Ludwig Phase II Clone Debugging and Miscellany

[R.G.]

The other Ludwig threads are pretty long. I started this one to help focus on the debug and bringup of the clone boards.

Ry is first up with his clone; I suspect there will be some others in pretty short order. And awaaay we goooo...

It's all soldered up.  I plugged it in and...nothing.  No LEDs, no sound, not even bypassed guitar signal.
I suspect there is something wrong in the power supply.  I'll start debugging it on Monday, working through the voltages.  I need to get a wah enclosure together and get the 5k pot in there as well.

You're on top of it Ry. If nothing at all happens, first suspect power supply. Well, that or wiring, which could include not getting power to it.

And that 5K pot in the wah enclosure presents the mechanical challenges of swapping it out and having to fit the gear to a different pot.

On that: too late for the board set, I did come up with a way to use the stock 100K wah pot. It presents the choice between doing mechanical work or electronics work.  The reason to use a lower value pot instead of a higher value one in general is the resulting input and output impedances of the pot. The output impedance of a pot is added to any impedance the source feeding it has, and is variable between 0 and 1/4 of the pot's end-to-end value. In this circuit, the pot's added impedance is 1250 ohms. You can fake that by using a higher impedance pot and then buffering the DC level (which is what comes out of the stock pot in this circuit).

If you want to try hacking that in, I'll post it up on geofex. The circuit is an opamp and a few resistors and caps. What it does is use the existing voltage feed to a 100K pot instead of a 5K pot; the opamp buffers the wiper value of the 100K wah pot, making it into a low impedance suitable for driving the input to the rest of the Ludwig PII circuit.

[digi2t]

And that 5K pot in the wah enclosure presents the mechanical challenges of swapping it out and having to fit the gear to a different pot.

Having done a series of different wah enclosure projects recently, I can only recommend one pot that will work well in a Crybaby shell for this project.

First choice - P.E.C. pots. The long shaft models. Completely enclosed, just about military grade. They are 2 watt linear pots, and I get them locally from Abra Electronics for around 9$. They carry 5K pots, as well. http://www.abra-electronics.com/


The long shaft is desirable since you can cut it to the desired length. As for the gear, the pot is a smooth shaft, so there are two options; 1) get the gear that uses the compression pin to lock it in place. This requires that you transfer drill a hole from the gear, through the shaft. With a drill press, and care in the setup, easily doable. Or, get the flat-side gear, and the flatten a face on the shaft with a file, using a Dremel with a fine cutting disc to score the shaft for the circlip above the gear. Then, for either case, cut the excess shaft off with a Dremel. The treaded collor of these pots fits well into a Crybaby, as the picture below illustrates (showing gear w/compression pin);



Possible second choice - Omeg conductive plastic pots, the modular ones, if you can find them. I've bought 22K ones from a guy in Britain, off EBay, but I don't know if he has 5K's. Anyway, they come in a long shaft form as well, all plastic construction, so not as "bulletproof" as the PEC's. Regardless, mine seems to be holding up so far, although I don't spend my days wanking on it. You can easily flatten a side on the shaft for the "flat-side shaft" gear, and as mentioned above, score the shaft for the circlip, as illustrated below;



Just note that the gussets supporting the pot should be thinned down with a grinder in this case. The threaded collar on these pots is not as long as the PEC's, so a bit of thinning will avoid using the last threads on the pot. Otherwise, if available, works OK. I just doubt that you'll get the same life span out of these as the PEC's. The PEC's are H.D. mofo's.

All gears are available at Small Bear.

Hope this helps.
Dino

[R.G.]

Good info on the mechanical changes.

