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Registered Member #2727
Joined: Tue Mar 09 2010, 02:39PM
Location: Montevideo - Uruguay
Posts: 33
You can use an isolation transformer to feed the osciloscope power, but be warned, you will be energizing the osciloscope ground!!. You can obtain one isolation transformer from two identical tranformers in cascade: Mains to primary1 secondary1 to secondary2 primary2 to osciloscope or watever you must isolate. Of course the power rate of the transformers must be equal or greather than the load. See you
Registered Member #2028
Joined: Mon Mar 16 2009, 08:13PM
Location: Norway
Posts: 319
I encountered some problems when i converted an ATX psu to serve as a power supply for a pinball machine. As it turned out, it had the +5V rail connected to chassis ground and mains earth.
I also have a small 110W ATX that i converted to a simple lab supply, and i cant measure any connection between any of the output rails and the chassis. Seems like there are several designs around.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
TheMerovingian wrote ...
Use a differential probe or two scope inputs with INV+SUM
This is what I would suggest, the latter.
Nicko wrote ...
Steve McConner wrote ...
Patrick wrote ...
the black wires to the mainboard are not ground
In every ATX PSU I've poked around, the black wires are connected to the case and the third prong of the power cord. This used to cause me trouble with ground loops in my old home recording setup.
Seconded - just checked about 10 ATX PSUs I have here from HP, Compaq, Qtech etc. & all have COM connected to chassis & mains earth.
Perhaps the ones I have taken a part and modded, are crap designs? I wonder how Sparkle inc. does it?
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ATX PSU weirdness
