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Forum Index : Microcontroller and PC projects : Maximite power-up fault - Resolution

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Ben Baker
Newbie

Joined: 19/11/2011
Location: Australia
Posts: 4

Posted: 10:09pm 20 Nov 2011

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Hi fellers. First, thanks to those who responded to my plea for help. I removed sw2and tested it - no problem with it, but the fault persisted. Whilst I stated that voltages were as expected with a digital meter, when re-tested more critically with an analogue meter,I noticed that the needle fluctuated a little. I thought that that may be related to the current draw as the LED flashed, so I tried a bench power supply in lieu of the plug pack. To my 'delight',the LED displayed a solid glow, and the LCD came to life as it was supposed to. I then checked the plug pack more critically and found some oxidisation around the centre of the plug, which was little sloppy in the power jack anyway. I cleaned this up and re-applied power to the MM with it -AOK. I can only think that the oxidisation combined with the sloppiness produced some sort of a high frequency intermittent power application which the PIC didn't like, and responded by trying to continually reset itself, accounting for the intermittent flashing of the LED. Putting sw2 back in circuit produced the correct response. Funny how your mind blames the designer, kit provider, or component manufacturer for one's own 'carelessness' or ineptitude, particularly as I was also concerned that I had destroyed the chip through static discharge. The simplest of faults ... So thanks again for those who tried to help. Ben Baker.

aargee
Senior Member