BBD to PT23999

[Crazy Voodoo Eruption]

MXR Time Delay SAD4096 seems to be dead. Anybody know if a pt23999 can be swapped in it's place with some jerry rigging?

[moid]

I'm not an expert here (so take some else's advice if it's given) but I think to do this would require a huge change of the PCB - you'd need a separate daughterboard for all the parts the PT2399 needs and I really doubt this could be done without destroying the original PCB... obviously getting a SAD4096 these days is either near impossible or ruinously expensive... I wonder if another, not so expensive / rare BBD could be substituted instead of the PT2399? You'd need someone else's opinions on whether that is possible though.

[Crazy Voodoo Eruption]

I would much rather replace it with a closer chip if possible so that's a good point. I know people were replacing dead BBDs from the big green MXR mx-118 analog delays w/pt23999 on a breakout board.

[ElectricDruid]

It's probably possible, but the PT2399 is a 5V chip, so the daughterboard is going to need a voltage regulator too. It won't be able to use the original clock, so the original delay control will have to be replaced too. All in all, it's a big job.

I'd be inclined to look at another 4096-stage BBD rather than use a completely different technology. Coolaudio make the V3205 and Xvive make a MN3205 (these chips may in fact be identical at the wafer level, but that's a different story). It'll still be a daughterboard solution since it won't fit the original pinout, but you're significantly closer to the original circuit so you shouldn't have to perform quite so much surgery.

[Crazy Voodoo Eruption]

Thanks Moid and Electric Druid! It seems like you are right about the mn3205 being a 4096 stage bbd that could be compatible w/some tweaking. My problem is finding one. Also thinking long term and about replacing my favorite bbd delays. I know people have been able to do some amazing work with pt23999 circuits implementing low pass filters so that consecutive delays sound darker, mimicking bbds. I know the old mxr 118 delays have been retrofitted to run with pt23999s so I figured maybe it's been figured out for 4096s as well. Well, it turns out it has! Found a website for the old Centaur pinball machines using the same chip and the original work around was an mn3205. I ventured further down the rabbit hole and found that people had developed a pt23999 mod as well. So, I know it can be done. I also now know I am simply not smart enough to do it myself. This will require time and energy I simply don't have. But the odds are someone else does.

[soggybag]

Seems like the best route to me would be to rehouse a PT2399 style delay in the MXR box. You can preserve the innards and possibly restore them for the future. All the new innards would be designed to work together.

[ElectricDruid]

My problem is finding one.

That's a temporary problem, I'd say - getting hold of lots of BBDs is difficult at the moment, along with many other chips, but I don't think that situation will last forever. Still, it might last a while - give it a year?!?

[Mark Hammer]

There was a thread here on how to adapt the old green M-118 Analog Delay for use with a PT2399, complete with pics.  That unit used a trio of SAD1024 chips, but also used the master clock to drive a tracking filter that adjusted the lowpass filtering with delay time to provide maximum bandwidth for whatever the delay was.

There were several models of what MXR called the Time Delay, a two knob and a 3-knob (shown in detail here: https://djjondent.blogspot.com/2017/10/mxr-time-delay.html ).  Which is yours?

[Vivek]

with some jerry rigging?

"Jerry rigging" is a very interesting phrase which seems to have entered the English language earlier than 1830


I wish to introduce a word with similar meaning but with some positive connotations

Jugad

It's originates in my country India, but was accepted into English dictionaries about 5 years ago

Jerry rigging implies shoddiness
Jugad implies innovation, inventiveness


https://en.m.wikipedia.org/wiki/Jugaad

[Mark Hammer]

The term "jerry", for reasons I am not familiar with, came to be used as a derogatory term for Germans during WWII.  In more recent years, perhaps because of a desire not to be discriminatory, or maybe simply because people misheard it (the same way many think the phrase "should have" is actually "should of", because of the way many pronounce "should've"), many will use the expression "jury-rigged". I suspect they are mostly unaware of why, only that it sort of sounds right to their ears.

An interesting, but irrelevant tangent to the thread.

Back on track: is it technically possible to replace an extinct analog delay with a much cheaper and infinitely more available digital chip?  Yes.  Whether the board and enclosure provide adequate means to install what is required is a whole other challenge, that I suspect cannot be overcome.

In this instance (but many others as well) I'm in complete agreement with Tom/EDruid  A Reticon chip is not a Matsushita or Coolaudio chip, and is decidedly not pin-for-pin compatible, but BOTH will require a biphase clock of pretty much the same frequency range, given that 4096 stages is 4096 stages, as well as a DC bias voltage on the input.  And both provide dual complementary outputs to be mixed and interleaved together.  That seems the more feasible alternative.  And if the current Reticon chip is socketed, or can be unsoldered and replaced with a socket, it may be possible to fabricate a daughterboard that plugs into the socket and distributes the 3205 pins to their appropriate locations in the socket pins.

[Crazy Voodoo Eruption]

The delay is an MXR M-166 Time Delay from the Commande series. I'm not gonna lie, I assume the Reticon SAD4096 is dead because it passes a signal otherwise when engaged w/the slightest bit of coloration (which I took to mean the circuit works), minus the bbd. Either way, I need to figure out solutions now for when my effects based on MN3005, SAD1024, etc inevitably kick the bucket. The gutshots are from my actual pedal. I recently purchased it from a seller who swears it worked before shipping. Before sending it back I figured I see if anyone had any experience bringing one of these back to life via a heart transplant.

[Mark Hammer]

Might be a stupid question, but have you tinkered with the bias voltage trimmer?  I.E., do you KNOW the Reticon chip is dead?

