David L. Jones wrote:
"Phil Allison" wrote in message
...
"Sylvia Else"
Phil Allison wrote:
** In an earlier post you state the PCB had been subjected to water
ingress and insect attack - so almost anything is possible.

Odds are, the switching transistor was forced hard on by the above,
taking out the 8.2 ohms and Q1 in quick succession.

Relace whatever parts you find are damaged, clean the PCB carefully with
detergent and a brush (as you would washing glass ware etc in the sink )
rinse with clean water and dry thoroughly with lotsa hot air ( ie a hair
dryer).

Then cross you fingers and try it again.

If all is well, coat the PCB is clear acrylic lacquer to help it
survive.

It's true that I mentioned brushing away a dead spider.

I wish I'd noted exactly where the spider was. It conceivably was around
the 200K resistor, which could explain both the failures, and the demise
of the spider.

Anyone know the resistance of a small spider before it dies from shock?


** If you see one with three red stripes across its abdomen

- means it is 2.2 kohms, +/- 20 % .............

Power rating?

And what's the pinout?


The power rating is certainly an issue. At 2.2 kohms, it would be
dissipating about 50W. I would expect to find it splattered around PS
cover, an effect which is noticeably absent.

At higher resistances, significantly more power would be dissipated in
it than in the 8.2 ohm resistor. It's hard to see how the resistor can
burn out without there being obvious signs of arachnid distress.

Sylvia.