Richard Clark wrote:


Follow the heat (literally). Wait for things to cool down and then
key-down for a shorter period and try to narrow in on that part that
warms first. Try one of those fish tank thermometers that is a sticky
press on type using liquid crystal phase shifting displays (AKA mood
ring technology). The heat is where the resistance is (and wire does
not often qualify except at a poor connection point).


A very handy device for tracking this down would be an infrared
thermometer. Radio Shack sells one for between 30 and 50 dollars,
depending on whether it's on sale. It covers 0F to 400F, switchable to
C or F, and when held close to an object will measure the temperature of
a dime sized area or less.

I have never used mine for this purpose, but I have used it to check the
temperature of transistor pairs in RF amplifiers as well as heat sinks
in PCs. They are also handy to see if auto engine parts have cooled
enough to work on.

tom
K0TAR