zardoz99 wrote:It seems that this is becoming a common problem. There are at least 3 posts that report the same.
Design/Manufacturing/Peripheral fault? Who knows....
Just use your monitor on a grounded mains plug, without a ground wire there will be half the mains voltage in between the whole monitor and earth, due to leakages in the power supply of the monitor, as it uses two small capacitors between the mains leads and the ground of the power supply (and thus the whole device). Very common, but not a real problem, as these (EMC protection) capacitors are very small. Again, just ground your monitor and the problem will disappear.jbeale wrote:maybe not relevant to HDMI, but I was about to connect an analog TV input to my R-Pi using an RCA plug. I turned on the monitor first, connected the RCA plug to it and as I brought the other end towards the Pi, I felt a little "bite" as my finger brushed the plug. Concerned, I checked the AC voltage between the ground of the plug and the ground of my R-Pi. Hmm... 54 Vac.
I then decided NOT to connect that monitor. I don't know how much current would have flowed- maybe it was a very high-impedance leakage path- but still a worry! (fwiw, this was not a consumer display, it is a professional monitor, with a set of BNC connectors.)
Sorry johnbeetem I didn't see your post. Thank you very much for the reply.My guess is that D1 is now shorted or open, but it's easy to replace with moderate soldering skill. You can test it with a multimeter to see whether it's shorted or open. In the highly unlikely case that it's still working, it should conduct in one direction and block in the other.
I used the ON Semiconductor data sheet for the BAT54, available from onsemi.com. ON Semi used to be the part of Motorola that made discrete semiconductors.
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.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?
Before sending it back, I'd test my hypothesis about HDMI pins 17 and 18 being shorted by the converter. It could also be the HDMI cable. It's easy to check this with an ohmmeter with all power off:Tom1989 wrote:BTW I have no intention of re-using the converter I bought. That is going strait back! I will only be connecting it to expensive converters and actual HD Televisions and monitors.
Yes, that's true. It's a pity that useful technical information like how much current a converter draws is not available at retail web sites or elsewhere. I didn't think of this since we have heard of the particular device working OK with other RasPis, so if the converter draws 200 mA or more you'd think it wouldn't work with any RasPi. Perhaps the lucky user has a particularly robust BAT54 which still contains its magic smoke, or perhaps power consumption depends heavily on VGA resolution.mahjongg wrote:No need for the converter to short the pins, only for it to draw significantly more than 200 mA through the BAT54...
As I said in an earlier post, the PMEG2010AET is a replacement that will do 1A instead of 0.2A.mad-hatter wrote:Hello,
Thanks for the reply and information.
I've had a look at the data sheet :- http://www.fairchildsemi.com/ds/BA/BAT54.pdf
and can understand that its a low powered device.
Would you care to recommend a replacement with a higher current rating.
I think a standard package type would be OK, and easier for me to solder.
Perhaps I will replace the power supply, at the moment 5Volt 1A.
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