Tektronix DMM4050 (Fluke 8846A) VFD brightness restoration by total Debranding

[Kiriakos GR]

The long story in sort, we have here a six years old (used) DMM4050, this is in perfect shape and retaining it calibration since Jan 2013 which this was manufactured.
This instrument was purchased Feb 2019 from Italy and this is now a Greek resident.

What was obvious after total internal and external inspection, this was that while this multimeter lived in to a distilled environment (active dust filters in the lab), the VFD glass this has premature aging issues, severe burning s that it is hard to be explained.

While I did come in communication with Noritake Itron and I did have now a very reasonable quotation for a new VFD glass, I was also wanted to further investigate and discover the all truth about the source of the problem.

The problem here is Tektronix it self.
Their re-branded 8846A it also differentiates from a Fluke 8846A in the regard of a much darker VFD filter (face plate) which this forces the end user to boost brightness from lowest setting at medium or highest.

Japanese Noritake Itron it is very clear regarding specifications’, their specific VFD has life expectancy of 20 years when this is not misused.

I did mention this situation and problem at TEK Europe and at Fluke headquarters, TEK ignored me and never answered in my two attempts at establishing communication.

Personally I never run out of options, I am used to reinvent the wheel when a manufacturer this is dead regarding spare parts support.
My extended conversation with Noritake-Itron applications engineer this helped me to start looking for alternative materials which they can be used as Filter. 

For the new filter I was able to find locally 2.3mm Plexiglas at correct transparency and tint.
My second key to success this was leftover stripes of self-adhesive film for windows shade (Car accessories).
I did install such film stripes at the sides only of my new Plexiglas window.
Third ingredient this is having a Kiriakos in the room, so him to do the job by not making a single mistake.

The rest of this story it is explained by the pictures below.
Today I do feel extremely proud of my self because my DIY wile this is not risk-free (adding screws), the end result this very satisfactory, and now I am enjoying 40% (at least) of a higher brightness in this Dot-Matrix VFD at lowest brightness setting.
I had never Debranding a DMM before, but I also never had to deal before with TEK customer support either.

[Kiriakos GR]

This project under the sun   

[overvolt]

DIY work this looking as factory work ... Only Kiriakos can do that.   

[Kiriakos GR]

I have become master at De-branding and at Re-branding     

In this case I got in to a NEW dilemma, now that I am up to replace my VFD active element with a new, which brand flag should I restore?
And I decide of me to team up with the most reasonable up to date...  manufacturer.

Previously I did sensed correctly  that Tektronix made a huge mistake about the choice of LENS Filter,  too much of VFD luminosity gets wasted by this filter. 

Today that I have and original FLUKE 8846A Lens as comparison point, now the TRUTH this shines too and proves me as CORRECT as investigator and also regarding my sanity.


There is only one way to check such LENS performance scientifically, and this is turning the lens back plate at a light source and then to measure the intensity of light which this coming out of it.
In other words we need to measured shadows intensity.
But here the differences they are so huge that even the naked human eye this can detect its one Filter behavior and performance.

Now the FLUKE filter, this is still covered in both ends by protective transparent nylon,  if this get removed, then the allowed light quantity this will be increased further more by 20%.   
After months of thinking and studying such Lens performance,  now I have earned much more experiences.

FLUKE product designers they did a much WISER LENS selection choice, which now I am also going to use.