Hello.
I noticed something.
There is a shortage of test equipment designed to accurately test ATX Power Supplies.
At the low end, there's the ULTRA brand go/no-go voltage tester that's pretty useless. At the high end, there's SunMoon and higher.
In the middle, well, there's nothing! Well, at least I couldn't find anything.
Until now.
Introducing the KeriProductions ATX338 PSU Load Tester. This is a two-channel load tester, allowing scope output and voltage display of two different circuits at once. The load resistors are switched via a bank of toggle switches. The ATX ON switch is interlocked to the POWER/FAN ON switch so that the fans must be turned on before the PSU can be activated.
It is based upon industrial wirewound resistors of 3Ω/50W for the 12V+, 1Ω/25W for the 5V+, .5Ω/25W (20w for now) for the 3.3V, a 10Ω/25W for the 5V standby and a 30Ω/25W for the -12V. The total wattage comes out to around 338. Which should be high enough for testing low to mid power PSUs. Extra space remains for two more resistors. They are mounted to the case with simple Carriage Bolts and have some wavy washers to allow for expansion.
The resistors are rated for temps up to 350C but derate rapidly over 50C The two fans appear to keep the resistors under 60C. (with the help of a borrowed infrared thermometer)
Load testing was done tonight with the help of a recapped TruePower 380. I have not yet wired the Voltmeters or scope outputs, but did verify that the fans run, a fair bit of heat is generated, the indicators for Power, ATX Power Good Signal and the rudimentary -12V load indicator all function.
Configuring the Velleman LED displays was an adventure, but I got them set for the 0-20V range with voltage dividing resistors despite the instructions written for people a lot smarter than me.
The casing was just a case that I picked up at Fry's. After drilling a GAZILLION holes in it and grinding out the rectangular holes with a Dremel tool and a file, I painted it with high temperature paint. The Label was created with OpenOffice DRAW.
The next step is to wire the selectors, voltmeters and scope outputs. As I understand it, decoupling caps should be attached to the scope terminals inside the case.
I should have it finished up this weekend.
Any comments or suggestions are welcome.
Thanks for all the help,
Keri
I noticed something.
There is a shortage of test equipment designed to accurately test ATX Power Supplies.
At the low end, there's the ULTRA brand go/no-go voltage tester that's pretty useless. At the high end, there's SunMoon and higher.
In the middle, well, there's nothing! Well, at least I couldn't find anything.
Until now.
Introducing the KeriProductions ATX338 PSU Load Tester. This is a two-channel load tester, allowing scope output and voltage display of two different circuits at once. The load resistors are switched via a bank of toggle switches. The ATX ON switch is interlocked to the POWER/FAN ON switch so that the fans must be turned on before the PSU can be activated.
It is based upon industrial wirewound resistors of 3Ω/50W for the 12V+, 1Ω/25W for the 5V+, .5Ω/25W (20w for now) for the 3.3V, a 10Ω/25W for the 5V standby and a 30Ω/25W for the -12V. The total wattage comes out to around 338. Which should be high enough for testing low to mid power PSUs. Extra space remains for two more resistors. They are mounted to the case with simple Carriage Bolts and have some wavy washers to allow for expansion.
The resistors are rated for temps up to 350C but derate rapidly over 50C The two fans appear to keep the resistors under 60C. (with the help of a borrowed infrared thermometer)
Load testing was done tonight with the help of a recapped TruePower 380. I have not yet wired the Voltmeters or scope outputs, but did verify that the fans run, a fair bit of heat is generated, the indicators for Power, ATX Power Good Signal and the rudimentary -12V load indicator all function.
Configuring the Velleman LED displays was an adventure, but I got them set for the 0-20V range with voltage dividing resistors despite the instructions written for people a lot smarter than me.
The casing was just a case that I picked up at Fry's. After drilling a GAZILLION holes in it and grinding out the rectangular holes with a Dremel tool and a file, I painted it with high temperature paint. The Label was created with OpenOffice DRAW.
The next step is to wire the selectors, voltmeters and scope outputs. As I understand it, decoupling caps should be attached to the scope terminals inside the case.
I should have it finished up this weekend.
Any comments or suggestions are welcome.
Thanks for all the help,
Keri
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