The picture below shows some components of the Samsung I900 Galaxy S, it points a test spots where to start a check up or troubleshooting procedures. It also show us which and what components needs to check first.
Samsung Galaxy S I9000 Not Charging Problem Solution
Here's some hints on how to fix the Samsung I9000 Galaxy S Not Charging Problem:
1. Ensure that the battery charger you are using is properly working or try to use another one.
2. Visually check the USB pin connector for possible damaged. Clean it if oxidized, re-solder, or replace it if necessary. You can read the VBUS charge voltage at the pin #1 if the USB connector is okay.
3. Check or read the VBUS Charge IN voltage this is the output from the VBUS charger control IC.
4. Re-heat, rework the VBUS IC if the 5V is missing. Replace if necessary.
5. The power management IC will be the next option to re-work at if the procedures above doesn't solved the problem.