Strange Defect

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February 16, 2024 - 3:18am
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facele
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Joined: Apr 14 2023 - 01:50
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Strange Defect
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File VID_20240209_185251.mp43.83 MB

Good morning everyone, I have this issue. When it starts cold, you can see characters flashing (video). If I try to heat up the C15 (7400) or the C13 (74175), it starts working fine: clear screen, reset ok, 480 uS and 3.5 uS perfect. Of course, I've tried replacing them. Grazie

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February 16, 2024 - 11:20am
justinmc
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Joined: Dec 13 2021 - 12:20
Posts: 36
Poor connection or nearby component

It's probably a poor connection in the solder or the sockets for those chips.  Depending on how you're heating them up it could also be a nearby component that you are warming up enough to get it working.

 

Justin.

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February 24, 2024 - 11:49am
facele
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Joined: Apr 14 2023 - 01:50
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74LS02
At the end of the story I had to replace a 7402 (C10) with a 74LS02, to find it I heated the individual ICs of the C13, C15, D15 and finally C10 chain. In fact, at the output of pin 4 there are very small differences between when it is cold and hot.
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