On 9/25/2010 6:17 AM, Michael A. Terrell wrote:

The Daring Dufas wrote:

I do more repair than new installation and there are scads of universal
replacement controls at the supply houses that are a mix of
technologies. The board may look very similar to the OEM board but will
have parts moved around with surface mount devices peeking out from
between the caps and relays. I'm getting to the point where I can't see
too well anymore so the through the hole stuff is a lot easier for me to
fix. I got tickled when somebody gave me a dead motherboard for a
computer system and the only problem was a blown fuse and PPTC that were
the size of a half grain of rice. 8-)


Keep your eyes open for a good stereo microscope. I preferred the
B&L I had on my bench at Microdyne. Also, I liked the 'Multicore .015"
rework solder. Surface mount isn't going away for small parts. A look
at the Digikey or Mouser catalogs over the years will show that the
availability of leaded parts is dropping every year. The same, with
components using real solder without tin whisker problems.



I just fixed a ViewSonic LCD monitor for a customer's POS system and
it turned out to be a common problem with a 16 volt 1000 uf cap on
the power supply board. Looking closely at the board, I saw another
pair of holes for a parallel electrolytic. I soldered in two 470 uf
35 volt caps in place of the original single since they fit the space.
The customer has had damage to various electronic gear due to power
surges and I've had to replace the KSU for his phone system when the
POTS line ports were blown. I don't understand why designers will
take such a cheap route when they know there's a possibility for a
piece of equipment to be subjected to aberrant voltages in the power
source for many of the end users. I remember how the original IBM
PC's were built like tanks and you paid a price for that robustness
but now so much of the electronics we get these days is a commodity
item and the penny pinching paper pushers (hey, I made a rhyme) want
engineers to spit out products as cheaply as possible. It's amazing
how just a few more dollars spent on an electrical/electronic item
will extend the life of that product.

TDD