Here's something I always do when I'm making custom mechanical parts that will be used and possibly wear out. I make two or more while I'm at it. I can generally make two or three about as easily as one, because the processes and procedures to make them are something that you discover on the first one, and get easier after that. Making a spare while you're at it is sometimes only a little more time and trouble than making one, and you have a ready spare. With the plastic pots, if you think they're going to wear out, buy two or three while you can get them. This only seems extravagant while you're at it. It'll feel really smart at the other end when you have a busted part to be replaced. 8-)

I'll post the info on the circuit. It's a good candidate for perfboard, being one 8-pin DIP and some other parts. The Ludwig using a 35V supply makes this a little bit of a PITA, because common opamps only go to 32V max on their power supplies, a bit less on their inputs. The opamp and two resistors are for what the circuit actually does; to get it to live it has to have a transistor, a zener, a capacitor, and two more resistors.

[Ry]

Interesting information on the 5k pot!  I have a slightly different dilemma to overcome first. 10-12 years ago, I bought three empty vox wah shells with big plans of using them in the Ludwig build I was breadboarding at the time (yes, I'be been here before).  The rocker has been removed from the base of all of them, so I need to go to the hardware store and find something to reconnect them at the pivot points.  I am dreaming of some perfect diameter aluminum rod with female threaded ends that allow me to screw bolts into it, perfectly attaching them for years of solid use.

In reality, I will more than likely have to engineer something less thrilling.  That's a task for tomorrow.

I have a short metal shaft 16mm 5k pot right now, so I'm going to go with it as I suddenly find that I really can't spare any change to go get other parts.  Luckily, I bought all of the plastic and rubber wah parts from small bear a number of years ago.  I have a couple other options sitting around if I run into serious issues.

Thanks for starting this thread, R.G.!  I have a feeling that I'll be back multiple times...

[Ry]

I found an error in the Wiring Guide that was the cause of yesterday's non-functional pedal.  On the left most side of the Console Board, the first three wire holes are for the power supply.  The problem is with the first hole.  This one is currently showing that it is connected to AC/DC1.  This is actually the power supply ground connection, currently shown in hole 3.

I currently have the leftmost hole connected to ground, then the second connected to +48v DC, and the third hole unpopulated.  And I also have a living, untuned Ludwig phase II!!!!     There are a few issues, one of the LEDs doesn't work and wow, it really needs to be tuned, but that's an adventure to start tomorrow.

And yes, the fuzz is wonderful!

[Keppy]

I have a short metal shaft 16mm 5k pot right now

That's what I used. Mine was a knurled shaft pot from Small Bear. It mounted just fine in my repurposed Rogue wah enclosure and accepted the shell's original gear.

And I also have a living, untuned Ludwig phase II!!!!    

Awesome! Congrats!

I keep meaning to re-tune mine & make another video...

[digi2t]

CONGRATS RY!! Welcome to the Ludwig Club.

As for tuning, I wrote this up not too long ago; http://www.diystompboxes.com/smfforum/index.php?topic=94478.0

I validated the process on both my units. This process does need the use of an oscilloscope, and a good DMM. But, with a DMM alone, you should be able to get into the ball park with the voltages alone. Please note; I'm assuming that the voltages from the originals will correspond with the clones. If you do use my numbers, please let me know how it goes. The video in the post is of a unit after tuning using the method I wrote up.

[pinkjimiphoton]

well done ry!!!!

definitely check out dino's tuning tutorial, but then spend a little time playing with the pots...you may find there's "sweet spots" on some of them.

i'm in pennsylvania at the moment, but have been using my ludwig at home a bit...and think the main difference between my pII and dino's is the tuning of the treadle...his is tuned if i recall so the "yoy" occurs at the top (toe down) of the treadle...mine is tuned to go PAST that, so that i have about 1/4 to 1/3rd more travel in the upper range. too much in the LOW range can make it get microphonic, which is pretty cool in it's way...but i can get past yoy and seem to get a yay as well.

keep us posted, and welcome, pioneer...you're now posessing the second pII ever cloned!! 

[R.G.]

