If you have display brightness problems with your expensive handheld multimeter VOLTCRAFT VC890, here is a solution for it!
A few month ago the OLED display of my not often used multimeter (bought ~2015 on conrad.de) was getting darker and darker. Now I can't see anything on the display anymore. After little research I found a forum thread in which the people discuss exactly my problem. But no one has found a compatible display, yet. And the Conrad support has not responded to this day.
So I decided to search for displays on alibaba.com. Previously I disassembled my multimeter and removed the display, it's very easy only few screws! After few pages of OLED displays I found a very very similar looking one with same dimensions for 36USD = 31€. So ... let's purchase and wait for it :)
The package arrived after a month. I quickly installed it and ... cool it works :D The display color is now white.
1) Display Mode: Passive Matrix
2) Display Color: Monochrome (white)
3) Drive Duty: 1/64 Duty
4) Wide viewing angel: >160 degree
5) Brightness: 100 cd/m2
6) Dark Room Contrast: >2000:1
7) Operating Temp.: -40---85°C
2. Mechanical Specifications
1) Number of Pixels: 128 × 64
2) Panel Size: 73(W) x 41.86(H) x 1.82(T)(mm)
3) Active Area: 61.41(W) × 30.69(H) (mm)
4) Pixel Pitch: 0.48 × 0.48 (mm)
5) Pixel Size: 0.45 × 0.45 (mm)
From user Bluebrain
To make the display brighter and crank up the voltage from 13V to 15V (which is within the specs of the display), install a 100k resistor between GND and the step-up regulator feedback pin as shown: