LS27 very odd behavior...

[StrayLight]

I have been a proud owner and user of a LS27 for some time, but mine just recently started exhibiting some strange behavior that defies logic: the emitters now operate in reverse order. The low setting now engages the Cree only and high then also engages the Nichia ring. This is the case with a PD Pak, C Pak, and Cx2 Pak (powered by 17670, my preferred setup).

In the interest of full disclosure, the LS27 head had been modded to increase the output level of the Cree emitter, but changing that sense resistor was the only work done on it. I had been using it daily for several months with no problems, and though it has endured some minor bumps on the job there was no impact or other event to coincide with the onset of this reversed output problem.

Help?

 

[maxspeeds]

I have been a proud owner and user of a LS27 for some time, but mine just recently started exhibiting some strange behavior that defies logic: the emitters now operate in reverse order. The low setting now engages the Cree only and high then also engages the Nichia ring. This is the case with a PD Pak, C Pak, and Cx2 Pak (powered by 17670, my preferred setup).

In the interest of full disclosure, the LS27 head had been modded to increase the output level of the Cree emitter, but changing that sense resistor was the only work done on it. I had been using it daily for several months with no problems, and though it has endured some minor bumps on the job there was no impact or other event to coincide with the onset of this reversed output problem.

Help?

This is an interesting phenomena, but I have seen it happen. You're right about upping the current on the GD daughter board. It has nothing to do with what you are seeing. What you're describing when the cree only lights up is when the ground connection from the battery is being sent to only the ring on the GD daughter board (and not to the Kilroy, which activates the BB mother board)

This can happen if the BB mother board is not fixed perpendicular to the piston and is askew a bit (probably occured when your light went through those minor bumps). It is simply the orientation of the two negative contacts (ring and kilroy) and either the piston (on the pd body) or the ground contact in the c-pak that is causing this reverse UI.

I hope this helps.

 

[maxspeeds]

My guess of what happened is that the glued connection where the BB mother board is mechanically (via screw) attached to the LS27 head has gotten loose from those minor bumps.

 

[McGizmo]

I have not encountered this nor have I heard of this behavior before. Clearly, something is not right. It may be that one of the converters is picking up a completed ground in a manner other than intended. My original design had an Achilles heel that I didn't realize initially. The threads in the MCPCB that anchor the converter package retaining screw were less than ideal in some cases and I ended up adding an aluminum threaded standoff that is also epoxied against the interior of the head as a means of beefing up the anchoring system. This proved to be viable but not ideal for future disassemblies and assemblies without proper care and attention.

When I got to the LunaSol 20's, I abandoned the need for the threads in the MCPCB and ran a short screw from the top of the MCPCB locking a standoff to the back side. This was then the receiver for the converter package retaining screw.

I have not been inclined to encourage modding these lights for a number of reassembly considerations and this is one of them. When you take the head off the sleeve, is the converter package loose at all within the head? If it can twist and if the kapton tape is not providing a good electrical isolation, this might be part of the issue. :shrug:

 

[StrayLight]

When you take the head off the sleeve, is the converter package loose at all within the head? If it can twist and if the kapton tape is not providing a good electrical isolation, this might be part of the issue. :shrug:

Nothing loose or moving. So this is likely some sort of errant ground issue and will require dismantling the head?

 

[McGizmo]

Straylight,
Yes, I think the head needs to be looked into! With the piston completely depressed, do you have both low and high LED's lit? I am concerned you might have a short in there somewhere as well as an unwanted ground.

 

[StrayLight]

Straylight,
Yes, I think the head needs to be looked into! With the piston completely depressed, do you have both low and high LED's lit? I am concerned you might have a short in there somewhere as well as an unwanted ground.

Soft depress (low setting): Cree
Full depress (high setting): Cree + Nichia ring

This isn't as simple as the kilroy being out of place, is it?

