WA-1185 explodes!

So I'm out with my dogs late last night with my M*g85 in hand. All of the sudden I hear a small pop then it went dark.

Yep, the bulb literally exploded! I took it apart and dumped the glass fragments into the trash can. There was a white/gray residue all over the reflector and lens. Cleaned them with alcohol and microfiber cloth.

Put in a brand new bulb and if fired right up. I left some small scratches on the reflector and lens but it doesn't effect the beam any.

So what could have caused this? I've only had the light for a short time so I don't know the age of the bulb. Also the temperature was about 14 degrees F. Could the cold/heat generated by the bulb cause this? It was only on for 5 miutes or less. Also it was near the end of the batery pack charge.

Or is it just the nature of pushing things to the limit?

Here is what is left:

Hi,

Same thing with my mag85 driven with hotdriver set to 11.3V, 3 li-ion D ...literally exploded in 1000 glass fragments, and also damaged my smooth carley reflector.

Just a guess. The pin on the left looks distorted. If you bend or stress the pins at all, it might fracture the glass envelope and you might not notice it. Tiis fracture may eventually lead to an envelope failure. And, as you mention, we are driving these at their limit so failures are to be expected.

I've had a 140 lumen bulb explode in a SF 9AN Commander. SF told me it was probably overpressurized in manufacture so they sent me a new one free. It also damaged the bezel so they sent me one of those too. I tried to clean it with a pipe cleaner but that didn't work too well.

How the lamp was installed is a possibility; if it was touched by fingers and not cleaned after, the oil left will deterioate the glass until it ruptures.

Be very carefull to leave no residue on the bulb when you install it.

I think, as BVH pointed out, the most likely cuprit is an envelope failure caused by the pressure that had been applied to that left pin. It looks like both pins have been pushed out into a V shape.

My opinion is that the pins were fatigued and the glass was stressed or fatigued but not enough to break the seal. When the lamp was heated up the envelope could not contain the pressure of the fill gas so the lamp exploded.

My opinion is based on a little research about what colors of residue we see in lamp failures. When a lamp envelope is broken while the filament is ON, or the filament is energized subsequent to the envelope having been broken, the compounds which form and their colors are:

Tungsten Nitride, (WN2), Brown
Tungsten Dioxide, (WO2), Brown
Tungsten Pentoxide, (W2O5), Blue-violet
Tungsten Trioxide, (WO3), Yellow

When a lamp envelope is broken while the filament is on, even briefly, you get yellow Tungsten Trioxide.

When a lamp envelope has failed previously to the filament being energized you get blue-violet Tungsten Pentoxide.

Here's an interesting thread where lamp failures are discussed.

A race to failure

Icebreak said:

I think, as BVH pointed out, the most likely cuprit is an envelope failure caused by the pressure that had been applied to that left pin. It looks like both pins have been pushed out into a V shape.

My opinion is that the pins were fatigued and the glass was stressed or fatigued but not enough to break the seal. When the lamp was heated up the envelope could not contain the pressure of the fill gas so the lamp exploded.

Click to expand...

Sounds like a good theory to me. I may have put the bulb too deep into the socket causing the pins to bend? How deep do you put the bulb in the socket?

I'm using the KIU socket and it seems like the socket holes that the pins insert into are a little wider spaced than the pins on the bulb. When the bulb is inserted into the socket it causes the pins to bend outward into the v shape. If that makes sense.

I don't know for sure as I bought this light with the (exploded) bulb in it. Perhaps it was already bent. I just pulled the new bulb and it seems to be in that v shape again?? Only thing that I can think of is I'm pushing it down too far.

Icebreak, thanks for providing that link to your "a race to failure", very interesting reading for sure.

isn't a hotdriver suppose to have a soft start to avoid bulb failures?

flex76italy said:

Hi,

Same thing with my mag85 driven with hotdriver set to 11.3V, 3 li-ion D ...literally exploded in 1000 glass fragments, and also damaged my smooth carley reflector.

Click to expand...

I also had an 1185 burst & shatter which left me with blemishes on a FM reflector. Soft start on a regulated HD or PIR doesnt matter when you severely overdrive bulbs like we do. BTH i was overdriving mine at only 11.1volts pn both my HD and PIR. Both regulators yielded same results. I have since backed off on the voltage and am quite happy with 10.8volts for the WA1185.x

cy -

I don't think even a well designed soft-start driver could prevent an envelope failure that may have developed by the pins being stressed.

