Could be graphics, RAM or processor. Any clues?

A french exchange student recently left my computer on, left a window open above it, and didn't think to switch off, shut the window or even tell me when thunder and lightening hit.

1. The computer got wet
2. He had also removed my surge protection
3. The computer doesn't work.

Being reasonably tech-ed up myself, the computer was a DIY job (with no warranty etc).

Symptom: The computer runs for approx. 10 seconds. Sparks are visible where the ATX power connector meets the motherboard. This motherboard no longer works. I replaced it with a [bold] ASRock K78 SX motherboard[/bold]. This motherboard doesn't have an onboard graphics chip, and [bold]warns against fitting any 3.3volt AGP card [/bold]. I plugged in an unknown AGP card which has these details printed on it: [bold]Powered by ATI. ATI-Radeon RV100[/bold]. Unfortunately I cannot find any more information about it so I don't know whether it is 3.3V or not. With the below specification the machine runs for approx. 17 secs before automatically shutting down. The PSU must then be unplugged for 10 seconds before starting again: [bold]

400W PSU (I've tried two different ones)
512 DDR RAM
AMD 2400+ Athlon XP CPU
Asrock K78 SX motherboard
no graphics, IDE drives, AGPs, PCIs or floppy drive. [/bold]

With the aforementioned graphics card (and standard monitor), the machine struggles to continue for 7 or 8 seconds.

Any clues?

PS. all my data is backed up etc., i'm not worried about that: I'd just like a working computer. Thanks

 

First I would hang the french exchange student from the window.
After that fun is done, Do you have an other system that you know works? I would test your HD, CD ete to make sure ok, by switching them on the other system.
I say this because if the HD is toast, I would look at starting from new or buying a used system. It is possble that most of the system when down when it got wet.

The 10 sec thing could be a short accross the ram. I would be very careful with it as, it can damage other systems if the ram is bad. Its the first thing ever bios runs through when started.

 

HD needed to be replaced anyway but isn't toast as I was able to dump entire contents onto my other machine(according to constant ActiveSMART monitoring when the computer WAS functioning), and I have backups etc. Also, according to Appian RV100 family user guide (as mentioned in above thread) the chip is AGP 2x compatible. However, the (DDR)RAM may be the issue. I'm currently short on cash (and my other machine is running on SDRAM) and therefore will not be purchasing anything in the next week or two, but I will look into it. Thanks guys - I'll keep the forum informed.

Leo

 

You noted the unit got wet. The cardinal no for electronics. This is just a thought and may have no bearing on your unit. I didn't hear any mention of drying the unit. As you built it, you should be able to disassemble the unit an dry the components (disconnect and use all safety precautions). Moisture will linger especially long in contact points and in enclosed components. You can use a hand held hair dryer to do the drying (don't overheat). Disconnect and dry all components and connections. Just an idea, but any moisture in the unit has to be removed if not already done. This has to be done before any tests can be accomplished. Moisture will short circuit electrical/electronic equipment. Usually sparks are a good indicator that something is shorted.

Computers are tougher than most think. I just had a system struck by lightning. It's an older P3 unit and not worth extensive work. I formatted the hard drive and reprogammed the computer. The only hardware that had to be replaced was the modem. As your unit was on, you may well have more extensive damage. This fix is also not possible (I realize) until the computer will stay on.

As another user stated, check the components first. Most suppliers and makers of hardware and components will give you specs on older components (not always). Much damage and most units are junk now as good basic units go for $400 to $500. Get on the net or phone and find the tech support service. Sometimes the info can be found running a simple net search. Drives can be checked on another computer. Plug in ram cards can be checked easily if you have another computer with a compatible board. Plug in and the computer will recognize and use it if good.

I used simple language here, but one bit of pure tech advice. Use a high impedance digital meter when checking continuity and resistance (ohms) as just any old meter can cause component damage. The meter can also give insight into shorted components when used correctly.

 

Thanks for that one brobear. Sorry I neglected to state that I took the computer apart, including removing processor and RAM from mobo etc. I [bold]did[/bold] leave them in a warm dry cupboard (by warm I mean 24 degrees centigrade) for 72 hours before "experimenting". Thanks also for the info on ohm monitoring.

Leo

 

Sounds like the unit is shorted, the sparks coming from the power connection to the motherboard is a good indicator. The first thing I would check is the power supply and make sure nothing is grounded that shouldn't be. Looks like you're in for a no fun session of component testing. I'd double check to make sure everything is dry. Here is a little trick. In suspected areas, like connector slots, use alcohol as a drying agent. Inject the alcohol into the space as necessary and blow it out with a can of compressed air. The stuff you clean your keyboard with. The alcohol mixes with water and evaporates much more quickly. Don't put the alcohol anywhere it might cause damage. Soft rubber and tape are damaged by alcohol. Use in a well ventilated area and no smoking or sparks.

I'm not saying it is the problem but moisture in circuitry will definitely short a unit. My neighbor had stereo equipment setting in a bay window area and it rained on it while he was away. He let the unit dry for days and there was enough moisture to still short the unit. The comparison is that, like a computer, you have power supplies, circuit boards, switches and memory chips. Anyway, before I knew what happened, he purchased a new unit and was going to trash the stereo. I took the unit, dried it, repaired one switch, and had a better digital CD/radio stereo unit than the new one purchased.

Good luck. From what you said of the unit, unless you have some background in electronics repair (or a friend that has) the trouble getting it fixed may be more than the unit is worth. That is unless this is a leisure activity and you don't consider your time as money.

 

I'm thinking this problem must be to do with RAM because processor, PSU and graphics card all work with my other machine perfectly well. Mobo has already been replaced so, again, that can't be it. I haven't tried running the machine with any drives or PCIs and sound and Lan are on the mobo. Don't expect anything from me for a couple of weeks: - I'll have some money for RAM then.

Best wishes to all
Leo

 

Did you take any voltage readings at the power supply plug. You had sparks to the MB, could have shorted the PS causing over voltage to other areas. Usually voltage and pin numbers on the supply box.(If the tag is still there).

Jerry

 

Good idea Jerry. However, I've tried my PSU with my second computer, and that works fine. Additionally, the PSU from the second (working) computer doesn't help my broken computer to work.

Thanks