dod fx96 mod for more delay time

[O'malley's Alley]

I recently bought the old version of the dod fx96, and the max delay time on it is like 220 ms.  The newer version of the fx96 has an internal trim pot which you can adjust the delay time, however the old version just has a fixed resistor, that I think is about 100k or so?  Well anyways, I hear that you can change this resistor to get more time out of it, but from what I read they said nothing on where this resistor is.  Has anyone done this mod, or know on the PCB which resistor it is?

[O'malley's Alley]

heres a schematic:

http://www.diystompboxes.com/pedals/schemsc/fx96schem.pdf

[george]

If you find the datasheet for the MN3101 which is the clock chip that drives the MN3005 BBD, it will show how the clock speed is set, and point you to where you need to look on this schemo.

There are datasheets on //hammer.ampage.org  for the MN series of BBDs

hth

[ExpAnonColin]

If you look at the clock generator, the MN3101 or 3102 as it may be, there should be a pretty low value capacitor between the 5th pin and the resistor from the 6th pin.  I find the best way to increase delay time is to raise the cap value, because then you don't mess with the pot's range directly.  If you have, say, a 220pf cap (common value for this capacitor) and you put 1000pf in it's place, keep in mind that you're 5-upling the delay time.  I'd personally recommend putting caps in parallel with this cap-IE, try a 100pf in series with it so that you get 320pf.  Experiment and keep it from getting to grainy.  You'll also start having to watch out for apparent clock frequency-a tiny bit of trimpot tweaking could be necessary, and if you're relaly into it you could even change the LPF's cutoff frequency a bit so that you can get even more low.

There's single schematics of all of the chips in there at the EA archives.

Bueña suerte...

-Colin

[Yuan Han]

heyo colin,

I think you mean adding a 100pf capacitor parallel to the already present 200pf capacitor instead of in series right ?

Han

[ExpAnonColin]

heyo colin,

I think you mean adding a 100pf capacitor parallel to the already present 200pf capacitor instead of in series right ?

Han

Right! Parallel!   :oops:

Sorry, it's late and I've been up writing an English term paper for a really long time.

-Colin

[george]

I recently bought the old version of the dod fx96, and the max delay time on it is like 220 ms.  The newer version of the fx96 has an internal trim pot which you can adjust the delay time, however the old version just has a fixed resistor, that I think is about 100k or so?  Well anyways, I hear that you can change this resistor to get more time out of it, but from what I read they said nothing on where this resistor is.  Has anyone done this mod, or know on the PCB which resistor it is?

check out Harmony Central review of this pedal - one of the reviewers tells which resistor to change to get a longer delay time