Is there an error in the usual Okko Diablo schematic?

[bordonbert]

Haha!  That bit is all my own. I wanted a way to show whether the 18V option (16.5ish on mine) was selected.  At first I considered just putting a LED and current limit resistor across the selected power line and the 9V line.  When the 9V line was selected there would be no voltage across the LED and it stays off, when the 18V line is selected it has 18V at the anode end and 9V at the cathode end and would turn on.  Then I figured that as LEDs draw significant current it might be a bad thing for the state of the MAX1044 generated 18V line which is only for light current use.  So I drew up that circuit.  It takes its power from the 9V line where there is more than enough and it is switched on or off by the selected voltage.

It uses more than it may have needed to achieve that but it is only a couple of general purpose cheapest in your box PNPs and a few resistors.  Unless of course you have to go for the Russian Super High Gain Germanium NOS types sourced from Middle Earth in the time of the Elvish Lords.  That would make it sound much sweeter! 

I have a PCB layout which you are welcome to look at based on fitting in a Hammond 1590BB enclosure.  I have attached a rough print of it.  In reality all of the copper regions which show hollow are filled, it's an eccentricity of the PCB design program I use to display them just hatched in.  It uses PCB mounting 9V power socket, voltage selector switch and jack sockets and it is self supporting in the box via these but the fit in the case therefore has to be via slots for the jacks and switch not just round holes.  It's not as complicated as it sounds.  I'll try to post a couple of pics of the install when I get time.

EDIT:  I attached a better version of the PCB so some of the comments above don't apply.

EDIT EDIT:  I should have pointed out that I used a smd version of the MAX1044.  It's easy with a decent iron and tip.  I would have like to do the whole thing in smd but I only had through hole J201s.  Maybe next time. 

[cooder]

Ah, clever stuff! Thanks for offering the pcb which looks very good.
However I will still go ahead at some point and make my own eagle layout with these changes as I like top mounted jacks and board mounted pots suited to my enclosure spacing.
Thanks again!

[bordonbert]

I'm with you on the board mounted pots.  I can't easily get the vertical with extended legs type here.

My first attempt was with separate pcbs, one for the gain stages and one for the pots along with their surrounding signal processing components.  It carried the 5 controls positioned above the board on stiff 1.5mm copper wires to slot straight into the case.  It fitted a treat and looked great.  The biggest problem was that the gain board had to go right to left and the pot board had to go left to right.

Installation and removal were a gem.  I came up with a system where the board was off centre with respect to the pcb jack sockets which were fitted to just protrude through the case sides. This meant that it could slide into one jack hole far enough to allow the other to slip into place on the opposite side, then it was moved back across and an insulating wedge slid down the side of the board locking it in place.  However the extra inter board wiring was a bit of a nightmare.  Predictably it oscillated!

I could have tried to fix it but I decided to cut my losses and came up with the single PCB you see and loose flying pots.  I think with top mounted jacks you could come up with a better pcb design.  Make sure you let us see it when you get it finished.

[jighead81]

Sorry for the resurrection, but does anyone make a pcb for this? Oshpark? I wanted to try the sabro vero but I think it's from the bad schem too


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[alanp]

This might sound dumb, but for years I've thought Okko was a 60's brand. It sounds like Shin Ei, or one of those quirky Japanese fuzz pedal names. Genuinely surprised that it's a modern German brand.