How common are PCB fabrication errors? I've run into my 1st...
Dec 1, 2008 at 11:34 PM Thread Starter Post #1 of 11

cfcubed

1000+ Head-Fier
Joined
May 1, 2007
Posts
1,174
Likes
15
And it cost me about an hour tracking down, pulling comps & replacing them...

Prior to applying power to a JISBOS board I did some sanity checks... And OUTPUT had 0 ohms to GROUND. Looked over everything w/loupe but couldn't see any problems.

Followed OUTPUT traces & they looked fine until I pulled the offset pot off ... Below it was a swirl of ground plane that attached to center lead of pot:

JISBOS_fault.jpg


Was quite tricky to find! Until I pulled the pot I kept saying to myself "This is IMPOSSIBLE!" But hey, I guess that's why its DIY
smily_headphones1.gif
 
Dec 2, 2008 at 12:13 AM Post #3 of 11

Punnisher

Headphoneus Supremus
Joined
Dec 4, 2007
Posts
2,655
Likes
40
They are pretty common. If you don't allow good enough tolerances sometimes things happen.

At work we have had tons go bad. Mostly because of the manufacturer of the boards, but sometimes also by design.
 
Dec 2, 2008 at 12:38 AM Post #4 of 11

MisterX

Headphoneus Supremus
Joined
Dec 30, 2002
Posts
3,880
Likes
23
Electrical testing virtually eliminates these types of errors but it would have nearly doubled the price of the boards.
Is this a group buy board or did it come from somewhere else?
(I visually inspected 85% of the boards I shipped so I have to wonder)
 
Dec 2, 2008 at 12:44 AM Post #5 of 11

cfcubed

1000+ Head-Fier
Joined
May 1, 2007
Posts
1,174
Likes
15
Thanks... I guess I've been lucky till now.

I'd thought it pretty uncommon, at least in DIY though-hole type audio projects... Seems to me our boards aren't asking as much of fabricators as, say motherboards or other mega-pin & mega-trace SMD type designs.

But I've only had about a dozen DIY audio PCBs through my hands, so I guess 1 in 10 or so is not that bad.

And, whenever I start saying "That's @#$*ing impossible!" it never is & I need to walk away for a while
beyersmile.png
 
Dec 2, 2008 at 12:48 AM Post #6 of 11

cfcubed

1000+ Head-Fier
Joined
May 1, 2007
Posts
1,174
Likes
15
Quote:

Originally Posted by MisterX /img/forum/go_quote.gif
Electrical testing virtually eliminates these types of errors but it would have nearly doubled the price of the boards.
Is this a group buy board or did it come from somewhere else?
(I visually inspected 85% of the boards I shipped so I have to wonder)



Got them in JISBOS kit from Jeff @ Glassjaraudio, having bought a few other kits from him have always been a great experience (this is certainly not any fault of his I'd say). And you sure can't complain about his pricing
smily_headphones1.gif
 
Dec 2, 2008 at 1:19 PM Post #8 of 11

deltaydeltax

100+ Head-Fier
Joined
Nov 18, 2008
Posts
312
Likes
10
I've only dealt with one boardhouse who gives 100% yield. They're a little hard to deal with though. If your gerbers have anything at all that looks wrong, the put your boards on hold and won't release until you clear up the issues. They've also called me at 3:00am asking for input on various layers and such.

Boards do have problems frequently. That's why the industry has "electronic re-work specialists".
 
Dec 4, 2008 at 2:41 PM Post #10 of 11

cfcubed

1000+ Head-Fier
Joined
May 1, 2007
Posts
1,174
Likes
15
Quote:

Originally Posted by FallenAngel /img/forum/go_quote.gif
They happen, that's about it
wink.gif

Good thing you found it though, take a razor blade to it and you've got yourself a JISBOS.



Dawned on me I should post some good news.. Same night I found this I X-Acto'd it & had these going in a SOHA derivative (40ma / +/- 12v) and do like the sound. Esp. bring my low-Z cans to life in a way that std SOHA w/opamp OB can't. I should note however that I never had opamp buffers in this particular build & its different enough not to make direct comparisons.

Bottom line is I like 'em & kudos once again to Jeff for service & pricing.. Edit: And of course Steinchen, amb, MisterX & others in it development & offering!
 
Dec 4, 2008 at 3:41 PM Post #11 of 11

linuxworks

Member of the Trade: Sercona Audio
Joined
Oct 10, 2008
Posts
3,456
Likes
63
I've had some traces SO close to each other (that didn't seem like they needed to, either) and when flux was there, there was some connectivity going on. deflux and its gone. or take an xacto and have at it
wink.gif


never saw a burr like that in your photo. that would highly annoy me, too! ;( and if hidden under a component, wow, that's a time killer, isn't it!
 

Users who are viewing this thread

Top