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Gps clock woes
Mr_Ploppy Posted: 3 Jan 2022, 11:01 AM
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Joined: 3-January 22
Managed to build unit for Christmas.

1st Issue. All the numbers on the right are missing the top segment.
Lead to 2nd issue, trying to see if loose connection lead to all numbers now show 88888888
Which lead to 3rd issue, now I have no lights, bar the gps unit which lights up

How dead is it?

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mit Posted: 3 Jan 2022, 06:01 PM
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yeah whatever

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It's most likely recoverable, but it depends what was done between the issues.

1st issue, this would be caused by a soldering mistake on the display driver chip for the right half of the clock. The top segment is segment A, connected to pin 14 of the max7219 chip.

(User posted image)


The second and third issues suggest a problem with the data signal between the ATtiny chip and the max7219. If the data is corrupted the display chip will either show nothing, or light up every segment (888888). The problem is just as likely to be at the ATtiny as at the legs of the max7219 - in fact, if both halves of the clock are not lighting up, it's almost certainly the ATtiny.

If you can describe what you did to try and fix the issues, I might be able to suggest something further.

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Mr_Ploppy Posted: 4 Jan 2022, 07:01 PM
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Joined: 3-January 22
Like a phoenix rising from the flames we're reborn.

So indeed dry joint on pin 14.

Removed ATtiny chip and found one pin bent at 90o so not sure how it ever worked. Straightened pin and reseated.

All up and running

Thanks for your assistance MIT.


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