Mutron Flanger dissection.

[armdnrdy]

(New images on page 12)

If you look at the DC jack on the component side image, you'll notice that it's sitting on a shim fabricated from scrap etched PC board.

We're dealing with an enclosure that has a few existing holes that may not have been in the optimum location.

The shims are two pieces of board, filed down to the total thickness of 2mm with holes/slots drilled for the DC jack.

The two pieces are "glued" together with 5 minute epoxy, glued to the DC jack, then the whole assembly is glued to the PC board. .

There is just enough "meat" of the DC jack's pins coming through to the board's trace side to achieve a good solder joint.

Gluing the DC jack to the board will keep pressure off of the DC jack's solder pins where a board mounted jack's failure usually occurs

This modification was necessary to align the DC jack with the existing hole. If you recall, we had to flip the input/output jacks upside down to make board mounted pots work with this enclosure. This is why the existing DC jack hole doesn't work without the shim.

One more thing of note.
The angle of the component side image doesn't show the board's output connector. The connector is underneath the "start" pot which is located on the bottom left side of the board. Although you can't tell by the picture, there is about 12.5mm of space under the pot body.

[armdnrdy]

Here is the LED/LDR board:



Here is the trace side showing the Effect and Pedal LEDs on the "outriggers".

[armdnrdy]

This morning I fitted the LED/LDR board into the enclosure.....perfect fit!

The Effect/Pedal LEDs are perfectly aligned! 

It looks like I know how to use a ruler and a caliper......who knew?

We're on the thoroughfare and can see the finish line.

[digi2t]

OMFG!!! YOU`RE KILLING ME WITH THESE BITS AND PIECES SUSPENSE.

You should take up writing thrillers. I`ve resorted to sitting here, and constantly clicking REFRESH for the next installment.

[armdnrdy]

Did Pope Julius II call out, "heya you! whatsa takin so long? Are you ever gonna finish thisa ceiling? when Michelangelo was painting the Sistine Chapel's ceiling?

I think not!

Good things come to those who wait.....Rome wasn't built in a day.....patience is a virtue....A half finished Mutron Flanger in the hand is worth two in the bush......

[wavley]

Did Pope Julius II call out, "heya you! whatsa takin so long? Are you ever gonna finish thisa ceiling? when Michelangelo was painting the Sistine Chapel's ceiling?

I think not!

Good things come to those who wait.....Rome wasn't built in a day.....patience is a virtue....A half finished Mutron Flanger in the hand is worth two in the bush......

[armdnrdy]

I've been slammed at work the last week......yes I have a job!
and I haven't had much time or energy to work on this project but...I worked this up:



The image of the main board is mirrored. This is the view when looking at the enclosure with the bottom cover removed.
You will actually see the trace/solder side of the main board. The wiring that crosses the main board will be hidden from this vantage point.

I just have to crimp the wires to the female connectors, plug them in, place the ICs and transistors in their sockets and with a little luck (do they have a crossed fingers emoticon?) we'll have flanging......or it will be the start of the debugging process!  

[armdnrdy]

Yesterday I cleaned all of the nasty fingerprints from the trace side of the board and coated it with Rustoleum matte clear.
Now it won't rust!  

Today...I finished the off board wiring, set all of the trimmers to about 50%, powered it up.....all the switching, indicator LEDs, and rate LEDs worked as expected! Looks good so far!  

Plugged my guitar in the input.....output of the pedal into my amp......Nothing! No bypassed signal, and no wet signal!  

Pulled out my meter and within five minutes found no continuity between the bypass switch and the tip of the output jack.

I removed the nuts from the board mounted components, lifted the board part the way out, and spied the output jack connector flying in the wind! It must have came loose when I was organizing the wires before trimming them and soldering.

Secured the connector, buttoned everything back up, plugged it in......we have clean guitar!  
Hit the effect switch..........we have flanging!  

Turned it over to adjust the pedal trimmers.......hit the pedal switch........we've got pedal sweep!  

Then I got tired of it and smashed it with a hammer.  
Just kidding!  

I'll work on dialing it in and get a video up as soon as I can.

I would like to thank Dino, Ian, Greg, Federico, R.G., DIYstompboxes, my girlfriend, the Academy, my first grade teacher, my parole officer, and last but not least.....Mutron for designing such a good flanger!  

