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How do I identify the amp

denden Posts: 6
in Crown Amplifiers
jBL MPro 418 I think . I got this years ago but haven't had need til recently. I plugged in a/c and protect came on. I brought it to a repair shop with no fix ,so I decided to learn as much as I can and found out I can fix this , but I can not find out what I have . The PWB 127450-6 , 1CT 10838 written by hand with a data 9/2/03 . Also when I did dive in after repair shop the speaker wires came up from speaker into amp and not connected, alone with a couple other wires. This all sounds good in my head ,I hope I've painted a picture for you'll to see to help I need.
I want to thank you for all your time , I greatly appreciate this site , the Generous intelligence of the folks helping folks out.

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Answers

  • denden Posts: 6
    131934-4_A.TIF FOR SCHEMATIC AND BOARD , I found it. MP418sp . Thanks for looking . Now I'll be searching for the schematics
  • scytechscytech Posts: 148

    Are you still looking for the schematic 131934-4?

  • scytechscytech Posts: 148

    How is your repair coming along?

  • denden Posts: 6
    Seems I am testing wrong, or my meter isn't working right. Most likely it's me getting older and thinking I am still all that. I need a little help how to test . Can you help me please.
    And thank you for checking back. Very nice .
  • scytechscytech Posts: 148

    What have been the steps you followed? What are your current issues?
    Has the Protect been disabled and power to the output sections?

    • This JBL418 power module (effectively a Crown CE2000 output module!) are output protected by Triacs, protection devices located across the speaker [output] rails. They act as a 'crowbar protection' circuit in case of an output DC voltage presence, catastrophic failure or speaker network issues. If these devices are currently damaged and shorted, they could cause some type of system protection to be enabled.

    How are your low voltage rails?

  • denden Posts: 6
    I decided to go back over the sodering , although with the meter things checked out, I did find 3 that cleaned and resoldered . Question, separate from the main board coming from the 2 big power caps is a little square connection point, what is that and you wouldn't happen to have a picture of one hooked with the wires on it .
    Other than still double checking soder that's about were I am at. Thank you A for helping me.
  • scytechscytech Posts: 148

    Could it be the main rectifier block? Greyish? This block should have four connections and should be screwed to main chassis. Two connections are for the AC input and two for DC output.

  • denden Posts: 6
    Ok here's is where I'm at, the amp had been repaired by previous owner. After countless hours and by accident I think I found the problem, on the board under a high power lens I found tiny balls of solder , it looks like a splatter like a bad weld . I made a list of each soldered price that tested questionable,the removed those 15 pieces and found the solder had made connection underneath the chip.
    I just couldn't give up. I believe the problem has been corrected.
    Now if I can see a picture of where the wires go , I'm lost as where they go.

    The schematics as far as wire placement are not helping, I need pictures or something like that.

    The rectifier , that's the one by the 2 big power caps ? That one also has been disconnected from wires, I need it's hook up too.

    Thanks for sticking in there with me
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