Mod: Increase delay time on older model FX96
Posted: Thu Feb 02, 2012 11:26 pm
I picked one of these up relatively cheap from ILFer Demon666. It arrived today. I knew that the version I bought had only 220ms of delay time, and that's just pathetic! 
So I googled for the schematic and found it hosted at the DIYstomp site:
http://www.diystompboxes.com/pedals/sch ... 6schem.pdf
And there was also a thread there about increasing delay time:
http://www.diystompboxes.com/smfforum/i ... ic=22010.0
I tried the suggestion from ExpAnonColin, which was to increase the value of C19. Most of the components are SMD, but luckily C19 is a plain-jane ceramic cap. It is stock at 25pf. I raised it to 220pf, and now the max delay time is about 1000ms. Of course, at the longest settings, you get some "Dalecks" type sounds in the repeats, but it actually sounds cool. Great for ambient, noise-rock stuff that you guys are all into.
There are two version of the FX96. The later one has an internal trimmer to adjust delay time. The early one (pictured below) does not, and that's why I swapped the cap. I've shown which cap with an arrow, and also you can read the silkscreen easily (C19).
You can either remove C19 and replace it (the better way), or you can add a cap in parallel to increase the value. It's at 25pf stock, so I'd suggest 100pf, 150pf, or 200pf to add in parallel. The more capacitance, the more delay time...but also the more noise you get at the longer settings. And there is a something of an upward limit no matter how much capacitance there is (probably about 1200ms).
EDIT: I have not tested this, but I'm 99% sure this same mod will also work on the FX-90. The clock IC is set up identical to the 96.
Guts overview:
Guts detail (C19):
Old version looks like this:
So I googled for the schematic and found it hosted at the DIYstomp site:
http://www.diystompboxes.com/pedals/sch ... 6schem.pdf
And there was also a thread there about increasing delay time:
http://www.diystompboxes.com/smfforum/i ... ic=22010.0
I tried the suggestion from ExpAnonColin, which was to increase the value of C19. Most of the components are SMD, but luckily C19 is a plain-jane ceramic cap. It is stock at 25pf. I raised it to 220pf, and now the max delay time is about 1000ms. Of course, at the longest settings, you get some "Dalecks" type sounds in the repeats, but it actually sounds cool. Great for ambient, noise-rock stuff that you guys are all into.
There are two version of the FX96. The later one has an internal trimmer to adjust delay time. The early one (pictured below) does not, and that's why I swapped the cap. I've shown which cap with an arrow, and also you can read the silkscreen easily (C19).
You can either remove C19 and replace it (the better way), or you can add a cap in parallel to increase the value. It's at 25pf stock, so I'd suggest 100pf, 150pf, or 200pf to add in parallel. The more capacitance, the more delay time...but also the more noise you get at the longer settings. And there is a something of an upward limit no matter how much capacitance there is (probably about 1200ms).
EDIT: I have not tested this, but I'm 99% sure this same mod will also work on the FX-90. The clock IC is set up identical to the 96.
Guts overview:
Guts detail (C19):
- DODFX96_timemod_02.jpg (80.64 KiB) Viewed 983 times
Old version looks like this: