I have a problem turning on my older system. It is a Packard Bell 820 designed for Windows 98 but I upgraded it to Windows ME. On the system there are two lights; the power light, and the hard drive activity light. When I push the power button my hard drive activity light turns on (very faint and sometimes bright) but the power light doesn't turn on at all. My monitor is blank but the CD drive light is on sometimes, the floppy drive light doesn't turn on at all. Sometimes when I turn on my system it get to the windows logo and then turns off, sometimes it just turns off at the black screen. All of the time when the HD light turns on and the power doesn't I hear the processor fan but not the power supply fan. I don't know what to do, please help me.

Possible power supply issue...had this started a while back or since the upgrade to Windows ME ?

I presume that you haven't changed anything inside the PC? Just a Windows / software upgrade?

Strange that the power LED doesn't come on yet the PC is actually running. Could be a dodgy PSU as D-A-L says.

I've had a similar problem this week with a PC that was only a couple of years old. Kept starting up and getting as far as the Windows desktop (well, normally as far as that) and then it would just switch off. Tried formatting and re-installing a C:\ drive image, replaced the graphics card, unplugged all the other drives, etc, etc. I then replaced the processor and, from what I could see from my brief test, that was the problem.

My system was manufactured in 1998, it uses single inlay memory modules(SIMM) which I can't find anywhere but I could get a new power supply. I've opened the case a few times and I disconnected/reconnected the power supply cables for all my hardware including the cd drive, hard drive, and floppy, but nothing works.

Do the bunch of leads coming out of the power supply unit (PSU) terminate in a single connector onto the motherboard (an ATX power supply) or two small connectors side by side onto the motherboard (an AT power supply)?

I would think that the AT power supplies would be hard to get hold of now and, if your PC is 6 years old, it's quite possible that that's what it's using.

I'm going to tell you as specific as I can how my power supply unit looks. There is one fan on the PSU, a voltage change switch(from 110v to 230v), there is one 20-pin lead that connects to the motherboard, there are three 4-pin connectors, and one small 4-pin connector for the floppy drive.

OK, so the PSU terminates in a single 20-pin connector on the motherboard. That makes it ATX - that's good.

The three 4-pin connectors are, as you've probably guessed, standard power feeds for your hard disk, CD drive, etc and the small 4-pin connector is, as you rightly said, the standard power feed for the floppy drive. These will be the same on any replacement PSU.

The other thing to consider when you replace a PSU is 'how do I connect the power switch so that I have something to turn it on with' !!

To be honest, it's years and years since I changed a PSU. Connecting the power switch used to be a problem in the old days but I think that all ATX systems have the power switch connected to the motherboard so that you can change your power supply without this being an issue.

To be sure, check that the power switch and the reset switch connect to the motherboard (normally in a similar place to the hard disk LED, power LED, etc). I think you'll find that the power button uses a white and black cable but don't quote me on that!

In terms of the voltage, all power supplies should run at 230v if you buy them in the UK. If you're in the US or somewhere else, then I'm not too sure.

P.S. Great diagram !! Although I can't see it on this web page, I did get it on the email telling me you had posted

Hope that info helps. Sorry I wasn't too definite about it all. Maybe someone can back me up with some more recent experience ?

Thanks for everything so far DJNafey, I checked the power switch and it is connected to the motherboard. Oh, and the voltage in the U.S is 110v.

Oh OK, that makes sense then. The UK is 240v and I think the rest of Europe is 220v - that's why the PSUs run at 230v - we can just about get away with that everywhere. If the US is 110v, then that's what the switch is for!

Thanks for the update

I just tried turning on my system and the hard drive light was on and the power light still off and the screen is still blank. So I guess what I need is a new PSU, right?