Hi, I'm about to convert an old AT PSU into a bench power supply, but there are a couple of issues that I need help with before starting.
- The first is about the cable that you need to connect to ground to turn the PSU on (normally a green cable): well, it doesn't have one; the only cable that is not one of the outputs or ground is a yellow cable that connects to "Power Down" on the board. The PSU turns on without shorting any cable to ground -just with the main switch- so I'm wondering if this cable is to turn it off or something else, and if I should use it or leave it disconnected.
- The second issue is the dummy load that most sites recommend. I turned the PSU on to test it, and it seems to work fine without any load; so, do I really need to add a dummy load, or is it just for ATX PSUs?
- Most sites also say that you need to connect all cables of the same color together to output the maximum amperage, but this PSU is just 78W (the highest amperage is for the +5V with 7A, followed by the the +12V with 3A; the rest are all under 1A).
- And last, do these PSUs have any protection, other than the fuses -like a current limiter or something-? I mean, what would happen if I exceed the maximum amperage -which for the -12V is as little as 0.3A- or if I accidentally short the outputs?
Thanks in advance for your help...
- The first is about the cable that you need to connect to ground to turn the PSU on (normally a green cable): well, it doesn't have one; the only cable that is not one of the outputs or ground is a yellow cable that connects to "Power Down" on the board. The PSU turns on without shorting any cable to ground -just with the main switch- so I'm wondering if this cable is to turn it off or something else, and if I should use it or leave it disconnected.
- The second issue is the dummy load that most sites recommend. I turned the PSU on to test it, and it seems to work fine without any load; so, do I really need to add a dummy load, or is it just for ATX PSUs?
- Most sites also say that you need to connect all cables of the same color together to output the maximum amperage, but this PSU is just 78W (the highest amperage is for the +5V with 7A, followed by the the +12V with 3A; the rest are all under 1A).
- And last, do these PSUs have any protection, other than the fuses -like a current limiter or something-? I mean, what would happen if I exceed the maximum amperage -which for the -12V is as little as 0.3A- or if I accidentally short the outputs?
Thanks in advance for your help...