This PCB any good?

[EBM_dude]

Hey folks,

I'm lazy (and overworked ATM) so instead of designing my own PCB for a LM3886 amp, I decided to look around for what can be bought. I stumbled upon this little PCB:

LM3886 Classic (Gainclone) stereo Platine bei eBay.de: Sonstige (endet 01.06.10 16:13:08 MESZ)

Doesn't look too bad but it has no star grounding. Will this thing hum badly because of the missing star grounding? The LM3886 datasheet doesn't suggest any layouts.

[timpert]

Don't buy it, it sucks. Here's why:

There seems to be no decoupling near the IC's supply pins, this is required.

There's no proper routing of the power traces, and why on earth need the small signal traces to be as thick (or even thicker) than the skimpy current carrying power traces?

The LM3886 needs pins 1 and 5 connected to V+, I don't see this being done, also when considering the possibility that the layout is given in mirror-image. It even seems like V+ and V- are confused. This board is not compatible with the LM3886, and it may well be that the board was designed for a different chip. But even then it still sucks.

The layout looks to me like someone made it who is only just learning to use his/her software, and in a hurry. Even calling this layout half-competent would give it too much credit. There are several phantom holes/traces/parts. See arrows on attached picture.

The bottom line here: stay away from this for now, unless the seller provides evidence that the board he actually sells is done properly and different from the picture posted. There are other offerings which are known to be good, search this forum and you'll find them.

[EBM_dude]

OMG this are myriads of screw-ups! I didn't even think about looking after those things! Thank you very much, you very likely saved my amp project!

[pacificblue]

The photo shows the PCB actually made like this. All unused space is filled with planes, but none of the planes is connected to GND or anything else. Calling for trouble.

That is probably why the vendor writes: "This PCB and kit are only recommended to the experienced tinkerer!"

Astonishing, because that same vendor offers a mono PCB, where everything is connected correctly. Not a well done PCB either, but at least a working one.

[timpert]

I also looked at the other offerings from this vendor. Most of the PCB's look like they actually might work, but none of them look like a good design. "below average" would be a fitting qualification for all these boards, but the TS picked out what would arguably be the worst of them all.

[EBM_dude]

Thanks @all!