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How to diagnose a problem

Discussion in 'General Electronics Chat' started by Weasel, Dec 26, 2002.

  1. Weasel

    Weasel New Member

    Joined:
    Dec 23, 2002
    Messages:
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    Location:
    Norfolk, UK
    Not to worry problem now sorted, it was the the 20.00 Mhz thingy in a silver can that was next to the PIC, changed it, and it came back on line.

    Thanks anyway

    Hi all,

    I am going absolutely mad trying to fix a chronoscope that was erm... accidently shot by somebody (else) while testing :oops:


    Basically the one on the left works OK the one on the right does not. The LCD took a direct hit and that is the part I replaced. This is the second LCD I've tried, the first one was a different model number and I thought that was the reason for it not working. However fitting one exactly the same did not help.

    I have also tried swapping both the PIC and Eeprom but both from the damaged scope work fine in the undamaged one.

    There is a buzzer built into the circuit that buzzes once to record each shot and runs continually for bad light around the sensors. On the damaged one this runs continually as soon as power is connected since I replaced the LCD.

    On power up the LCD should display a sscolling welcome message before moving to the menu, but this one displays nothing.

    Is there an easy way to at least check that the LCD is Ok ?

    From the voltage checks already carried out,

    I am getting 5V from top left pin on PIC, on both Chrono,s but the bootom left pin is 0V on damaged but 5V on working chrono.

    I might add that I have changed several of these before, all without problem

    I know boxing day is not for this but it is driving me mad not knowing whats gone wrong.

    All help appreciated.

    Regards,

    :?:
     
  2. kinjalgp

    kinjalgp Active Member

    Joined:
    Oct 28, 2002
    Messages:
    1,851
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    Location:
    INDIA/USA
    That 20MHz silver thing is called "CRYSTAL OSCILLATOR".
     

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