LaTeX generated PDFs on my PRS-500 always had a very faint look to them that made them difficult to read. Following these instructions
, I was able to find a position for the RV1601 potentiometer that greatly improved the display of PDFs. I also drilled a small access hole in the back cover of the case so that it is possible to adjust it later without disassembling the reader.
There is a little more ghosting and the background has a slightly darker gray tint, but overall the readability of PDFs formatted with fonts like Times and especially Computer Modern
is really remarkable.