Cor van de Water wrote:
Electronic circuits (The silicon wafer that carries the transistors
and other circuitry) is affected in its operation by light.
That's a good possibility. Note that *any* semiconductor on the board
(the micro, other chips, transistors, diodes, and even LEDs) might be
the light-sensitive culprit.
I once had a board that used a common zener diode as its voltage
reference for the power supply. The zener was in a clear glass case,
typical of inexpensive 1N52xx family zeners. When sunlight hit that
zener, its voltage changed. Since it was the power supply's reference,
that changed the voltage of the power supply, throwing everything else off.
Older products used to use EPROMs. You were supposed to cover the window
on top (which was there to erase the part if it ever needed to be
reprogrammed). But people often left it open. Sunlight hitting the chip
inside could not only erase the memory; but would cause errors long
before the exposure was enough to actually erase it.
As someone else observed, it's also possible that the product has a
light sensor to adjust the backlight or display brightness to compensate
for bright ambient light. If the power supply is weak, then sunlight
could "command" more brightness than the wimpy power supply could
supply. I've seen this happen with the Cruising Equipment/Heart
Interface/Xantrex E-meter/Link10 family of meters.
--
We cannot waste time. We can only waste ourselves.
-- George Matthew Adams
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, [email protected]
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