I am looking at an old Heindenhain LS623 optical slide with with a LM339N comparator and an MC3487p line driver. This slide is about 20 or more old and can not be repaired anymore by Heidenhain. I found out that the that printed resistors on the ceramic substrate are not stable anymore and therefore I intend to recreate new electronics for this slide. It took me a while to understand the working but all of that is clear now with the exception of the small capacitors at the outputs of the line driver channels. What is the purpose of these capacitors? Maybe the are there to reduce incomming noise ? Actually I have no idea? Both channels are in use Y and Z.