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Home > Archive > Electronics repair > April 2005 > Compact Fluorescent Failures
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Compact Fluorescent Failures
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| Matthew Smith 2005-04-16, 3:16 pm |
| Greetings
Over the last couple of months, I have had a spate of failures of
compact fluorescent lamps (electronic ballasts). (All of the lamps in
our house, barring the ones that aren't kept on for any time, are CFLs.)
Whilst a couple have been generic Far-Eastern ones, I've had a couple of
failures of Philips units as well. (Back in England, one of the first
Philips electronic CFLs was still running well after seven years.)
One failure was within a week of installing a replacement - that went
straight back to the shop for replacement. (I've taken to writing the
installation date on the base.) In another, the electrolytic capacitor
had failed (end blown out); I replaced it and it runs fine, although I
have yet to replace the thermal fuse.
Of the others, it's a bit of a mystery; I've performed the following tests:
* Check appropriate DC voltage exists after bridge rectifier.
* Check electrolytic capacitor out of circuit.
* Check switching transistors out of circuit.
I'm now painstakingly tracing the circuits of two of the Philips units
so that I can mark up some voltage readings against "healthy" units. I
was rather surprised to find that even the latest units are constructed
with through-hole, discrete components. (What, no integrated switcher?)
None of the fittings are enclosed that the units would be getting
particularly hot.
We are on a single-wire (19kV SWER - read "highly unreliable power
supply") HV system - I don't know if this might have any bearing on the
problem (spikes, etc).
Some questions:
1) Does anyone have any figures for commonest causes of failure? (In
other words, where do I look first?)
2) Are the thermal fuses essential? Not all units seem to have them -
at least that I can identify. Whilst I'm not one to go removing safety
devices willy-nilly, more recent units do seem to have slightly lower
component counts, fuses included in some. Should I fit thermal fuses to
ones that don't have them?
3) Are these devices sensitive to spikes/surges and, if so, should I put
MOVs in any that I repair?
I know that these only cost $5 AUD each, but there's a principle at
stake here...
Cheers
--
Matthew Smith
South Australia
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| Shawn D'Alimonte 2005-04-16, 3:16 pm |
| Matthew Smith wrote:
quote:
> 1) Does anyone have any figures for commonest causes of failure? (In
> other words, where do I look first?)
I have seen a few with really bad soldering. The switcher transformer
almost fell out of its holes. Also something blew the FETs on a few.
They haven't failed again since I changed the FETs and fuse.
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| I had one with bad solder joints that I repaired and is still working.
I had a few where the starter filament on the CF tube went. I have
not had one last anywhere near 7 years. They are used outside and on
all night every night.
Anybody know how much it matters if they are mounted base up or base
down regarding both light output and relibability. Base up seems to
work better but I don't have any real data.
Mark
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"Matthew Smith" <usenet2005@spam.trace.yp.cx> wrote in message
news:4251fba5$1@duster.adelaide.on.net...
quote:
> 1) Does anyone have any figures for commonest causes of failure? (In
> other words, where do I look first?)
I've heard it's a large electro (often in the base of the lamp) which is
often the fault.
--
N
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| Matthew Smith 2005-04-16, 3:16 pm |
| NSM wrote:
....
quote:
>
>
> I've heard it's a large electro (often in the base of the lamp) which is
> often the fault.
I can vouch for that being the case in one of the failures I've observed
- end actually blown out.
After the posting regarding the poor soldering, I've found some very
dodgy looking joints on one of the units; I'll re-flow them and see if
that works - before I continue testing the components one by one.
Cheers
M
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| James Sweet 2005-04-16, 3:16 pm |
|
quote:
> Some questions:
>
> 1) Does anyone have any figures for commonest causes of failure? (In
> other words, where do I look first?)
Aside from what you've already checked, I've had a number of lamps with
shorted mylar caps in them, other times one of the cathodes will open so
check those for continuity.
quote:
> 2) Are the thermal fuses essential? Not all units seem to have them -
> at least that I can identify. Whilst I'm not one to go removing safety
> devices willy-nilly, more recent units do seem to have slightly lower
> component counts, fuses included in some. Should I fit thermal fuses to
> ones that don't have them?
