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Yeah, the forum does appear to be having some issues, there's a note on the homepage up at the top right.

Yeah, it's been doing that a while now. Occasionally I get someone else's account on the main page...

Think the mystery is solved, still, might be interesting to trace and see if there was any other alterations to the circuit... I do notice an extra diode in the astable section area.

This is seriously cool. LMK if you need a donor. Not that there are any 3004s to build anew 

The thing is you wouldn't need MN3004s because this version is clocked low enough that you could use MN3007s and clock it at normal freqs and get the same results.

There are two 4013s in the pedal, each with two flip flops. One of the 4013s dedicates one flip flop to each of the MN3004s to make the biphase clock pulses so each MN3004 has its own driver. Im honestly not sure this is even necessary considering the clock freqs (13KHz to 500KHz), which are roughly halved compared to an SAD1024 unit or generally any Panasonic BBD equipped flanger pedal. The other 4013 is the oscillator. Of the 4 flip flops available, I believe 3 are used.

I was reading the old schem wrong about the BBDs being in parallel. The input pins of the two MN3004s are connected in my unit and the clock phases are matched which IIRC is the differential operation shown in the SAD1024 datasheet. Maybe the folks at MXR looked at the performance of the Panasonic BBDs and traded super short delay times for better performance with differential configuration? The sound of the pedal is spectacular. Better than an SAD1024 MXR IMO.

The only DIY project I have seen that offered these alternate BBD configurations is the BYOC flanger, but Im pretty sure they were running parallel multiplex and calling it differential.

Side note - The lag here is like an hour or two for posts to appear. Never experienced that on another simple machines forum.

Thanks for that, so it's just using one half of each CD4013? What an odd design choice... Definitely not using the chip handling oscillator division in parallel? That might make a little more sense in lieu of a clock buffer, given the BBD's have equal clock capacitance to an MN3007.

The BBD's were in series in the original which it did look like was the direction it was heading in the gut shots Jessenator sent me, is parallel confirmed?

Are you able to measure the clock frequencies as well out of interest?

If someone posts some decent gut shots it shouldn't be too hard to trace and confirm seeing as we already have the 117 schematic.

I'll PM you. Let me know if you need different angles than what I captured.

Thanks, unfortunately to get a good look at the traces you'd need to unsolder the pots.

But, I thought of a much simpler solution... just test for continuity between pin 2 of both MN3004, if it beeps, they share the same clock.

If it doesn't beep, check pin 2 of one doesn't match to pin 12 of the other.

Still no beep? Then it's time to test the CD4013 for continuity.

Probed around in mine. One half of the inner 4013 handles generating the two phase pulses for each MN3004. The  outer 4013 is then the other half of the clock circuit although I believe based on photos earlier in the thread that there is a single oscillator feeding the two flipflops. BBDs are in parallel like the original design.

If someone posts some decent gut shots it shouldn't be too hard to trace and confirm seeing as we already have the 117 schematic.

I'll PM you. Let me know if you need different angles than what I captured.

Thanks, unfortunately to get a good look at the traces you'd need to unsolder the pots.

But, I thought of a much simpler solution... just test for continuity between pin 2 of both MN3004, if it beeps, they share the same clock.

If it doesn't beep, check pin 2 of one doesn't match to pin 12 of the other.

Still no beep? Then it's time to test the CD4013 for continuity.

Probed around in mine. One half of the inner 4013 handles generating the two phase pulses for each MN3004. The  outer 4013 is then the other half of the clock circuit although I believe based on photos earlier in the thread that there is a single oscillator feeding the two flipflops. BBDs are in parallel like the original design.

Looking at the Peavey DSC-4 dual clock chorus. It has 4 controls, 2x speed and 2x depth controls for each "clock". It really only has one clock, but 2x LFOs(072s) that look to be combined into a comparator(U3-B)and fed into the 3101. I would think this could confuse or glitch the 3101 but it makes for a very lush chorus.
Perhaps something similar is occuring in the MXR. Or it is somehow creating a decade of the LFO?

There are a bunch of dual LFO choruses from that era and in practice the clock just sees a different pattern of rising and falling voltages over time than with a single LFO. The LFO with the higher depth control generally has more influence over the movement of the overall voltage. With both depth controls in the middle you can get interesting non-linear LFO movement.

IIRC the Peavey is a little different because it has two different LFO shapes.

I haven't poked around in mine but is the SAD1024 MXR parallel multiplex or both sections in series? I thought it was multiplex which would make sense here as well with two devices and short delay times. I also haven't checked the clock freq here.

Should be sold out now  I got it for $100 and shipping+tax

So glad it went to somebody on the forum! And it's a steal of a price. Congrats. It is a fantastic flanger. I wouldn't recommend using the rubber foot control pieces though. The pots are the Achilles's heal of these in that they have plastic shafts, and aren't easily sourced. Using a foot to turn them is a great way to snap them off.

Smallbear stocks a small 3/8" bushing pot if replacements are necessary.

I only just saw this thread. I'm not sure how a CE-2 would sound with a purely sine wave modulation. I think it might ened up sounding a little lop sided because the peaks and valleys would be much more drawn out.

Shortening the delay time helps with a sine LFO quite a bit in my experience. You get that super smooth sweep without spending a ton of time at the long end of the clock sweep.

I scooped one because of this thread and it sounds great. I haven't compared to the earlier version but I was a little surprised to see the MXR doesn't use the multiplex configuration found in most other pedals that started with an SAD1024. Would be interesting to tap the output off the first MN3004 as an alternate sound.

The 125B may predate the 1590N1. Hammond added a bunch of enclosures in the last decade or so that weren't available when I started building pedals and the N1/BB2/B2/etc... that don't follow the 1590(letter)(letter) format in their names are all relatively recent. Or they may be ported over to the 1590 series from one of Hammond's other lines that was not common in music industry products. Around the same time is when they started offering a few enclosures in half a dozen colors other than black and natural. You're probably right that it was only available with ribs.

The reason 125B is more prevalent is likely based on cost. When 4Site enclosures came onto the market they were half the price of a 1590N1 or less. Since the enclosure is often the most expensive part of a pedal this is a huge savings on BOM cost for a manufacturer and you end up with many people referring to that part number because its just what they use for their products.