My DOD FX60 Build Needs Help! The 6 0DD FOXes Chorus

[bloxstompboxes]

Alright guys, I rarely ask for help but it's hard to concentrate with a toddler and a newborn around me all the time. I've made a layout for the DOD FX60 Chorus and called it the 6 0DD FOXes Chorus for no good reason. lol. Problem is, it isn't working. I get a clean signal with the exception of a little blah sound when rotating the Speed knob. It isn't boxed. I did find that I had missed a ground on the LFO and connected that with an extra long lead off of the C6 cap. I have a build document and voltages linked below.

If enough people are interested, I may order some boards once I get this working. I can get rid of the two jumpers if I have them made. They would probably be around $5 a piece or something, plus shipping. Otherwise, there is the mask in the document for all of us etchers.

I used an LM358N for IC3 and TL022CP's for the other opamps and the rest were of course a MN3101 and MN3007.

If I get a chance, I will post some pics of the board. I am really busy with the kids and overtime these days so I appreciate your repsonses but I may be slow to reply back.

Finally, why did I bother in the first place. I have a couple of reasons for you.

     1. Because no one else has yet and I am addicted to making layous.
     2. There is no other chorus, that I know of, that is stereo and available for DIY on one board.

Build Document: https://www.dropbox.com/s/09cvrrr5nejvyic/6%200DD%20FOXes%20-%20DOD%20FX60%20Stereo%20Chorus%20Build%20Document.pdf?dl=0

Voltages: https://www.dropbox.com/s/myo7jaj3xa1lf11/Voltages.jpg?dl=0

Thanks in advance to all who can help!

[Kipper4]

Interested mate.
I love doing layouts too but then I don't have young children to distract me or overtime.
I'm time rich, money poor.
I did a layout for a stereo small clone, made it then modded it after I boxed it in a rack mount box.
Have fun
Neat looking board and a nice doc.
Thanks Eric

[bloxstompboxes]

Interested mate.
I love doing layouts too but then I don't have young children to distract me or overtime.
I'm time rich, money poor.
I did a layout for a stereo small clone, made it then modded it after I boxed it in a rack mount box.
Have fun
Neat looking board and a nice doc.
Thanks Eric

Thanks kipper! Yeah, I wish I had more time on my hands to get more involved in my builds. I have no time to breadboard anything it seems. I drew this stupid thing twice and the extra long jumper still irritates me. The first had way more jumpers but may have been a bit cleaner looking. It's gone now though. lol. I am too lazy to redraw the whole thing another time unless it is to get it working.

Hopefully, someone will chime in and point out some stupid thing I've missed.

[bloxstompboxes]

Anybody got any ideas yet? I may have a few minutes tonight since the wife and kids will be gone for a little while.

[tubeguy]

Hi, I was also working on a chorus of this style few days ago. There is a missing 220k resistor between pin 3 and pin 6 of the TL022 (LFO).

[bloxstompboxes]

Tubeguy, thanks for the reply! However, according to the schematic, there are 3 220k resistors immediately connected to the LFO. I have them labeled as R15, R16, and R17. None of those look to be connected to pins 3 and 6 of the LFO in the schematic and are all present in my layout. Could you please take another look and make sure you didn't mean something else?

[tubeguy]

Yes, Although in scheme only appear three 220k resistors, on the actual pedal there is a fourth resistor, this one joins pins 3 and 6 of the LFO.
You can try this small change without much trouble and see what happens...

[bloxstompboxes]

Hmmm. No change. This sucks. Can't concentrate today with all the distractions mentioned above and a few others. Resistor added correctly to pins 3 and 6 of the LFO but still nothing.

[tubeguy]

Calm, give it time. There is another difference; in my pedal it does not appear R6, pin 3 of opamp goes straight to Vref. I do not think this will change much but I do notice.
Whenever I get a free moment, I take the voltages of the LFO.

[bloxstompboxes]

Thanks tubeguy. It's just been a bad day is all. This wasn't helping much. I'm sure it will be solved. I am planning on getting an original that may need fixing but should be useful anyway. I appreciate whatever help you can give.

[bloxstompboxes]

Haven't given up on this. I did get an original without the buffers and so on. Got it not working for $20 something on ebay. Replaced the electros and she fired up and sounds close to a Boss CE 2 to me. So much so that I wanted to reverse engineer it and fix my layout but other things were going on and so it hasn't happened yet. I had taken some pics and had my wife read the stripes on the resistors... remember, I'm color blind. I labeled the components in 1 pic of the component side. And today, I mirrored the trace side and started comparing. So far there are quite a few errors. Like, did they just pick a schematic they had laying around, maybe the 1rst version and say, "lets just give em this one?" lol.

It will be a little while before it's done and I might still get some boards made. For sure I'll update the build doc.

[bloxstompboxes]

Alright, so got a new board drawn up, error checked and found a few, should have error checked again as you will see below. Put the new board together and tried to rock it. Seems I made an extravagant but nice sounding buffer. Controls do nothing. This is worse than before. I take a look at the board again for shorts and opens. I have been really careful on this one since I wanted this to work pretty badly for some reason. I get out my meter and find like less than two volts on the power pin of the LFO. That won't work. I find that I took the power off the wrong pad. Fix that and now I have a pretty decent vibrato but no chorus. Damn it. Look at the board and the schematic again. Don't see anything new. Decide to try different set of MN3007 and MN3101. No change. I socket those on my original FX60 and decide to check my stock of MN3s. All check out OK. That's good and bad. Good that my supplier is a good source for BBDs, bad that the issue of no chorus remains. To be continued...

