Eye Current: Finding the Hot Spots

Friday, January 26, 2007

Finding the Hot Spots

It can be helpful to find what is heating up, when attempting to repair a piece of equipment. I had an old Army instructor who drilled into our heads, "Whats the first thing you look for after you turn on the equipment?" The answer is "look for smoke and fire." The first step in testing an unknown piece of equipment is to look for smoke and fire. Check for strange smells or a visible wisp of smoke. At the most primitive level we just look for burned components or perhaps some smoke and fire. While this can be destructive, most of the damage is already done by the time we get a chance to open it up and look around.

There are tools to help monitor temperature:

Infrared temperature monitors are real handy. They can find hot spots fast and is an inexpensive solution. We use a couple of inexpensive EXTECH in our shops. A major advantage to these devices is a person does not need to actually make contact with the equipment under test. This is a big advantage when checking out CRT monitors and radio equipment.

Infrared thermal imaging is another method. Although this method is getting more inexpensive every year, it is still pricey. These devices are great to see all the components that are getting hot and isolating the cause. As they say, a picture is worth a thousand words, or in this case several thousand dollars.
Another method is thermocouple digital thermometers. These are often available as calibration equipment and are generally inexpensive. We have several in our shops from a high-priced Fluke 724 Temperature Calibrator to an inexpensive Omega 871 thermometer. Generally speaking, a thermocouple can be attached using either kapton or masking tape. A real advantage to thermocouple thermometers is they can be monitored over a period of time. The Omega we use has a milivolt output so that temperature can be monitored and logged over a period of a few days.

Although temperature isn't the first thing a technician thinks of for test equipment, it often is a valuable tool when chasing down intermittent and stability problems.