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I've noticed on a few Pulsar boards that have crossed my path recently, that there is something that looks like a voltage regulator attached to the card. It is a three legged device soldered near the bottom of the board and surrounded by copper ground plane - very easy to identify.

I've noticed on a couple of my boards that the middle lead is not soldered to the pad. On one board, the middle lead is connected to the PCB through what looks like an SMD diode.

I'm just wondering if anyone else is seeing this? The lead looks like it should be soldered to the board. It seems to be making contact with the pad but just hasn't been soldered. I suspect these are hand-soldered devices. Maybe the lead is supposed to be left dangling? I think it might be a ground connection for the regulator. Anyone know anything about this?

On some Voltage regulator models, the heat sink plate is connected to the ground pin so, depending on your circuit, bolting or soldering the plate to the ground plane is sufficient.

As for the diode, I couldn't be sure without taking a look at the circuit diagram. Maybe other pulsarians with more electronic design experience than me could answer this one.



RedSun .:.

I have limited knowledge of voltage regulators. [apart from those on aircraft;]
But I know enough not to start soldering on my dsp boards!

Yep!

If it ain't broken...



RedSun .:.

Yes, don´t touch it!
I have the same on my 2nd XTC baord, but it works just fine. So i assume it has to be like that.

I took a closer look at one of the unsoldered boards. The middle pin must be ground - the circuit trace beneath the pin leads directly to the ground plane. So obviously it doesn't matter if the lead is soldered or not (I suppose). The lead is touching the pad - just not soldered to it.

Yet, on another (newer) board, the middle pin is tied to the same circuit trace but there is an SMD diode soldered to the trace and the middle lead soldered to the other end of the diode.

I agree with the "don't fix it" philosophy but I don't agree with the "ignorance is bliss" stance. Being an engineer, I'm just naturally curious about this stuff. I simply wanted to know a little bit about this as this did not look normal to me. Why they would choose not to solder the lead is probably related to operator through-put on the production line or else they were just trying to reduce the possibilty of solder shorts between the leads. Clearly, this is a hand-soldered device.

Ehh.. whatever.