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Discussion Starter #1 (Edited)
Greetings to all!
After reading a number of posts about problems with PU scopes, I deside to make short manual. I'll try to show how to disassemble and repair PU scopes.
Today I post part 1- how to disassemble pu scope.
At first I want to excuse if I will use some incorrect technical terms, and if you will note some mistakes in my posts, English is not my native :)
Ok, lets start!

CAUTION ! Don't disassemble your PU scope without need, just to look on it! Even considering that PU has very strong and simple construction, it's an optic device, and could be easily damaged! After full disassembling scope should be calibrated.
Anyway, just disassembling scope, and then reassembling, you will NOT fix any problem! But you could get them, and your scope most possibly will lose impermeability. The smallest problem you could get is damaged screws and blueing. The biggest -you will damage some important details, especially lenses. From my expirience, even nice looking lense could crack during disassembling - because it could have some invisible micro-crack, and when tension of metall rim will dissapear, it will broke up.
In 90% of cases there is no need to disassemble scope. How to fix some typical problems, I will write in next post.
Before you will start, carefully read all instructions. Use correct tools, and be very carefully, another way you could damage scope.
You make all operations with your scope at your own risk!
I hope that soon we will not see a number of topics such as "I broke my scope while disassembling it, what I should do now?"
:)


Also here are few important additions from turbodan

A few points:

-Don't use whatever grease you have on hand inside these scopes. Common greases are not intended for use in optics and tend to break down, leaving fogging and splattering on the lenses as the lighter components of the grease separate out. I use a synthetic damping grease for the reticle which does not break down and is designed to fill tolerances and absorb vibration.

-Be very careful with the reticle. As you can see, the tiny filaments are very flimsy and just touching them can destroy the reticle. Its also very easy to get them dirty, which makes your reticle look like its growing tree bark. Cleaning or repairing the reticle is not for the average guy.

-Do not unstack the front or rear lens assemblies unless its actually necessary. They are assembled with a shellac-like adhesive called Canada Balsam. Its an old school type of optical cement which I actually prefer to modern adhesives. It can be cleaned and reapplied rather easily, but you don't want to have to fix anything that isn't broke. It is sensitive to shock if not properly supported, so once you unstack the lenses it can come apart easily.

The good news is that most parts among like scopes are interchangeable, even with some repros. If you mess something up or require replacement parts you can find another scope and mix and match. The SVT PU scopes are mostly unique, though they share a few parts with the standard PU.


1. We need PU scope and some tools :)
In original PU repair manual, issued in USSR, discribed some special tools for scope repair. But I'm very doubt that somebody have them, so I will use tools that everybody could have. Also note handmade tool from alloy, later you will understand where you will use it. Alloy is softer then steel, so it will not damage it. Also it is preferable to use small screwdriver instead of stationary knife, but I don't have it.





2. Let's start the process
At first we need to unscrew 2 lense blocks. The main problem, that sometimes waterproof grease at the thread could dry up, and it will be very hard to unscrew lens blocks. At first, cover scope with cloth, and put to vice grips.
Take alloy tool, and try to unscrew rear lense block, without removing small screw on it
If you don't succeed, try to melt grease - cover scope with wet cloth, leave only thread area uncovered, then briefly heat up the place where internal thread is located. To remove front lense block, alspuse alloy tool,
Also you could use the rod with alloy tool (there are 2 holes for it), it will help to unscrew lense blocks more easy.








3. If it is necessary, we could deattach rear lense block.

Remove small screw, and unscrew the rim with alloy tool.







4. Remove central lense block
Unscrew 2 small screws at scope's body. Unscrew central lense block






5. Remove turrets
Unscrew 3 screws. Unscrew turret caps and remove internal details.
Unscrew 2 internal screws. Unscrew turret axis.








6. Remove reticle.
It should fall out himself, when you remove turret axis.
Be very careful with it, it could be easily damaged.


That's all!
Attention! To avoid the penetration of moisture to scope, attach scope in dry and warm room, also use grease (synthetic damping grease) for lense block threads.




Oh, I almost forget! Do you remember bottle opener between tools?
Take a beEr, open it and enjoy :)


 

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Alex-- Should be a very helpful Post to many!!! ...............Thanks.............

