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        Contest Spot the defect(s)

#1 PLD May 29, 2009 08:50 AM

Spot the defect(s)
3 Attachment(s)
As a manufacturing business, there's never a shortage of first-pass failures coming off the assembly line, these failures can be anything from a part in the wrong place, orientated wrong, bad luck with the soldering or even literal bugs on getting into the wrong place at the wrong time.

So, since this is something that's invariably unique and certainly not predictable I thought it'd make for a good routine competition.

The way the process will go is this;

1) I will post up a photo which will illustrate a defect, it might be obvious, it might be more subtle, in fact at times there could be multiple defects however I'll try to provide a selective indicator as to which one I'm seeking.

2) I'll state what the prize(s) will be and how many are available. The prizes won't be hugely expensive/valued but they will be something that is manufactured here at NQRC.

3) Send your guess/answer to me in PM (I'll reiterate this each time) and I'll grant the prize to the first correct answer(s) based on the timestamp of the PM. I'll inform you if you are correct and if you have been quick enough before the prizes are all gone.

4) After 72 hours, I'll close the competition and describe the fault.

* You can choose to either claim the price (if you have not won in the previous two events), or you can choose to have your correct-answer attributed to your Glory points.

* After 3 months, the person with the highest number of glory points will win a larger price :)

Remember too - this is meant to be fun and informative, so don't get too upset if you miss out the first couple of times, there'll always be more.


Table of Glory
DonQ: 5
Dusk: 3
mudman1959: 3
Glydr: 2
Neilmy: 2 +3
Gussy: 2
kentucky: +2
gman326: 1 +1
HawkerTyphoon: 1
Sparkysko: 1
Charles Beener: 1
littlewing78: 1
rchmc: +1

#2 PLD May 29, 2009 09:14 AM

CLOSED: Competition #1, starting May 30, 2009
2 Attachment(s)
Two fastest answers came from Dusk and Tiggrrr.

Starting out moderately 'easy' this time around.

Here's a pair of "identical" boards that have come out of the reflow process, however there's a small problem with one of the boards that caused it not to be able to be programmed.

First two (2) correct answers to different people will be awarded with a brand new PLD-BAC-MINI shipped via post. The PLD-BAC-MINI is a great little 5V regulator for small gliders such as HLG/DLG or seaside slopers such as the Alula with 2 servos. For more information, see http://nqrc.com/?vp=PLD-BAC-MINI

HINT #1: It's nothing to do with the type or value of the parts on the board, they are all in the right place (even if some are a tad skew).

#3 GotrekGurnisson May 29, 2009 09:42 AM

I can see two potential issues, but your pic is a bit low res to be certain if either is actually a problem. I take it answers need to be PM'd?

Edit: Ah yes, I should actually read the first post....

#4 PLD May 29, 2009 09:48 AM


Well, in this case the difference is substantial enough to not be at the limits of the resolution (okay, it's moderately close ;) ). Send to PM and we'll see :)

#5 PLD May 29, 2009 10:55 AM

HINT #1: It's nothing to do with the type or value of the parts on the board, they are all in the right place (even if some are a tad skew).

#6 PLD May 29, 2009 11:08 AM

Okay, we have our first winner - congratulations Dusk from Canberra AU... obviously working hard into the evening.

One more BAC-MINI left... now panic mode sets in ;)


#7 jimbyjoe May 29, 2009 05:00 PM

good idea Paul!

#8 PLD May 29, 2009 06:02 PM

Good morning all,

Well, didn't I just wake up to a barrage of emails this morning - that'll teach me for going to sleep leaving a competition running :eek:

We do have our second winner, Taggrrr of Hawaii slipped in a couple of minutes earlier than the next correct guesser(s).

The fault is that on the right hand chip, the bottom right corner, there are two pins that are bridged together from solder, this is shorting out two of the programming pins. The spacing between the pins is less than half a millimeter ( roughly 0.010" ) so spotting such things can be a real task. However a good light and a large low maxnification lens can help a lot.

In this case, the bridge was removed just by touching the soldering iron to the pair of legs after putting on a drop of flux, this causes the solder to reflow with some of it going to the soldering iron and the rest dividing between the two pins.



#9 PLD May 29, 2009 06:21 PM

Okay, a summary...
1 Attachment(s)
Learned something already on this quick little competition, namely that there's quite a few people who like the challenge of the comp but are happy to abstain from the prize claim. With this in mind, I think in future I'll make it that when people submit their answers they can let me know if they're just in it for the fun or are also seeking to win the prize.

Attached is a modified picture of the board, showing the fault with a red-overlay on it.

#10 PLD May 29, 2009 06:32 PM

I just realised something, I could use you all as cheap labour, if I've got a real problem that I can't solve, I'll post it up here as a "competition" pretending I know the answer and just let everyone take their best shots at it....mmmm... cheap labour :D ;)

Now, time for some coffee.

Feel free to discuss or generally chatter about the comp/stuff in here, there's also the general discussion thread as well.

Once again, great to have had you all paying attention, was fun for me too. Only thing now is that I have to try and come up with another defect soon :)


#11 dusk May 29, 2009 06:57 PM


Originally Posted by pldaniels
Obviously working hard into the evening.

Couldn't resist the lure of a challenge :D

This morning, when my wife asked why I didn't get to bed before 2am in the morning, I could reply "But I was saving us money, honey." ;)

But now I have to come up with the goods to make my story believable, so, Paul, I'll take you up on that prize.
The BAC-MINI looks like a great piece of engineering. Perfect for that Alula clone I have waiting to be built.

That was a fun challenge. Keep'em coming!

#12 PLD May 29, 2009 07:37 PM

I should start another thread but for software ;) Just kidding, no one would ever win prizes in the software version because there's always more bugs to grind out.

I've got some ideas already for the next comp but I need to wait a a week or so before running the next one, if I run them too soon I'll run myself out of stock :p


#13 GotrekGurnisson May 30, 2009 08:28 AM

Bigger pics damn you! I couldn't decide if they were bridged pins, pxellation, or just dodgy eyesight. :(

#14 PLD May 30, 2009 04:41 PM


Yes well, I think the same thing when I'm trying to debug the boards, even with a reasonable dioptre lens and halogen lights :) Actually, the photo presented is about the 'same' as what I get to see (under the lens).

The ones that are -really- annoying are the bridges that can/do occur underneath the body of the chip itself. What happens is that sometimes you get a smearing of paste getting onto the black epoxy body and when the reflow occurs if forms a very fine conductive trace perpendicular back from the leg, under the body and then over to another leg or a via. You can't see it, you can't fix it (directly), instead you just have to lift the whole package off and resolder it again :(


#15 PLD Jun 04, 2009 05:49 AM

CLOSED: Competition #2, Starting June 04, 2009
2 Attachment(s)

Yep, I did it again, had another defect :D


* PM me the answer
* Tell me if you're in it for the prize or for fun. Being in it for fun means that you get some glory but you let the comp run a bit longer and some other needy person can claim the prize ;)
* If you won a prize in either of the last two events then you're only to enter for the fun (but on the next event you get to be in it for the prize again). - This is mostly so that we don't get any braniacs hogging all the stuff ;) :p

Today there's two lost-model-alarms to be won. Very handy little fellows, especially when you can't find your beloved in the grass, also useful when you've lost your plane too! :eek:

The board can be flashed fine, the input power and output power is fine but there's missing activity :(

The fault is that there's no solder on the right hand pad of the LED at the front of the unit. If you look at the pad and around it, you'll see there's no discolouration or matte effects.

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