K149资料和原理图

The first thing to do is inspect the PCB for shorted or open tracks or other
damage. Be aware of the static warning when doing this check. When you are
satisfied that all is well, then you can proceed.
Start with the flattest parts first, which are the resistors. Hold each resistor body
by the thumb and forefinger and use your other hand to loosely bend both of the
leads over at right angles at the same time. Try not to make the bends too sharp,
and you will find that they slide straight into the mounting holes on the board.
Leave the pigtails on each of the components until after soldering as the extra
lead length serves as a heat sink for the component. Try not to leave the
soldering iron on the components too long or you risk damaging them. The usual
method is to hold the iron tip so that it touches the component lead and the PCB
pad at the same time, and then apply a small dab of solder. This operation
should only take about a second or two. If you are unsure of your soldering
ability, find some spare components and practice on these before building the
programmer board.
Check that each solder joint is bright and shiny and doesn't look like a big dull
blob which could mean a dry solder joint. The solder should flow freely onto the
component lead and solder pad if it is to be a good joint.