gscartsw LPF Toggle Switch
This page shows you how to add a switch to toggle the low-pass filter on a gscartsw, using the THS7374.
This is for the gscartsw only, not the 'lite', as the lite doesn't use a chip with a filter.
This mod toggles the low-pass filter on the THS7374 amp that's inside the gscartsw. When going from
analog to digital, you'll always want one LPF in your chain, or you can get interference on the
screen. The only "problem" with LPF's is when more then one are in the same chain; The end
effect results in a slightly blurred image. As a result, I find the LPF in the gscart extremely
handy, but like the option to turn it off.
Quick reference chart:
Direct into a flat-screen
Direct into a capture card
OSSC (use it's LPF instead)
Any time another device already has one built in (including in the above scenarios), such as a console with
a THS7314 mod.
Start by unscrewing everything, but make sure to save every single spacer and
screw!!!!! Then flip it over and look for this spot (notice the VGA port on the top for
Next, carefully desolder and move the "R39" resistor over, as this is the spot on the board that
goes directly to the LPF toggle pin. You'll want to move it over, so it's covering the "R39" lettering
and make sure the pads aren't connected at all. Then solder a wire to the other side of the
resistor. I like to tack the wire down with a tiny bit of glue (seriously, those are SMALL
dabs....remember this is a close-up!), so that the wire isn't flopping around. I then run it through
the unused pin 3 of the EXT port out to the top. DO NOT SOLDER THE WIRE TO PIN 3, just use it as a way
to route the wire through to the top of the board. Click for full-sized:
Next solder wires to pin 1 (ground) and pin 4 (5v) on the Ext port:
Then solder the three wires to a 2-position, 3-pole switch. Make sure that the wire
coming from the pad & resistor is in the middle position. The orientation of the other two
don't matter, but note that Ground = LPF On and 5v = LPF Off.
Switch mounting and reassembly
Fair warning: Drilling through thick acrylic is a pain! If I didn't have
someone helping me, I'd just have epoxy'd it underneath the top portion of the switch and not even attempted
to drill. Also, there are so many screws and washers holding this together, so be careful not
to lose any!
I actually found that there's still some kind of filtering happening in the gscartsw,
even with the LPF turned off! It's really only noticeable when you zoom in, but it's definitely a
In comparison, here's the gscartsw_lite:
If you want more control over the filtering in your SCART chain, then I highly recommend this
mod. If not, the switch is totally fine, just the way it is!
If you came here while reading
the RGB Guide, please move on to the section that shows how to
get RGB from each game system! That section also has info on audio enhancements, which versions of each system
output the best quality, plus some other helpful info! Alternatively, head back to the main
page to see what other retro-awesomeness is available on this