And perhaps it's the 4013 flip-flop.  Consider replacing that before you start doing surgery on the pedal.  No flip-flop, no clock pulse.  No clock pulse, no delay.

And thanks for the pics!

[moid]

with some jerry rigging?

"Jerry rigging" is a very interesting phrase which seems to have entered the English language earlier than 1830


I wish to introduce a word with similar meaning but with some positive connotations

Jugad

It's originates in my country India, but was accepted into English dictionaries about 5 years ago

Jerry rigging implies shoddiness
Jugad implies innovation, inventiveness


https://en.m.wikipedia.org/wiki/Jugaad

That's a fascinating word, I'd never heard of it before... I've certainly never heard anyone use it in England. Which doesn't mean anything specifically; we do have a lot of loan words (okay, mostly stolen ) from India in English, but I don't think that one has made it here yet in general use. I found it in the Oxford English Dictionary, but they don't list it as commonplace at all - quite the opposite, but I suspect that because we already have words for this term in England that would mean we might not adopt it - English usually acquires a word when it describes something that didn't exist in England, or that has become desirable to own or know in England.  There's another English word which is similar to jerry-rigged / jugad that you might like, and that is 'bodge' - that means to make something out of random parts / things you find lying around and somehow make them into a functioning item - very similar to jugad in this case. A bodger is someone who bodges things together (the original term actually implied a skilled woodworker who could 'bodge' things out of timber that were of good quality, but the meaning changed over the last few hundred years to be a bit more negative and implying that the bodged object works, but only just and looks like it could fall apart at any moment!)

Sorry about the etymology lesson everyone, feel free to return to the important discussion of fixing this pedal!

[PRR]

The compound word "jerry-built", a similar but distinct term referring to things "built unsubstantially of bad materials", has a separate origin from "jury-rigged".

[Crazy Voodoo Eruption]

@Mark Hammer
I only adjusted one trimmer and it wasn't the bbd trimmer. Is it possible that if the 4013 were dead, the circuit could pass a clean signal? I don't know for a certain that the bbd is dead. This was an assumption and I would love to be wrong! Also, I am a big believer in getting more pictures posted when there are any issues in a circuit. I have learned so much from you and all the others who gave knowledge and know how for free. More than one time I've pulled up an old thread where someone was diligent enough to leave pictures and years later, I was able to diagnose or fix my own issues because of them. Some obscure piece of knowledge or detail can be the thing someone needs. Hopefully, someone can use these one day for whatever reason they may need them.

[Mark Hammer]

There will be two trimmers associated with the BBD.  One of the sets the bias voltage.  If it is not set right, the chip will not pass signal.  Set a little too high or a little low, the BBD will pass signal, but it will be distorted and at a much lower level.

The other trimmer is likely for the balance between the two BBD outputs.  Setting it just right will reduce the clock noise.  Setting it wrong will still pass signal, but you won't like how it sounds.

Both trimmers can be adjusted without any harm to the BBD.

The 4013 flip-flop can be used for many things.  Sometimes it is used for switching.  In this case it is used to turn one clock pulse into two complementary pulses - tick and tock - that the BBD needs.  If it is not working, the pedal will still work in bypass.  I mention it because CMOS chips can easily burn out.  I have a Commande series flanger that wasn't working.  Mike Irwin took a look at it and replaced the CD4069 - a CMOS chip that provides the HF clock - and restored it to working order.

So, if you're up to the task, perhaps it might be worth desoldering the 4013.  If you try it, make sure to use desoldering braid, because things are pretty tightly crowded on that board.

[Crazy Voodoo Eruption]

I have no trouble desoldering. And I should have a fresh 4013 in my stash. When the pedal is engaged there is no delay. Sound goes through with very mild coloration when the effect is turned on and engaged. But no delay action whatsoever. This is why I was initially inclined to believe the bbd was probably toast. I didn't adjust the bbd trimmers (which are conveniently marked for optimal resistance), because I didn't want to risk frying the chip if it wasn't. Very unscientific approach, I know. When I get time I will go through the circuit properly and post results.

[Rob Strand]

If you *really* had to do a plug-in PT2399 retrofit I suppose you could take the existing BBD clock and feed it into a PLL-phase detector then take the clock-out of the PT2399 and feed it into the other PLL-phase detector input.  You then feed the output of the PLL into the PT2399 clock control.     You might need some extra dividers to get the delay times to match (I haven't checked).   It could turn out you have to work hard to get the PLL to track over a wide range of frequencies.

I'll let you think about it.

[Crazy Voodoo Eruption]

I really don't have to go w/the pt2399 swap. I have the option of returning the pedal to the seller. I just hate to do that if I can help it. I was just curious for future instances of bbd failure and thinking that this chip is readily available and it's been done before w/the M-118 analog delays w/some people even saying it sounds really good. Of course as Mark Hammer pointed out those are SAD1024 bbds. But now I'm curious if an mn3205 would sound good. Looks like I have some work to do when I get free time.

[ElectricDruid]

There's another English word which is similar to jerry-rigged / jugad that you might like, and that is 'bodge' - that means to make something out of random parts / things you find lying around and somehow make them into a functioning item - very similar to jugad in this case. A bodger is someone who bodges things together (the original term actually implied a skilled woodworker who could 'bodge' things out of timber that were of good quality, but the meaning changed over the last few hundred years to be a bit more negative and implying that the bodged object works, but only just and looks like it could fall apart at any moment!)

Good article on Wikipedia:

https://en.wikipedia.org/wiki/Bodging

Since a bodger improvised a pole lathe in the woods where they were working, this gives us the modern meaning of an improvised solution. The negative connotation is a bit unfair, really!

Sorry for the further OT, but the sidetracks in this thread are as interesting as the main thread!