Odd d-i-y PC fault

[T i m]

Hi All,

My 15ry old's PC was due for an upgrade (won't play SIM's 2 smoothly ) and I have been collecting the upgrade bits over a while for her.[1]

As she built her last PC I asked her if she would like to do the same with this and she said she would ;-)

So, anticstaic mat, wristband, parts screwdriver and away we went.

When we came to the magic moment (mobo, cpu, ram, wires all in) we had power (front panel led, cpu fan etc) but no POST beep? We fitted the video card and still nothing (in case there was a problem with the speaker etc).

I rechecked all the basics with her (I was especially careful when she fitted the brass mobo standoff pillars) but couldn't see anything wrong.

I told her I would sort it out for her (assuming something was 'dead') and left it for another day.

Yesterday I took the mobo out and ran it on the bench, all was fine! (starting it with small screwdriver, so psu, mobo, cpu, ram, video all ok).

Re checked the case standoffs and even fitted fibre washers on them, re-fitted the board into the case and the front panel wires (power / hdd led, power and reset switches) turned on .. nothing? ;-(

I pulled all the front panel wires off again, started it with a screwdriver and it ran !

Hmm, re-fitted the 'reset' switch .. won't start so held the reset switch in and power cycled .. still nothing?

Measured the resistance across the reset switch wires and it was 'short' no matter what you did with the switch .

Pulled the front panel and switch out and there was a nice solder splash across the reset pair ... I have seen a few incorrectly wired switches in my time but can't remember seeing this before. I was just annoyed we missed it at the time, assuming something was duff (some of the bits weren't brand new etc) and I didn't think to check for something so obsure (the case at least was new) ... ;-(

The strange thing was the heatsrink covering the solder joints on the back of the switch would have to have been added *after* the solder joints were made, so you would have thought they would have seen the 'splash / whisker' at that point?

I have since told her what the fault was and she's looking forward to finishing the build off soon. I wished she had soldered the switch on herself .. the last project she made had over 100 led's and that worked first time!

All the best ...

T i m

[1] 'Mum' is having her old PC ;-)

[Rick]

I once had 250 hard disks that worked when on the bench but not in the case :-)

Rick

[Bob Eager]

Not the famed IBM 0661, with screws half a mm too long?

[T i m]

Oooerr .. did you ever get to the bottom of that Rick?

(wasn't there an issue with some hdd's where the body was isolated from their chassis as they floated at 5V or summat (till the mounting screws shorted them out etc)?

T i m

[T i m]

And other models Bob ... someting I would check before I put the drive in the case (and sometimes spaced out the scres with washers).

I still have a quick look these days but they seem to have that covered now ;-)

All the best ..

T i m

[Michael Mcneil]

You realise that a question about making home made bombs would be more in keeping with the general run of topics on this group?

[T i m]

Hey, I'll try harder next time ;-)

All the best ..

T i m

[Rembrandt Kuipers]

I pulled my old Amiga apart several times - each time it was apart it worked, assembled it did not.

Eventually I guessed it was interference from the monitor that sat on top of it. I reassembled it with a piece of tinfoil inside and it worked fine ever since in the same arrangement. :)

Rem

[Rick]

Not those disks, but after days of searcing, it was the same problem.

More weird we also had a tapedrive that worked in one 19 inch rack, but not a different one.

Those were the days when computers were fun, and IT was not a customer service dept, but a tecnology dept.

Rick

[T i m]

Computers and WiFi .. all witchcraft I tell ye!

All the best ..

T i m

[T i m]

I'm with you there Rick.

I moved from a Field Support role to running a 'Help Desk' for similar reasons at the time .. electronics repair was going out and box swapping was coming in (similar to board / panel swapping in the TV game and complete hubs rather than just bearings in the garages .. ).

When I was manning the 'Help Desk' it was still a technical role and they still exist but you have to get through the 1st line (and possibly 2nd line) drones to get to them ;-)

As with my daughters PC there was little you could actually get wrong yourself so building one *might* be something that everyone could do .. however with weird faults like mentioned so far you can see why everyone doesn't (apart from all the other reasons that is) ;-)

All the best ..

T i m

p.s. She's now got both PC's (old and new) on our network and migrating all her data across. Then the new will become her current PC (she can swap the FDD / DVDRW over at that time) and we will see what stuff (apps / utils / drivers) we have forgotten about!

[Bob Eager]

The 0661 had a specific provlem - it was in a composition 'frame' and would not work if the inner casing was earthed. It was'nt a case of hirtting a vital innard.