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'62 Guild 98RT: need a little help

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  • '62 Guild 98RT: need a little help

    Picked up an old Guild 98RT for good deal because it needed a tube change and has a non-working trem.

    Opened her up to check if the 3prong grounding was done properly and noticed that someone had done some 'work'
    I need a little help wiring this guy up properly again.
    I uploaded a few pics.

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  • #2
    Here's a better view of the switch/fuse.
    Attached Files

    Comment


    • #3
      Um... You have a whole bunch of pictures of the power switch. Other than making it neater, what exactly do you want to do? Does the amp turn on and operate?

      Details we might quibble:

      No ground wire, so replace existing 2-wire power cord with a 3-wire grounded one. Ground wire to the chassis.

      Hot wire from mains ought to go to fuse first, instead of the switch first, THEN a wire from fuse to switch, and then from switch to power transformer primary. And the neutral wire from the mains goes directly to the other end of the power transformer primary.

      In American power cords, the black wire is hot and the white wire is neutral, so your photo has that backwards.

      That yellow cap from the power switch to the chassis can be removed.
      Education is what you're left with after you have forgotten what you have learned.

      Comment


      • #4
        Originally posted by Jonny toetags View Post
        Here's a better view of the switch/fuse.
        Another minor side note (if you're picky* about date accuracy) is that it's at least a '64 as the pot date code in the pic above indicates =)

        *For no other reason, I'm "picky" about it because I'm acutely on guard to be able to note revision differences.
        Start simple...then go deep!

        "EL84's are the bitches of guitar amp design." Chuck H

        "How could they know back in 1980-whatever that there'd come a time when it was easier to find the wreck of the Titanic than find another SAD1024?" -Mark Hammer

        Comment


        • #5
          Originally posted by Enzo View Post
          Hot wire from mains ought to go to fuse first, instead of the switch first, THEN a wire from fuse to switch, and then from switch to power transformer primary. And the neutral wire from the mains goes directly to the other end of the power transformer primary.

          In American power cords, the black wire is hot and the white wire is neutral, so your photo has that backwards.
          In case it's not obvious from the above, an unused pin on a tube socket should never be used for a tie point of the AC wiring. It appears that is what has been done here.
          Originally posted by Enzo
          I have a sign in my shop that says, "Never think up reasons not to check something."


          Comment


          • #6
            Originally posted by Enzo View Post
            Um... You have a whole bunch of pictures of the power switch. Other than making it neater, what exactly do you want to do? Does the amp turn on and operate?

            Details we might quibble:

            No ground wire, so replace existing 2-wire power cord with a 3-wire grounded one. Ground wire to the chassis.

            Hot wire from mains ought to go to fuse first, instead of the switch first, THEN a wire from fuse to switch, and then from switch to power transformer primary. And the neutral wire from the mains goes directly to the other end of the power transformer primary.

            In American power cords, the black wire is hot and the white wire is neutral, so your photo has that backwards.

            That yellow cap from the power switch to the chassis can be removed.
            The amp works and sound fine (minus the usual pops and cracks I'll fix later)
            The pilot light doesn't light up, but I was associating that with the power wiring (the bulb is tested and fine)
            That cap is between the fuse and switch, not the chassis.

            Comment


            • #7
              If the power wiring were faulty, the amp would not power up. There is no way the primary wiring can selectively kill the pilot light but not all the tube heaters. When I say faulty, I am ignoring the stuff we should correct.

              Your bulb may be fine, but it has to make good electrical contact in the socket.
              Education is what you're left with after you have forgotten what you have learned.

              Comment


              • #8
                Originally posted by g-one View Post
                In case it's not obvious from the above, an unused pin on a tube socket should never be used for a tie point of the AC wiring. It appears that is what has been done here.
                I figured as much. What would be the best way in this situation? I was going to move it to a small terminal strip.

                Comment


                • #9
                  That would be the proper way to do it .
                  Originally posted by Enzo
                  I have a sign in my shop that says, "Never think up reasons not to check something."


                  Comment


                  • #10
                    Does anyone know the proper preamp tubes for this thing?
                    I've found a few schematics and a few sites and they're split: 2x6SL7 and 2x6SN7 or 3x6SL7 and 1x6SN7

                    Comment


                    • #11
                      UPDATE:

                      Grounded the plug, switched the white and black (brought the black to the fuse, then to the switch)
                      The pilot light lights up now, but sort of fluctuates now and then (it dims). Is this normal?
                      Other than that, the amp works fine (other than the trem, which i'll start a new thread about )

                      What is the cap between the switch and fuse for?
                      Last edited by Jonny toetags; 08-12-2014, 12:32 AM.

                      Comment


                      • #12
                        The cap between the fuse and switch should be removed. Hard to tell how it was originally wired. Not sure how it is wired now, can only be one of two ways: a) parallel with wire connecting fuse to switch, in this case remove it as it is doing nothing
                        b) connected one side to hot, one side to ground, in this case, also remove it as it is a safety hazard.
                        Originally posted by Enzo
                        I have a sign in my shop that says, "Never think up reasons not to check something."


                        Comment

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