I ordered an NSP-3 from Apex

https://www.apexgunparts.com/night-vision-nsp-3-scope-w-transit-case-acc-vg-to-ex.html

And it does not work.  So I figured that would be the case and started poking around a bit last night.

The unit does power up, but it is crowbaring the input voltage.  I tried both a DC supply and (3) D-cell batteries.

The tube does give a short flash just before each 'tick'.

This appears to be a common failure for these as I have found at least one other purchaser describing the same problem.

Any hints by any SMEs would be appreciated.



My next move will probably be to check the power output of the multiplier circuit with no load and then with a simulated load.  If the output looks good then I will have to assume it is a tube problem, which would likely end this project as I doubt a replacement tube can be sourced.

This guy:
http://www.kalashnikov.org.uk/accessories/Page_1x.html

Has a pretty in-depth webpage about Russian NVD and sells some parts. He may be able to help?

Thanks!

I had found his NSP-3 page, did not realize he sold parts.

The ad says...



So, yeah...or something.

They were sold "not guaranteed to function"

I got the tube pulled apart as much as I think I can this evening.



I have some hope that there may be a bad junction on the first two high voltage connections to the tube.  Note the condition (blackened) of the two connections closest to the camera vs the others.



Also note the condition of the connection of the red wire nearest the camera.

I am going to re-cut and re-solder these connections, clean up the clamps and tube connections, use some corona paint on anything that looks exposed, and button it all back up and try it again.

Hooked everything up external to the scope tonight and powered it up.

Got a different noise this time...more of a bad connection sparkle than the repeating tick tick tick.

I will try the corona paint on some areas I think may have short issues and button it back up and try it.

Thats a pretty cool project you have. Fingers crossed that 1) you maintain your patience, and 2) you get it to work!

Sometimes that tick tick tick and tube strobing is the high light cutoff circuit. Not sure if yours has one but the 1pn34s do.

Interesting, H.

I tested the unit per the totally dark specs.  Polarizing filter at max dark and tri selector at max dark.