The $20 delay (Fab Echo mods photoessay) 56K warning!

[elmo7sharp9]

Saw one of these for 10GBP,
rushed home to check if it was moddable,
found this thread, bought the delay and did the 3 mods.

I used a 100k log pot for the delay time, with a 1/4" socket in parallel, for a 100k expression pedal.

On shorter delay times, the expression pedal gives me manual flanging.

Wet-only use with the expression pedal is hilarious .

Thanks for the photoessay!

The only unanswered question is...
why did they market a pedal with such a vital parameter missing

[Jdansti]

Thanks for all of the great information on this mod. I've had my echo for a while and wasn't too impressed with it.  It's a lot more functional now. I did the three mods. I took some photos since I am installing switches for the infinite repeat and wet mod:

I decided to try this ribbon cable I got very cheap at Fry's. It's 28AWG and works really well for SMD work. Most if us have a few of these from old computers. You can make your own 2,3,n pair leads:



Here are the two wires for the infinite repeat switch.  I used hot glue for strain relief:



Here are the two wires for the wet switch mod:



Here's where I removed the resistor for the delay mod:



My first attempt to solder the pot lead to pin 6 for the delay mod. Got a nice bridge between pins 6 and 7:



Fixed the bridge, but still had to clean flux and a little solder off of the surface of the board to get it to work:



Here's a look at the board after soldering all of the leads:



Works great!  I'll post some pics of the pot and switch installation after I finish. Thanks again!

[CodeMonk]

I did this mod for myself a few years ago, then did it to several more FAB Echos for a local music store.
The thing I did different than what I have seen others do with those mod is to use a 9mm 100K pot for the time ( Smallbear has them).
100K gives you about 1200msec of delay time (IIRC).
Although once it gets past around the 80k mark or so, it sounds, uhm, not so good.
I would drill 3 holes in the PCB (which trashes 2 traces, but a few jumpers fixes it, no problem) lined up with the other pots.
Hot glue and some super glue hold it in place quite well.
This, IMO, makes it look so much better, as there is an unused gable there.
Makes it look like it came that way from the factory.

I don't have the pedal anymore, and I don't have any pics

[Jdansti]

I did this mod for myself a few years ago, then did it to several more FAB Echos for a local music store.
The thing I did different than what I have seen others do with those mod is to use a 9mm 100K pot for the time ( Smallbear has them).
100K gives you about 1200msec of delay time (IIRC).
Although once it gets past around the 80k mark or so, it sounds, uhm, not so good.
I would drill 3 holes in the PCB (which trashes 2 traces, but a few jumpers fixes it, no problem) lined up with the other pots.
Hot glue and some super glue hold it in place quite well.
This, IMO, makes it look so much better, as there is an unused gable there.
Makes it look like it came that way from the factory.

I don't have the pedal anymore, and I don't have any pics

Thanks.  I see that unused gable. That's pretty tempting.  I just don't know if I want to rearrange the board for my personal use. It looks like I can install a 16mm pot to the left or right of the PCBs.  There are indentions there that look designed to take a component.  I'll have to ruminate on that one  .

[Jdansti]

Here's my method of installing the pot and switches.

This is where the pot is going to go:



I removed the ring shown in the previous photo:



Test fitting the pot. I'll trim the legs later:



Drilled holes for the switches and test fitted them:



Notched the PCBs to make room for the pot. Had to be careful to avoid traces:




Here's everything wired and installed:


All back together. The switches move up and down, not forward and backward as it might appear.



The only trouble I had was this circuit seems to be sensitive to leftover flux on the board. It stopped working for a while and I spent several hours troubleshooting. As a last resort, I decided to take some alcohol and scrub the board. It magically started working again after that.  It could be a coincidence but it's the only thing that seemed to work. Anyway, I really like the sounds I can get out of it now. Thanks to everyone who contributed to this mod!  I used a lot of information from here.

[pinkjimiphoton]

i messed mine all up...broke pin 6 off the 2399. scraped away with a dental tool, and just barely got a little wire on the close to microscopic nub.
phew.

still can't get feedback...one slap, that's it.

but...i put a 16mm 100k pot from tayda below the bottom board... a bit of dremel work, and i whacked a hole fright thru the a in FAB. just fits.

THAT part works great.

don't like the shorted resistor for the level, it has some pretty nasty noise when cranked...tho fuzzy echo at a really short delay with just one slap almost sounds backwards.

now i've gotta get the feedback thing happening.

but the pot location i thought may be useful for someone in the future...peace!

