Sorry for the long post, but I wanted to include all the detail. My flatmate and I cant wait to use the Pi, but our first concern is repairing/replacing an expensive TV and knowing whether any of these components are safe to use again without breaking the replacement.
My Samsung LE32R88BD TV went pop last night when was trying to get the Pi to work and now it refuses to do anything once taken off standby. There are three candidate causes, so I thought I"d discuss the setup here to warn others as well as find answers to these questions:
1) What caused the TV to break?
2) Is it likely to be repairable?
3) Is the Pi still safe to use on another TV?
4) Is the powered USB hub safe to use?
5) Is my 4-way mains adapter safe to use?
I"d managed to get the Pi to boot with debian6-19-04-2012 connected to my TV via HDMI, but it was not accepting responses from either of two simple wired keyboards. It didn"t make a difference whether I had a wired optical mouse plugged into the other port or not, nor which port I used. The keyboard was apparently not receiving power from the USB port at all, as the caps/num/scroll lock indicators never lit up. Unfortunately, I didnt have a voltmeter handy, so I couldn't measure the voltage, but I tried two working phone charger cables (one was 5V, 1A, the other was 5V, 700ma). Ill try to measure the voltage tonight and post that here. Whatever the voltage, the mouse, when connected, was receiving power as the red light underneath was lit.
Thinking that power might be the problem, I plugged a powered 7-port USB hub (http://tinyurl.com/7bra564
) into the Pi and into the mains and connected the mouse and keyboard through that. Still nothing from either keyboard, so I was unable to login. However, I noticed that sometimes when I disconnected the Pi from the mains, it would remain on by apparently drawing power back through the USB peripheral cable from the powered USB hub. This only happened once, and I didnt leave it on for long, but I thought it might be important.
Also potentially important: the TV, Pi and USB hub, when plugged into the main, were all plugged into the same 4-way UK extension cable/splitter, which is fused to 13A.
Ok, so here"s the bit where it turned to the worse. I continued to try various configurations and eventually had the following situation:
Pi is turned off (not connected to mains)
Pi connected to Samsung LE32R88BDTV HDMI port 1
Pi connected by USB to 7-port powered USB hub
Wired optical mouse and simple wired keyboard plugged into USB hub
USB hub and TV plugged into same 13A-fused 4-way UK mains extension
When I reached forward to plug the Pi back in, as I had safely done before, before the mobile phone charger was even close to the 4-way socket extension there was an electrical flash and the AC power went off in the flat. Given that I hadn't yet plugged the Pi in, the suddenness of the flash must have been from nudging one of the already-connected cables. After my flatmate reset the circuit breaker, the TV was broken. It now buzzes (as if shorting-out) from the area where both the power and HDMI cables connect to it.
So which of these happened when the cables were nudged?
1) The Pi drew power from the powered USB hub and a surge passed up through the HDMI to the TV? Is this possible? I don"t know how the HDMI connectors work but I"d already seen that the Pi could receive power from the Hub.
2) The hub shorted internally, causing a power surge that broke the TV via the shared 4-way extension before the circuit breaker tripped.
3) Movement on the HDMI cable caused a short in the HDMI socket on the back of the TV, causing a surge.
Note that the 13A fused extension didn't blow. I"ll post the Amp rating of the circuit breaker tonight.