How long have some of you left your tubes on in the drawer to try and remove a tube burn? How long was needed and what is the most severe burn you managed to remove?

I picked up a tube with a burn, and I'm trying to figure out how long is needed and when to call it a lost cause. :-)

NVM.

Tech forum. Smartassery elsewhere.

I left mine in for a day or two after some knuckle head swept the targets with a red laser. 

It removed about 80% of the damage to the point I couldn't really see the laser's path unless I really looked for it. Now its pretty much gone. 

and how many hours would you think that you've put on it since it was swept including the hours in the drawer?

I minimized a burn from a swipe of a chrome bumper with an IR laser by doing this for 12 hours. Did another 24h and it's almost totally invisible.

Drop it in the drawer, will foil over the objective when you get up in the morning and pull it out when the sun goes down. 12-14 hours has worked well for me.

Which tends to work for minor burns. I am wondering what some of the more substantial burns have been reduced to or healed completely.

Scroll down to see that I'm totally wrong.

It's "burn-in" like how phosphor-based CRT screens would get burn-in. Research how CRT burn-in is lessened. Basically, you "burn" the rest of the phosphor to match the burned spot. Repairing "burn" doesn't usually happen. What does happen is "cinges" or "light toasts" are "healed" if you can even call it that.

If the phosphor is completely burned, it's not gonna grow back.



Now, NV I2 isn't exactly like a CRT, but it's pretty similar. Maybe Dino or someone who knows their shit can chime in.

It sounds like Chosos wants to explore the grey area between what can and cannot be repaired.

It's hard to know what was almost unrepairable. It's easier to tell what was almost repairable.

I bounced IR laser in 0.7mW off of dry dirt at close distance and burned my tube while the PVS-14 was hard mounted for a laser zero procedure. The exposure was for a few seconds at 3 feet. I had a pretty good size dark grey blob with no distinct edges. I used the high-gain no light remediation method for about an hour. That helped a bit. I figured I could work around the blemish so I just ignored it. By the end of the first night's use the image was almost clear. After a couple of weeks (of nightly use) I had a small, distinct, black blemish permanently burned into my image.

I have seen some guys that I respect and admire in the NV community argue about how and why damage both occurs and heals to no end. I doubt we will come to any better conclusion on the scientific end of things. If we run this thread well we can compile a significant compendium of anecdotes. If we don't run it well we can argue about how things that we know happened didn't happen and we can all be angry at each other.

Put a new battery in, capped the front, put it in the safe and walked off.

My personal experience is that damage that has "soft" edges go away, anything that has a hard edge is permanent. That being said I've opened the safe a few time and been pleasantly surprised after 30 or so hours.

This is the gray area I am trying to cover with this thread, because it also helps answer a lot of questions people have had over the years. I know this topic is sorta taboo because there isn't anything out official out there about this type of topic.
Basically, what is the worst thing you were able to "heal" or "lessen" by leaving it on overnight. Before and after pictures would be outstanding.

Examples:

- If you left the daylight cap on and left the device on sitting out on the kitchen table - was that something that was repairable?
- You spent a night on observation (hours) and had lights or other bright objects burned in from prolonged exposure.
- Reticle burn in
- etc

I don't sweat this. Any damage from incidental exposure from incandescent or LED lights all fades with time. There may be permanent wear from excessive exposure but that is something I live with.

If I get any burn in a tube from looking at lights then it is usually gone by the end of the night. I don't use the reconditioning trick too much because I have learned to ignore tube blemishes. If you are active then the blemishes are typically irrelevant. If you are hunting white walls then they are very annoying.

Holy crap this thread is scaring me.  Is it really this easy to burn a tube?  Is my @TNVC WP filmless tube going to be just as susceptible as the damaged tubes previously posted?  I have never owned something this fragile so I guess I have a lot of learning to do.

