Holy Fried Grail

[buffalono]

In a dunder head move, I plugged the wrong polarity power supply into my EH Holy Grail. I smelled frying circuits and saw smoke. Is the thing salvagable? Does anyone have a schematic? I hope I just burned out something in the power supply and didn't blow up the main chip. Tried tracing the circuit but figured I would try to find a schematic first since the board is all SMD and you almost need a microscope to trace it, at least I do with my 50 year old eyes.

[oc disorder]

Hi buffalono - course once the holy smoke has escaped...

My limited experience with these points to a rather large smd resistor
(aprox 7mm x 4mm ) "4R7" which is 4.7ohm 1 watt.
This is before the regulator.
There are various revisions of the board I think later ones have a diode as well
so if you can find the resistor..here may be a diode close by.
Got lucky with one and as the dc "feed wire" connects to this first was able to remove it and place an regular resistor in series with the wire and terminate
it where the smd was with a big relative blob !
If you can find an authorised EH repair shop they can get replacement boards with a bit of effort ..think they come via New York but almost the price of the whole pedal ! you better check locally on that.
Just for interest if you can find a copy of the Crystal CS4811 evaluation board
there is a schematic there the EH HG was based on.
Attaching a pdf I still had relating to it.Cirrus Logic make the chip.

Edit: just found a thread
EHX Holy Grail Schematic [Archive] - Harmony Central Musician Community Forums
echodeluxe's photo modified attached.

[buffalono]

Thanks for the helpful info. I think the unit is toast because proper voltage readings are found coming from the voltage regulator and a Zener that I also found that supplies the digital side of the chip. The smoke must have come from the resistor you mentioned, it looks burnt but measures about 4 ohms and passed voltage ok, about 9V. Oh well, guess I learned a lesson...ouch!