Regards
Art
 

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Very informative post! Thank you. Hope they make it a sticky here or in the sniper forum.
 

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Nice. I was thinking too, if you wanted, you could reassemble, except for the last piece (first piece removed) in a 100% nitrogen environment if you used a simple homemade glove box and a tank of HVAC nitrogen. I have been thinking about building a box to do this type work in. It would be simple. Put your parts in and then pressurize the box with a slow bleed of 100% nitrogen. Wait a little while and reassemble the last part in the box. Hmmm another winter project now...
 

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Discussion Starter #10 (Edited)
THAT WAS GREAT! Makes me wish I had one just to try that whole operation! Thanks Ratnik!
Anyway, don't deattach scope without need. Even considering that PU has very simple and strong construction, it's an optics, not Kalashnikov :) Some details could be damaged easily. And after such procedure it should be calibrated.
90% of typical problems could be fixed without full deattach, later I show how.

Nice. I was thinking too, if you wanted, you could reassemble, except for the last piece (first piece removed) in a 100% nitrogen environment if you used a simple homemade glove box and a tank of HVAC nitrogen. I have been thinking about building a box to do this type work in. It would be simple. Put your parts in and then pressurize the box with a slow bleed of 100% nitrogen. Wait a little while and reassemble the last part in the box. Hmmm another winter project now...
Originally, scopes don't were filled with any inert gas. But if there is such possibilty, of course it will be usefull. In this case all threads shold be be covered with grease, to reach impermeability.

By the way, what brand you drinking there, Ratnik? ;)
I prefer our local beer :)
 

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Anyway, don't deattach scope without need. It's an optics, not Kalasnikov :) Some details could be damaged easily. And after such procedure it should be calibrated.


:)
Ratnick:

As always you have posted some very interesting information and excellent photos. And I do extend my thanks. I am however confident that many will ignore your cautious advice and disassemble scopes that do not need to be fooled with. I fear many a disabled and inoperable scope will result from your excellent instructions. Unfortunately there are many who are born tinkerers and can't leave well enough alone. And that, Mr. Ratnick, is not your fault. :)
 

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Discussion Starter #12 (Edited)
Ratnick:

As always you have posted some very interesting information and excellent photos. And I do extend my thanks. I am however confident that many will ignore your cautious advice and disassemble scopes that do not need to be fooled with. I fear many a disabled and inoperable scope will result from your excellent instructions. Unfortunately there are many who are born tinkerers and can't leave well enough alone. And that, Mr. Ratnick, is not your fault. :)

Richard, you noted very important moment... I will update my head post with caution of such "just to look" disassembles
 

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Discussion Starter #13 (Edited)


CAUTION
A few points:

-Don't use whatever grease you have on hand inside these scopes. Common greases are not intended for use in optics and tend to break down, leaving fogging and splattering on the lenses as the lighter components of the grease separate out. I use a synthetic damping grease for the reticle which does not break down and is designed to fill tolerances and absorb vibration.

-Be very careful with the reticle. As you can see, the tiny filaments are very flimsy and just touching them can destroy the reticle. Its also very easy to get them dirty, which makes your reticle look like its growing tree bark. Cleaning or repairing the reticle is not for the average guy.

-Do not unstack the front or rear lens assemblies unless its actually necessary. They are assembled with a shellac-like adhesive called Canada Balsam. Its an old school type of optical cement which I actually prefer to modern adhesives. It can be cleaned and reapplied rather easily, but you don't want to have to fix anything that isn't broke. It is sensitive to shock if not properly supported, so once you unstack the lenses it can come apart easily.

The good news is that most parts among like scopes are interchangeable, even with some repros. If you mess something up or require replacement parts you can find another scope and mix and match. The SVT PU scopes are mostly unique, though they share a few parts with the standard PU.

Part 2
How to fix most usual problems

Problem 1. Most typical problem is that scope don't hold recoil (distance scale turns very easy).
This problem exists, because spring #13 (exploded view, or #1 at photo below) is too weak. To fix it, we need to remove turret caps (paragraph #5 in Part 1)
Then we should take the spring #1 (photo below) and make it more curved. Also it is possible to add a shim which similar to shim#2 (photo below), but I prefer don't do this.







