Burning-charred atx psu socket? Oh no! Ideas?

[Brangwen]

Colleagues:

I've a problem the solution of which may be apparent to some members.

I was using my Iwill KK266 system and it rebooted on it's own several times, making a clicking sound in the area of the sole HDD, then I smelled burning wire / plasic.

I shut down of course.

Armed with a flashlight, I noticed that pins 4 and 6 (red wires counting from the right side of the "P1" side) on the socket coming from the ATX 300W PSU <u>AND</u> the corresponding [2 wire] slots on the mobo were burnt. I'm posting this in hopes that someone will have an idea why.

Components:

1. Iwill KK266 mobo
2. 1.33 TBird
3. 512 MB SDRAM
4. 6 case fans
5. Baycooler
6. Fanbus
7. IBM ATA100 HDD
8. Plextor CDRW
9. Creative CDrom
10. Matrox G450 dual head 32MB vidcard
11. 2 monitors (17" CyberVision, 19" Samsung)
12. SB Live Value and Cambridge Soundworks speakers
13. Creative modem blaster (ISA)
14. All cables rounded

I hope someone can discern the problem given the number 4 and 6 wires that are involved and became hot.

This system has been running rock stable: cpu temp under full load never exceeded 104F.

If more info is need, or a photo, <u>please</u> let me know.

Thanks for your ideas.

Brangwen http://www.sysopt.com/forum/wink.gif

PLEASE LOOK AT MY POST ON BOTTOM!

[This message has been edited by Brangwen (edited 08-22-2001).]

[Cody]

Use your fingernail (or a q-tip), be very gentle, and lightly rub the charred part 1 or 2 times. If it comes off, I should think you are OK.

Check to make sure that PSU switch on the back of the computer 113/??? is set to the correct setting.

Oh, and of course... &bump&

[Brangwen]

Prior to my computer rebooting, it would make a clicking sound in the area of the IBM HDD. I'm wondering what would make the 2 red wires (4 and 6) on the power supply socket get hot? Anyone?

Thx.

Brangwen http://www.sysopt.com/forum/wink.gif

[Bovon]

Several possibilities come to mind. One being of course something is shorted. What is shorted may be difficult to find. What I think I would do is, fire it back up momentarely and observe the wires, if they can be determined to be getting hot again, shut down and detach everything, remove all cards from the system, unplug the mouse and keyboard. Leave only the mobo, ram and cpu attached and re apply power. Of course you will get post errors, but the few items still energised will be powered. Observe the wires for heat. If they are now ok, reattach all devices one at a time until the heat problem re appears.

If by removing everything possible, and the wires still get hot, the problem is ram, cpu or mobo.

If you suspect the HDD (or any other part, you can detach this part first as an effort.)

Without complicated test equipent a shorted circuit usually only can be narrowed down by trial and error.

The psu itself could be the culpret. If the regulators went south, the psu is capable of supplying much more voltage (and amperes) than normal. This usually will melt wire insulation, and damage circuits attached to the psu.

[Brangwen]

Thx, Bro Bovon. I'll give that a go and post results.

Brangwen http://www.sysopt.com/forum/wink.gif

[Brangwen]

Odered new psu and KK266 Plus Raid... anyone hear of this Iwill mobo?

Brangwen http://www.sysopt.com/forum/wink.gif

[Brangwen]

Very Interesting:

The pins that show burn / overheating marks are (numbers) 14 and 16 on the ATX power socket. 14 = Power On/Off and 16 = Ground. My case was painted and I <u>know</u> the "Power On" switch has gotten stuck "on" before as the paint has made it sticky.

Question: Can a "stuck on or partially stuck on case power switch" cause the burn marks I've described?

Thx.

Brangwen http://www.sysopt.com/forum/wink.gif

[Bovon]

In an ATX psu are two separate power supplies (you may know this, but just in case...) The extra supply is 5 volts, and is on all of the time the power cord is plugged into a live 120 volt AC circuit. What happens is, this 5 volts is connected in some way to the switch on the front of the computer case by way of the switch wires to the mobo. When the switch is depressed, it sends that 5 volts back to the psu to 'tell it' to turn on the main supply. this is done thru wire 14 and I think maybe wire 16 is in this circuit someway because to turn the main supply off...ground is applied thru wire 14 to the same circuit in the psu to tell it to shut down. How this actually works is beyond me...I have a schematic of a psu and I can see the inputs and they say that +5 volts turn it on, and 0 volts (ground) turns it off...but exactly how wire 14 gets +5 volts at one time, then 0 volts the next, I do not know...but must be some kind of circuit on the mobo that flip-flops the voltage. Now, I would think that if the +5 volts were continually applied thru a stuck switch, could possibly cause trouble.

I know a little about the Iwill KK266, and the raid version is almost the same with the addition of the AMI raid controllers. I have the KK266 here, but have not put it together yet...It is supposed to be a very good board, and several guys that have come to the Iwill boards from others, say it is a better board than what they left behind. Of course, some have not been quite as pleased...but thats life.

[Brangwen]

Thanks, Bovon. I'm using the non-raid KK266 and think it's the best. The new board I ordered is a non-raid KK266<u>Plus</u>: I believe the "Plus" simply meants a KT133A chipset vs a KT133 chipset. I couldn't find the original KK266 Iwill non-raid board yesterday: great board though.

Brangwen http://www.sysopt.com/forum/wink.gif

PS: Thx for the great replies.