Power supply eruption

**arch0nmyc0n** · July 14th, 2004, 03:25 PM

We sold a power supply to a local computer onsite guy (Nerds Onsite). And he brought it back because when he plugged everything in the wire connected to the floppy drive began to smoke and melt. (I can get a picture of it if anyone is interested.) The same thing happened to me a few years ago and I chalked it up to the plug not being all the way on the floppy drive... I don't know much about electrical current or the way electricity works in general. My question(s) is (are), what can cause this to happen? Is it improper installation? Is there any way to tell what happened? was I right with my analysis of my experience perhaps? Just wondering...

I just gave him another PS (reluctantly) and I haven't heard from him... I told him my previous experience and he said "I've attached about a hundred of these before and it's never happened", so I replied "I've attached several hundreds of these and it only happened to me once"

**ilovetheusers** · July 14th, 2004, 04:06 PM

Did you try the one he returned in a different system?

**jitBob** · July 14th, 2004, 04:12 PM

I saw one go up in smoke when the power connector to the floppy drive was connected one pin off. They missed the fourth pin and were off to one side, really let the smoke out of that box!

**amyb** · July 14th, 2004, 04:30 PM

I'd like to see a picture of it..

**joelen** · July 14th, 2004, 04:57 PM

Originally Posted by jitBob

I saw one go up in smoke when the power connector to the floppy drive was connected one pin off. They missed the fourth pin and were off to one side, really let the smoke out of that box!

YUP- This is what your guy did- i have seen this several times by our guys here in the shop- they are not always all that carefull-- we never take power supplies back that have a melted floppy cable-- 100% of the time it's because the power to the floppy was off one pin... test it-- try using a old or cheap power supply and see for yourself... it usally does not damage the floppy or any otehr components, as long as you unplug it before the fire spreads

**Ruslan** · July 14th, 2004, 10:58 PM

Originally Posted by jitBob

I saw one go up in smoke when the power connector to the floppy drive was connected one pin off. They missed the fourth pin and were off to one side, really let the smoke out of that box!

I've seen it happen many times,(at least 5 times - that's for sure) especially with cheap PSU... And I'm sure on 110% what it is his only fault... most likely happened exactly what JitBob just described... For some reasons overload protection doesn't work in that case and even thick wires can start melting!

Many times I've seen systems returned back by customers - "no power"... Of course, no power - floppy power is connected wrong way... If you could see faces of those customers when after few seconds of "troubleshooting" PC started working... I told them next time it will blow everything inside the case and it will be not covered by warranty...

Works! Next time they will think twice before making changes by themself...

**TripleRLtd** · July 14th, 2004, 11:16 PM

Originally Posted by Ruslan

Many times I've seen systems returned back by customers - "no power"... Of course, no power - floppy power is connected wrong way... If you could see faces of those customers when after few seconds of "troubleshooting" PC started working... I told them next time it will blow everything inside the case and it will be not covered by warranty... Works! Next time they will think twice before making changes by themself...

I let a customer pick up a pc instead of delivering it, and he switched the connections of the mouse and keyboard I discovered when he told me it didn't "work" . Yes, of course he couldn't use the mouse or keyboard after he booted up into windows! And, I had to retrieve and "fix" the problem pc which would then no longer boot up properly.
It then needed a new video card and sound card, and I had to cover it under warranty. Damn!!!!!!!!!!!!!
I really wish I hadn't sold him that pc, and from now on, I will NOT let them take, but I will deliver it!!

PS
I HAVE to stop being so nice to my customers....

**beshman2** · July 15th, 2004, 08:45 AM

Just had that happen here last week. I was not in when it happened but our senior tech plugged in a power supply, walked away, and came back to find the power lead to the floppy smoking. Replaced the unit (Antec 350W) with another and everything was fine including the drive. Never did figure out the cause although the edge of the IDE cable to the CD was melted with a wire exposed also, maybe a short between the two?

**arch0nmyc0n** · July 16th, 2004, 10:23 AM

Wow thanks for the replies... I'll bookmark this if he ever comes back...

**Tekboy** · July 16th, 2004, 11:13 AM

I saw this happen on the first Athlon machine in Fairbanks here, and 3 techs went over all the connections before applying power to the board. In this case, the floppy drive itself was the culprit, however, since the controller board on the drive itself started burning immediately. But it was definitely NOT a pin off in this case.

**Outcoded** · July 16th, 2004, 01:03 PM

Originally Posted by jitBob

I saw one go up in smoke when the power connector to the floppy drive was connected one pin off. They missed the fourth pin and were off to one side, really let the smoke out of that box!

Happened to a friend of mine - Damn we took the piss!

The reason it happens is simple, the two centre pins are both grounds, so tend to be connected together inside the drive. If you offset by one pin, you immediatly short out the voltage that's still connected, normally the +5V. Take a look what the +5V rail is rated at on a modern PSU. On a basic Antec 330W PSU, it's 30A, which as about 150W... and it's rated to deliver that before the overload protection kicks in! That's about 2x the thermal design power of an Athlon 64. Luckily, the floppy drive power wires tend to only be able to conduct that amount of power for a relativly short amount of time before doing a fair impression of a thermal fuse

**arch0nmyc0n** · July 16th, 2004, 04:59 PM

Originally Posted by Outcoded

Happened to a friend of mine - Damn we took the piss!

The reason it happens is simple, the two centre pins are both grounds, so tend to be connected together inside the drive. If you offset by one pin, you immediatly short out the voltage that's still connected, normally the +5V. Take a look what the +5V rail is rated at on a modern PSU. On a basic Antec 330W PSU, it's 30A, which as about 150W... and it's rated to deliver that before the overload protection kicks in! That's about 2x the thermal design power of an Athlon 64. Luckily, the floppy drive power wires tend to only be able to conduct that amount of power for a relativly short amount of time before doing a fair impression of a thermal fuse

that's the explaination I was hoping for... now I just hope mr genius onsite nerd comes back to the store so I can inform him of his not paying attention ways

I think it's safe to say we all occasionally do thing like this... but I just wanna shatter his holier than thou attitude...

**arch0nmyc0n** · August 20th, 2004, 01:09 PM

As an update, I have added the pictures I took to my yahoo share... finally...

Take a look here:

http://ca.pg.photos.yahoo.com/ph/arc...lbum?.dir=8d67

Burnt Wire.jpg and Scorched Coupler.jpg are the pics I draw your attention to.

**NooNoo** · August 21st, 2004, 10:56 AM

pretty nice collection

**arch0nmyc0n** · August 22nd, 2004, 10:08 AM

Originally Posted by NooNoo

pretty nice collection

well thank you.... I would have had a lot more different things... like the worlds dirtiest computer... but we didn't have the digital camera around before I had to clean it...