Some have fusible resistors instead, if there's any sort of protection,
replace it for sure. If there isn't any it wouldn't hurt to add a low value
fusible resistor but they should all have something.
quote:
> 3) Are these devices sensitive to spikes/surges and, if so, should I put
> MOVs in any that I repair?
>
Not worth it, the MOVs will cost more than the lamp generally.
quote:
> I know that these only cost $5 AUD each, but there's a principle at
> stake here...
>
Exactly, I *always* try to repair them when they fail, it's a simple
excercise if nothing else.
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| James Sweet 2005-04-16, 3:16 pm |
|
"Mark" <makolber@yahoo.com> wrote in message
news:1112725620.171315.212200@o13g2000cwo.googlegroups.com...
quote:
> I had one with bad solder joints that I repaired and is still working.
>
> I had a few where the starter filament on the CF tube went. I have
> not had one last anywhere near 7 years. They are used outside and on
> all night every night.
>
Most of them are rated for 6K-9K hours. The 7 year figure is assuming a few
hours a day as you'll see in the fine print. Even so, a standard lamp only
lasts about 1K.
quote:
> Anybody know how much it matters if they are mounted base up or base
> down regarding both light output and relibability. Base up seems to
> work better but I don't have any real data.
This will depend on the design of the lamp, base up is likely to work better
at least on the spiral lamps because the dimple at the end to control vapor
pressure will be the coolest point as designed, base down it'll be hotter.
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| Edd Whatley 2005-04-16, 3:16 pm |
|
--------------------------------------------------------------------------
My number one common failure fault finding is the units raw B+ filter
cap(s). They inherently have to be mechanically small to fit within the
cramped casing restraints. [Seems like someone mentioned one venting on
them...hopefully with a....BANG!!!... like mine did.] Therefore, that
tends to have them at woefully smaller values than could be optimal.
They really take a hammering from the ~40 khz operating frequency
repetitions of squarewaves. If you have facilities/capabilities of
doing an ESR test on some used units you should find them onsetting to
high ESR levels in a hurry. Not having that, just a running of a unit
(open cased for access) for a warm up period of 10 minutes and then
totally disconnecting from AC power and subjecting to a finger tip
temp/warmth test should reveal units that are in ESR excess. (Will be
quite warm or hot/versus just cool.) Also one could make connection
across a cap at a time with a clip leaded AC voltmeter for a ripple
test, bet you will find it quite high with their selected
(necessitated?) values of caps.
Some units that I did enact a repair upon , ended up in a location that
physical width provided no restraint, so I utilized healthier cap values
as well as 105deg temp ratings (for sure). The new caps then extended
thru 2 holes of the plastic housing with epoxied plastic insulative
"warts" encasing their slight protrusions. 4 years and counting now.
73's de Edd
--
Edd Whatley
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"Matthew Smith" <usenet2005@spam.trace.yp.cx> wrote in message
news:4251fba5$1@duster.adelaide.on.net...
quote:
> I know that these only cost $5 AUD each, but there's a principle at
> stake here...
I've bought them at the (US) dollar store (rather a cold phosphor). At a
buck each I don't fix them.
--
N
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| Stein-Olav Lund 2005-04-16, 3:16 pm |
|
Matthew Smith wrote:
quote:
> Greetings
>
> Over the last couple of months, I have had a spate of failures of
> compact fluorescent lamps (electronic ballasts). (All of the lamps in
> our house, barring the ones that aren't kept on for any time, are CFLs.)
>
> Whilst a couple have been generic Far-Eastern ones, I've had a couple of
> failures of Philips units as well. (Back in England, one of the first
> Philips electronic CFLs was still running well after seven years.)
