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Marshall Model 8880/8100 guitar head

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  • Marshall Model 8880/8100 guitar head

    Good evening to all....been awhile since I was here actually.....I have a problem and hoping somebody here might be able to help me out....this unit has two model numbers on it....there is a silk screening on the front that says model 8100....on the rear of the chassis there is a paper sticker that says Model 8080......the issue I have is that I had to take everything out of the chassis including the transformer....now the card for the camera is corrupt and I can't get the pics off it to see where all the wires to the transformer. go......I have the two white wires and the associated black wire hooked up to where they are supposed to go but can't figure what wires go to the other side of the transformer....I guess you could say the secondary side....there are 4 wires, Purple, Yellow, Orange and Red...by any chance does anybody have a pic of where they go?? the schematics that I am finding show an auto-transformer in the unit but I don't see it..I only see the main power transformer which has a winding with three terminals on one side(where the two white wires and the associated black wire goes to) and four terminals on the other side....any help , advice, insults, lol....etc greatly appreciated....

  • #2
    See if the photos in this thread help you

    misterc57

    https://music-electronics-forum.com/...ll-8080-issues

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    • #3
      Originally posted by Delta362 View Post
      See if the photos in this thread help you

      misterc57

      https://music-electronics-forum.com/...ll-8080-issues
      Looks like from the top down...Red, Yellow, orange and Purple..... Thank you....I would like to get my hands on the correct schematic for this.....thank you for the help....

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      • #4
        The difference between 8080 and 8100 is the power transformer.
        If you look on the notes in the power amp schematic (attached) there are some resistor values that should tell you which one you have. (R101,R102,R97,R117)
        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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        • #5
          Originally posted by g1 View Post
          The difference between 8080 and 8100 is the power transformer.
          If you look on the notes in the power amp schematic (attached) there are some resistor values that should tell you which one you have. (R101,R102,R97,R117)
          Ok. I see that....but the power transformer that is in this unit shows a center tapped primary...the schematic does not....the schematic shows two single windings that can be wired for U.S. or British power??? unless I am looking at this wrong....I will have to get my wife to take some pics and post them here....I have everything removed from the chassis as I had to pull the board and couldn't get it out without removing the transformer as well....there was not enough room and no matter what I did I could not remove the board...

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          • #6
            The PT should have 7 wires coming out of it. Do you see the number 784-352 or 785-279 on it?
            Pics will definitely help. I don't recall having to pull a PT to flip the board on these, but it's been awhile.
            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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            • #7
              OK. Finally got back on this site...couldn't access it for quite some time....I do hope everything is ok with the site owner.....I sorted out that Marshall after.....

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              • #8
                Originally posted by bsco View Post

                Ok. I see that....but the power transformer that is in this unit shows a center tapped primary...the schematic does not....the schematic shows two single windings that can be wired for U.S. or British power??? unless I am looking at this wrong...
                SECONDARY is center tapped. Roughly 30 + 30 VAC

                PRIMARY has two 120V windings which can be can be wired in series for 240V or parallel for 120V.

                Triple check that and in any case plug into Mains through a light-bulb limiter.
                Juan Manuel Fahey

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                • #9
                  Originally posted by J M Fahey View Post

                  SECONDARY is center tapped. Roughly 30 + 30 VAC

                  PRIMARY has two 120V windings which can be can be wired in series for 240V or parallel for 120V.

                  Triple check that and in any case plug into Mains through a light-bulb limiter.
                  I got that sorted out after....there was a problem where I couldn't access the site for some reason....it is ok now....so I don't really know what the cause was....
                  thanks for the reply...

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