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We have a machine which is using a timer and the timer has an LCD, a few of the displays, with no reason all of a sudden displays a black box blinking... If I switch off the machine from power switch and wait for 5-10 seconds, everything goes back to normal, but if I switch off and on very quickly, like in a second, it doesn't go away.

any leads ? ideas, you may give me would be helpful, Thank you

This only happens, maybe 10-20 lcds out of 1000 enter image description here

enter image description here

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closed as off-topic by Ignacio Vazquez-Abrams, Passerby, Andy aka, Chetan Bhargava, Camil Staps Apr 9 '14 at 8:34

This question appears to be off-topic. The users who voted to close gave these specific reasons:

  • "Questions on the repair of consumer electronics, appliances, or other devices must involve specific troubleshooting steps and demonstrate a good understanding of the underlying design of the device being repaired. See also: Is asking on how to fix a faulty circuit on topic?" – Ignacio Vazquez-Abrams, Andy aka, Camil Staps
  • "Questions on the use of electronic devices are off-topic as this site is intended specifically for questions on electronics design." – Passerby, Chetan Bhargava
If this question can be reworded to fit the rules in the help center, please edit the question.

Looks like the microcontroller is not being properly reset along with the display controller, so that the blinking cursor is being randomly displayed. If it does it in normal operation it is probably bad timing design in the firmware also.

enter image description here

Better reset hardware design and better firmware design and coding is probably the solution.

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