-- Ivan Reid, School of Engineering & Design, _____________ CMS Collaboration, Brunel University. Ivan.Reid@[brunel.ac.uk|cern.ch] Room 40-1-B12, CERN KotPT -- "for stupidity above and beyond the call of duty".
When I saw the radio antenna in that video I thought he was going to investigate an RF pulse cause for the problem, rather than an optical one.
-- Graham. %Profound_observation%
Here's the source on the RPi forums:
On the second page, somebody shows a scope connected to the 3.3V line. It drops to zero for a moment then fluctuates, spiking up to 4.5V. Oops.
Somebody says that shining a 100mW laser pointer at U16 causes the failure too (but no mention of the 3.3V line so hopefully it fell rather than going overvoltage).
They say that U16 is an SMPS chip, an On Semiconductor NCP6343
The writing on U16 is too small on this image (U16 is roughly equidistant between the CPU, the HDMI connector, and the power-in connector.
On that page it only has "Features" and "Benefits", no "Bugs" or "Problems".
I wonder what ON Semiconductor has to say about this...
Presumably the problem applies to the A+ and B+ as well...
It was a common problem back in mini-computer days. Many incidents of key projects going live, press invited, snap a few pictures, instantly followed by the prestige project crashing literally in front of the cameras.
-- Andrew Gabriel [email address is not usable -- followup in the newsgroup]
So the problem presumably being that the black encapsulation material is not as opaque as you'd imagine?
Shades of the early production glass OC71 transistor that could be turned into the more expensive OCP71 photo-transistor, by scraping off the black paint.
-- Graham. %Profound_observation%
No, the A+ and B+ seem to use a different chip. People (including me) have tested the + models and found no problem with them. (apologies for reply off-list. I hit the wrong button)
In a mad moment - Graham. mumbled :
Reminds me of early mice in sunlit classrooms - Wandering cursors!
-- |)ryn [vans mail to - BrynEvans@bryork.freeuk.com
When my daughter was little, she had a bright pink VHS cassette of cartoons that would not play in the top-loading machine in the mornings, unless the curtains were drawn.
-- Graham. %Profound_observation%
Yes (although it wasn't all black back then - there were white ceramic packages too).
Of course, if you had an EPROM which didn't have a metalic sticker across its window, that would do it for sure, but even in the absence of such obvious light access (that effect was well-known), it would tend to happen.
Did that myself once, just to verify it worked.
-- Andrew Gabriel [email address is not usable -- followup in the newsgroup]
Once the makers cottoned on to what was happening they started to use a misty fluid in the OC71s. However a brief run in the spin dryer with the leads pointing drumwards soon fixed that :)
-- W J G
I wonder if the same treatment would discourage tin whisker growth inside an AF117?
-- Graham. %Profound_observation%
IIRC soaking in acetone was more effective
-- Everything you read in newspapers is absolutely true, except for the rare story of which you happen to have first-hand knowledge. ? Erwin Knoll
Speaking of bizarre, I've got a phenomena at home which I cannot really explain. I got a pi, that is connected to a lcd pc monitor, via a hdmi to vga adapter. Works good.
One meter above it there are two fluorescent tubes.
When they are turned on, the lcd goes black. In most cases, it will come back on ok after 20-30 seconds, but once in a while, the colors are inverted when it comes back.
Only way to fix is unplug/pulg in the hdmi cable.
Why is that, that turning the light on kills the lcd for a while?
Does the LCD have an ambient light sensor and automatic backlight brightness system? The sudden change in light level may confuse the brightness system.
No - or a least it does not react to other lights that go on/off and it does not change light level when all lights are shut off at bedtime.
And I've noticed that it happens when the tube-light starts to blink. (They blink a couple of times and then they are on) At first blink - lcd goes off.
It is just like it gets some kind of EMP - but nothing else notices it.
Quite possible Blown halogen bulbs put out a fair amount of rfi
Convincing staff in a certain bank that the cause of the buzz on their telephone was a blown bulb in the display unit used to be a lot of fun, they never believed it until you got them to switch the lights off :-)
-- 667: The neighbor of the beast.
Does someone know whether this issue is solved now?
I'm asking because up to now I am using b and b+ and am quite satisfied with them, but of course, some day I may upgrade to the more sophisticated version with 1 G RAM.
B.t.w., which version was concerned here? Version 1.0 -- as this version very often shows strange side effects? Would be very helpful to know which version we should NOT look for :-)
Best regards,
Markus
-- Please reply to group only. For private email please use http://www.dipl-ing-kessler.de/email.htm
Just bung a bit of blu-tak on the affected chip, and it's fixed.
---druck
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