>
<snip>
In another, the electrolytic capacitor
quote:
> had failed (end blown out); I replaced it and it runs fine, although I
> have yet to replace the thermal fuse.
quote:
> I'm now painstakingly tracing the circuits of two of the Philips units
> so that I can mark up some voltage readings against "healthy" units. I
> was rather surprised to find that even the latest units are constructed
> with through-hole, discrete components. (What, no integrated switcher?)
I have gutted a couple Philips lamps with an LBA202(?) SMT IC.
Little else of interesting components in such a lamp...
All the rest (far Eastern, as well as European made Osram and Sylvania)
using a couple transistors in a power oscillator circuit.
Of the several (must be more than twenty!) I have gutted the
electrolytic most often has failed. I changed it in one of the lamps,
which held more than six months afterwards. The lamps which show
darkening of the FL tubes are nothing to keep, they probably are at the
end of life.
I have seen exploded transistors, but only in a couple of the lamps.
They are small video output transistors in a 'long TO92' case in the
far-East imports.
I collect the ferrite toroids and the hi-voltage caps after measuring
them. Some are nice replacements in tube gear..
The caps are marked with values and are nearly always within tolerances.
quote:
>
> Some questions:
>
> 1) Does anyone have any figures for commonest causes of failure? (In
> other words, where do I look first?)
Electrolytic. It dries out from high ripple current/high temp in the lamp.
quote:
> 2) Are the thermal fuses essential? Not all units seem to have them -
> at least that I can identify.
Some have only a glass-cased fuse in one of the socket wires, some have
fusible resistors. I have seldom seen temp fuses.
Stein
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| James Sweet 2005-04-16, 3:16 pm |
|
"NSM" <nowrite@to.me> wrote in message news:KIK4e.3157$VF5.2053@edtnps89...
quote:
>
> "Matthew Smith" <usenet2005@spam.trace.yp.cx> wrote in message
> news:4251fba5$1@duster.adelaide.on.net...
>
>
> I've bought them at the (US) dollar store (rather a cold phosphor). At a
> buck each I don't fix them.
> --
I've really grown to like those cold phosphors, especially the daylight ones
but most everything around here is yellow 2700K.
Yeah they're not really economical to fix from that standpoint but it is
kinda fun, I always at least take a crack at it when one dies.
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| James Sweet 2005-04-16, 3:16 pm |
|
quote:
>
> I have gutted a couple Philips lamps with an LBA202(?) SMT IC.
> Little else of interesting components in such a lamp...
> All the rest (far Eastern, as well as European made Osram and Sylvania)
> using a couple transistors in a power oscillator circuit.
> Of the several (must be more than twenty!) I have gutted the
> electrolytic most often has failed. I changed it in one of the lamps,
> which held more than six months afterwards.
It's funny, I'm always hearing about this problem but somehow I have yet to
ever run across a single one in which the lytic checked bad (ESR meter) or
blew, I know it's coming but so far never had that happen.
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| Ken Weitzel 2005-04-16, 3:16 pm |
|
James Sweet wrote:
quote:
> "NSM" <nowrite@to.me> wrote in message news:KIK4e.3157$VF5.2053@edtnps89...
>
>
>
>
> I've really grown to like those cold phosphors, especially the daylight ones
> but most everything around here is yellow 2700K.
>
> Yeah they're not really economical to fix from that standpoint but it is
> kinda fun, I always at least take a crack at it when one dies.
Hi...
Durn, I've been using them for about 10 years now - don't
have a single incandescent left in the place - but never yet
had one fail. Mostly Sylania; but a few Globe badged.
Did throw one away because the light output had dropped too
much.
Waiting to fix one  Downside is that looking at them, I
can't imagine how I'd getting one apart without destroying
it. Is there a trick I can't see?
Ken
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| James Sweet 2005-04-16, 3:16 pm |
|
quote:
>
> Durn, I've been using them for about 10 years now - don't
> have a single incandescent left in the place - but never yet
> had one fail. Mostly Sylania; but a few Globe badged.
> Did throw one away because the light output had dropped too
> much.
>
> Waiting to fix one Downside is that looking at them, I
> can't imagine how I'd getting one apart without destroying
> it. Is there a trick I can't see?
