Measurements of voltage in the power supply adaptor
We can not accurately measure voltage using programs like everest or speedfan or programs provided by the manufacturer of the motherboard because of the large (within 0.5V) margin of error. It follows from the fact that the voltage measuring circuits in the motherboard cost manufacturers just a few cents and given the price, voltage measuring circuits are not able to give us accurate and precise outcome however, for atx standards each 0.1V is of great importance. Therefore, to measure the voltage we should use only the cheapest electronic meter.
prior to the measurements make sure that:
- the meter is properly calibrated (by using a high-power meter or laboratory power adapter) meter calibrations can be done by electronic service.
- battery is not running out. "dying" battery may create a large measurement margin of error
- probes are thoroughly cleaned, preferably clean them with acetone before measurement
line -5v and-12v are practically not used nowadays, so their results can be somewhat treated not so seriously. The most important result that should interest us in particular is the result on +12 v line.
The table below shows the tolerances for the voltage margin of error. For each line shown in these tables, margin of error is so large that the power supply adapter that exceeds any of the values can be considered as damaged or not meeting the requirements of your computer configuration.
accepted norms for cables:
- yellow correspond to the voltage of +12v
- blue correspond to the voltage -12v
- red correspond to the voltage of +5v
- white correspond to the voltage -5v
- orange correspond to voltage +3.3v
Test running the power supply
Power supply test running means running the power supply adapter without a computer. Thanks to such a start we can thoroughly test all the pins and measure voltage power to exclude incompatibility with our motherboard.
To test run the power supply just shorted together pins 14 (PowerOn - it is mostly green cable) to 15 (gnd), permanently, it will run the power supply, let's not exaggerate the number of turn ons and offs of the power supply because it causes a very heavy burden on the electronics which could lead to damage.
remember also to never run the power supply without burdening the two most important lines, this is: +5v and +12v - it is best to connect these pins to a circuit test, or when we do not have this option for several devices (fans, optical drives, hard drives).
the most common problems associated with power supply adapters
incorrect state of the signal at pin 8 (power good) - the most common symptom is the work refusal of the computer operating system.