Holy grail reverb mod

[mozz]

I have a EHX holy grail reverb pedal i picked up in trade. It's pretty road worn but works fine. The pedal lets you choose between 3 modes but the chip inside actually has 8 modes. I have wired up 3 toggle switches and can pull each input high or low to get all 8 modes. I want to use a 8 position rotary switch with diodes to get all 8 modes. Best i can figure is 3 or 4 diodes and some jumpers across the switch, any thoughts? Pins are PIO0 PIO1 PIO2, they are normally high.

[Mark Hammer]

Here's how EHX does it on the Holier GRail, which taps a little more from the same Cirrus chip.

[mozz]

Thanks, firmware might be different, going through the truth table to see if that matches what i have written down.

[Daniel Stockwell]

Hey, can you explain, what is the result of this mode?

[mozz]

Instead of the 3 factory choices, you can have 8.

[Daniel Stockwell]

Well, but there is only 3 factory modes. Here is no more mods on chip, as it seems to me. 5 slots are empty, or not? Who tried these mods in real?

[mozz]

Look for pins PIO0 PIO1 PIO2, you put switches so they can be high or low, you get 8 modes, see the holygrailpdf datasheet, i have done it, it works fine.

[Daniel Stockwell]

Have you got some demo of the result? What is the result on sounding?

[Daniel Stockwell]

And what about control knobs foe delay and tremolo?

[komitet]

I am also interested in this mod...can you post a quick how to? I came here because I got a HG nano that had a bad mode switch. I'm trying to find a way to put in a better switch that won't fail again because the one that came original is cheesy. Saw this and thought I could get a better switch and more out of the pedal.

[mozz]

You need the schematic for the nano to see if any mods are possible. There is no quick how to, find what chip they use and find the datasheet for that chip, see what modes are there and how many are implemented.