>
The name brand ones do tend to be more reliable, as you say the lumen
depreciation will nessessitate replacement before a really well made one
completely fails. The problem is the name brands are rather expensive so the
cheap Chinese junk sells, admittedly my house is full of them.
Some are easy to open, some aren't. Most of the ones I have will pop apart
with a scredriver at the seam between the upper and lower section of the
ballast housing.
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| Matthew Smith 2005-04-16, 3:16 pm |
|
quote:
....
[vbcol=seagreen]
> Some are easy to open, some aren't. Most of the ones I have will pop apart
> with a scredriver at the seam between the upper and lower section of the
> ballast housing.
Haven't had one yet that can't be opened with a screwdriver like James
says; of course, you do need to pick the right screwdriver ;-)
Cheers
Matthew Smith
South Australia
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| James Sweet 2005-04-16, 3:16 pm |
|
"Matthew Smith" <usenet2005@spam.trace.yp.cx> wrote in message
news:425784a4$1@duster.adelaide.on.net...
quote:
>
>
> ...
>
apart[vbcol=seagreen]
>
> Haven't had one yet that can't be opened with a screwdriver like James
> says; of course, you do need to pick the right screwdriver ;-)
>
> Cheers
>
> Matthew Smith
> South Australia
They may be quite different in Australia, dunno. Most of the ones I've
opened were either Feit or Commercial Electric. I have one right here
awaiting a look, it's a TCP #18814/31, which is a somewhat hard to find
3100K lamp which I like in the bedroom lamp.
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"Ken Weitzel" <kweitzel@shaw.ca> wrote in message
news:pBI5e.934796$8l.322945@pd7tw1no...
quote:
> Waiting to fix one Downside is that looking at them, I
> can't imagine how I'd getting one apart without destroying
> it. Is there a trick I can't see?
Start by cracking off the metal base - should be easy.
--
N
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| Stein-Olav Lund 2005-04-16, 3:16 pm |
|
quote:
> It's funny, I'm always hearing about this problem but somehow I have yet to
> ever run across a single one in which the lytic checked bad (ESR meter) or
> blew, I know it's coming but so far never had that happen.
>
I have found _some_ good electrolytics in the lamps,maybe 10 percent of
them.
I measure ESR (some caps measure about right cap. value, but has high
ESR (>20 ohms at 50kHz)
quote:
>
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| In article <1YJ5e.3609$H_5.1653@trnddc01>,
James Sweet <jamessweet@hotmail.com> wrote:
quote:
>Most of the ones I have will pop apart
>with a scredriver at the seam between the upper and lower section of the
>ballast housing.
If you're really lucky, failed ones will pop themselves apart along the
seam, to facilitate you repairing them. It's a design feature, I think
A couple of ones I've had have failed like that: A loud bang, a smell
of burnt toffee/toast, which seems to come from the epoxy-like substance
used to seal inside them. Yum. Obviously the crack in the side let the
smoke out ... not opened one yet to see what went.
--
--------------------------------------+------------------------------------
Mike Brown: mjb[at]pootle.demon.co.uk | http://www.pootle.demon.co.uk/
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| James Sweet 2005-04-16, 3:16 pm |
|
"Mike" <mjb@posie.local.dom> wrote in message
news:d3eplc$f6d$1@posie.local.dom...
quote:
> In article <1YJ5e.3609$H_5.1653@trnddc01>,
> James Sweet <jamessweet@hotmail.com> wrote:
>
> If you're really lucky, failed ones will pop themselves apart along the
> seam, to facilitate you repairing them. It's a design feature, I think
>
> A couple of ones I've had have failed like that: A loud bang, a smell
> of burnt toffee/toast, which seems to come from the epoxy-like substance
> used to seal inside them. Yum. Obviously the crack in the side let the
> smoke out ... not opened one yet to see what went.
Those are electrolytic cap failures for sure, there's no epoxy holding them
together but when a capacitor really goes it can blow it's top and knock
things out of the way. Never had that happen but it sounds exciting.
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