Problem 2

Turrets stagger
This problem could appear when leather spacer at turret axis is worn.
Make new spacer and replace it.




Problem 3
Foggy\dirty lenses.
It could be caused by 2 reason - scope was not impermeable, and moisture condensed inside scope body, but gluing of the lenses is undamaged. In this case just unscrew front and rear lens blocks, and disassemble rear lense block (paragraph#2 & #3 at the Part 1). Clean lenses and assemble with waterproof grease



Next reason - gluing of the lenses is damaged. It's a big problem.
2 lenses from rear lense block (30\31 at exploded view) could be easily extracted, then unglue, and glue again.
I think there is no need to describe how to unglue and glue lenses, it is real to find many instructions in this area.
But 2 lenses from front lense block (27\28 at exploded view) seamed into the rim. So if you have possibility to replace that element , just replace it. Because when you will try to unseam lense rim, most possibly you will damage lenses. But if you have no choise, try to hook seam with thin and sharp tool. But before use small rasp to make metal seam more thin, without this I doubt you will be able to hook the seam. After that, because lenses are glued at the rim, you need unglue them. Put lense block to solvent for a few days, or carefully boil it, preferably in glycerol (as original manual says).




Problem 4.
Reticle is too low\high at maximal\minimal distance or moved to right\left too much when set to 0.
Unscrew 2 screw at half-turn. Then move reticle up\low (left\right) to suitable level and fix screws

Correct position!
Reticle should be at center when top scale is set to 9, side is set to 0


 

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A few points:

-Don't use whatever grease you have on hand inside these scopes. Common greases are not intended for use in optics and tend to break down, leaving fogging and splattering on the lenses as the lighter components of the grease separate out. I use a synthetic damping grease for the reticle which does not break down and is designed to fill tolerances and absorb vibration.

-Be very careful with the reticle. As you can see, the tiny filaments are very flimsy and just touching them can destroy the reticle. Its also very easy to get them dirty, which makes your reticle look like its growing tree bark. Cleaning or repairing the reticle is not for the average guy.

-Do not unstack the front or rear lens assemblies unless its actually necessary. They are assembled with a shellac-like adhesive called Canada Balsam. Its an old school type of optical cement which I actually prefer to modern adhesives. It can be cleaned and reapplied rather easily, but you don't want to have to fix anything that isn't broke. It is sensitive to shock if not properly supported, so once you unstack the lenses it can come apart easily.

The good news is that most parts among like scopes are interchangeable, even with some repros. If you mess something up or require replacement parts you can find another scope and mix and match. The SVT PU scopes are mostly unique, though they share a few parts with the standard PU.
 

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Discussion Starter #18 (Edited)
A few points:

-Don't use whatever grease you have on hand inside these scopes. Common greases are not intended for use in optics and tend to break down, leaving fogging and splattering on the lenses as the lighter components of the grease separate out. I use a synthetic damping grease for the reticle which does not break down and is designed to fill tolerances and absorb vibration.

-Be very careful with the reticle. As you can see, the tiny filaments are very flimsy and just touching them can destroy the reticle. Its also very easy to get them dirty, which makes your reticle look like its growing tree bark. Cleaning or repairing the reticle is not for the average guy.

-Do not unstack the front or rear lens assemblies unless its actually necessary. They are assembled with a shellac-like adhesive called Canada Balsam. Its an old school type of optical cement which I actually prefer to modern adhesives. It can be cleaned and reapplied rather easily, but you don't want to have to fix anything that isn't broke. It is sensitive to shock if not properly supported, so once you unstack the lenses it can come apart easily.

The good news is that most parts among like scopes are interchangeable, even with some repros. If you mess something up or require replacement parts you can find another scope and mix and match. The SVT PU scopes are mostly unique, though they share a few parts with the standard PU.
Thank you for very important addition. I think it will be neccesary to update my posts, because somebody could finish reading before your post.
When reticle gets dirty during disassemble, most possibly it could be noted only when scope is assembled again.
It could be cleaned with brush from squirell fur. Unscrew front lense block, you will see reticle. And VERY, VERY easy, without pressure, try to remove dust
 

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Thank you Ratnik for the great information and pictures.

And Turbodan, your additional info is appreciated.
 
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