaking then your mobo may be the problem.
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Old 10-03-2011, 08:02 AM   #3 (permalink)
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Default Re: bad power supply

I agree. There are many things that will prevent a computer to turn, although a bad PSU is certainly a primary one. I would try to swap in a known good power supply first, before spending any money.
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Old 10-04-2011, 04:51 PM   #4 (permalink)
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Default Re: bad power supply

These are some tips which can helps you to solve your problem
  1. Make sure the | / 0 power switch at the rear of the power supply unit is in the l position.
  2. Unplug the power supply at the rear of the PC, and then press the power button on the front of the unit. Plug the power supply back in and see if it works.
  3. Replace the power cord with another known good cord. This is the same type of cord your monitor uses.
  4. Clean the unit. You can vacuum or air-blast the outside of the unit to remove dust and hair debris. Vacuuming the outside is preferred as blowing will cause the debris to go into the power supply.
  5. Try plugging the cord directly into the wall. Do not use power strips as they may have failed.
  6. Toggle the voltage regulator switch from 115V to 230V then back again. If you are in North America, this switch must be on 115V.
  7. Lastly, you may need to go inside the case and confirm the thin wires running from the front power and reset switches are connected to the motherboard.
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Old 10-04-2011, 06:50 PM   #5 (permalink)
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Default Re: bad power supply

I don't recommend using a vacuum on the inside of the case because most motherboard have electrical jumpers that can be sucked off.

Don't toggle the voltage regulator switch from 115V to 230V while power is applied. If by some freak accident the PC turns on while the switch is in the wrong position it will damage the power supply and possibly other components. And it takes less than a second for things to go terribly wrong.
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Old 10-05-2011, 10:47 AM   #6 (permalink)
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Default Re: bad power supply

Quote:
I don't recommend using a vacuum on the inside of the case because most motherboard have electrical jumpers that can be sucked off.
I have never experienced that but I can see how that is possible with jumpers that are worn and/or have lost their clamping tension. However, the greater concern with using a vacuum inside the case is destruction from ESD. As the dust and air particles zoom past and crash into the nozzle end (especially with plastic nozzles) extremely high potentials of static electricity can build up in the nozzle. And when the nozzle comes in to close proximity to ESD sensitive devices, such as the CPU, memory modules and other high density integrated circuits (ICs or "chips), that static can easily be discharged through the device, totally destroying it - often without the user even knowing a discharge occurred.

For these reasons, vacuuming is NEVER preferred. Taking the computer outside is always better. If it is pouring down rain, and taking it outside is not practical, you can use a vacuum, but EXTRA care must be taken.
  1. Unplug the computer from the wall.
  2. Touch bare metal of the case to discharge any static in your body, and most importantly, to put you and the computer "at the same potential".
  3. Wrap your hand around the nozzle end and extend a pointed finger out to plant it on bare metal when reaching in with the nozzle to prevent the discharge and build-up of static.
  4. Use a soft, natural bristle (not synthetic) paint brush to gently persuade the dust to the nozzle.
  5. Better yet, wait for it to stop raining.
Note I use an air compressor and a soft, natural bristle paint brush in (or rather, outside) my shop to blast out electronics all the time. HOWEVER - there are special considerations that MUST be adhered to when using an air compressor on electronics.
  1. The compressing process WILL create condensation inside the tank. This condensation collects on the walls of the tank, then runs down to the bottom. If allowed to build up, water particles can be spewed onto the electronics - never good. So periodic draining is required and all air compressors have a pitcock valve for this purpose.
  2. Ensure the compressor is an "oil-less" type.
  3. I prefer upright compressors to keep any condensation way down at the bottom.
  4. ALWAYS - as in EVERY SINGLE TIME - use a inline moisture and particulate filter.
  5. Never see how fast you can make a fan spin - you can easily exceed design limits and destroy the bearings (I use wooden glue/Popsicle sticks to hold the blades stationary).
  6. Most compressors can deliver 90-120PSI. Toggle down to 80PSI when blasting dust from electronic.
Note that cans of dusting gas will do in a pinch, but note it is not canned "air". It typically consists of toxic difluoroethane and should not be inhaled.

Finally, make sure any case you buy in the future has a removable, washable air filter. These, as a minimum, cut in half the number of times you need to clean out the interior.
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