Electro Harmonix - Holy Grail Neo switch/traces mess

[friedd]

Hi,
I recently got a butchered Holy Grail Neo reverb.
the pedal have 3 reverb algorithms (Spring/hall/plate) depending on the switch position.

Mine is stuck on one of them because the switch, and the traces around, got messed up.
I tried to simply put the switch in position and repair the dead traces but switching don't change the algo.
So i tried to understand what trace(s) was(were) missing and where, but i can't figure it out by myself, looks like it makes no sense to me ...

I can't find a picture of both sides of a working pcb, only this one side which is in the end not that much of a help.
I've taken some pictures of my broken one, here attached, and humbly ask for your help !
One is a side, the second the other side, and the third a compiled version of the too.
R2 and R30 are 10k missing resistors if that changes anything.

Any help on this ?

Fred

 

[Khron]

That switch is likely hooked up to two digital inputs of the processor, and the missing resistor are likely the pull-ups to the 3.3v(?) supply.

Switch in the middle = both signals logic "high" = one algorithm
Switch to position 1 = one signal logic "high", the other logic "low" (pulled to ground via the switch) = 2nd algorithm
Switch to position 2 = same story as above = 3rd algorithm

The relatively easy part of that is the electronic repair - doable with some thin wire strands, kapton tape (ideally conformal-coating pen), thin-tip tweezers and lots of patience. The mechanical repair though, is much less likely.

You could consider some panel-mount on-off-on switch, that you'd attach with flying wires to the respective points on the board (after recreating the ripped traces, of course).

 

[friedd]

That switch is likely hooked up to two digital inputs of the processor, and the missing resistor are likely the pull-ups to the 3.3v(?) supply.

Switch in the middle = both signals logic "high" = one algorithm
Switch to position 1 = one signal logic "high", the other logic "low" (pulled to ground via the switch) = 2nd algorithm
Switch to position 2 = same story as above = 3rd algorithm

The relatively easy part of that is the electronic repair - doable with some thin wire strands, kapton tape (ideally conformal-coating pen), thin-tip tweezers and lots of patience. The mechanical repair though, is much less likely.

You could consider some panel-mount on-off-on switch, that you'd attach with flying wires to the respective points on the board (after recreating the ripped traces, of course).

Thanks a lot for that precise and fast answer !
so, to you, no trace is missing ? i mean except the obvious 3 ripped ones on the back ?
I already ordered a on/off/on switch that i'm waiting for.

once again thank you.

 

[Khron]

so, to you, no trace is missing ?

Well, the plating inside the holes for the switch pins may well be history as well. That's relatively bad news especially if that happens to be a 4-layer board (which i've only just realized)...

 

[friedd]

Well, the plating inside the holes for the switch pins may well be history as well. That's relatively bad news especially if that happens to be a 4-layer board (which i've only just realized)...

Damn, haven't thought about that ...
I think it is as the left middle hole (right middle hole in the 2nd picture) doesn't look like it's connected to anything but has continuity with ground, so ...

i guess i only have to try a meticulous repair crossing fingers ...
If that doesn't work, i'll be left with a 1/3 working reverb pedal, which is still more than nothing !