SOLVED Deadend FX Mangel Wurzel No chorusing (Ibanez RC99 Rotary Chorus clone)

[Fontelroy]

howdy folks, I'm having issues with a build, it's the bbd chorus from deadend fx. Here's the build doc link for those interested - https://drive.google.com/file/d/1OpvxwDCM6n1V6RT3K5LvCE-sm3y7ayhj/view?usp=sharing
The issue is I'm getting no chorusing and no reading from the pad used to dial in the clock with the trimmer
a few things to note:

• I'm using JRC4558 ic till the ones called for in the BOM get to me as I had to Ebay them, since the circuit is passing signal I assume the 4558's still work but could the chorus really on the uPC4570's called for in the build docs?
• I accidentally soldered a red wire to ground and didn't realize it till i had connected the two board so i just rolled with it

(pls excuse the messy desk)

 

[Fontelroy]

Hold the fort, just realized i screwed up the pinout of *one of* the transistors....

 

[Fontelroy]

Update… was able to get a reading and dial things in but no audible chorusing is happening so something is definitely still up

 

[Feral Feline]

Some of your pot-legs look like there's no solder on them.



Are you getting dry signal at least?

 

[eh là bas ma]

Digi2t, the electronic wizard from DEFX is often active on diystompboxes.com.

You could try posting there too, he might notice and help, especialy if you mention DEFX in the thread title.

 

[Fontelroy]

Yes dry signal is there on bypass and when the chorus is “on” and I should be getting chorusing. This isn't true bypass and the output is in stereo, wierdly output b seems to have a little more output/gain. for the pots there is solder on the other side but ill add some more

 

[Nostradoomus]

Did you eBay the BBD chips too?

Also you may want to clean up the top board spots where the wire passes thru to the other board, there’s a lotta solder there and potential for shorts.

 

[Fontelroy]

No, I have a stash of good bbd, both cool audio and originals and I’ve tried a few of both for the 3102 and the 3207
Edit, had to double check but currently have the cool audio repros in

 

[eh là bas ma]

I think it's good practice to reflow our soldering joints after cutting the legs.

I just built a Schalltechnik_04 omnilooper, excellent instructions, they always insist on that point.

 

[Fontelroy]

Did you eBay the BBD chips too?

Also you may want to clean up the top board spots where the wire passes thru to the other board, there’s a lotta solder there and potential for shorts.

View attachment 73760

that freaked me out when i was checking stuff before i posted as I was getting continuity at the clk junction and the con junction so I consulted the schematic and that checks out for the clock junction and kind of for the con j, the conj should have continuity if the mix is at 100% and not otherwise which is what I have going on. I’ve attached the stitched schematic

 

[Feral Feline]

I know the build-doc says not to use spacers bigger than 3mm, but maybe you have some sandwiched solder-nibs bigger than 3mm?
Rather, perhaps you have 2mm solder-nib on one board contacting the 2mm solder-nib on the other board.

 

[Fontelroy]

I was worried about the boards butting up against each other. Truth be told, while I love deadendfx’s choice of projects. I am not a fan of his board layouts. When someone doesn’t use different footprints for large film caps it can rub me the wrong way but there’s plenty of bigger issues too. This sort of sandwich is a nightmare to troubleshoot for multiple reasons, however I ran electrical tape across the contacts of the control board that you can kinda see in the pic. Now if something’s poked through and made contact I have no idea but I’m gonna sleep on this, thank you all for your help so far!

 

[music6000]

Here is the top PCB board with white components highlighted.
There are a lot of areas that are prone to touch the bottom PCB with only a 3mm spacer as Feral pointed out!!!
This barely fits in a 1590BBS with a 3mm spacer is a bad design.
You may have to seperate the PCB boards and nip of all the excess solder knibs if you didn't prior to stacking them.
Electrcal tape has proven to fail far to often on standard pcb's under pots!

 

[Feral Feline]

Agreed that the layouts are less than ideal for several of the DEFX boards (often needlessly large, too).

If you run out of options as to what may be wrong...

If you've got a Dremel, hell, even an electric drill or borrow a friend's Dremel, I'd
GRIND down the nibs, then a quick reheat with the solder iron to ensure no cold-joints were created while grinding.

 

[Fontelroy]

Update: no real progress but lots of work lol, I got the eBay ics and replaced the 4558s, dry signal still works and sounds the same. I wanted to separate the boards again and in an effort to remove the variable of the two boards shorting against each other I used long leads on the junctions for the time being. It still isn’t chorusing tho Idk this might have defeated for the time being.

 

[eh là bas ma]

Electrcal tape has proven to fail far to often on standard pcb's under pots!

Oh ?

I guess the pointy ends of the soldering pads can pierce through the tape, but if we use several layers, 3 or 4 layers of tape, aren't we safe then ?

On boss pedals, there are some thin plastic sheet between the back of the enclosure and the pcb. Maybe some similar material could be slipped between the 2 pcb here ?

 

[music6000]

Do you get chorus now you have eliminated the touching of the PCB's

 

[Brett]

This sort of sandwich is a nightmare to troubleshoot for multiple reasons

Gross.

but if we use several layers, 3 or 4 layers of tape, aren't we safe then ?

If a circuit board design depends on the use of electrical tape in order to work properly, it probably shouldn't be a commercial product. I can't be the only person thinking this.

 

[Fontelroy]

Do you get chorus now you have eliminated the touching of the PCB's

No

 

[music6000]

I can't make out the Resistors clearly in the pictures but that is where I would start.
That 4th band catches so many people out!!!
Click on Bands for 5 Colours:

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