[Jdansti]

i messed mine all up...broke pin 6 off the 2399. scraped away with a dental tool, and just barely got a little wire on the close to microscopic nub.
phew.

still can't get feedback...one slap, that's it.

but...i put a 16mm 100k pot from tayda below the bottom board... a bit of dremel work, and i whacked a hole fright thru the a in FAB. just fits.

THAT part works great.

don't like the shorted resistor for the level, it has some pretty nasty noise when cranked...tho fuzzy echo at a really short delay with just one slap almost sounds backwards.

now i've gotta get the feedback thing happening.

but the pot location i thought may be useful for someone in the future...peace!

Hey Jimi, if you really want some fun, why don't you replace the SMD 2399!  Just kidding. 

I like the idea of putting the pot where you did.  If I can pickup another cheapo I'll give it a try.

My brother in law and I were upstairs messing around with my modded echo a couple of weeks ago while the girls were downstairs doing girly stuff. He was playing while I was tweaking the knobs, and the amp was a little louder than necessary.     I turned on the infinite repeat switch and then slowly rotated the delay knob towards shorter delays and it sounded like a freaking alien spaceship taking off.  Then I quickly turned the delay all down and it sounded like a gigantic explosion!  We were laughing our *sses off. My wife didn't think it was so funny, though. 

[pinkjimiphoton]

screw smd!! pia!!! gawD!!!

lol...i decided, when the %^#^&#^ wire broke off the %^^#^%$% pin that i was gonna just literally take it apart. so i did. it is unsalvageable.

i'll use the casing for something useful, like a fuzz or something. i finally got the repeats working on it..

shaky hands and smt don't go together. good for vibrato, bad for fly turds. one slip of the iron...like, a millimeter... and wango. another resistor (i think) stuck to my iron.

i'll leave the hard stuff to the guys who can get it...not me. i'll build something bigger.

sucks tho, cuz this thing sounded great with the 100k pot..very echoplex-y. i may buy another to try and get it right...someday. i don't know why, cuz, i gotta crapload of delay pedals, rackmounts, even a pair of echoplexes..

i don't like to admit defeat, i guess. and i'm a total gear whore. PAS, brother, PAS.

[Jdansti]

i don't like to admit defeat, i guess. and i'm a total gear whore. PAS, brother, PAS.

I know the feeling. Sometimes I wonder if I'm OCD...

[AM]

I'm using this photo to ask a question regarding a new mod. Not exactly a mod, more of an add on.
I'm adding another circuit AFTER the Fab Echo, using the existing box. I wanna have this new circuit hardwired to the output of the Fab Echo. It will always stay on (The new circuit)!
So, I wanna tap into the 9v + of the Fab Echo to power the new FX board. I wanna tap into it before any current limiting resistors in the circuit. What is the best place? Can somebody point it at the above photo? I also want to disconnect Fab Echo's output from the output jack and connect it straight to the input  of the new circuit board.
Then I will take the output of the new fx board and wire it to the existing output jack. Which pin of the output jack in the picture above is the tip?
Last question, should I connect the ground wire of the new FX board to the unused pin of the output jack or somewhere else.

The output jack traces in the photo are the ones on the lower right side.
Thanks a lot in advance!!!

[Jdansti]

>So, I wanna tap into the 9v + of the Fab Echo to power the new FX board. I wanna tap into it before any current limiting resistors in the circuit. What is the best place?

This might be a difficult because you have to deal with the battery and the power jack. Since the power jack switches the battery in and out of the circuit, you can't just tap off of one or the other unless you plan to only use one or the other.  We really cant tell just from the photo.  We'd need to look at a schematic.

>I also want to disconnect Fab Echo's output from the output jack and connect it straight to the input  of the new circuit board. Then I will take the output of the new fx board and wire it to the existing output jack. Which pin of the output jack in the picture above is the tip?

I haven't looked at those jacks in a long time. You should be able to use your meter to check for continuity between ground and the terminals of the output jack to answer this question.

>Last question, should I connect the ground wire of the new FX board to the unused pin of the output jack or somewhere else.

All of the grounds should be connected to each other. When you finish the mod, be sure to check for ground continuity. Do this by placing one probe on a ground connection and use the other probe to check every one of the other ground terminals and ground board connections. Don't move the first probe to another location while doing this.

[AM]

OK, here is the same picture but with all the connections labelled: This should make it somewhat easier to trace things.I marked the 220uF cap and diode traces surrounding the 9v jack. I assume these are for polarity protection (?). So maybe they could give an extra clue about the ground path. Thanks again!


