Those darned tree lights...

[Terrypin]

I should know this, but could someone remind me how a simple set of 3-
wire Xmas tree lights works please? iOW a basic circuit diagram, so
that my trouble-shooting becomes more methodical.

And those lamps with a bit of white paint - what's special about them?

Current status is: half of the set of 60 (from 240 Vac) are unlit. I
found two that from visual inspection are open circuit (one of which
is one of those special sort). Last night pretty well the whole lot
were lit. Local stores have no stocks of this style (we like static,
plain), or I'd have taken the easy way out.

--
Terry, UK

 

[krw@att.bizzzzzzzzzzzz]

On Sun, 18 Dec 2011 01:43:06 -0800 (PST), Terrypin <terrypingm@gmail.com>
wrote:

I should know this, but could someone remind me how a simple set of 3-
wire Xmas tree lights works please? iOW a basic circuit diagram, so
that my trouble-shooting becomes more methodical.

A sting of 100 will have 50 on one string in series (one wire) and 50 on
another (second wire) and a third "common" going to the end of both strings of
50, and the chaining female outlet.

And those lamps with a bit of white paint - what's special about them?

Blinkers? Socket or bulb? Perhaps the "one goes out the rest stay lit"
feature is in the socket rather than the bulb. That socket may be the one
that doesn't have this feature so the string can blink. Just a guess.

Current status is: half of the set of 60 (from 240 Vac) are unlit. I
found two that from visual inspection are open circuit (one of which
is one of those special sort). Last night pretty well the whole lot
were lit. Local stores have no stocks of this style (we like static,
plain), or I'd have taken the easy way out.

Your setup is different than what I'm accustom to so there may be other
differences. The common bulb, on this side of the pond, has the "one goes
out..." feature built in so visually inspecting the bulb doesn't do much good.
Even if the filament is open the string should light. My suggestion is to
replace the bulb in the "special socket" (if that's what it is) and then do a
ROL on the others, starting with a known good bulb. Getting one of the
non-contact voltage testers would save a lot of work, though.

 

[fungus]

On Dec 18, 10:43 am, Terrypin <terrypi...@gmail.com> wrote:

I should know this, but could someone remind me how a simple set of 3-
wire Xmas tree lights works please? iOW a basic circuit diagram, so
that my trouble-shooting becomes more methodical.

A load of bulbs connected in series. Enough to spread
out the mains AC to a reasonable level.

eg. With 110V AC and 20 bulbs then the bulbs are 5.5V
each.

If you've got three wires then you'll have two strings of
bulbs in series and one will be ground (return to plug).

And those lamps with a bit of white paint - what's special about them?

They might be the ones that make the others flash on/off,
it depends on your lights.

Current status is: half of the set of 60 (from 240 Vac) are unlit.

ie. One of the two strings has an open bulb in it (or more than
one).

found two that from visual inspection are open circuit (one of which
is one of those special sort). Last night pretty well the whole lot
were lit. Local stores have no stocks of this style (we like static,
plain), or I'd have taken the easy way out.

In an emergency you can short out one of the bulbs
but bear in mind that the voltage across all the others
will go up a bit. They might start to burn out as well.

eg. If you short out two bulbs on a 20-light string
then the voltage will go up 10% on all the others.
I don't think I'd do it for more than that.

OTOH this is an electronics group so you should
be able to calculate a suitable resistor to replace
the dead bulb.

If you can't calculate a resistor then ignore all of
the above because you might end up burning
your house down.

 

[Terry Pinnell]

"krw@att.bizzzzzzzzzzzz" <krw@att.bizzzzzzzzzzzz> wrote:

On Sun, 18 Dec 2011 01:43:06 -0800 (PST), Terrypin <terrypingm@gmail.com
wrote:

I should know this, but could someone remind me how a simple set of 3-
wire Xmas tree lights works please? iOW a basic circuit diagram, so
that my trouble-shooting becomes more methodical.

A sting of 100 will have 50 on one string in series (one wire) and 50 on
another (second wire) and a third "common" going to the end of both strings of
50, and the chaining female outlet.

And those lamps with a bit of white paint - what's special about them?

Blinkers? Socket or bulb? Perhaps the "one goes out the rest stay lit"
feature is in the socket rather than the bulb. That socket may be the one
that doesn't have this feature so the string can blink. Just a guess.

Current status is: half of the set of 60 (from 240 Vac) are unlit. I
found two that from visual inspection are open circuit (one of which
is one of those special sort). Last night pretty well the whole lot
were lit. Local stores have no stocks of this style (we like static,
plain), or I'd have taken the easy way out.

Your setup is different than what I'm accustom to so there may be other
differences. The common bulb, on this side of the pond, has the "one goes
out..." feature built in so visually inspecting the bulb doesn't do much good.
Even if the filament is open the string should light. My suggestion is to
replace the bulb in the "special socket" (if that's what it is) and then do a
ROL on the others, starting with a known good bulb. Getting one of the
non-contact voltage testers would save a lot of work, though.

Thanks both.

After another couple of hours in vain, I'm giving up. The major problem is
that I have no spare bulbs left, of either normal or special type.
Improvising with metallic kitchen foil was unsuccessful. Tedious and
awkward tests with my DMM didn't help either.

--
Terry, East Grinstead, UK

 

[ehsjr]

Terrypin wrote:

I should know this, but could someone remind me how a simple set of 3-
wire Xmas tree lights works please? iOW a basic circuit diagram, so
that my trouble-shooting becomes more methodical.

http://www.ciphersbyritter.com/RADELECT/LITES/XMSLITES.HTM

The above site may help.
Ed

And those lamps with a bit of white paint - what's special about them?

Current status is: half of the set of 60 (from 240 Vac) are unlit. I
found two that from visual inspection are open circuit (one of which
is one of those special sort). Last night pretty well the whole lot
were lit. Local stores have no stocks of this style (we like static,
plain), or I'd have taken the easy way out.

--
Terry, UK

 

[Terry Pinnell]

ehsjr <ehsjr@nospamverizon.net> wrote:

Terrypin wrote:
I should know this, but could someone remind me how a simple set of 3-
wire Xmas tree lights works please? iOW a basic circuit diagram, so
that my trouble-shooting becomes more methodical.

http://www.ciphersbyritter.com/RADELECT/LITES/XMSLITES.HTM

The above site may help.
Ed

Thanks Ed, excellent article.

--
Terry, East Grinstead, UK