(My first post, yay!)
I am currently working on converting an old (~10 years old) Dell psu into a lab unit that I can use to test my other electronics projects.
(see http://web2.murraystate.edu/andy.batts/ps/powersupply.htm)
I am mounting the unit in a cardboard shoebox so that I can have more room to work with. I have cut slots in the shoebox for the fan, wall plug, and side vent. I have mounted a toggle switch in the front of the box and connected the gray wire (ps_on) to one lead and black ground wire to the other lead (I know that Dell didn't stick to the ATX standard back in the day and thus I used pinouts.ru to determine which wire is which).
Now for my question:
When testing for continuity (to make sure that I didn't short anything), I discovered that all the wires (and I mean ALL the wires) running from the psu appear to connect at some point (I suspect the unit's metal casing). Suspicious, I checked another ~10-year-old Dell psu and found the same results. What I found really odd was that the ps_on wire, of all wires, was grounded. Startled, I compared this to a newer BesTec psu (not sure of the age, but it had the 20-pin mb connector and the 12V 4-pin connector) and discovered that most if not all of the wires, EXCEPT the green ps_on, were connected to the case in someway.
Can someone please explain what is going on here? Why are all of the Dell connections shorted together, but not all of the BesTec ones? Why are most the connections meeting at the metal casing? Shouldn't that cause a short circuit?
Also, with regards to my project, what safety precautions should I take to reduce the risk of burning the shoebox?
Thanks,
Jesse
I am currently working on converting an old (~10 years old) Dell psu into a lab unit that I can use to test my other electronics projects.
(see http://web2.murraystate.edu/andy.batts/ps/powersupply.htm)
I am mounting the unit in a cardboard shoebox so that I can have more room to work with. I have cut slots in the shoebox for the fan, wall plug, and side vent. I have mounted a toggle switch in the front of the box and connected the gray wire (ps_on) to one lead and black ground wire to the other lead (I know that Dell didn't stick to the ATX standard back in the day and thus I used pinouts.ru to determine which wire is which).
Now for my question:
When testing for continuity (to make sure that I didn't short anything), I discovered that all the wires (and I mean ALL the wires) running from the psu appear to connect at some point (I suspect the unit's metal casing). Suspicious, I checked another ~10-year-old Dell psu and found the same results. What I found really odd was that the ps_on wire, of all wires, was grounded. Startled, I compared this to a newer BesTec psu (not sure of the age, but it had the 20-pin mb connector and the 12V 4-pin connector) and discovered that most if not all of the wires, EXCEPT the green ps_on, were connected to the case in someway.
Can someone please explain what is going on here? Why are all of the Dell connections shorted together, but not all of the BesTec ones? Why are most the connections meeting at the metal casing? Shouldn't that cause a short circuit?
Also, with regards to my project, what safety precautions should I take to reduce the risk of burning the shoebox?
Thanks,
Jesse