Don't be scared. Learn. There are limits to exposure before permanent, perceivable damage but, short of laser burn, most of it is easily avoidable. I would not call an MX11769U/V fragile in the sense that you imply.  A new WP FL tube can be damaged in the same way - any Gen 3 tube will react similarly.

The normal caveats do a lot of work to protect your unit:

Don't stare at any bright lights unless it is needed. You will get some haze at the burn location and there may be a very minimal loss of gain at that location. The perceptible damage will typically go away after several hours of use.

Do not let a laser swipe you. Do not let your laser reflect towards you from a highly reflective surface or a very close neutral surface.

If you follow those two rules then you are pretty safe - barring any abject idiocy, which I cannot reasonably cover in tis post.

Great advice. Very good advice. I wish stuff like this was in the manual, but it was always covered in training.

Don't let your buddy point an IR laser at a chrome bumper while he's wearing your NOD. -- this one is big. Same applies for handling weapons with lasers in a vehicle where you've got glass and mirrors around.

Don't let people hold both the laser and wear the NOD at the same time.

lol - That is like being scared to use your new laptop because you are scared of getting a computer virus. :-)

Use it as you need to, but educate yourself and if something happens, be prepared and know how to deal with it. If you use these devices, you will cause wear and tear on them. They were tools designed for some pretty extreme battlefield use with some super high power lasers. Most burns you can see through and they lessen over time or go away. The ones I am asking about in this thread would be some of the most exteme cases of those and how long it took for them to lessen or become more bearable.

It is a relevant question because tubes have finite lifetimes sort of like light bulbs - they are rated for X # of hours, so if you toss something in a sock drawer for 500 hours, you've just pissed away a bunch of batteries and ~5% of your supposed tube life. I am really trying to figure out if there is any data correlation - like is there a certain # of hours at which point this type of "fix" has diminishing returns - for example, maybe 30 hours fixes 90% of the problem, and 30-200 hours fixes 5%, and 200+ hours fixes less than 1%.

The other piece of this is - the more bright light you expose the tube to the more is also prematurely wears down the tube's lifecycle or at least that is how it was explained to me.

I am hoping someone more knowledgeable on this stuff can chime in because I love when we start digging into the science behind this stuff.

David has conjectured that reconditioning may be neutral with respect to hours MTTF. The hours of lifetime is typically described as actual use. Reconditioning MAY actually extend the life of the tube. Once again, this is conjecture - but reasonable conjecture. If I were to run a tube in for the night then I could use a rechargeable battery (which I do not normally use) and the net cost would be near zero.

How much protection does the LIF offer against lasers and bright lights? Will it prevent burn-in from accidental exposure? I use one just as a sacrificial cover but I figure it offers some additional protection as well.

LIF is for a very specific wavelength

So I believe the tube in question had the daylight cap left on while the device was powered on, which caused a significant blem. The darkest spots are still transparent, just very dark, so the tube is still completely usable.
Here is the reference image.
Attached File


24 hours in the drawer
Attached File


If I notice no change, after 48 hours I'll call it a day and consider the damage permanent. I may need to change the battery at some point too, because it has been running off the same CR123 cell the whole time.

After the first 24, it did seem to improve slightly. The whole thing is wrapped in bubble wrap and then wrapped in tin foil and placed inside my safe.

Yes!  Send them to me for safe keeping. Immediately!  No time to lose.

Better safe than sorry bro!

I don't have much to compare it to but that looks pretty severe, no?  

It looked the "socking" it helped a little.

Gather all of your used CR123s and stage them to run this thing for a long session. I have seen one worse than that recovered. It would be less expensive if you had a "AA" housing. I could run mine (essentially) for free on rechargeables.

I have 3D printable AA battery housings - to run rechargeables, like you. I had this spare CR123 that I wanted to test it with, so I duck taped the wires... lol. I thought the battery was dead, but it is still going strong after 24 hours. ;-)

So how many hours had to be run in order to "save" the one that was worse than this? The tube is otherwise good with a small blem at the edge of zone 1.

what is the purpose of the tinfoil? This is all new info to me.

