so you get sound fine and the picture is ok but black and white ?
You are probably using the wrong video system, ntsc and pal are not interchangable, most modern tvs will read both but older tvs usually have only one system so you need a converter to convert it to the correct system study you tv manual and the bluray manual to see what video system they use.
perhaps you have a setting to change the video system in the bluray or tv manually, check that first.
if you lack manuals then i suggest a google search most manuals are online , but you need a little more than "old tv" there should be an exact model number on every device somewhere. often on the back
hm I assumed you meant you had proper picture with no colors that is very common with wrong video system , but this sounds more like grumpy says it could be your system not supporting the copy protection system then you would get mostly black with some white flickering and of course the sound is not encrypted that much , try to put a non copy protected dvd disc in the drive and see if that gives a pic be sure it does not use macrovision (if it says on it its copy protected it does, if you can copy the disc to pc with normal copy and get good picture it should be fine) , if you get proper pic with that then your system does not support macrovision. Im not sure if you wired it up correctly also , I dont know what kind of converter you used or what outputs or inputs you wired to where. if you get no pic, not even a menu pic from the bluyray then you wired it up wrong or the systems are not compatible or used the wrong settings.
http://www.retrevo.com/support/Sony-KV-27FS100L-TVs-manual/id/274ag715/t/2/
theres the manual for the tv, its always useful to have handy
I assume you used input nr 4 on page 17 of that manual ? did you wire them in the wrong order ?
if you plug color into the Y signal it will work kinda crappy, are the leads labeled properly in the same way the tv is ? Y is the black and white video signal , if youre not sure what is what try different plugs into only that one , the one that gives you a good black and white pic is the correct one. the two next ones are the color difference signals if they are switched out you get wrong colors.
is there a wire from the converter labeled composite video ? if there is try that in input 3 video
it could be the converter is the wrong type for your tv and not outputting the r and b difference signals, that is not the same as rgb which is common for these things. if you have rgb then plugging the G into Y should give you a good black and white picture for the movie.
http://download.p4c.philips.com/files/b/bdp2900_12/bdp2900_12_dfu_eng.pdf
manual for the bluray