Home › Forums › Help/Technical Questions › Holy Grail Nano toggle switch wiring?

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  • March 27, 2020 at 6:38 pm #86192
    Suproman58
    Participant

    I’ve modded a couple of my pedals with some very pleasing results, though I still have much to learn about electronics. In a moment of ambition and enthusiasm, I decided to open up my Holy Grail Nano to see what I could see, and of course I busted the toggle switch.

    I managed to get the switch off the board (which is an ON-ON-ON type), and it still functions in Spring mode. I have an ON-OFF-ON switch that I can retrofit (maybe), and I think I can get it to work, but want to be sure everything gets connected as it’s meant to. Right now, with no switch on the board, it seems to be stuck in Spring mode (which isn’t what I expected). Regarding the pins on the toggle switch, touching the center pin on the side of the switch closest to the pot to the pin closest to the power jack gives Flerb, and it seems that the same pin touched to the pin next to the Flerb pin gives Hall.

    What I want to know is: is anything else going on here? Does anything else need to be connected for the pedal to function as it’s designed to? I feel like I’m missing something, because if that’s all there is, they could have done the same thing with an ON-OFF-ON single pole switch.

    Help???

    March 28, 2020 at 11:49 am #125961
    j_flanders
    Participant

    I have both the nano and the old sheet metal box version but I have only modded the old big box version.
    So, the info below applies to the old circuit, but the newer nano version might be very similar in operation (even though it uses a different chip)

    The info below explains how the switch works:

    * fsb forum post explaining how the switch changes the reverb mode electronically: https://www.freestompboxes.org/viewtopic.php?f=11&t=1138#p194980

    * block diagram: reverb mode/preset switch: https://i.postimg.cc/xCDCVV2P/Screen-Shot004.jpg

    * holy grail big box schematic: reverb mode/preset switch: https://i.postimg.cc/s2ZXLDtX/Screen-Shot003.jpg

    As I never use the flerb setting, I changed that setting to something that seems to be large room or different type of hall reverb.
    With 3 binary options there are 8 different reverb modes.
    The 3 way switch gives you 3 of them
    You could use dipswitches to have access to all 8.
    On my big box I only found 4 of them worthwhile.

    The factory demonstration board for the chip that was used in the big box had these 8 effects, but in the Holy grail pedals those are not the ones you’ll find when ‘unlocking’ the remaining 5 modes, as EHX implemented them differently. That spring reverb+tremolo mode would have been great though.
    https://i.postimg.cc/q7Q5dCgL/Screen-Shot005.jpg

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