Locked out, what to I try next?

Please Help I cannot get past boot errors. It started like this.... Power supply went south, so tried to fix it 5 capacitors looked overloaded so replace these in the hope that this would fix the problem. No joy. So scrapped that plan and bought a replacement from ebay, unfortunately go the model for an Optiplex 755, checked pinputs and power ratings and these seem to be identical, so move to the next step. Tried to boot the computer but end up with the boot manager, I can get into the Boot Options with F12 and the Advanced Boot Options with F8. Have tried all options but only end up in Window Error Recovery again and again, have tried putting a recovery disk in onboard CD, remote Cd and USB drive in Safe Mode it only loads files up to CLASSPNP.SYS the goes back to Windows Error Recovery screen ... What do I do next???

What do I do next???

First and foremost. You should never mess around with a PSU unless you know how to work on something like that and the understanding of electrical safety. Those capacitors can store a deadly charge for a very long time and can kill you if it hits your heart just right. I believe we're talking about a tenth of an amp.

Now, how did the PSU go legs up?

What do I do next???

Check the hard drive with disk checking software like Hard Disk Sentinel. Hard Disk Sentinel - HDD health and temperature monitoring And/Or use the HDD manufacture software. The live boot environment from Hiren's Boot CD has some HDD checking software.


A power issue can have the potential of taking out computer hardware. Up to and including the HDD. When I say power issue I'm talking about a surge, power sag, brown out, abrupt power loss, near by lighting strike (think in the miles), etc. I use a UPS (Uninterruptible Power Supply) made by Cyberpower for this reason. If for example the power goes out even for a brief second, I'll still have continuous power so my hardware won't take a hit. Even if my PSU has built in safety technology. If there's a total loss of power I have approximately 15 minutes to do a proper computer shut down. Thereby saving my hardware from an abrupt loss of power potentially damaging the hardware and of course my data.

I'll see if I can't find the specs on those two PSUs here in a second. What concerns me is that they are for two different models. They are probably the same or greater Amp rating on the 12 and 5 volt rails, but I need to verify that. Even then, the PSU is more than likely not your problem. It's sounds like the HDD.

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Well, as suspected trying to find PSU specs from a Dell OEM PSU is like trying to find a needle in a hay stack. Since the wattage is more for the 755 than the 760, I'm assuming it's gonna power the motherboard, the CPU and all the other hardware without issue. It's just that these PSUs are OEM and may be specific on the amps provided by the 12 volt rails and what not. Even though the motherboard connectors and whatnot may be the same, it's your rail's amp capacity that's the real factor. Where's is for a custom computer build using an Antec PSU or what ever, they tell you what the rails are capable of and whatnot.

Anyhow, I think it's more than likely a good PSU candidate for the computer. They do sell PSU testing hardware. But those won't tell you Amp capability on the rails. Even if you used a clamp meter in DC mode you're only getting Amp draw. I know there is a specific piece of equipment (probably expensive) that will show Amp capability. I've seen them used for Li-ion batteries. Not sure about PSUs though. I'm sure they got 'em.

Hello F22 Simpilot, thanks for the advice, I don't think the power supply is a problem as it powers the computer OK and allows me to move through the various function key options, also running test diagnostics from the hard disk. As mentioned the cables are the same and the power ratings on the side of the units are the same. I have tried to repair the OS and reinstall it from scratch from the hard disk and this appears to work OK, however, on rebooting the system just goes through the Windows Error Recovery screen again and again.

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I think the power supply just died through old age. 5 capacitors ranging from 680 microFarad to 2200 microFarad 16 volt were clearly stressed, so I though it worth replacing them, as I had done so with a previous computer to good effect. Obviously there was a further problem beyond my capability to troubleshoot. So I then decided to replace the unit.

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Checked the disk with the basic windows tools provided chkdsk x: This finds no disk errors, hardware check tells me that all hardware passes the testing, including the hard disk. Can't understand why reinstalling windows from scratch does not resolve the issue. The only problem reported was "Failed to transfer logged messages to the event log with status 50" on doing the chkdsk

Thanks for the comment Samuria, not too sure if that fits in as the OS doesn't report any errors when re-installing, also all the tools load and cmd runs OK

Hello SIW2, use of your tools sounds a good idea, many thanks for that. I tried repair of the disk and of the boot sectors from the windows toolset, and then in desperation a complete reinstall, which also didn't work. I then used cmd and found the current location was a sub directory on X: which had a few windows files, possibly a subset for the tools. So I did a chkdsk on it.

I have a backup of my data and a copy on my new laptop so I can reinstate it once up and working. How do you suggest I proceed with the tools?

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Not sure I have managed to load anything from any installation media apart from the HD, The computer reads a list of files from CD and USB but only as far as CLASSPNP.SYS, it then restarts again.

Thanks for the tools SIW2, a bit of a revelation. no wonder I couldn't find c: it doesn't exist. I have:-

RECOVERY (E:) 5.16 GB free of 11.7 GB
RECOVERY (R:) 5.16 GB free of 11.7 GB
SYSTEM (S:) 260 MB free of 299 MB
WINDOWS (W:) 905 GB free of 919 GB
BOOT (X:) 28.6 MB free of 31.0 MB
F: is CD Drive (internal)
G: is Removable Disk (USB stick)

I suspect that E: and R: are mapped onto the same files, contents are:
RECOVERY empty
WIM
Image.swm 3,788,794 KB
Image2.swm 2,374,410 KB
WINPE
boot.sdi 3,096 KB
WINPE.WIM 302,616 KB

I tried a System Restore in Dism++ using the file WINPE.WIM as the Target Image but it could not find the file

What do I do now?