18 Dec
2011
18 Dec
'11
11:21 a.m.
Tony Duell wrote:
I reas really suprised earlier today. I have a very cheap small, (5.5"
CRT) B&W protable TV/monitor that I use on my workbench for displayiug
the output of home computers, etc. It's handy becuase it's so small.
Anyway, althoug it was very cheap, it's not too badly made. I am not
suggesting it's like a Barco. but at least all the component positons are
labelled _on both sides of the PCB_. Connections and presets are
labelled, that sort of thing. The only thoign I didn;'t like was that the
components were not 'formed' nicely, they had long wires, not fitted down
to the PCB (I know, of course, that it's a good idea to space components
that disipate a lot of power off the PCB, but not things like disc
ceramic capacitors).
Anyway, today I had to crack open the wall-wart that powers it, a simple
13.5V (nominal) thing. Crack open being right, it's gleud together.
Anyway, I had 2 suprised :
1) The trnasformer hs an internal thermal fuse in series with the primary
-- this thing is safer than a lot of wall warts out there
Hmm, most of them that gets imported here are build this way.
Secially the cheap chargers for electric tools that are build out of
a wall wart and an external current limiting resistor in the accu receptacle
and nothing else. People where overcharging the former used Nicad cells for
sure this way, some time a single cell fails with an internal short,
the current gets to high and the thermo fuse in the primary is blowing up
the entire shit to waste.
Had such problems often in the past.
There was a german company that build wall warts with changeable thermo
fuses in the past. You could get the fuses for small money but I don't
think that they still make such "expensive" things.
> Fine Print. Warranty may be void under the
condition the user applies
> electric current this product. I think standard caps are only good for a
> few 1000 hours. You get what you pay for.
Not really true. There is apparently little attention to thermal design
or component quality. Ergo: Built-in obsolescence. If we ask "who
2) The smoothing capacitor in the wall wart (which is a linear thing,
tranformer + bridge rectifier + smoothing capacitor) was labeled 105
degreeC. Better than I'd have expected.
On the other hanmd they saved all of a penny by not fitting a bleeder
resistor, for all there's space on the wall wart PCB for one. I've
remedieed this...
Some sayed that the lead that gets trough the bullets of hunters and
as plummet of fishing rods into the environment is much more than that from
solder in electric waste...
Regards,
Holm
--
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benefits?" we get a useful answer, too.
I have a big problem with it!!!
As do I/ I also have a problem wit h the fact that many of the so-clled
'green' measures do more harm than good. For example leded solderwould
not be a polution problem if things werer repaired, and thus didn't go to
landfill until they were at least 50 years old...
-tony Ben.
So we all now have no problems with that, or what?