HID troubleshooting help

"Mark Atanovich" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I'm trying to troubleshoot my homebrew HID headlight:

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=1393

In a moment of cranial flatulence, I reversed the red and black wires
when I assembled my battery and as a subsequently applied reverse
polarity to the lamp. An acrid smell ensued.

Questions:
1) Did I fry the lamp, the ballast or both?

^^^^^^^^^^^^^^^^^
The link you supplied says: "Reversing polarity will damage lamp."

On 30 Oct 2006 09:09:50 -0800, "Mark Atanovich" <[email hidden]>

Quoted message said:

I'm trying to troubleshoot my homebrew HID headlight:

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=1393

In a moment of cranial flatulence, I reversed the red and black wires
when I assembled my battery and as a subsequently applied reverse
polarity to the lamp. An acrid smell ensued.

Not trying to be flippant, that acrid smell was probably the chip or
power transistor for the oscillator that drives the step-up
transformer; it was frying. A more robust design of unit would have
included a diode to prevent such damage when user brainfade caused a
polarity reversal, but not every electrical circuit designer takes
that sort of thing into account.

Quoted message said:

Questions:
1) Did I fry the lamp, the ballast or both?

The "ballast" if a fluorescent light is essentially just a
transformer; the driver for an HID lamp is more complicated since
there must be an increase in the voltage level in order to fire the
lamp, and this is accomplished by using an oscillator and step-up
transformer to provide the high voltage required. Unfortunately,
solid-state circuitry which is not protected against polarity reversal
by a diode and/or fuse can be destroyed by polarity reversal very
easily.

Quoted message said:

2) The lamp ohms out open. Is this normal?

Yes. Unlike a conventional hot-wire incandescent lanp, the light in
an HID setup is produced by an arc across a gap, usually through a
slightly conductive vapor such as mercury or iodine. See
http://en.wikipedia.org/wiki/High-intensity_discharge_lamp for a
simplified explanation of how they work.

Quoted message said:

FWIW, battery is a 10 cell NiMH

As long as the reverse power applied was beyond what the circuit could
handle without frying (and that's pretty low in most cases when no
protective components are used), the unit was going to be destroyed
whether you used NiMH, alkalines, or citrus fruit with copper and iron
electrodes stuck in them.

Contact the shop where you bought the light to see what you'll have to
do in order to get a replacement for the destroyed part. It may be
cheaper to buy a new complete unit at the moment, given the
end-of-season sales that are going on.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

Werehatrack said:

On 30 Oct 2006 09:09:50 -0800, "Mark Atanovich" <[email hidden]>

Quoted message said:

I'm trying to troubleshoot my homebrew HID headlight:

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=1393

In a moment of cranial flatulence, I reversed the red and black wires
when I assembled my battery and as a subsequently applied reverse
polarity to the lamp. An acrid smell ensued.

Not trying to be flippant, that acrid smell was probably the chip or
power transistor for the oscillator that drives the step-up
transformer; it was frying. A more robust design of unit would have
included a diode to prevent such damage when user brainfade caused a
polarity reversal, but not every electrical circuit designer takes
that sort of thing into account.

Or, the smell could have been that reverse polarity diode and/or the
printed circuit board feeding it going up in smoke (protecting the
"expensive bits"😉. But since the diode probably costs $0.01 to add,
it's probably not there. Sigh...

<good advice snipped for brevity>

Quoted message said:

Contact the shop where you bought the light to see what you'll have to
do in order to get a replacement for the destroyed part. It may be
cheaper to buy a new complete unit at the moment, given the
end-of-season sales that are going on.

And the good news is that you'll then have two batteries plus a spare
lamp when the new one burns out (so the cost of the new unit won't be
entirely wasted) In fact, you'd almost certainly pay more for a
second battery and a spare lamp, so in the end you're SAVING money.

(OK, weak logic, but hope it makes you feel better anyway). ;-)

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

Werehatrack said:

On 30 Oct 2006 09:09:50 -0800, "Mark Atanovich" <[email hidden]>

Quoted message said:

I'm trying to troubleshoot my homebrew HID headlight:

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=1393

In a moment of cranial flatulence, I reversed the red and black wires
when I assembled my battery and as a subsequently applied reverse
polarity to the lamp. An acrid smell ensued.

Not trying to be flippant, that acrid smell was probably the chip or
power transistor for the oscillator that drives the step-up
transformer; it was frying. A more robust design of unit would have
included a diode to prevent such damage when user brainfade caused a
polarity reversal, but not every electrical circuit designer takes
that sort of thing into account.

Quoted message said:

Questions:
1) Did I fry the lamp, the ballast or both?

The "ballast" if a fluorescent light is essentially just a
transformer; the driver for an HID lamp is more complicated since
there must be an increase in the voltage level in order to fire the
lamp, and this is accomplished by using an oscillator and step-up
transformer to provide the high voltage required. Unfortunately,
solid-state circuitry which is not protected against polarity reversal
by a diode and/or fuse can be destroyed by polarity reversal very
easily.

Quoted message said:

2) The lamp ohms out open. Is this normal?

Yes. Unlike a conventional hot-wire incandescent lanp, the light in
an HID setup is produced by an arc across a gap, usually through a
slightly conductive vapor such as mercury or iodine. See
http://en.wikipedia.org/wiki/High-intensity_discharge_lamp for a
simplified explanation of how they work.

Quoted message said:

FWIW, battery is a 10 cell NiMH

As long as the reverse power applied was beyond what the circuit could
handle without frying (and that's pretty low in most cases when no
protective components are used), the unit was going to be destroyed
whether you used NiMH, alkalines, or citrus fruit with copper and iron
electrodes stuck in them.

Contact the shop where you bought the light to see what you'll have to
do in order to get a replacement for the destroyed part. It may be
cheaper to buy a new complete unit at the moment, given the
end-of-season sales that are going on.

Thx. The "shop" (an online battery outfit whose 1st language is likely
not English) writes that short term polarity reversal should not be a
problem. The ballast is made by Welch Allyn, which supplies all the
major brands including Nite Rider and Light & Motion so FYI to all you
DIY'ers out there.