"William Sommerwerck" wrote in message
...
This is a common problem in servicing. As an EE, I want to know
exactly why something isn't working correctly. But I learned a long
time ago that it's more important to simply get the damned thing
fixed. If that means shotgunning likely components, so be it.

Shotgunning is, IMHO, very bad practice, and often leads to the
creation of more problems than it fixes. I am actually quite surprised
that you would advocate doing this, William.

I don't understand how shotgunning can /create/ problems, as long as the
replaced components are correct replacements. Unless you mean the customer
might get upset.

As an experienced service technician, you know that the cause of a given
problem is not always obvious, even after extensive troubleshooting. The
customer is paying for your time, often more than what the parts cost. Why
burn up the customer's money when replacing a half-dozen parts is likely
to
fix the thing?



Every component that is replaced, increases the potential margin for error
by the person replacing it. I have had many items cross my bench over the
years, which have been 'elsewhere' first, and have seen wrong values fitted,
caps in backwards, diodes in backwards, damaged print and so on, amongst the
many components that have have obviously been shotgunned, as evidenced by
the flux all over their joints. I have also seen unsuitable substitutes
fitted, where technicians have had insufficient understanding of the
requirements of a circuit's design, and have just put in 'what came to hand'
in order to complete their shotgun.

Very occasionally, it is necessary to replace a block of components, when a
fault is particularly obscure, but I would never recommend it as an
acceptable procedure to anyone who wasn't hugely experienced in the field of
service work, and particularly in the case of a simple problem such as the
OP has with his TV's field scanning, and which would be easily diagnosed
with the use of appropriate test equipment.

Arfa