On Mon, 08 May 2017 17:19:50 -0700, mike wrote:
Thanks for all the good advice on IR guns and imagers.
On a dense surface mount board, you can easily tell if a part is
getting hotter than the surroundings.
Before IR imagers, I used a liquid crystal sheet.
https://www.teachersource.com/product/292/chemistry
I have a small selection of various temperature ranges. Obviously, it
won't work with non SMT PCB's that are full of "lumpy" components.
While I can't really see individual tiny components, I can at least
find hot spots. I used to call this my "poor mans" IR imager, except
that liquid crystal sheets have gone up in price, while IR
thermometers and imagers have gone down.
It'll cost you $200, but if your time is worth anything, it will
quickly pay for itself.
I have my finger on the buy it now button. Someone help me to resist
the temptation.
If I pass my 12:1 IR temperature probe across the resistor, the highest
reading I
can get is 71F if I stick it as close as possible to the resistor.
You really need the area being sensed to fill the whole field
of view of the sensor. Pretty much useless for today's electronics.
Yep, and the further away you get, the worse the problem. For small
parts, I use either a thermistor probe, or the cheap type K
thermocouple probe that came with my DVM.
The built-in laser pointer is useless for close up work. Parallax
causes you to point to the wrong place.
I once had a cheap IR thermometer that had two lasers. The idea is
that it would bracket the spot allowing the user to better locate the
spot. Unfortunately, this model had the lasers just as badly aligned
as the models with a single laser. I ended up cracking the glue used
to hold the lasers, and using hot melt glue to properly position them.
Up close, the parallax problem made them useless, but at a distance,
they were fine.
With the seek, you can find the shorted cap on your laptop
board by putting a little current thru the power trace and
see
where the heat stops. I had one laptop that was driving me
nutz. Turned out there was a cap hidden under some other
component that was bad. It was a .1uF cap. Those rarely
short. I would never have found it without
the thermal imager.
Nicely done. I'm still using the liquid crystal sheets, or putting
the palm of my hand over sections of the PCB until I find the hot
spot. However, I would never have found a shorted cap located under
some other components.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558