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800xl/130xe power rails reversed


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I have a 130xe that I think may have had the power rails on the power supply reversed. So basically the 5v went to ground and the ground went to 5v.

 

Beside toasting the whole machine what would be the result in this case?

 

I haven’t started diagnosising it but wanted a vague idea where I should start looking for dead components.

 

Thanks.

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Anything/everything could be blown, did it smoke at all ?

Do any chips show signs of overheating.

How long was power applied, the longer, the more chance capacitors could blow, if momentary, they may well survive.

Also circuit tracks could also have burnt.

Did it blow the mains fuse ?

 

Take some closeup photos top and bottom of the main board and post here.

 

 

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I doubt the mains would even know about it.  You'd probably not get a short if components blew out and if you did it'd be likely that fine tracks would be the weak point that'd melt and go open circuit.

 

But as for ICs... I don't think many would well tolerate running with current in the wrong direction.

It would be interesting though to know what survives and what doesn't in this case.

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2 hours ago, Rybags said:

I doubt the mains would even know about it.  You'd probably not get a short if components blew out and if you did it'd be likely that fine tracks would be the weak point that'd melt and go open circuit.

 

But as for ICs... I don't think many would well tolerate running with current in the wrong direction.

It would be interesting though to know what survives and what doesn't in this case.

When I took an electronics course I connected a 3906 transistor with the circuit wired for a 3904, the "crack" as it failed was heard by the entire class.

Edited by BillC
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If you reversed the power and the ground a bunch of bad things could have happened.  It would have blown out the first component and saved the rest of the board or you could have toasted everything on the board. Just because there was no sound or smoke doesn't mean it isn't all cooked.  Not a good thing to happen unfortunately.  Maybe you got luck and just cooked the first thing from the power source and all the rest is ok.  Good luck, would like to know what you find.

Gavin

 

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On 5/22/2021 at 12:34 PM, BillC said:

When I took an electronics course I connected a 3906 transistor with the circuit wired for a 3904, the "crack" as it failed was heard by the entire class.

Had a similar experience in my second semester of electronics class.  Working on a 12V breadboard I accidently plugged a 470uF radial electrolytic cap in

backwards.  When I hit the on switch I heard the sound of sizzling bacon for a second.  About the time I realized what I had done and was reaching for the

power switch, the top of the cap blew open and it's super hot guts flew into the air including on the bottom of my forearm.  To this day I'm not sure if I was

madder because of doing something so dumb and getting laughed at by my fellow classmates, or the little scars it left on my arm.

 

DavidMil          

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Just now, DavidMil said:

Had a similar experience in my second semester of electronics class.  Working on a 12V breadboard I accidently plugged a 470uF radial electrolytic cap in

backwards.  When I hit the on switch I heard the sound of sizzling bacon for a second.  About the time I realized what I had done and was reaching for the

power switch, the top of the cap blew open and it's super hot guts flew into the air including on the bottom of my forearm.  To this day I'm not sure if I was

madder because of doing something so dumb and getting laughed at by my fellow classmates, or the little scars it left on my arm.

 

DavidMil          

Tantalum capacitors are supposed to be worse, most of the guts of electrolytic capacitors is basically aluminum foil but when tantalums heat up the metal becomes molten before it explodes. Even after cooling down there are minute particles of tantalum everywhere.

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