Crown CE1000

Discussion in 'General Electronics Chat' started by ScaleCraft, May 21, 2014.

  1. ScaleCraft

    Thread Starter New Member

    May 21, 2014
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    I read the OLD six-page thread on these. We had a failure three days ago...blinking "fault" lamp. About 4 hours after a heavy set, lots of volume, swinging light fixtures, full drum kit with 8 mics, bass, and acoustic with one vocal.
    The failed amp was only for our big sub-woofers, left and right.
    We did the normal stuff...unplugged inputs and outputs, let it sit for 2 full days....still a blinking fault lamp.
    I went through the troubleshooting comments. Reset button did no good.
    The local shop said these were a bear to get apart, wanted three hundred bucks to diagnose it.
    Bought a new Crown, brought this into my shop...10 minutes and the top was off, and main board out.
    And that was stopping to re-light the stogie.
    I cold ohmed all the power transistors, the heat sensors, all the bits....all matched resistance readings, good channel to bad channel.
    Scratched head.
    Put the main board back in, left the input stage plate off.
    Powered it up. Two clicks, no blink.
    Okay, shut down, put the input plate in, powered up, two clicks, no blink.
    Let it burn in for an hour....no blink.
    I'm about ready to tag it, place it back in service and see if it fails.

    My guess is, undo all the plugs, plugged them back in, and any issues were in a poor plug connection?

    CE1000's went into service with the new overhead array 9-10 years ago.

    Anybody run into this before?

    Dave
     
  2. #12

    Expert

    Nov 30, 2010
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  3. ScaleCraft

    Thread Starter New Member

    May 21, 2014
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    I'd gone through the manual....found, what, five causes of the "fault" lamp to light....hence the removal of inputs and outputs, reset button, cooldown.
    I really, really hate intermittents.
    If I had my way with this system, it would be vacuum tubes.
    Dave
     
  4. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Do you have a PCB microscope? You should check all the power components and anything that looks like it gets hot, for circle fractures on the solder joints.

    I use a little RadioShack 30x handheld PCB microscope.

    Like this;

    [​IMG]

    Plenty of them cheap on ebay and amazon. :)
     
  5. #12

    Expert

    Nov 30, 2010
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    I've been fooled by bad solder joints so many times that I shotgun the board with my soldering iron...then inspect it some more!
     
  6. alfacliff

    Well-Known Member

    Dec 13, 2013
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    also, are the connectors in side the tinned molex type? after a while, they corode, and tin oxide is non conductive and invisible. sometimes just unplugging and plugging the connectors does the trick. if so, get some light silicone grease, clean the connectors and put a light coating on them, keeps the air off the contacts to prevent corosion.
     
    #12 likes this.
  7. ScaleCraft

    Thread Starter New Member

    May 21, 2014
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    Been at 'trons for many decades. Officially 1965, but I quit counting!
    Primary business for.....past 20+ years was strictly electronics.

    I went over the solder joints with a magnifying hood and light.
    Usually, I can spot issues, but not always, I know.

    The spade slip connectors.....not necessarily the multi-pin (not sure they are Molex.....something slightly different than the Molex we used to use) but the single pin spades.
    Can't see corrosion, but the fact I could unplug the main board, remove for inspection and test, and when re-installed the problem was gone, makes me think strongly of connectors.
     
  8. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    But there's the satisfaction of actually SEEING the fracture in the solder!

    Sometimes the solder looks perfect to the eye, but under 30x magnification you can see a perfect 360 degree circle fracture, complete with some burnt looking evidence deep within the fracture (showing it has been intermittant for some time).

    Fiddling with connectors might be a fix, OR it might have just wiggled the real fault and got it going for a short time. The microscope is well worth it. :)
     
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