Raspberry Pi -- HDMI question

There are some useful suggestions at the RasPi Troubleshooting Wiki: http://elinux.org/R-Pi_Troubleshooting#Display.  I find my display blanks out if TP1-TP2 voltage drops too low.

Is TP1 and TP2 where you can connect a volt meter and test the Pi to see if it has sufficient voltage going thru?

Yes -- there's a nice photo showing how to do it at the RasPi Hardware Wiki: http://elinux.org/Rpi_Hardware#Power_Supply_Problems.

Tested with SD card inserted and tested TP1 and TP2. My voltmeter read 4.84v. So its between 4.75v and 5.25. Maybe it should be around 5.xx?

When I use a composite video cable it comes in fine.  Not sure why the HDMI doesn't work though. 

4.84V is just barely enough voltage to drive the board. With all of those loses, as soon as you start using more stuff on the pi, such as the HDMI output, you'll see the voltage drop. More current used == more voltage drop over resistive devices such as the polyfuses and bad cables and terrible PSU's. Your second post shows us the results.

You should see all of the other power problems manifest as well: failing keyboards/mice, network sketching out, hdmi not working. Suggest during your testing (hope you can get a spare PSU to try) that you utilize ssh to remotely connect to the pi and diagnose its problems from a perfectly working computer which has no unknown problems. There's a lot to be said for a working keyboard and display when troubleshooting.

There's many more guides to be referring to when it's about power problems. Just remember that sometimes HDMI problems are actually power problems. Sorry for not posting links but it's too late at night here. Good luck!

4.84V is just barely enough voltage to drive the board. With all of those loses, as soon as you start using more stuff on the pi, such as the HDMI output, you'll see the voltage drop. More current used == more voltage drop over resistive devices such as the polyfuses and bad cables and terrible PSU's. Your second post shows us the results.

You should see all of the other power problems manifest as well: failing keyboards/mice, network sketching out, hdmi not working. Suggest during your testing (hope you can get a spare PSU to try) that you utilize ssh to remotely connect to the pi and diagnose its problems from a perfectly working computer which has no unknown problems. There's a lot to be said for a working keyboard and display when troubleshooting.

There's many more guides to be referring to when it's about power problems. Just remember that sometimes HDMI problems are actually power problems. Sorry for not posting links but it's too late at night here. Good luck!