Hello,

I was apperently really sloppy while designing a PCB layout for my audio power amplifier and I accidentalyl switched the Source and Drain pins. The board was already paid and shipped so I cant fix it. I was wondering if anyone might have an alternitive solution for me. It's the output stage power MOSFETs two of them and there will be about 5A of current through each of them. My first thought was to just wire it using normal wires to reconnect them properly. Another idea of mine was to simply twist the two legs of a transistor and swap them that way, but I really dont know if that would be functional.

Any advice is welcome, thank you for your help,

Niko

 

What package? If through hole, that is really easy to fix (e.g., insert from the back, bend the leads, or turn it around). If SMD, it depends on the size.

 

It's through hole the first pin is in the right place that would be the gate but the second and third are swaped. So you're saying I should just bend the leads so they fit and it will be fine right?

Package: 2SJ162 lateral MOSFET from Hitachi

 

Yes, why not? If they aren't long enough, solder solid wire to them. It might be neater to flip it so drain and sourse are correct and run a wire to the gate, since it is very low current. I have also just crossed the drain and source legs.

If you use a gate resistor, you could flip, then solder that resistor to the gate and to its proper spot on the board.

There is actually a type of construction called "dead bug" where such things are done on purpose.

 

Okay, great idea. I'm going to try the dead bug technique, it sounds promising.

Thank you for your help again.

 

With 5A in a linear circuit don’t they meed to ne on a heat sink?

Edit: Oh, it might be class D, not linear.

Bob

 

They do need a heatsink yes, but that's not a problem.

 

Well, it means you can’t turn it around as suggested.

Bob

 

If the legs are long enough , sleeve and bend them to fit the holes, if not use tinned copper wire.

 

Well, it means you can’t turn it around as suggested.

Bob

Sure he can. If the heat sink is attached to the mosfet. None of us have a picture of either the board or the heat sink -- at least I don't.

 

Swap them for a IRFP240/IRFP9240. You'll need rather more bias.