Heidenhain Encoder - strange waveform help request

can it be that i destroy the Controller PCB when i change the scale  with  power on  ? thats in fact what happend  
i think its a very old scale  the mill was build in  1984 as fare i can see ther is only one scale replaced not thise one  

sivaraj wrote:

Scales of newer version will have infrared LED and invisible to naked eyes .

You can often see IR LEDS with a digital camera, though.

i do the check with an exe 601 box  
the scale work partly  so it will be a dirt ploblem  how do i have to clean  this  ? i see a lot of movie  on youtube