On Jun 20, 10:50 pm, Meat Plow wrote:
On Wed, 20 Jun 2007 20:25:39 +0000, noone wrote:
I have a couple of ~15 yr old fluoresent shop lights which have quit
functioning. They are the "instant start" type, yet don't use a canned
starter. I took them apart and traced out the wiring and found that they
just use a couple of chokes and a couple of R/C's to light up two F40CW's.
If I correctly traced the wiring, it looks like this diagram I scratched on
the back of a piece of junk mail:

http://usera.imagecave.com/Davetech/fluoresentdiag.jpg

The chokes look okay, the 150K resistors are fine, but the cheap paper/foil
capacitors have been hot (scorched sides!), swollen, and one had a crack
where the smoke apparently got out. My problem is there are no markings on
the caps. Anyone venture a guess at what the value would be? Is the value
critical?

I know, replacing the fixture would be inexpensive and intelligent, but I'm
retired, on a very tight income, don't have a ready ride to the dept store,
and hate to add to the landfill stuff that could be fixed. Besides, I'm a
tinkerer at heart.

Thanks for any help,

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Some information here on cap values.

http://www.affordablelighting.com/fa..._lamps.php#fb1

BUT, and here is the biggest BUT.... at least one of those beasts in
there is not a choke, but a "primary autotranformer" to make the
different voltages required.

As to replacing the fixture/ballast vs. a couple of caps.

Home Depot/Dollar Store/Lowes will sell you a "shop-light" complete
with tubes for about $12. You will spend several $$ for the caps, they
will need to be AC rated at 200V or better, and you will need either
to order them on-line and pay shipping or find an electrical supply-
house and pay 'retail'. I betcha that purchasing a new ballast
outright (and save the sheet-metal, sockets and lamps) will be your
cheapest option,

Capacity does matter.

Be careful. you could be seeing the most expensive savings ever. And
if you do decide to repair the unit without proper testing of the
choke and transformer, you will wind up still having to replace the
fixture at the end, notwithstanding the possibly spectacular method
whereby the unit tells you to try something else.

Peter Wieck
Wyncote, PA

On 21 Jun, 14:51, " wrote:
On Jun 20, 10:50 pm, Meat Plow wrote:
On Wed, 20 Jun 2007 20:25:39 +0000, noone wrote:

I have a couple of ~15 yr old fluoresent shop lights which have quit
functioning. They are the "instant start" type, yet don't use a canned
starter. I took them apart and traced out the wiring and found that they
just use a couple of chokes and a couple of R/C's to light up two F40CW's.
If I correctly traced the wiring, it looks like this diagram I scratched on
the back of a piece of junk mail:

http://usera.imagecave.com/Davetech/fluoresentdiag.jpg

These are resonant circuits on both sides, and cap value is critical.

As for how to determine the value, either measure a working one, find
a similar type of ballast and see what value it uses, or maybe ask at
the expert sites such as sci.engr.lighting, or ask folk like Don etc
at their expert sites.


I know, replacing the fixture would be inexpensive and intelligent, but I'm
retired, on a very tight income, don't have a ready ride to the dept store,
and hate to add to the landfill stuff that could be fixed. Besides, I'm a
tinkerer at heart.

Thanks for any help,


As to replacing the fixture/ballast vs. a couple of caps.

Home Depot/Dollar Store/Lowes will sell you a "shop-light" complete
with tubes for about $12. You will spend several $$ for the caps, they
will need to be AC rated at 200V or better, and you will need either
to order them on-line and pay shipping or find an electrical supply-
house and pay 'retail'. I betcha that purchasing a new ballast
outright (and save the sheet-metal, sockets and lamps) will be your
cheapest option,

Capacity does matter.

Be careful. you could be seeing the most expensive savings ever. And
if you do decide to repair the unit without proper testing of the
choke and transformer, you will wind up still having to replace the
fixture at the end, notwithstanding the possibly spectacular method
whereby the unit tells you to try something else.

Peter Wieck
Wyncote, PA

Tinkerers usually use salvaged parts that cost nothing.

As for the claim that reliability of old fittings is bad, the opposite
is in fact the case, with old fl fittings enjoying greater average
life expectancy than new.

What isnt worth salvaging is old halophosphate T12 tubes. Theyre free,
but new lower powered T8s will pay their cost back in use plus a bit
more.