(Do you have another hat to wear while doing this?)

edit: and bubble wrap does what?

They ran it in for a few days - maybe a week. It was totally unusable before they started. It still had image burn when they were done with run-in but it was good enough to go back into service. They let normal wear resolve the rest.

Some people speculate that tube blemishing may happen at different layers in the tube - explaining why different blemishes have different characteristics and why some are recoverable, while others are not. There are sometimes hard-edged, permanent blemishes inside of soft edged, recoverable blemishes. The speculation is that these are separate blemishes that overlap each other because they are in different planes, and that one plane can "heal" while the other cannot. Once again - speculation. I do not own this idea and I am not qualified to defend it, but it makes sense to me.

Side note: In electronics manufacturing we toss the terms MTTF and MTBF around interchangeably. The military considers them to be distinct terms - both relating to failures, but of different natures. You need to understand the distinct definitions before you can understand the life estimates.

The best or worst unit anyone ever saw started to degrade the moment it was put into service. People need to understand that these things are consumable, though over a very long term. They often do not go "lights out" at the time they are considered unusable. If the gain or resolution fall below a certain level they fail the acceptance test. We don't see nearly as much of this in Gen 3 as we do in Gen 2 because Gen 3 lasts longer and because Gen 2 has been in service longer. Eventually we are going to see a lot of Gen 3 tubes floating around that still have "some" life left in them but that do not nearly perform like new. This is a testament to their ruggedness - not their fragility. The fact that they suffer temporary and permanent blemishes, lose gain and lose resolution should not scare anyone. The amount of abuse that it takes to get to that point is substantial.

A babied unit can "last" longer but I posit that it has never been truly used and that no value has been made of the purchase investment. The nice thing about a beaten unit is that it continues to get used and provide value. A lot of the "perfect" units only get taken out of the safe to impress someone's friends - providing no real value. This irony does not escape me.

The foil is just to provide a light-tight barrier. If you do not have a light-tight environment, you will just create a different burn problem.

Often times a safe is not light-tight. If you have automatic lights in your safe, you probably already know this because you can see light escaping the gaps when you lock the door.

EDIT: The bubble wrap is superfluous to the burn repair.

You're trying to prevent any and all light from entering the tube, even a sock drawer can have some minute ambient light coming in from cracks/seams, etc.  Tin foil just goes the extra length to block as much light as possible.  

I guess I've been pretty lucky... I've had high powered lasers reflected off mirrors, walls, vehicles, even shined at me (yes, this resulted in an extremely long and harsh "talking to"), and I've never had a significant enough burn to require the "sock drawer" trick, though I've had streaks and "ghosts" that faded after a little bit of use, but never anything so persistent as to require running it in darkness for a day or more (I have used and received blemmed and burnt tubes before, but I have no direct knowledge of what caused those burns).  

What I mean to say, is, while I would agree with the consensus that burning your tubes is a very real, and potentially quite expensive (and emotionally devastating, if you paid for the tube ) danger, and to be extremely careful with it, I will also note that again, in a decade plus of real world-use, most of that, admittedly with NODs that I didn't pay for, and therefore did not care that much about damaging, I've never had anything so severe occur in my use that it left a permanent blemish that I can remember, and I've been around and played with a lot of high-powered toys.  

Point being--be aware of the risks and avoid foolishness, but don't be afraid to use the device normally.

~Augee

the bubble wrap was to prevent the circuit shorting itself out since the foil is conductive. It was also to prevent any scratches on the input/output glass. I am currently 3d printing a fat anvis adatper that i will add some contact pins to and wire this directly to a AA battery housing for the sole purpose of testing tubes. I had some spare PVS-5 objectives to but those don't apear to be compatible with MX10160 tubes.

