Troubleshooting Hint - Short

[Dillon Aumiller]

I just wanted to drop a note in case anybody else runs into this problem.

My board wasn't powering up, and upon testing I noticed the supply rails were shorted. After way too much multimeter probing, I found the short at R12's VCC connection.

It looks like the ground plane overran to me (pictures attached). Not sure if it's just my board, or my soldering job, or what; but drilling out that through-hole, and running a jumper to C8 instead, fixed my short.

Now that that's out of the way, super excited to start playing with my Z80!

[Jon Langseth]

That's definitely a manufacturing defect from the board house. And a really bad one at that: that kind of etching error should not pass their QC, and on top of that, a defect at that location is a dead short of VCC and GND.

I am very sorry this board passed through my hands to you with this fault. I try to do a visual QC on the boards I receive, but this inspection tends to be general and quick. I'm going to have a closer look at the boards I currently have in stock.

[Steve Cousins]

Yes, that is a poor production job by the manufacturer.

The boards I get from EasyEDA/JLCPCB claim to be electrically tested. 

Are these boards supposed to have been electrically tested by the manufacturer?

Just curious if electrical testing claims are of any value.

Steve

[Jon Langseth]

The board fab I currently use is organized through Seeed Studio, and they do visual inspection but not electrical testing. They provide a service of full impedance control, for a fee. With the amount of boards I have them make, and the relatively low complexity of the boards, the cost has been too high for the LiNC80/Z50Bus series of products.

So far, I've spotted two boards with defects, and gotten Dillions report here of one that slipped through my fingers, across all PCB's I've had from Seeedstudios. I think I'm getting close to 500 boards from them, across all my projects and products. I am looking at testing other board houses, and at the same time I will gladly speak well of Seeed (as I have on my sporadically updated personal blog, where the "road to the sbc1" is documented, see http://defcon.no/tag/homebrew ).

The board house I currently use work from Gerbers only, unlike EasyEDA/JLCPCB who also have the schematic. Trying to do electrical check based on the Gerber files alone would require significant setup to be able to do an electrical test, and I suppose that's why Seeed charges a significant fee for impedance testing, even after requiring the customer provides the impedance control information. Personally, I would be surprised if JLCPCB actually do any testing at all, considering the amount of setup and labor needed.