Hawkeye

LoopA V2 Introduction, Features & Support Thread

137 posts in this topic

Here is the "minimum system" with +5V in red, 0V in blue. Also PA11/PA12 as before. Try pulling off the diode too!

 

5ef7acbbc0f09_LoopA_USB_5V-0V.PNG.8e96f9

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Posted (edited)

Maybe stupid but... A faulty usb cable? The one you use with LoopA is necessarily different from the one you use directly with the waveshare, so...
On sait jamais ;)

Edited by Antichambre

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Just now, Antichambre said:

Maybe stupid but... A faulty usb cable? The one you use with LoopA is necessarily different from the one you use directly with the waveshare, so...
On sait jamais ;)

tried 3 different ones

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Posted (edited)

Just now, Altitude said:

tried 3 different ones

Obviously ;)

Anyway, this problem is fascinating to follow, what a suspense, we can not wait to discover the outcome ;)
I hope it's not too much frustrating for you!

Edited by Antichambre

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Posted (edited)

Solved!

And this is some crazy ass shit too: I was friction fitting the core with the mainboard to see if removing the TVS fixed it (it didnt) so the plan was to try the temporary headers like andy suggested with the minimal setup but my trimmed down, solder coated ones were not fitting the sockets i had so I decided just to put new headers on the core, not a big deal, suck out the solder and pull the pins out one at a time.  When I did the first row and pulled off the plastic header there was a fair amount of solder where the plastic was (like it puddled there).  I just ignored it thinking it was from the desolder gun and cleaned it all up but after the clean up, and new headers, it fired right up.  In hindsight, there was way more solder there than should have been, I was sucking out solder through one end and pulling the pin out through the other, what was left there after I removed the plastic was in the shape of the plastic header like a mold, there is no way that came from the desolder gun especially since it sucks solder out or from any other soldering I did since those were on the other side of the header.  I checked all the IO pins for shorts to ground and +5 but NOT to each other which seems to be what was happening here, must have happened in the wave machine when those headers were soldered on at the factory. Just dumb luck i decided to replace those, I would have never found it otherwise, should have taken a picture

 

Edited by Altitude
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This has to be reported to the Waveshare team for their QC.

IMG_1929.JPG?raw=1

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7 hours ago, Altitude said:

Solved!

And this is some crazy ass shit too: I was friction fitting the core with the mainboard to see if removing the TVS fixed it (it didnt) so the plan was to try the temporary headers like andy suggested with the minimal setup but my trimmed down, solder coated ones were not fitting the sockets i had so I decided just to put new headers on the core, not a big deal, suck out the solder and pull the pins out one at a time.  When I did the first row and pulled off the plastic header there was a fair amount of solder where the plastic was (like it puddled there).  I just ignored it thinking it was from the desolder gun and cleaned it all up but after the clean up, and new headers, it fired right up.  In hindsight, there was way more solder there than should have been, I was sucking out solder through one end and pulling the pin out through the other, what was left there after I removed the plastic was in the shape of the plastic header like a mold, there is no way that came from the desolder gun especially since it sucks solder out or from any other soldering I did since those were on the other side of the header.  I checked all the IO pins for shorts to ground and +5 but NOT to each other which seems to be what was happening here, must have happened in the wave machine when those headers were soldered on at the factory. Just dumb luck i decided to replace those, I would have never found it otherwise, should have taken a picture

 

 

Wow, what a saga! I'm really sorry that you had to go through all of that. I'll discuss with Peter as to how we can compensate you for the trouble. It's the first time we've seen something like this and of course it will be reported to the manufacturer. Seems like fab errors crop up from time to time but it always sucks to get stumped by them.

Well done again for sleuthing it out. Hope the rest of the build goes better.

Best,
Andy

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Posted (edited)

no compensation needed. I know how these things go.

I wish I could have found the actual spot where it was shorting, it definitely wasn't a board problem since I did inspect the underside pins after I cleaned it off  and it worked with the new header so that only leaves the solder bridge and that fits the symptoms.   Checking for shorts to adjacent I/O pins would have identified the issue, might be worthwhile to spot check a couple in inventory to make sure it was just a fluke and not a batch thing.

anyway, that's that.  

IMG_20200629_084743a.jpg

Edited by Altitude

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any 10 pin female header that style will work, the height on that one wont matter

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ok when height dont matter than this is the only replacement at the moment: (2,54mm, 2Row, 10 Pins, Female, Thruhole, without cutting a more pinned header...)

https://www.mouser.at/ProductDetail/3M-Electronic-Solutions-Division/929975-01-05?qs=bX1%252BNvsK%2FBrGbqaIqQvrfA%3D%3D

i phone mouser now.... to change my order... want to start solder ;) not to wait.

EDIT: mouser munich - nice - ok will get it soon ;)

thx

Edited by Phatline

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Your proposed part substitution should work.

Check the interboard spacing:
16mm M2 spacer
3M FF header socket 8.26mm
TE thru-board header 6.5mm
14.76mm, you have >1mm to spare.

FWIW I've used large strips of FF sockets for years, just cut down with a dremel-like tool and you lose that position as the tool "melts through". But it works fine and is cheaper than individual sockets of the right size.

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