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Testing Methodology Discussion Questions and comments regarding the testing methodologies used on jonnyguru.com

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Old 06-27-2013
Philipus II Philipus II is offline
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Default testing the safety funktions

Hi,

I'm once again working on my chroma testing program. This time i try to integrate the testing of the protection functions.
I already remembered it would be a great idea to put these tests at the end of the test program because of the risk of killing the psu.

I think I managed to integrate OVP and OPP testing. OCP is already in for the +5V rail (+5V overload test), I just have to adapt this test for each of the +12v rails. We'll see if my way of doing it works out as soon as I'm at the chroma.

Where I'm stuck is the UVP protection. There is no value for triggering it specified in the ATX specs. Just take the triggering point of typical ICs?

SCP won't be tested at the Chroma because testing SCP means the chroma needs an early recalibration. In most cases of shortcuts, other protections (UVP, OCP, OPP) should kick in anyway, but I plan to build a short cut tester for testing at home.
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Old 06-27-2013
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Trigger UVP? How did you trigger OVP?

A home made SCP tester should be easy.
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Old 06-27-2013
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On most ICs you won't trip the UVP with a voltage less than 15% under the nominal value. Meaning 10.2V @ 12V at the most, 4.25V @ 5V at the most, and 2.85V @ 3.3V at the most. There are some secondary ICs that are way less sensitive, going as far as 25% below. You're much more likely to trigger every other protection there is than UVP, which is largely redundant. The only way I see to provoke it, is to partially short a PSU that has horrid voltage regulation, but not enough to trip OPP and OCP. This is, in fact, the reason for UVP's existence - it is a fallback, last-measure SCP.
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Old 06-27-2013
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The Chroma 8000 ATS claims triggering OVP can be done using the DC-source. I'm going to try when I'm in Hamburg again.
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That's assuming the PSU uses v-sense wires... Fooling the controller IC into thinking that it's the PSU that puts out too much voltage, when in fact it's sensing a voltage sourced from elsewhere.

Or is it based on the premise that a computer PSU is a voltage source, so when you connect it to another voltage source with higher potential, the voltage within the PSU will be "dictated" by what you set your source to?

To illustrate, if I connect a 15V voltage source to the 12V input of the Chroma, then connect a PCI-E cable, for example, could there appear 15V on the 12V rail in the PSU?



Damn, where's Travis when you need him?
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Old 06-30-2013
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Testing SCP is fun. I use a chunk of steel across a couple contacts fed by the CPU power cable.
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