Hi, I have made a few 'video switching' circuits that are failing, hopefully someone can give me some tips .. perhaps my board layout is not good for this purpose ? (not enough ground plains perhaps ?). Firstly the board layout can be viewed at http://www.quack.cc/video.jpg p15v332-Q PDF can be viewed at http://www.quack.cc/P15V.PDF The 18 pin IC in the middle is a PIC 16f84 (DIP Through-Board) running with a 4mhz ceramic resonator, which receives serial signals from a host and configures its outputs (portA and portB, mixed) to control the video switch chip, which is a P15v332Q (QSOP surface mount package chip). Perhaps the resonator is causing some interference in the circuit ? - i have never dealt with any RF or video circuits before, maybe im missing some really simple rules that must be followed for a good, clean signal ... ? The problem: After soldering them up, they work nicely for a brief period of time. After about an hour or so, the video signal gets visible iterference, it seems to accumulate. After a day or so its completely unusable. Some of them i did a re-soldering job on the P15V (surface mount component), basically i just melted the solder again, and this makes it 'work' cleanly once again. some of them continue to work forever, some of them stuff up again. But all of them have a slightly 'dirty' signal, even the 'working' ones. I have not used SM components before, so perhaps my technique is not good. I have tried quite a few techniques, but i find the following to be the easiest to do and achieve what i think is a good result. I dont have special tools or anything for surface mount. The technique i use it to make my PCB using BLUE PNP paper printed from a laser printer (part# PNPB100 - www.www.techniks.com), i iron that on, peel it off and etch my boards in Ferric Chloride. This gives a fairly good result, and no shorts and good, solid tracks. I then coat the board in "flux 140" which is a dispenser pen which has both flux and a protective coating for the board to stop oxidization. This has worked wonders for all other work i have done. (part# 363-6539 @ £7.29 from RS components, www.rswww.com if anyone is interested) Then to install the Surface Mount video switch, i wet each pad with just enough solder to 'paint it silver", (using 60/40, flux loaded solder). (i read somewhere that silver loaded solder is better for SM components because it conducts the heat faster and therefore minimises component damage because its soldered on quicker, and something todo with metal bonding ?? could this be my problem perhaps ?) I then position the chip under magnification and hold it down while i lightly and quickly touch the top of each pin with a fine solder tip at about 400' degrees. this melted the pads just enough for the legs to stick nicely, and leaves a good looking clean job. I then proceed to test its connection with a continuity tester, to ensure that the top of each leg does infact have connectivity to its track, and that there are no shorts. these tests work out fine. (even after the 'signal degradation', the continuity test still shows no problems, even when they completely dont work !! what is going on ?!?) Im at a loss why these are failing ? i cant see any problem. Any hints or suggestions would be great! Alex. PS : i cant change 'video switch' chip brands, due to the large stock i now have of them, the P15V332 must be used, and in SM form. I wish i could have got them in through-hole form, but unfortunantly they just didnt come that way. I chose these largely because of their availablitity and price. They cost only $2.10 from www.digikey.com.