PSU Issues

  Dirk Diggler 20:08 04 Mar 2008

I have an emachines 370 which is about 5 years old and I think the PSU has given up the ghost.

Was using it this morning no problems and switched it off in the correct way.

Came home tonight and went to switch it on and .... nothing!!

I have checked the main fuse but to no avail and have ensured the power switch on the back hadnt been knocked so I am guessing the PSU - unless anyone can suggest anything else I may have overlooked?

So the question is - what should I be looking for when trying to find another PSU to try?

Are there different types etc?

Any thoughts greatly appreciated


  wotbus@ 20:33 04 Mar 2008

First conform there is power to the socket (plug in a table lamp or something to check).
If YES, then something on the PC has died but it could be just the ON/OFF switch ;-)
If you are able, open the PC case and with the it connected to the mains, short the ON/OFF switch temporarily with some insulated long nose pliers or the like. (don't worry - small voltage here).
If nothing happens then start looking at the PSU.
Just try to find a replacement to the one you have then it's one out/one in with no complications.

  Technotiger 20:38 04 Mar 2008

click here

Just make sure the physical size of the new one is the same as the old one, actual sizes do vary. I would get at least a 400w, your PC being a bit on the older side, you probably would not need anything more powerful - unless you have lots of peripherals, like extra hard drives, ROMs etc.

  Dirk Diggler 20:46 04 Mar 2008

Have found and old PSU from a redundant machine and went to try it out - however, it seems the conectors to the mobo are not the same.

On my machine there is the 20pin connector (same as the replacement) but there appears to be a 4-pin square socket on my mobo and I cannot find a corresponding connector coming off the replacement PSU

Silly question time - does this mean I cannot try the replacement

As per earlier comments - I hace confirmed that the socket has power - but not too sure/confident in trying the short-circuit option


  Technotiger 21:00 04 Mar 2008

You can still fit the 20pin socket.

  Fruit Bat /\0/\ 21:01 04 Mar 2008

modern boards need the 4 pin for cpu

  citadel 21:02 04 Mar 2008

the better quality psu's have the 80% plus logo these are efficient and don't waste as much electricity, keeping the bill down. they also tend to be quieter. a 400w would do you.

  Dirk Diggler 21:05 04 Mar 2008

So if I just fit the 20pin - would I get fans and/or lights and then can I definately say it is the PSU and be confident in buying a new ATX one with the 4-pin socket then

  Dirk Diggler 21:19 04 Mar 2008

Have just offered up the replacement PSU (without the 4-pin connector) and switched on

Had an amber light on the front of the machine and managed to open and close the DVD drive using the power source ... so ...

Am I correct that it was the PSU?

Thanks for all you replies so far - it has been a very frustrating bet very informative evening :-)

  Technotiger 21:37 04 Mar 2008

Hi, the board in question is about 5 years old!

Dirk Diggler - Am I correct that it was the PSU?

... almost certainly a Yes to that.

  Fruit Bat /\0/\ 21:47 04 Mar 2008

If renewing a PSU check:

1. The physical size of your PSU, some are hard to replace due to being a non standard size.
2. The amount of power need from the PSU don't skimp.
3 The correct connections for your equipment

1. Physical Dimensions

Besides the specs and form factors, the physical dimensions are also important factors in selecting a compatible power supply. Here is an outline of the physical dimensions of most standard power supplies:

# ATX: 6x3.5x5.5", HxWxD. Most common. Uses 4 mounting screws.
# Mini-ATX: 5x3.5x5", HxWxD. Rare size. Uses 4 mounting screws. Can be used in a regular ATX case, but often not the other way around.
# MicroATX: 5x3x4", HxWxD. Use 3 mounting screws. Not interchangeable with ATX or miniATX.
# Flex ATX: Even smaller than Micro ATX. Various sizes according to case specs; often not interchangeable.

Use the data above to determine if a particular power supply would fit your case.

The quality of a power supply can be estimated by its weight. While this is not a true scientific or thorough measurement of the power supply reliability, it is nevertheless a very simple and easy way for ordinary PC users to estimate and compare the quality of a power supply.

2. Power supply calculator click here

3. Correct connections
Some boards have 20 pin connectors others 24 pin
There is often a 4 pin plug required to power Intel CPUs
Molex D plugs for IDE HDD and CD/DVD drives
SATA power connections for latest HDDs and DVD drives.

Guide to changing PSU
click here
click here

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