Hi, I just fixed a 19" monitor rescued from the kerb (LICOM N9054LP), and I
got there before the annoying man who goes aroung cutting off all the cables
from appliance did!

Horizontal but no vertical. The Vertical chip was TDA 0472 (couldn't get any
data).

The obvious fault was an overheated R501 fusible resistor probably a 1W
size. If feeds the chip with 15V as per the diagram. Its value changed quite
dramatically when you flexed the leads from about 60R to hundreds of ohms.
My problem is that the heat had caused the colour bands to change colour and
were undecipherable.
My question is what is the method for calculating a value for these
protection resistors? I assume we want to minimise Voltage drop and have the
resistor run within its rating. What base load would you run through the
resistor? I ended up with a .68ohm with .6volts dropped across it. This
seemed to restore vertical. The resistor thus dissipates .5W. IS this ok?

15V supply
______|
__| /
| \e--------^^^^^^------ pin2 /TDA0472
NPN _|_ R501 _|_
__ _ _
|__________ |
GND

Regards

Russell