 

[McGizmo]

You can try lifting Kilroy up so that it is definitely the first to be contacted by the piston lip. You can take the piston out of the sleeve and with the battery in it, bring it to bear on the converter anode, kilroy and ultimately kilroy and the contact ring. If for some reason the piston lip is making contact with the contact ring first, that would explain what you are experiencing. :shrug: :thinking:

 

[StrayLight]

You can try lifting Kilroy up so that it is definitely the first to be contacted by the piston lip. You can take the piston out of the sleeve and with the battery in it, bring it to bear on the converter anode, kilroy and ultimately kilroy and the contact ring. If for some reason the piston lip is making contact with the contact ring first, that would explain what you are experiencing. :shrug: :thinking:

Okay, I tried this with a battery in the piston and it exhibits the same problem. I did not do the mod on this light, and felt extremely apprehensive about opening it up, but my curiosity got the better of me.

On close examination, the board which sits on edge (I admit to not knowing which board is which) has a small break in the kapton tape on its outer edge near where the screw passes through the other board (I hope that's clear). With the two boards pulled free of the head, the battery-in-piston test lights everything correctly:

battery to anode
piston to kilroy lights Nichias
piston to contact ring lights Cree
piston to kilroy and ring lights both

The only place this exposed spot on the board would seem to possibly touch is the tapped cylinder which holds the screw. I don't have any kapton tape and nail polish didn't work.

Could this one spot be causing the problem?

 

[socom1970]

Sounds like it's time to send your LS27 to Don to have it serviced!

 

[McGizmo]

There are a number of ways an improper or compromised assembly can pick up some unwanted ground contacts with unwanted results. What you have described is certainly one of them. If you have some mylar tape or even the good clear packing tape, you can try a small piece over the curcuit board to keep it isolated. The fastening screw as well as any lock washer must not make contact with the contact ring either. If you can't get it sorted out, contact me via e-mail about sending it to me.

 

[StrayLight]

The fastening screw as well as any lock washer must not make contact with the contact ring either.

Success!

The lock washer was apparently the problem, because even though it was cemented in place it was touching the contact ring. Pryed that little sucker loose, shifted it away from the ring, screwed the board back into the head, and all works as designed. Considering that the washer was glued down, but still apparently shifted at some point, what should I be using to re-cement it in place... Loctite?

Also, anyone know where I can acquire a very small bit of kapton tape? Even though it may not have caused the problem this time, I still want to properly cover the gap in the tape on the circuit board edge.

 

[darkzero]

I contacted Straylight about this light as I was curious. Turns out I did work on this light previously. To be honest I vaguely remember doing this one but regardless I take full responsibility. Although Don does not encourage his lights to be modified, Don is well aware that I do mod his lights upon request & in past converstaions I have also made it clear to Don that I fully warranty my work.

For those of you that own a McGizmo that I have modded, wether you are the original owner or not, if the light fails in relation to the mod that I performed I will waranty the light as I do with all my mods. So if it's got my name on it, Don should not be responsible for any of these & IMO he should not be responsible for any light that has been modded by others as I am not the only one who does these.

In regards to the standoff that Don has mentioned. Every LS27 I work on I will spend the time to address this "issue" regardless of what mod is performed on the light. Keep in mind that this is not an issue. If the light is never disassembled (as encouraged not to) or handled with care then there is no worry, some come loose easily, some do not. Since I do disassemble them it becomes my responsibility. Off all the ones I have done, there is only one that has failed (that I know off) which was because of the standoff & FYI I repaired the light which required component level repair. This is why I always service this as a precaution regardless if they need it or not. I also reapply fresh kapton tape to the daughter board.

Straylight, I did not glue the lock washer in place. In fact I never even remove the lock washer from the driver as it's always "stuck" to the driver when I disassemble them. I'm not sure if Don does in fact glue the washer but my guess it's just held in place by the coating Don uses. I've noticed other PDs don't even have this lockwasher. I'm not sure what happened here & how it eventually came in contact with the contact ring but as long as the mounting screw is secure then it should not move. Although you have resolved the issue you are more than welcome to send me the light if you would like for me to look over it. I'll even cover the shipping for you.

 

[lavalight]

For those of you that own a McGizmo that I have modded, wether you are the original owner or not, if the light fails in relation to the mod that I performed I will waranty the light as I do with all my mods. So if it's got my name on it, Don should not be responsible for any of these & IMO he should not be responsible for any light that has been modded by others as I am not the only one who does these.

:wow:Class Act Will you are an honorable gentleman:twothumbs

 

[McGizmo]

Straylight,
Glad you got it sorted out. :thumbsup: