On 9/20/2015 6:29 AM, Uncle Monster wrote:

Caps are cheap (more or less). I've seen folks selectively replace only
the "defective" caps on a board. Where's the logic in that? Do you
think the others are less likely to fail or will somehow be more
convenient to replace at a later date?

The bean counters working for most manufacturers insist on the cheapest
parts that will work. Saving a dollar on each circuit board really adds up
when they're producing millions of units. I repaired some POS (Point Of
Sale) ViewSonic monitors that had GRONKED in a hot kitchen. It was bad
electrolytic caps in the power supplies that had the lowest voltage and
temperature ratings the manufacturer could get away with. Of course I
replaced the failed caps with the highest voltage and temperature rated
electrolytics of the same value that the supply house had in stock. It's
been five years and those monitors are still cooking in that hot restaurant
kitchen. An identical monitor in the restaurant office has never failed.

I have a dozen *spare* monitors (in addition to the 12 or 13 that are
currently in use) that I've rescued over the years. I have 3 more 21"
and two 24" monitors waiting for attention. They'll get added to the
spares as soon as I get around to pulling them apart (bad FETs in
three of them; caps in the other two).

In addition to voltage and capacitance (which tend to affect the physical
size of the component), you can typically purchase 85C or 105C temperature
grades. Beyond that, you can also purchase 2000Hr, 4000Hr, 5000Hr, etc.
rated components. There is a cost premium involved but more than offset
by the effort required to disassemble the device in order to make those
repairs. I have no desire to repair something *twice*!

Soome manufacturers also tend to be better than others -- assuming you
avoid the schlock manufacturers altogether!