Help Rehousing a DOD FX56 - American Metal

[hubb]

Hey Folks,

I'm looking for a hand with a project i've got dialed up.  A buddy of mine has an old DOD FX56
that i'm looking to rebox for him with a standard Boss style power outlet and with true bypass.
I've read a few posts regarding DOD rehousing with 2 basic recommendations.

1) one guy said that when power is applied to the circuit it starts up in "on" mode, meaning that using
standard true bypass switching the effect should function properly.  I tried this out with my testing
rig / breadboard and I found that it works properly *most* of the time.

2) another few posts i've read suggests that the ??fet?? switching mechanism can be disabled.  The poster
stated that he was able to successfully do this with a DOD FX96.

* Q3 works as an MUTE for delayed signal in BYPASS mode (by grounding RC pin of U2B) - just remove it, so it' not muted anymore
* Q2 connects P4 to dry signal path in DELAY mode (makes P4 able to alter volume of dry signal going thru) - remove it and bridge PCB pads for it's drain and source pins (2 and 3), so the P4 is permanently connected
* Q4 bypasses STATUS LED in BYPASS mode (LED does not shine, all current goes thru Q4) - remove it and use one switch of your 3PDT to do same the thing (one pole of switch will lead to Q4 collector's PCB pad, second to the Q4 emitor's PCB pad /or to the ground/ - switch must be ON in (TRUE)BYPASS mode, OFF in DELAY mode)
http://www.diystompboxes.com/smfforum/index.php?topic=86845.0;wap2


This way you will have circuit always in DELAY mode and LED ready to indicate state of the 3PDT switch, now you can wire usual true-bypass switching using remaining two switches of 3PDT switch."


I unfortunately can't read schematics (yet) and can't really tell if his recommendations apply for the fx56.

Can anyone who understands schematics give me a hand / point me in the right direction?

Thanks

-Chris

[wgc]

Most pedals are "on" by default when they have power. The switch just takes it in and out of the signal path. A delay pedal and a distortion pedal are very different circuit wise. I think you get this...

Given what you have to work with, I'd leave the on board flip flop switching as is and pursue #1, but with a nicer switch that's soldered.  You may be having mechanical bounce back or bread board issues that are causing the inconsistency. 

Regardless, learning to read a schematic will go a long way and isn't that hard in most pedal circuits.

[hubb]

OK cool.

I'll give option 1 a try. 

Seems like the circuits are simple enough that i'll be able to figure out the schematic at some point.  I try following the traces on the board but it ends up doing some weird many-to-one component connections, so that's where i get lost.

I'll post progress here. . .

[hubb]

Alright.

So after a few tests with my testing rig, it does indeed appear that the effect defaults "on".

Here's the rig and the setup.  Those solder pads are (Left to right) -
Ground - White on my test rig
Power - Red on my test rig
Switch - Not connected on test rig
LED - Not connected on test rig
Output - Black on test rig
Input - Yellow on test rig

I'm going to work up the 3pdt switch wiring with the LED and test the circuit again.  Based upon the enclosure i'm building it in, I'm going to change those noisy POTS too.  They're W100k pots, so i had to order replacements from ebay.. .  still haven't arrived.

Anyhow, I'll post progress as i get the 3pdt figured out and tested.

-Chris

[hubb]

So . . .

The EBAY purchase of POTS was from china, and of-course (my fault) they went to the wrong address.

I wanted to see if there was a POT that I could substitute either from Mammoth or Smallbear (w100k?) that would work for this pedal.

I did my level best to meter the POTS and i've attached the chart.

From what I can tell it is truly a w-taper pot at 100k (81.2k measured)

Here's the question for the group:  It seems to me the best choice as a replacement would be a 100k linear pot.  I'm guessing that the downside to using a linear pot is that from 10:00 to about 2:00 the knob response won't be great . . . in other words, the level from 10:00 to 2:00 won't be as different from say 2:00 - 4:00.  Do I have this right?

Thoughts / suggestions would be greatly appreciated.

[Govmnt_Lacky]

Contact DOD directly....

I had the exact same problem with the exact same pedal a while ago (bad 100KW pot) and they actually sent me a replacement for FREE. W100K long pin right angle PCB mount pot.

I am sure, if they will not just send them out, that they can sell you what you need.

[hubb]

That's awesome.  Thanks for the tip!

[Govmnt_Lacky]

How many do you need? I think I ended up abandoning the project and still have the original PCB and that 100KW pot somewhere.

Let me know and I will see if I can find it all for you 

[hubb]

i only need 1.

Let me know if you can track this POT down.