New(to me) PVS14 with black spots.

Tactical Gear Optics & Mounts
1

A local shop gets these in from time to time from a guy that rebuilds them. I have been waiting a while and finally managed to snag one today for not even half the normal cost. I am aware that all tubes have some spots. And this one was more than inexpensive enough that I am not going to complain. But I would like some expert opinions on two things.

1: Are these spots mostly damage or does a lot of it look like debris?
Some looks like debris to me but I am no expert.

2: If it is debris what is the best route to go about cleaning it up.

2

A better pic against a clean white wall would help more.

But going off of what you posted, some are definitely blems- good sized blems. And some could be trash- the technical term thereof being “debris in field” if you want to talk like a cool daddy NV guy LOL.

So PROBABLY the trash aka “debris in field” for you techie types :slight_smile: is on the eyepiece lens. Let’s hope it is cause that would be the easier fix.

Get yourself some good lens paper and some alcohol (like rubbing not Vodka)- some will argue strength of it matters, let’s not get into the weeds too much here, let’s just help him clean up his unit. And one more thing- worst case- a Q tip. Not IDEAL to use a q tip but you probably don’t have anything else in the house.

The objective lens may or may not unscrew easily- holding the front of the unit with your right hand, use your left hand to turn the eyepiece lens counter clockwise. These can be set really tight. There is a special tool for this, but I don’t honestly know what you would find that would duplicate it if you don’t have it.

If you can unscrew it by hand your in business. Unscrew it all the way and remove it from the unit. Bad news is that you now lost any nitrogen purge you MAY have had but let’s not worry about that at this point.

pic

While you got it opened up, be sure you see a metal ring holding the top of the tube down, trying to get some pics to load but my country internet is running slow…

pic

If you have a magnifying loop, get it and examine the eyepiece lens under the loop. Start with a can of computer duster you probably have and turn the lens upside down in your hand and blow the lens with the compressed air turning the lens in your hand as you go. Note- I always direct the air towards the inside of the lens, there is a lot of little spots in there that can “hold” debris that will produce a clean looking view when first assembled but will bounce out into view under usage. Suffice to say “debris in field” is a VERY common NV issue.

Check it under the loop after blowing out (hopefully that’s all it will need). If not start with lens paper and clean it that way. Final step if your still seeing crap is alcohol on a swab- again a Q tip is NOT the ideal situation but you likely don’t have anything better just sitting around at your house.

After alcohol, use a lens paper to dry liberally and compressed air, check again. You can get tiny bits of alcohol left in there that the air will drive out into view, so you may have to clean and check multiple times.

You can also check the eye side of the tube screen for debris and clean that if any appear. A loop is extremely helpful for this.

I’ll try to make a 2nd post with the pics, they aren’t loading for some reason, sorry.

3

IMG_0181.jpg

This has the eyepiece lens off and the retaining ring and lightpipe removed. Check the screen as shown here also for debris.

4

Was this unit shipped to you or did you pick it up? Reason I ask is that I wonder if it was shipped and beat the hell out of in shipping. Not meaning damaged, but often times debris that is on the periphery can often be knocked loose after a lot of use or in rough transit. This was why I mentioned above trying to get the compressed air up into the eyepiece lens with it being held upside down.

It’s VERY easy to get debris in field and it’s extremely common. What your seeing in that pic is either a boatload of it, or a lot of blems and a little debris.

Once you clean it up you should see a helluva difference. Be sure to post some “after” pics when you clean it also. Good luck.

5

Thank you for all the advice.

The tube was delivered locally. But that doesn’t really mean much around here. Ha!

I will look into cleaning it using the advice you gave. Thankfully due to 3D printing and electronics work that I do as hobbies I have 99% IPA and fine cleaning materials for just such work. Once I build up the nerve and drink enough bourbon I will take a crack at it. Then I will head over to your website to get the mounts and stuff I need for it!

6

One final thought-

You do have the daylight/pinhole cover off as well as any demist shields, etc right?

These will GREATLY distort the view making it looks like there are blems and trash where there isn’t. Can’t tell you how many freak out calls I’ve had over the years where people had installed demist shields (why?), had the pinhole cover on, etc. and were complaining about “blems” that weren’t blems but the filters, etc. distorting the view.

Always check the view with nothing on any of the lenses.

7

I do have a protective lens on it but not a pinhole cover yet.

One thing I did notice while messing with it. These spots can all be seen when it is turned off.

8

That would lead me to think debris in field, aka trash in the lens.

Super curious now!!! Let us know how it works out.

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Will do. I will also do my best to document it. If I get it right then we can see. If I fail spectacularly (likely) then we can all have a good laugh at my pain.

Thanks again for your help. I am very much a novice at this and your judgement free advice is appreciated.

10

No worries. You can do this. I probably made it sound too complicated trying to over explain it.

I’ll try to take some more pics and post them also. If you run into snags just post about them and I’ll try to help.

11

Well that was Nerve wracking… But holy shit. ’

So I took the ocular lens off and could immediately see dust on the tube. A lot of dust.

I cleaned it as advised, didn’t’ even use the IPA though since it didn’t appear to be needed.

This is the end result. You could say I am happy!

I think those spots on the outer edge are still dust and will mess with it later. But at the moment I am good with it.

12

Nice to see a happy ending to this one. Great job man.

13

What does the loss of nitrogen affect?

14

Wow, great job! That looks way better, glad that worked out for you.

15

Nitrogen purging reduces the potential for moisture inside the optic.

16

Yes ideally he would purge it now. Doubt he wants to drop $2,000. on a proper purge kit however.

There is some DIY methods that folks use- I cannot attest to their efficiency- including Argon wine preserver spray.

If he did the work inside in a relatively climate controlled structure, he should be fine without a purge truth be told.

If you DO get any fogging issues OP, then you will have to address it.

That was a metric arse ton of trash inside! I’m guessing what you still see is actual blems as they didn’t show up well in a pic. “Pepper speck” which is the teeny tiny blems smaller than .003 rarely show up in pics and none of the tube manufacturers chart them or acknowledge stuff that small as blems. Only way they bother people is the guys that Mommy won’t let out of the house so all they seem to do is stare at sheetrock with their NODs :slight_smile:

You cleaned that up nice OP, congrats!!!

17

I have also heard of people using compressed air in place of a true purge. Any thoughts on this?

The tiny spots do still see do only show up when looking at a flat surface. Once mommy lets me out to play with them I am sure I won’t even notice. And I expected those types of spots from my pre purchase research.

18

What you have there now is a relatively clean tube- looked like some blems in Zone 3 near the outer edge. Very common.

In actual usage you won’t notice those at all.

I wouldn’t try compressed air to purge it. I would just leave it be until/unless you see some fogging issues.

Purging also has to be done under a certain pressure. One time I messed up the setting on our purge device and the nitrogen went in too high. What was a beautiful clean tube was now covered with crap. Had to disassemble and clean everything again- and you know how fun that is.

You may want to also check the overall integrity of the housing. On the area with your tube retaining ring the little green coloring seemed really odd- almost like it lost a seal at some point, got moisture in the set or something. If you start experiencing fogging that could be the cause of it also. Check for cracks in the housing, missing screws, etc. Be worth a look over.