PC wont boot

[adamou166]

Hi all,

I have an emachines 420 PC. There PSU blew so I brought a recommended replacement, pretty much the same one.
When I plug in power the orange HDD LED on the front flashes constantly. Even with no hardisk connected. The PSU is one of the ones with the switch on it just above where you connect the power cable, this is switched on.

Even when I remove all PCI cards, Hardisk, etc.. it still does it.
The CPU fan does not spin but when the power is first turned on you can see it nudges a bit but does not manage to get going.

Any ideas?
many thanks!
Mike

[adamou166]

PC now boots but i cant get the hardisk working. That is why the orange light flashes. I know this hardisk works because I used it in an external caddy for a while.

[adamou166]

ok this is strange. if I unplug all the power connectors to the HHD, CDROMS and floppy the PC will boot. I can then wait for it to boot and plug the power cables back into the components (while the pc is running) and use the PC.

However if I try to plug the power cables into the components before the boot all I get is the orange flashing light and no boot at all.

[mjc]

I can then wait for it to boot and plug the power cables back into the components (while the pc is running) and use the PC.

Great way to make things extra cripsy....hot plugging power connections on a drive is like playing Russian Roulette...

Disconnect all the drives...hard, optical, floppy....

Wait...you said drives in reference to opticals. Did you add another drive or any items that did not come with the machine?

If so, just connect a single hard drive (if more than one) and see if it boots.

It is looking like the power supply is not able to supply enough (probalby 12 V) voltage on one of the rails to actually boot the system.

[adamou166]

thanks. you are probably right, what sort of power supply do you recommend?

[mjc]

To fit an eMachines case?

Hard to say, because most eMachines I've seen take a micro-ATX PSU...and there isn't enough room for a full size unit.

[adamou166]

I replace the PSU with an almost identical one and still no luck... Why wouldnt it work if everything is the same as before?

i even unhooked the DVD rom drive so it wouldnt draw power from the PSU.

[Sylvander]

"Even when I remove all PCI cards, Hardisk, etc.. it still does it.
The CPU fan does not spin but when the power is first turned on you can see it nudges a bit but does not manage to get going."
Connect only: PSU, mobo, CPU+heatsink+fan, internal speaker.
[No RAM or video card]
If you're really keen, connect the mobo out of the case on an electrically non-conducting surface.
Short the start switches pins on the mobo unless certain the switch works.
If the PSU powers up, the BIOS's POST should run and test and warn that the 1st RAM test has failed.
This lets you know the POST is running and testing and warning, and that the internal speaker is working.
Lets see what result that gives before proceeding.

Use these for background and assistance...
Sylvander’s Diagnostic Flowcharts
Download a copy of my diagnostic flowcharts from here
www.erniek.eclipse.co.uk/downloads/sylvanderdiags.zip
and print them to leaf through.
Begin on the STARTUP chart.

Use the following to specify how far Startup gets in the following?

A typical and successful startup sequence
1. Start of Boot Troubleshooting Walkthrough
http://www.pcguide.com/ts/x/boot/walk/index.htm
2. Yes: The system power supply is functioning
http://www.pcguide.com/ts/x/boot/walk/power1.htm
------------------------------------------------------
You should hear a single short beep at about this point indicating the successful running/completion of the POST.
Some PC’s beep much later, possibly as late as just before step 12.
------------------------------------------------------
3. Yes: Something is being written to the screen during boot up [This may be only a flashing cursor]
http://www.pcguide.com/ts/x/boot/walk/video1.htm
4. The video BIOS message is displayed on the screen for a few seconds and then clears from the screen, or more messages display under it
http://www.pcguide.com/ts/x/boot/walk/vbios1.htm
5. Yes: The system BIOS startup screen is appearing
http://www.pcguide.com/ts/x/boot/walk/bios1.htm
6. The memory test completes successfully
http://www.pcguide.com/ts/x/boot/walk/ram1.htm
7. The BIOS accesses the floppy drives and the boot continues
http://www.pcguide.com/ts/x/boot/walk/seek1.htm
8. The system is able to autodetect IDE devices successfully
http://www.pcguide.com/ts/x/boot/walk/auto1.htm
9. The system is not Plug and Play compatible, has no Plug and Play devices, or has PnP devices but identifies them properly
http://www.pcguide.com/ts/x/boot/walk/pnp1.htm
10. Boot sequence is A: before C: (floppy disk first)
http://www.pcguide.com/ts/x/boot/walk/seqAC.htm
11. The floppy disk makes a noise and the light comes on
http://www.pcguide.com/ts/x/boot/walk/fd1.htm
12. The floppy disk light goes off and the hard disk light comes on as it starts booting
http://www.pcguide.com/ts/x/boot/walk/fd1hdd.htm
13. The hard disk boot process will continue here, if you want to follow it.
http://www.pcguide.com/ts/x/boot/walk/hd1.htm
14. The system continues booting from the hard disk and the message "Starting MS-DOS" or "Starting Windows 95" is displayed
http://www.pcguide.com/ts/x/boot/walk/hd1os.htm
15. Operating System Loaded From Hard Disk. The system has found a boot sector on the hard disk and is now starting the load of the operating system. The hard disk is working. You have successfully completed the hardware part of the boot process. Any problems encountered after this point should be diagnosed by looking for a more specific problem with a component, or under the section that contains run-time error messages.

[adamou166]

I dont think you understand or I havent explained fully.
Everything works, I know this because I have gone as far as got into windows when I plug the molex cables in while the PC is running.

It just wont start with the molex cables in before the pc is running and all i get is the flashing lights on the front of the tower.

[mjc]

It still won't boot with just the single hard drive attached?

[Sylvander]

"if I unplug all the power connectors to the HHD, CDROMS and floppy the PC will boot"
I think what you aught to be saying is that the "PC will complete the POST".
It cannot possibly boot if it has no powered drives from which to load an Operating System.

"I can then wait for it to boot [complete POST] and plug the power cables back into the components (while the pc is running) and use the PC"
Sounds like you don't have the drives set to "Auto" in the BIOS Setup.
The HDD parameters don't match the HDD, so if you have the HDD connected and powered, the BIOS detects that the parameters are wrong and halts the POST.
So what you then do is disconnect the power to the drive, the POST detects no HDD connected, there are no problems, the post completes, you connect the power to the HDD and the BIOS proceeds to load an OS from a drive it would refuse to load if you didn't trick it.

"Everything works"
Not really.
If you manage to fool the BIOS you can get it to load an OS from a drive it shouldn't use [not if the parameters are incorrectly set].