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GK 250ML

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  • #1

    GK 250ML

    Been a while since I've been on the forum here. Getting back into some guitar amp repair. I've had this one sitting in the closet for a while. Trying to piece it back into working order. When I bought it there was a slight hum coming thru. Took it to as tech a little over 10 years ago. He was mainly a tube amp tech but decided to give it a try. Unfortunately while he was working on it something happened and now no output. I got it back and stuffed it in the closet. It's time to see if I can get this thing going. A quick question I have as a novice. I normally will power these solid state amps on with no speaker load. Some of the things I have read about this one makes me wonder if it's finicky and has to have a load while powering it up to troubleshoot it. Just wanted to make sure......Thanks!
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  • #2
    I meant to put this in maintenance and troubleshooting. can an admin move it over there?

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    • #3
      No load required for testing the 250ML, and is preferred till all DC conditions are correct.
      Service manual attached.
      Attached Files
      Originally posted by Enzo
      I have a sign in my shop that says, "Never think up reasons not to check something."


      ​

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      • #4
        Originally posted by g1 View Post
        No load required for testing the 250ML, and is preferred till all DC conditions are correct.
        Service manual attached.
        Thanks! ...from what I can tell this amp was specifically designed for a 16 ohm load. I have read both sides saying it will take an 8 ohm load with no problem and I've read someone claiming that if it's not 16 ohms it could damage the amplifier. Conflicting points of view. Asking you guys for the real scoop. For now there is no load while I work on the power section to get it functioning properly. So far I found a 10 ohm resistor (R163A) slightly burnt reading 11K. I have replaced it and in the process of checking components upstream and down stream of it before I power it up again.

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        • #5
          The amp is designed for 8 ohms per side minimum. The internal speakers are 16 ohms so any speakers you plug into the ext. spkr. jacks can not be less than 16 ohms.
          That is where the confusion comes from. 16ohm minimum ext. speakers, 8 ohm minimum total load.
          Originally posted by Enzo
          I have a sign in my shop that says, "Never think up reasons not to check something."


          ​
          • Likes 1

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          • #6
            The other source of confusion is people not understanding that this is s stereo power amp.
            "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

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            • #7
              Originally posted by The Dude View Post
              The other source of confusion is people not understanding that this is s stereo power amp.
              Yeah it took me a few to grasp that.

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