Fixing board with broken DC-DC converter

• Unsolder the DC-DC converters one by one and measure the resistance between the 2 pins with have the smallest distance. If the resistance is about 150 kOhm the converter is ok and one has to proceed with testing the next converter. If the resistance is significantly smaller (typically about 0 or 300 Ohm) then the converter has to be replaced.
• Check resistors near the backplane connector (e.g. R73). It should be 2.7 Ohm (note that in older revisions of the board 4.7 Ohm was foreseen). If the value is larger than 10 Ohm, the resistor has to be replaced.
• Check the transistor U35 and other components next to it. These might have to be replaced, too.