Using a Thermal Gun / Infrared Thermometer for electronics

[whit3rd]

On Monday, May 8, 2017 at 5:21:14 PM UTC-7, mike wrote:

On 5/8/2017 10:24 AM, bruce2bowser@gmail.com wrote:
On 5/8/2017 11:36 AM, ohg...@gmail.com wrote in sci.electronics.repair:

One thing a lot of people don't realize is that these work great, but won't work on reflective surfaces.

But, for accurate temperature measurements on a running
system, I had to normalize the emissivity. Somebody suggested that
spraying the board with spray-on foot powder would work. It worked great.
But they forgot to tell me that you can't get the stuff off.
I didn't have any solvents that could remove it without harming
some components on the board.

There is a valid use for blackstrap molasses!
.... I'm sure the foot powder tastes better on pancakes, though.

 

[MJC]

In article <cd72hcdoq7eptg8380d5css6d0ldq6enor@4ax.com>,
jeffl@cruzio.com says...

On Mon, 8 May 2017 11:46:44 -0400, rickman <gnuarm@gmail.com> wrote:

I can put mine up to my ear canal and read 96 °F.

Are you sure that it's not reading the temperature of whatever is near
the other ear?

(Sorry, I couldn't resist).

I believe you can keep the fluff out of the line of sight using mental
floss!

There was a quote from the Goon Show that Eccles (IIRC) didn't have a
light in his eyes - it was the sun shining through the back of his
head...

Mike.

 

On Monday, May 8, 2017 at 8:21:14 PM UTC-4, mike wrote:

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.

I've seen a lot of those little smd film caps short recently on TV mains and tcons. I don't have an imager, but I give the circuit board a dose of freeze spray, feed in a limited current to the shorted line, and see where the white frost blanket thaws first. With any luck, it's the actual component that thaws first. Problems arise when the offending shorted is close to zero ohms and some feeding component gets hot.

 

[mike]

On 5/9/2017 8:23 AM, ohger1s@gmail.com wrote:

On Monday, May 8, 2017 at 8:21:14 PM UTC-4, mike wrote:


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.

I've seen a lot of those little smd film caps short recently on TV mains and tcons. I don't have an imager, but I give the circuit board a dose of freeze spray, feed in a limited current to the shorted line, and see where the white frost blanket thaws first. With any luck, it's the actual component that thaws first. Problems arise when the offending shorted is close to zero ohms and some feeding component gets hot.

That's why it took me so long to find that one.
It was absolutely, positively zero ohms. It shut down the power supply
instantly.
I had to tap into the correct branch of the power distribution and
apply current there to generate any heat.