Seller Note “No video output”
- These little cards often seem to have core issues, especially the passively cooled versions.
- VCore – 13.3Ω
- VMem – 449Ω
- PEX – 4.5KΩ? (not sure if this is PEX, I would like to know that PEX is high enough, I can see a value of 6Ω near what I think could be the PEX source…)
- 5V – 0.7Ω
- 3.3V – 7.11KΩ
- 12V – 11.1KΩ
- Seems to have a short on the 5V rail. As shorts go, 5V ones can turn out OK. Still, let’s see!
Investigating the short on the 5V rail
Taking a look at the photo and datasheet https://pdf1.alldatasheet.com/datasheet-pdf/view/1060268/UTC/78D05LG-AA3.html, we can see that pin 1 (left) is the 12V source, pin 2 (middle) is GND and pin3 (right) is the 5V output (shorted). We need to try and identify the source of the short. Quite often it can be the LDO itself.
OK, I guess I can plug the card in to test despite the 5V rail short. Well, the controller is certainly working hard if it isn’t the source of the short, as the thermal camera is showing it’s temperature as ~120°C! I couldn’t feel or see any other hot components.