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  1. #1
    Lead Foot
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    Default BEL 940 Failure Analysis and Repair

    I picked up a 940 cheap via E*** that could not beep or speak. Since I paid a whole $25 for it ($14 of which was non-refundable shipping) I decided to fix it. It took a while to figure out how to crack the case without damage, but it was worthwhile as I found the following:

    (3) SMD resistors were loose: one on one side of the board, two on the other side. Furthermore, one of the resistors was skewed from its pad. All it took was 1 minute and the repair was achieved.

    If I read the ser. no. properly, this unit was built in the first quarter of 2005. The reason I am pointing this out is that BELs pick and place station was fubarred at this time. A $10 Taiwanese sound card shows better registration and soldering of passive components than seen here. The skewed device should have been reason for rejection prior to final assembly.

    OTOH, now I have one that works for $25. Maybe BEL sells kits

    Bill

  2. #2
    Newcomer
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    Default

    Interesting...

    What'd you do to fix the loose resistors?

    How'd you crack the case? I've tried, but gave up because I thought I was going to break it (couldn't get the front loose!)

  3. #3
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    I have an old cobra, no sound but the light work.. if you want it 8)

    must have burned something.. I inverted the power :?

  4. #4
    Good Citizen
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    May 2005
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    Default

    Quote Originally Posted by hankd
    What'd you do to fix the loose resistors?
    Resolder.

  5. #5
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    Default

    There's a needle-nose dual tip "forceps" type soldering tool for this purpose. Otherwise, you use tweezers to hold the component on its pads and at low heat reflow the solder one side at a time. Practice on something you can toss first.

  6. #6
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    Default

    The nosepiece is held on by two tangs that run on both sides the height of the detector. After removing the 2 screws, the case opens as a vee converging at the nosepiece. The top submerges just fore of the buttons. You have to gently twist repeatedly to unseat the tangs.

  7. #7
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    Cool...thanks man!!

  8. #8
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    Default

    Be careful as the display is on a daughterboard that is soldered and epoxied to the mainboard. Overall, it's rather robust on the inside. Also, the light pipe for rear laser detection should be placed beside the horn assembly (there's a port on the side) before you squeeze the case shut.
    Otherwise it will curl up in the case and break, methinks.

  9. #9
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    Default

    If I need to open it again, I will take pictures.

 

 

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