No display on standby PC

[JohnD]

When my main PC had a PSU failure last week, I pulled out my old one and tried to use it. It had hard disk fault, presumably old age. I took out the PSU to swap into my main PC, but it did not have a 4-pin plug which the m/b needs so I re-assembled it.

I changed the hard disk, and although I heard it ticking away at the disk, there was nothing showing on the display at all - even on start up and POST (so not a Windows fault).

I checked the display (an old CRT type) by plugging it into my main PC when it was going again, but no display at all. The SIS m/b has onboard graphics, I fitted an old graphics card but nothing from that either. The m/b is PC266 with SIS730S chipset. The processor is Athon XP1800. the power plug is 20-pin.

I deduce that I must have disturbed something when I took the PSU out, and I imagine it is on the m/b. Any ideas what the prob might be?

 

[Softus]

It's faintly possible that the BIOS is crashing when reading CMOS settings that have become corrupted as a result of a faded m/b battery.

Reset CMOS settings to factory default, remove/disconnect all ancilliary components (including HDD), and then try to boot.

 

[JohnD]

Thanks!

I tried that...and it worked ... sort of. I did the jumper reset with everything disconnected, memory and processor out, PSU out. On reassembly it had display, started up, said no drives present. I reconnected the old hard drive which it detected but couldn't find a boot seg.

So I reconnected the old CD drive with a Windows disk in it... and display gone again I tried resetting on the jumper but no luck.

Disconnected everything again, reset, reassembled, got a tiny puff of smoke (poss from the processor ) and the PSU stopped

Disassembled, reset, reassembled, PSU fan now runs but no display now. I think it's for the skip

 

[Softus]

Sorry to hear of its demise John.

Don't forget to put a sledgehammer to the disc if there's anything personal on it.

 

[DIY_Donkey]

It could be that the power supply unit is either not powerfull enough or is faulty. If you got a display having connected just a HD drive and it POSTed okay then it suggests that the MOBO is okay and so is the HD.
Did you try disconnecting the HD and connecting just the CD-ROM drive and booting up?
Also, the ribbon connector you used to connect the drives to the MOBO. Is it colour coded?
If so, the blue end must connect to the mobo. Also check the jumpers on the drives. I would recommend setting them both to CS (cable select). This means it doesn't matter whether the cd-rom or the hd are connected to the top or middle connections of the ribbon cable. You would just have to make sure in the bios that it cd-rom is 1st boot device and the hd is the 2nd boot device so that if you put a system disc in like Windows it will try to boot from this 1st.

 

[Softus]

I thought this was a machine that used to work, so the PSU used to be man enough.