DOD 280 PCB and schem don´t match ?

[Samy]

I need a little tip on this problem !
DOD280 Tonepad Rev4 Schem and PCB they don´t match or i´m reading that wrong !
There is a 22k resistor on the layout connected to gnd, to led and 4,7k resistor, the schem is different ! In the schem there is a 2,2k resistor connected to a 4,7k res., led and Fet ...
I found an old post that the 2,2k resistor wasn´t there, it was a different version...
Thanks .

[Samy]

Anyone ? 

[phaeton]

Since one is called a "Rev4", you might be looking at two different versions of the same pedal, which is pretty common.

Also, since the schematic is from Tonepad and not DOD, there is always the chance of:

1) Artistic Licensing:  Perhaps the author of the schematic you're looking at preferred their way to accomplish that task.

2) Modification: Similar to above, but there are a lot of older pedals that have been improved upon (or at least changed up) over the years by the DIY community.  Common modifications include true bypass switching or buffered switching, substituting parts or assemblies that were prone to breaking (FET switches come to mind), more gain, better tone controls, less noise, PNP to NPN conversion, etc.  Contrary to popular belief, electronics parts manufacturing has  gotten better in the last 30 years.  Some of those changes might also be related to:

3) Parts substitution.  The older the pedal is, the higher the chance that there are specific semiconductors that are not available, or passive parts values that are hard to find.  This is probably not the case in your schematic, but it does happen fairly frequently.

My verdict:
The design on the PCB obviously works.  I'd be willing to bet that the schematic from Tonepad works too.  They may both sound and act identical, or the Tonepad schematic might work even better.

However, I'm just a n00b, so let the other guys chime in too

[Samy]

Thanks phaeton  but i´m very well informed about that !

My question is simple, in the tonepad_dod280comp.pdf file, the "Dos Ochenta, Rev.4.Jan.17.2005" project, there is something that i believe that doesn´t match !
I might build only by looking at the layout and probably will work, but the schem and the components list don´t match . I just want a tip on this .

[slacker]

I've just had a look at the pdf and yes you're right the layout doesn't match the schematic. I think the schematic is correct, those components form the millenium bypass and they look right. To make the board match the schematic the 4k7 resistor needs to go where the 22k one is, in parallel with the LED and the 2k2 resistor goes where the 4k7 one is on the board. Or if you're using a 3PDT switch you can leave that whole section out.