Raspberry PI2 turns off when hit with a Xenon Flash Light - Page 1
Forum section: electronics / general

author: soaringmonchi
author_rank: Newbie
timestamp: February 08, 2015, 01:20:01 pm
content: Hey Dave,I was taking a photo of my Raspberry PI2 today and it powered off immediately. Interestingly, it was very reliable to reproduce, also from other people on the webs:http://www.raspberrypi.org/forums/viewtopic.php?f=28&t=99042It would be fantastic to see a blog from you measuring and explaining what is going on there!Take care,Pascal

author: ivan747
author_rank: Super Contributor
timestamp: February 08, 2015, 01:38:45 pm
content: Yep, it's being talked about somewhere else on the forum. It's quite amazing and would make for a good video (maybe with a lot of views, Dave!!!). Besides, a RasPi is only $35 US bucks and he has mailbag monday, which is a nice way of trying to convince Dave of what to do.

author: dave_k
author_rank: Frequent Contributor
timestamp: February 08, 2015, 01:41:00 pm
content: Sounds like EMF or some interference from your flash is causing it .. could be hard for someone else to replicate if they don't have your exact flash unit...

author: plazma
author_rank: Frequent Contributor
timestamp: February 08, 2015, 01:43:04 pm
content: In one device I fixed a similar problem. There was a light sensitive flip chip LDO. The LDO was replaced with an encased model and the problem was fixed.

author: c4757p
author_rank: Super Contributor
timestamp: February 08, 2015, 01:44:32 pm
content: Quote from: dave_k on February 08, 2015, 01:41:00 pmSaw this on /. just now too - funny how many people don't read and see that blocking light from reaching the SMPS chip stops it...The chip appears to be an NCP6343, which is a WLCSP "package" - ie, solder balls stuck to the bottom of a die. The back is translucent...

author: soaringmonchi
author_rank: Newbie
timestamp: February 08, 2015, 01:55:10 pm
content: Sorry guys, I didn't see the other thread.Apparently it boils down to the SMPS chip being photo-sensitive, but I'm sure it could still be an interesting video about photosensitivity in general and different methods of debugging such issues (including EMI :-)).

author: electr_peter
author_rank: Unknown
timestamp: February 08, 2015, 07:42:27 pm
content: Quote from: c4757p on February 08, 2015, 01:44:32 pmAnd typical PCB is translucent as well (to some degree). I have seen cheap cameras to produce the output image with shadow of ball grid and tracks because other side of the PCB was in semi translucent plastic case (not shielded from light).

author: EEVblog
author_rank: Unknown
timestamp: February 08, 2015, 11:44:19 pm
content: Quote from: soaringmonchi on February 08, 2015, 01:55:10 pmYes, looks like a basic photosensitivity issue. From one photo I saw the chip was a non-encapsulated bare died flip chip or something similar?

author: Stonent
author_rank: Super Contributor
timestamp: February 10, 2015, 02:20:42 pm
content: That makes me wonder about FCPGA and FCBGA chips in general.For much of the late 90s and early 2000s, higher end video cards tended to have a big flip-chip RAMDAC chip on them.I know flip chip devices are still common but typically they seem to be used when heat transfer is important, so you can't really test them with a flash without risking overheating first.

author: CRCasey
author_rank: Newbie
timestamp: February 19, 2015, 02:36:50 am
content: Posted this elsewhere,But why not use this to explain what would happen with a true EMP both solar or human caused.