Colorado Fatboy -

A KIU? OK those have a pretty good performance history. (I don't have one) I think that component between the pins with the spring in it is were the fill gas is injected into the lamp. I think FiveMega's newer adaptors don't allow it to touch the potting. What I do know is that the glass doesn't like metal. If the glass is touching metal receptor tubes that might be a problem. I'm sure that if the glass is touching the metal reflector that will be a problem.

It could be that BVH nailed it right off with that bent up left pin.

An explosion like that is rarely a bad bulb. I bet the bent pin did it in.

Thanks for that link, Icebreak. I'd missed your original posting. Cool stuff.

Josey

I don't know for sure as I bought this light with the (exploded) bulb in it. Perhaps it was already bent. I just pulled the new bulb and it seems to be in that v shape again?? Only thing that I can think of is I'm pushing it down too far.

Click to expand...

That V shape is common with Kius and I'd guess not a problem, the angle being so low and all. The suspicious bit is the kink half way up the left pin. Until you get the "feel" of a Kiu, it's easy to think both pins are started, when really only one is, and you can mangle a pin. Never put more than a little pressure to insert - if you need more, the pins aren't lined up. It looks like the left pin was severely bent, then straightened.

Thanks, Josey.

I had thought if we could identify the residues of failed lamps that would help determine the inititial cause of lamp failures. With some help from Greg, Jim and Google I think we can see what is happening much of the time based on the color of the Tungsten oxide.

In the next few days I'll add Colorado Fatboy's lamp to that thread. Its failure tells us a lot and seems to verify js's original suspicion about the pins noted a couple of years ago.

I think it was just your Karma that it exploded. Remember that time with the frogs and firecrackers in the back yard?

Bob_G said:

That V shape is common with Kius and I'd guess not a problem, the angle being so low and all. The suspicious bit is the kink half way up the left pin. Until you get the "feel" of a Kiu, it's easy to think both pins are started, when really only one is, and you can mangle a pin. Never put more than a little pressure to insert - if you need more, the pins aren't lined up. It looks like the left pin was severely bent, then straightened.

Click to expand...

That could definatley be the case as I don't know the history of the bulb.

It seems like there is no other way with the Kiu socket. Did a little experimenting and if I raised the bulb too much it wasn't working right either. It seems like it needs to be seated most of the way down which causes the v shape.

I also think the bulb could have been in contact with the reflector. The reflector has a very small opening and it's very possible I didn't pay that close attention to it. I put the guts in a new host when I got the light and wasn't really aware of all the attention to detail that this setup needs.

Thanks for all the great insight!

It's good that Bob_G chimed in with great detail on how to and how not to install the lamp.

It sure looks like the problem is pointing at that left pin being horsed around a little.

On the off chance that contact with the reflector is the culprit, I wanted to ask if your reflector was cammed. If the opening for the bulb is small the cam action can jack the reflector just enough to make it touch the lamp.

Good job with the description and especially the photo. That made it so much easier to analyze. Now that it seems you probably have a solution I wanted to congratulate you on your exploded lamp. You blew the smithereens out of that thing!

You're not going to find a Mag reflector on CPF with a hole too small for that bulb. But, the bulb will rarely be centered in a Kiu when first inserted, so with a small hole reflector, I suppose it's possible, if a person didn't carefully center the bulb in the Kiu before adding the reflector, it could scrape the bulb and weaken it for future drama. I visually line the bulb up with the screws for equal distance, then rotate the light 90° and check the other orientation. I'm careful about this because I'm usually taking the whole head off with reflector in place, so the bulb needs to be well centered when I put the head back on. Be very gentle with any manipulations of the bulb in place in the Kiu. And stick it all the way in but don't force it.

If the opening for the bulb is small the cam action can jack the reflector just enough to make it touch the lamp.

Click to expand...

That's good to know, I'd never thought of it. One thing I have seen, off topic a bit, is reflector to bulb base contact when the base is wider than the main envelope (Kiu + camless.) It's easy to miss the little bit the reflector is off its perch, actually resting on the bulb base. Fun ensues when you try to focus it

The relfector is camless. I believe it came from litho123.

I did have to do some very careful adjusting of the bulb as it was not centered good in the reflector hole.

Thanks again!