Tom1989 wrote:mahjong, thank you very much!
Hmm I will update the wiki with the info you have just told me. It sounds like this could happen to other people looking for the cheapest solution.
Ok so is it possible to replace this diode? I presume that my HDMI output is stuffed until this is fixed?
Yes, the BAT54 is a simple SOT-23 schottky diode, as common as anything, maker is unimportant, dozens of manufacturers make this one. Use a cutter to cut off the one lone lead on the side of the package with one lead in the middle, then with a soldering iron you can heat both other legs, and remove the diode, then remove the remaining lead. Clean with solder wick, or pump, then you can solder another BAT54 diode, which should cost only a few dimes, but read on before proceeding.
There is probably still a short, or overload, in the power line of converter which must be removed or dealt with.
The raspi is designed to deliver the 50mA for a small EEPROM containing monitor capabilities in the TV, (which is according to HDMI specifications) and this power is (mis) used by this adapter, and also will probably be much larger than the 50mA allowed . A BAT54 is good for 200mA, but if the adapter uses much more than 50mA its a more fundamental design error in the adapter (which should work with the 50mA that is normally available to it). I guess the device is so cheap because its ignoring many specs, not being externally powered as it should be if it needs more than 50mA (which is almost certainly the case) is one of them I guess. I also guess that it might overtax the raspi's power supply, as it almost certainly doesn't draw 50mA.
What I would do in a situation like this is using the opportunity that a removed diode offers to measure the current the converter draws, (measuring on the solder pads of the diode) if its much more than 200mA (which I suspect) a BAT54 won't cut it, and you also will run into trouble with your PSU which must source the extra current, and with the input fuse of the Raspi, which is rated for normal use, that is 500mA for the R-PI and 2 x 100mA for the USB devices, nothing more!
Provided the PSU can source the extra current, and the polyfuse doesn't blow you could try to mount a heavier diode, for example a PMEG2010AET which can conduct 1A.