[ElectricDruid]

Fix that and now I have a pretty decent vibrato but no chorus. Damn it.

Vibrato but no chorus means the clean signal isn't making it to the output mixer, but that the LFO, Clock, and BBD are all working fine. That doesn't leave much, since the clean signal must be ok where it comes in. Check the final mixer, particularly the input resistor (and cap if there is one) for the clean signal.

HTH,
Tom

[bloxstompboxes]

Fix that and now I have a pretty decent vibrato but no chorus. Damn it.

Vibrato but no chorus means the clean signal isn't making it to the output mixer, but that the LFO, Clock, and BBD are all working fine. That doesn't leave much, since the clean signal must be ok where it comes in. Check the final mixer, particularly the input resistor (and cap if there is one) for the clean signal.

HTH,
Tom

Thanks for the reply Tom. Maybe vibrato was too strong a term. I can here the LFO impacting the signal. The speed control does change the rate of impact, but it is not a vibrato, I suppose. The depth control does not affect the signal like it does in this video of a modded CE2 when set to vibrato. In fact, the depth control on mine does nothing at all currently.

I know these are different pedals but the idea should be the same. there is one trace coming off pin 1 of IC1 in my layout that then leads to R29 and R36, which are the input resistors for mixing the dry back into both outputs. I get continuity from pin 1 to both of these resistors. So it's got to be something else. If I get a chance this week, I'll try to upload a video of what is happening.

Here's what I have so far:

My original's board (component side): https://www.dropbox.com/s/kw9e31b18biksgk/DOD%20FX60%20Stereo%20Chorus%20%28My%20Pedal%27s%20Board%29.jpg?dl=0

My original's board (trace side mirrored): https://www.dropbox.com/s/7bekvmbypno8187/DOD%20FX60%20Stereo%20Chorus%20%28My%20Pedal%27s%20Board%20trace%20side%20%28mirrored%29%29.jpg?dl=0

My build document based off of the above: https://www.dropbox.com/s/x2i7vionb16xl41/DOD%20FX60%20Stereo%20Chorus%20Rev%203%20Build%20Document.docx?dl=0

Need to update the schematic in the build document but my scanner won't scan for some reason. Here are the errors I found and corrected in my new layout in the build document:

Errors Found on Schematic of DOD FX60 Chorus
1.   C3 is 2.2nf and not 22nf
2.   R6 is not there. Short it.
3.   C9 should be 47uF and not 330uF
4.   C12 is a .0022 or 2.2nF not a 2nF. Not really an error but part supply issue probably.
5.   Lug 3 of the speed pot goes to Pin 3 of IC3 not pin 2.
6.   Pins 1 and 2 are shorted on IC3, not 1 and 3.
7.   Missing a 220kohm resistor from Speed lug 3 to pin 6 of IC3.

[Ben Lyman]

How's this coming along?
Do you have an original and would it help you at all?
Someone posted this today near me for $35:
http://sacramento.craigslist.org/msg/5832180014.html
He might not ship but I could try to grab it and send it to you for an additional
$17 USPS Priority w/insurance, maybe less if it fits in the small Priority Mail box

[bloxstompboxes]

How's this coming along?
Do you have an original and would it help you at all?
Someone posted this today near me for $35:
http://sacramento.craigslist.org/msg/5832180014.html
He might not ship but I could try to grab it and send it to you for an additional
$17 USPS Priority w/insurance, maybe less if it fits in the small Priority Mail box

Hey Ben. Yeah, I have an original now as I mentioned somewhere above. I redid the layout after reverse engineering the original. There were several errors and a missing component or two when compared to the schematic on the web. I found an error or two in my new layout and have since corrected them. It is still not chorusing for some reason. Though I am closer than where I was. It's something stupid I am missing; that much I am sure of. I haven't given up on it. I just moved on to some other things so I can come back to it with a fresher mind. The post right before yours has some images of the unit I bought and some of my work so far. I'll get back to it soon.

Were you interested in a build yourself or just offering some help?

[Ben Lyman]

I just remembered your thread and thought of you when i saw the ad this morning. I am interested in building a chorus someday though. I don't even know if you can get the proper chips for this or the CE-2 anymore, I don't even know what they are called, MN30000000something 
I love stereo stuff and i have two amps but first I plan on experimenting with a stereo phaser/vibe contraption... maybe after that I'll get on to a chorus.

[thermionix]

Off topic, but what song is the dude playing in the youtube video above?  It's something I know, but just can't quite remember.  Now it's bugging me.

[bloxstompboxes]

I just remembered your thread and thought of you when i saw the ad this morning. I am interested in building a chorus someday though. I don't even know if you can get the proper chips for this or the CE-2 anymore, I don't even know what they are called, MN30000000something 
I love stereo stuff and i have two amps but first I plan on experimenting with a stereo phaser/vibe contraption... maybe after that I'll get on to a chorus.

The chips for this are still very much available. I have a couple dozen or so I got of ebay pretty cheap and so far, all of them are good. Mammoth, I think, and smallbear have them too but they are much more expensive since they are verified good and are U.S. sources. They are the MN3101 and MN3007. I can throw some your way for very little once I get this sorted out. I'll try to remember to send you a message when I do. The CE2 and small stone are great choruses. This is similar to the CE2. Tonepad has a board for it but requires a separate board for stereo mod.

[bloxstompboxes]

Off topic, but what song is the dude playing in the youtube video above?  It's something I know, but just can't quite remember.  Now it's bugging me.

The Way It Is by Tesla.