One of the other things I've noticed from some of David's older posts - he showed tube that had an old power supply that had a massive downgrade in resolution and performance as the device aged. When it was repotted with a newer PSU, the performance was significantly improved. This is not to say it saw any better or worse at night, but the image quality did improve.

Nope, it's not like that. Usually, with little to no light coming out of the phosphor, there's no burn. It has more to do with charge effect on the MCP.

Anyway, it works with Gen2 and Gen3. I had a burned PVS-5 tube back when losing a tube was a real problem as I had no spares. Left it on looking at a drawer and could clearly make out the drawer when it was turned on next. Severe burn...

Left it about 2 days in the sock drawer wrapped up in tinfoil. Result? Nearly complete removal of the burn and what little could be barely seen faded after a few more uses.

True phosphor burns in NODs are rare... I've seen a few, mainly in Russian inverter Gen2's that had been left all night looking at bright lights during surveillance operations, but generally it's difficult to burn a modern Gen3 - The power levels are so low, and the brightness controlled, not to mention BSP.

Any severe damage is more likely to burn the photocathode than the phosphor, and there's nothing you can do about that. Extended use over weeks or months may damage the phosphor severely, or intense light overnight maybe, but even then I've seen the charge effect contribution undone and only the unrepairable damage remains.

Can we discuss this:
What does a photocathode burn look like compared to a phosphor burn?

If we can get a cogent answer to this then the thread will have a serious learning point attached to it.

BTW, how is the tube doing after further reconditioning?

Unfortunately, it looks about the same. It decreased ever so slightly after Day 1, but if there is no change tomorrow, I am probably going to call it and just get a cheap commercial housing for it.

First of all, a serious phosphor burn will be visible when the tube is off. If this is the case, you know it's a phosphor burn.

Second, if you can't tell with the tube off, use a bright light. Photocathode burns will inhibit the halo effect, since the light can't get enough electrons to bounce off the MPC and cause the effect. Phosphor burns will reduce or eliminate brightness, but will still show a halo as the bright light source approaches the edge of the burn.

This is how to tell the difference.

The dark area does not seem to be getting any better. I turned it off this morning.

So typically it's damage to the MCP that causes "laser burns" on the tube?

Interesting. Then it's totally not like a CRT.

I use ir lasers and that's why I use lif filters on all my night vision. They are a cheap safety net to prevent damage

I might be wrong, but I don't think a LIF offers any protection against IR lasers. It would have to block the IR wavelength from the laser to provide any protection and that would make the laser dot invisible. They do a very good job at protecting against green lasers.

I will concede I'm going on information there from another researcher when I talk about the light burns we get on our CRTs after leaving on when I refer to charge effect. But no amount of sock drawer treatment is going to affect physical damage to the phosphor... So charge effect makes sense. 

Outside of that? It's totally like a CRT... But when have you known overnight use of a VCR to destroy a CRT based TV? I recall some TVs being left on all night with the same image on, and no visible burn in after weeks... That much usually takes a few years with the same static display. ( Remember screen savers on the old PCs so they didn't end up with a permanent windows bar and stuff like that? ) - Meanwhile, we can get burn in from as little as a few hours under bright conditions... And yet, can see it all disappear quite rapidly when it's in the sock drawer.

So the suggestion was that some of the damage on such tubes isn't permanent damage to the CRT, and was caused by charge effect. Is it right? I don't know.  I still don't have a good answer for it that I'm completely happy with, but that's the best explanation I've heard so far. Outside of that, sock drawer treatment is kind of like magic. We all know it works. 

The LIF isn't designed to protect against green lasers - That's kind of an after-effect of what it is designed to do. It very specifically targets one ( possibly two ) IR lasers.

But you are correct that they are specifically designed to pass most laser light in the spectral range of the Gen3 photocathode. That includes most common IR lasers.

 

Just as a final update to the thread. This damage was not repairable with multiple days in the sock drawer. I ended up trading the tube to someone who plans to reuse the power supply.