Philips L4135 Leak transformer 135W/180W SOX ballast comparison

here is what I think is an interesting comparison of 2 ballasts of the same model destination but separated by probably 30 years!

I always thought the more modern brown L4135's where identical to their older grey counter parts, apart from the colour/label scheme and terminal block style, but it turns out the more modern one is a little bit longer! (if anything id expect the older one to be longer!)

its also worth noting that the older ballast has a 200V tap and while that terminal is physically present on the newer ballast, its unmarked and indeed unconnected (which is something I had wondered about for a while), I wonder when the 200V tapping was dropped exactly

it is interesting to note how other than the above, the wording (and layout to a good degree) of the ballast etch/label is almost identical between them still despite the different styles and age difference

sadly the older grey ballast on the left has failed with internally shorted windings hence why I have the recently acquired brown ballast which was kindly supplied to me by Andy, and something im quite pleased to have, as the grey ballast died many years ago and since then I had been without a proper 180W SOX ballast until now