NT

On Jun 21, 10:24 am, wrote:

What isnt worth salvaging is old halophosphate T12 tubes. Theyre free,
but new lower powered T8s will pay their cost back in use plus a bit

T8 lamps will require a different ballast... Not a bad idea ultimately
if the first-cost for new lamps and ballasts can be carried. Of
course, for ~$17, Home Depot will sell you a new 2-tube T8 shop-light,
complete. Our local one had a stack of them out front @ $16.99 + tax.

Peter Wieck
Wyncote, PA

wrote in message
ups.com...
On Jun 21, 10:24 am, wrote:

What isnt worth salvaging is old halophosphate T12 tubes. Theyre free,
but new lower powered T8s will pay their cost back in use plus a bit

T8 lamps will require a different ballast... Not a bad idea ultimately
if the first-cost for new lamps and ballasts can be carried. Of
course, for ~$17, Home Depot will sell you a new 2-tube T8 shop-light,
complete. Our local one had a stack of them out front @ $16.99 + tax.

Peter Wieck
Wyncote, PA



Over here in the UK, T8's and T12's are sold interchangeably as merely
"standard" or "slimline" - no different ballast or fitting required. I have
many 15 or more year-old fixtures here, that came with T12 tubes originally,
that now have T8's in them.

Arfa

On Jun 22, 4:00 am, "Arfa Daily" wrote:

Over here in the UK, T8's and T12's are sold interchangeably as merely
"standard" or "slimline" - no different ballast or fitting required. I have
many 15 or more year-old fixtures here, that came with T12 tubes originally,
that now have T8's in them.

Just don't go the other way - and - if you are still using magnetic
ballasts, you are not realizing any savings... OK, the difference
between a nominal 40W (really about 38), and a nominal 34W (really
about 32), with the ballast taking nearly 30W in its own right. vs.
less than 10W for the typical electronic ballast and 5W for a high
efficiency ballast.

And, if you are running a T8 on a T12 ballast the T8 will run dimmer.
But, I would have thought you would be running mostly T5 by now?

Peter Wieck
Wyncote, PA

On 22 Jun, 11:41, " wrote:
On Jun 22, 4:00 am, "Arfa Daily" wrote:

Over here in the UK, T8's and T12's are sold interchangeably as merely
"standard" or "slimline" - no different ballast or fitting required. I have
many 15 or more year-old fixtures here, that came with T12 tubes originally,
that now have T8's in them.

Just don't go the other way - and - if you are still using magnetic
ballasts, you are not realizing any savings... OK, the difference
between a nominal 40W (really about 38), and a nominal 34W (really
about 32), with the ballast taking nearly 30W in its own right. vs.
less than 10W for the typical electronic ballast and 5W for a high
efficiency ballast.

And, if you are running a T8 on a T12 ballast the T8 will run dimmer.
But, I would have thought you would be running mostly T5 by now?

Peter Wieck
Wyncote, PA


This sort of thing often happens in these discussions. UK and US
standards are different, we dont even have the same type of 4' tubes
you have.

Here (UK) there are 2 types of 4' tube:
T12 40w
T8 36w
Both are designed to run on the same ballast, IOW the T8s are retrofit
tubes rather than requiring a new standard of ballast.

Thus there are 2 ways to save a very little energy:
1. replace T12 with T8
2. Replace mag ballast fitting with electronic.


NT

Over here in the UK, T8's and T12's are sold interchangeably as merely
"standard" or "slimline" - no different ballast or fitting required. I
have many 15 or more year-old fixtures here, that came with T12 tubes
originally, that now have T8's in them.

Arfa



The UK T8 lamps are different than the US lamps. My friend and I have
discussed this quite a bit and came to the conclusion that the true 40W T12
lamps over here in the US are the same as in the UK, though the old standard
phosphor types are all limited to 34W now which never happened there because
the lower lamp voltage when used with a choke just increases the current to
compensate and no power is saved.

US T8 lamps are 32W for the 4' size. The ballasts they use are all high
frequency electronic, if you put one in a standard rapid start T12 fixture
they will light up, but not very bright and lamp life will be decreased.

This sort of thing often happens in these discussions. UK and US
standards are different, we dont even have the same type of 4' tubes
you have.

Here (UK) there are 2 types of 4' tube:
T12 40w
T8 36w
Both are designed to run on the same ballast, IOW the T8s are retrofit
tubes rather than requiring a new standard of ballast.

Thus there are 2 ways to save a very little energy:
1. replace T12 with T8
2. Replace mag ballast fitting with electronic.



The savings you can get with an electronic ballast are significantly less
than what we see when replacing an autotransformer ballast. A standard 4'
twin tube rapid start ballast burns up something like 18W just in the
ballast itself. A choke ballast for 240V mains and the same tubes burns half
that or less.