[Govmnt_Lacky]

Great to hear Larry!!! 

Can't wait to see what comes of this! Definitely on my build list!!!

[armdnrdy]

Still working on adjusting the flanger.
Came across a small issue in achieving the lower range that Dino pegged as "sounds best at". (50kHz-800kHz)

I was only able to reach 88Khz at the lower range no matter where the two clock trimmers were set.

I reviewed the 4046 data sheet and did some research on 4046 clocks. A 4046's frequency is set by three components. A timing cap across pin 6 & 7, a resistor from pin 11 to ground, and a resistor from pin 12 to ground which offsets the base operating frequency set by the other two components.

Increasing the capacitance across pins 6 & 7 will decrease the frequency. I tried a few values and found that an additional 100pf was needed to achieve 50kHz at the lower end.

Dino's Flanger has a 120pf and 10pf ceramic caps in parallel for the timing cap. A board shot of a different unit shows one timing cap and empty holes where another would go. The original factory schematic depicts only a 120pf.
I believe this means that the actual capacitance for the timing cap would be chosen when the flanger was calibrated.

[Fender3D]

Kudos Larry...

you did a great job.

About the clock cap:
I use 2 solid wires (those used in LAN cables  )
cut them ~2cm long and twist 'em together, you'll obtain a small cap...
Then, as Dino says, cut the pair 1mm a time until you don't reach the desired value.
A rare, more-than-mojo component.

PS
When looking for the exact lower clock, check the higher clock too

[armdnrdy]

Kudos Larry...

you did a great job.

PS
When looking for the exact lower clock, check the higher clock too

Coming from you....that's a great compliment! (remember....you helped me with my first flanger build....MXR with a MN3007)

I'll check the upper frequency as well. While adjusting the trimmers I've seen it up into the low MHz!
The two trimmers are very interactive much like the ADA clock trimmers.

[Govmnt_Lacky]

CANNOT WAIT TO BUILD!!!! 

[armdnrdy]

I encountered a ticking problem that I was able to isolate in short order but.....the fix took a bit longer!

As you may know, we are retrofitting this circuit into a different enclosure (Morley) which includes predrilled jack holes and limited space to locate controls. (wedge shaped pedal)

The trace that runs from the LFO to lug 2 of the board mounted Rate pot was located too close to the input jack. (J1)
This trace is screaming!
After trying everything....and I mean everything! I had to cut the trace, ground it, and run a jumper wire away from the input jack.

I reworked the board to move this trace as far away as possible from the input jack. It should be good to go now.



Overall....this is a great sounding flanger! The sweep pedal aside, the flanger itself is very versatile! The Stop/Start controls add another dimension with a whole array of tone/textures available. This is one of my favorite flangers now!

Video coming soon.

[digi2t]

Video coming soon.

Anxiously awaiting!! 

[UKToecutter]

Larry,

Are you going to make a batch of boards for this?

[armdnrdy]

Larry,

Are you going to make a batch of boards for this?

Hey Andy,

I wasn't planning to do to lack of interest.....only a small handful of people seem to want to build one of these.
I think it's a great, versatile flanger. Definitely at the top of my list.

[Govmnt_Lacky]

I wasn't planning to do to lack of interest.....only a small handful of people seem to want to build one of these.
I think it's a great, versatile flanger. Definitely at the top of my list.

Hey Larry...

Any idea on if or when you will be able to release the PCB and document? I know you are pretty bogged down but, I am itching to get this built and the wife wants the Morley Volume off of her table ASAP!   

[armdnrdy]

I'll see if I can get it done today.

I'm working on CAD drawings for a few sizes of sloped aluminum enclosures.

A friend works at a sheet metal manufacturing company. I talked to the owner who has agreed to make some prototypes for me.

It seems that we are always looking for a larger, sloped enclosure to house bigger builds or multiple circuits. I've searched the net many times and haven't found anything that will work at a reasonable price.

If the price is right...I may be offering these for sale.

The first design is a cross between the old EHX enclosures and the Mutron Biphase enclosure, with measurements of
8" X 6" - 3" in the back sloping to 1.9" in the front.

[Zwachi]

Does someone have a schematic for this flanger?

Links/pics are dead and I'm very interested how Mu-tron has done it.

Thanks a lot!