Uploaded with ImageShack.us

[slacker]

Battery negative will be going to jack ring so that's jack 1, jack 3 seems to be connected to the same place as the Cap negative so that looks like ground so that's the sleeve. That leaves jack 2 as the tip, looks reasonable as there seem to be components connected to it.

On the DC jack, it looks like 9v  1 is connected to the same place the cap negative and jack 3 so that's ground, 2 looks like it goes to battery +, so 3 must be the connection to the DC jack positive, so that's where you want to tap off your 9 volts.

If you have a meter you can check all this pretty easily. lug a lead into the input jack and test for continuity between the tip and jack 2, if you get it that's the tip connection. Same with the sleeve and jack 3. You can check the DC jack the same way plug a lead in and test for continuity between the outside and 9v 3.

[AM]

Thanks slacker!
I thought that was pretty much what was going on but I couldn't confirm it. My multimeter is broken so I went with whatever I could trace by looking at the pcb and thought I should ask the knowledgeable guys here for confirmation and advice.

[gogul808]

hehe bought one of these coz it was cheap and modded it similar to the last post with the pictures (except I used 3 100k pots ) it was all working well until the switch(the old style version that is on the power board pretty much fell apart ! don`t ask me how I dunno lol    )
Anyhoo , as the the soldering and prelim sound test indicated that it worked before my switch gave up the ghost I was wondering If anyone could please tell me how the 4 solder joints underneath the switch housing would correspond to a dpdt switches wiring ?as I will prolly re house it in a new chassis
For my 1st pedal mod i`m chuffed It works ,and is a pedal I would use ,once i get a dpdt switch in it !  unlike before it was modded (the switch I blame on cheap shoddy design ^^)

all the info in this thread was great , including the warnings about how easy to fudge up the teeny tiny resistors .

[AM]

It worked! Thanks again gents!
I desoldered the output jack, and bent the output pin so it doesn't touch the Dano's circuit anymore. I hard wired the output of my new diy board on that pin.
I soldered the input of my diy board to where the output jack pin used to be soldered. Then I soldered the other two pins of jack back on the Fab Echo's circuit board.
Soldered the ground wire of my diy board on pin 3 of the output jack.
I soldered the 9V+ wire of my diy board right on the diode so I could take advantage of the polarity protection circuit that is already installed on the Dano.
Worked really well and I'm very happy with the final result.

[bizbiz]

Hi all,
Like many others I lifted the resistor right off the board when doing the infinite repeat mod.
Does anyone know the value of that resistor?  The only schematic I came across said 100k, though someone else mentioned it is .47ohm
Would like to replace that resistor and add a momentary switch inbetween cap
Kinda new at this and really excited to get that guy workin.
All other mods worked great, thanks to this thread!
 

[Jdansti]

Probably not 0.47R. I assume the resistor vanished into thin air or the carpet when you removed it , but if by chance you still have it, place it on the sticky side of a piece of masking tape and secure the tape to your bench sticky side up with a couple more pieces of tape. Now you can measure the resistance.

If you don't have the resistor, solder a couple of leads to the pads where it was and connect those to a pot with some clips. Start with a the snallest pot you have and adjust it to see if you find a spot that works. If it does, then being careful not to turn the pot shaft, remove the clips and measure the resistance across the same two lugs where you had the clips connected.  You want to remove at least one of the clips when you measure the pot resistance because the board could affect your reading if you don't.

If the first pot doesn't work, try the next size up and keep experimenting until you find a resistance that works. Heck, it might be interesting to see if a pot here might give you desireable results.

After you figure out the resistance, just place a regular resistor of the approximate value that worked on one lug of the switch. Hope this helps.

[bizbiz]

I assume the resistor vanished into thin air or the carpet when you removed it , but if by chance you still have it, place it on the sticky side of a piece of masking tape and secure the tape to your bench sticky side up with a couple more pieces of tape. Now you can measure the resistance.
 
Heck, it might be interesting to see if a pot here might give you desireable results.

. Hope this helps.

Thanks JDanski!
Yes, the resistor was lost in a poof of smoke as it ascended off the board 
After measuring pot resistance to find the right value, it became obvious that keeping the pot in there vastly expands the feedback time from whats included stock, so i left it..
This is it packaged:

[Jdansti]

Cool!  You accidentally found a new mod! Nice box too! I like the white plate. I've got some cigar boxes that will have to have similar plates!