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T-524 effects loop help request

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  • T-524 effects loop help request

    Hey Everyone
    Hope all is well.

    I tried researching on The Organ Forums and there is a lot of good info on an effects loop insertion into a T-524c Hammond
    Im just confused.

    1.Pin 3 of the recovery amp as an INPUT? ( coming from output of effects chain)
    2.What about An OUTPUT to go to the input of my effects chain?

    Any help much appreciated

  • #2
    Ok, I think I got it. I was not seeing the big picture while examing the Schematic.
    1.Pin 3 of Recovery/Non Vibrato Amp OUTPUT
    2.Pin 8 of Power and Reverb Amp INPUT.
    3. I insert my effects loop somewhere in between.
    Is this right?
    Any suggestion as to where in the circuit to solder in the 2 1/4" Jacks and a switch?

    Click image for larger version  Name:	t500_block_diagram.gif Views:	0 Size:	137.3 KB ID:	656161

    Comment


    • #3
      Yup, either end of those two places. The thing is to remove the connector from the pin, then you have an in/out. You can even put a toggle switch to bypass the loop and allow the signal to carry from connector to pin as normal.
      It's possible a buffer might be needed in there if your pedals etc lose the trebles.
      I vaguely recall having an FX loop but it didn't end up as part of my final thing, mostly cos' the organ's output was too strong for most guitar FX.
      If you're just after overdrive the recovery amp itself makes a nice one: in short, replacing the UM input resistor with a pot, the LM gets attended to on the accomp board, let me know if you want details, otherwise carry on!
      -1958 Hofner 550 archtop guitar -1959 C3 and PR40- -1964 Busillachio Harmonium- -1964 M101-
      -1967ish Leslie 122- -1975 T500 (modded..chopped, and reassembled!)-
      -DIY 760 FrankenLeslie/rat hideout-
      -1980 Electrokey Electric Piano- -Yamaha electric Harmonium (early 80's?)-
      -1990 Jansen GMF150 amp- -1992 Korg 01W/fd- -1992 G&L S-500 geetar.

      Comment


      • #4
        Thanx Brendon for your quick response and confirmation.

        "If you're just after overdrive the recovery amp itself makes a nice one: in short, replacing the UM input resistor with a pot, the LM gets attended to on the accomp board, let me know if you want details"

        I think before I try the effects loop, I want to try out your suggestion of replacing the UM Input resistor with a pot, and attending to the LM on the recovery board.
        Can I please get those details from you when you can.

        (Note: I am waiting for the parts to do Carsten Myer's Modifications skill #2)

        Thanx a million

        Comment


        • #5
          Hi Jimmy!
          My notes aren't complete, but found this:
          In place of R856 of recovery amp I've added the following:
          A 1.2K variable trim in place of R586. In parallel with that is a10K pot and toggle switch. This allows an upper manual volume boost which can also provide a saturated and warm transistor distortion in the recovery amp.

          LM Vol boost for left hand basslines:
          Lower manual volume boost: Remove R853 and put a 500ohm (or 1k) pot in place, adjusting soft volume on accompaniment board trim. If you don't have the accomp board make it the 1K.

          It's not detailed in my notes, but I recall there was another pot at the output of the preamp. This is important because the above mods make it all get louder! When the preamp's really loud it can distort the power amp too, which isn't as nice.
          R870 is the output trim, which has your volume set for your regular clean sound. Run wires from it to a pot of equal or larger size will be better(probably 10K, maybe 100K) to operate as a parallel trim pot you can access while playing. This will reduce resistance on the output from what you've got set on the original trim anywhere down to zero resistance. If the new pot is too small it will make the original volum drop, too large and it might dull the tone of the organ.
          It'll pay to put a toggle switch before the new pot so it can be taken right out of circuit when not needed.

          Does all of that make sense?
          -1958 Hofner 550 archtop guitar -1959 C3 and PR40- -1964 Busillachio Harmonium- -1964 M101-
          -1967ish Leslie 122- -1975 T500 (modded..chopped, and reassembled!)-
          -DIY 760 FrankenLeslie/rat hideout-
          -1980 Electrokey Electric Piano- -Yamaha electric Harmonium (early 80's?)-
          -1990 Jansen GMF150 amp- -1992 Korg 01W/fd- -1992 G&L S-500 geetar.

          Comment

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