Boss Super Overdrive - Parts Question

[vanhansen]

I'm looking at the schematic for the Boss SD-1 (service manual) and am curious as to what D3 an R31 (470 ohm) do.  I was reading about somebody else's mod and they say to remove both of them.  It looks like they do some power filtering or small spike protection.  Is that right?  D1 is the reverse polarity protection diode so they can't be for that, unless Boss is doing double protection for that.

Schematic here: http://www.godiksennet.com/images/sch/SD1PG2.JPG

Thanks in advance.

[MartyMart]

Erik IIRC they are to reduce the voltage from the original ACA 240v adaptors, which gave approx 12v and not 9v.
Removing them from an original early 80's board, makes the use of PSA adapters more suitable.
Those parts are not on newer Taiwan versions.
Marty.

[vanhansen]

Hi Marty.  Thanks.  I totally forgot about that in the old models.  Of course, I had to go and open mine (Taiwan made) to see for myself if they are there or not.  Turns out those two parts are there right in the same spot.  If I don't need them, I may as well remove them, or just lift one leg of each to take them out of circuit.

[MartyMart]

What !!
That's wierd, I assumed that they wouldn't be in series with the PSU connection on the new ones 
That means a small voltage drop, unless I have that wrong .... can't see any other reason for them !
I've removed and jumpered similar components on a few "old" Boss pedals, as they would cause the LED to look
quite "dim" when power engaged and it was recommended for powering with newer PSA adaptors.
I think that it's mentioned on "Stinkfoot's" site .... I'll go have a look see .....

MM.

Here you go :
http://www.stinkfoot.se/andreas/diy/articles/bossadapt.htm

[vanhansen]

Holy crap....LOL.  That's crazy stuff.  I think I may have read that before and just forgot about it.  Mine does say "Use Boss ACA Adaptor Only" and from what I remember, I did get it post '97.  I've used it with a PSA adaptor just fine.  So, I guess it doesn't really matter if I remove those components or not.  Ah well, I lifted one leg on each of them so it's easy enough to reverse back to stock.

Thanks for the help, Marty.