I found an error in the Wiring Guide that was the cause of yesterday's non-functional pedal.  On the left most side of the Console Board, the first three wire holes are for the power supply.  The problem is with the first hole.  This one is currently showing that it is connected to AC/DC1.  This is actually the power supply ground connection, currently shown in hole 3.

Dang! I'll update the docos. I *did* tell you that you'd be a pioneer, didn't I? 

And I also have a living, untuned Ludwig phase II!!!!     There are a few issues, one of the LEDs doesn't work and wow, it really needs to be tuned, but that's an adventure to start tomorrow.

Which LED? It's always possible that it's another bug. But do check for the LED being turned 180 degrees in the hole. That's one of my favorite jokes to play on myself.

[R.G.]

Ludwig Phase II Clone buildit article updated at http://www.geofex.com with latest info.

http://geofex.com/Article_Folders/Ludwig_P2/Ludwig%20Phase%20II%20Clone.pdf

[Ry]

Thanks for all the comments, Keppy, Jimi, Dino, and R.G!  This is quite the club to be a pioneer in!

As for tuning, I wrote this up not too long ago; http://www.diystompboxes.com/smfforum/index.php?topic=94478.0

I validated the process on both my units. This process does need the use of an oscilloscope, and a good DMM. But, with a DMM alone, you should be able to get into the ball park with the voltages alone. Please note; I'm assuming that the voltages from the originals will correspond with the clones. If you do use my numbers, please let me know how it goes. The video in the post is of a unit after tuning using the method I wrote up.

Dino, I read through the tuning post over the weekend (and listened to the impressive demo).  Tuning will be my next stop this afternoon.  I have a couple DMMs and a couple scopes to chose from.  Unfortunately, my best scope only has one channel.  My dual channel one is an old stereo scope from the 80's (like a Techniques or something) that should work well for the low-speed oscillators in this pedal.

And I also have a living, untuned Ludwig phase II!!!!     There are a few issues, one of the LEDs doesn't work and wow, it really needs to be tuned, but that's an adventure to start tomorrow.
Which LED? It's always possible that it's another bug. But do check for the LED being turned 180 degrees in the hole. That's one of my favorite jokes to play on myself.

R.G., the non-functional LED is LED 8, connected to the Counter switch.  I need to buzz out the switch again, I had to ream out the pads for the board mounted switches quite a bit, I may have missed a connection when I had to route the traces with wire.  I also see that there is a jumper that it is connected to, I will double check it as well.

I went to the local hardware store with my empty Vox wah case and found that a #40 1/4 x 3 inch bolt will perfectly connect the base to the top foot pedal without any bolt slopping over the egdes of the base.  Now I can wire up the rocker pot correctly before I start tuning it in.

[Ry]

No worries about the LED, it was a shorted out part.  It was new from the baggie, I've never seen one fail, but I'm sure there are some cases of it.

[theehman]

Errors on BOM:

2.7K    R48- R70 should be R48-R63, R65-R70

47K    RF+3 should be deleted.  It's actually 68K (already listed there)

470K    RF32 should be R32

PNP EBC should all be QF instead of Q


PCB problems:

Holes for Q6 should be bigger

C12 should have the same footprint as C8


I may work up a spreadsheet with the parts I used so they can be easily ordered from Mouser.

[pinkjimiphoton]

ron, that would be awesome..
much easier than spending hours picking parts like always seems to happen to me 

despite having an original, i can't wait to get my hands on the ol' soldering iron and raise this phoenix.

[R.G.]

Errors on BOM:
2.7K    R48- R70 should be R48-R63, R65-R70
47K    RF+3 should be deleted.  It's actually 68K (already listed there)
470K    RF32 should be R32
PNP EBC should all be QF instead of Q

PCB problems:
Holes for Q6 should be bigger
C12 should have the same footprint as C8

Thanks for checking and posting. I'll go beat this against the documentation.

I may work up a spreadsheet with the parts I used so they can be easily ordered from Mouser.

That would be a nice thing to do for the guys who build their clones in the next month or so.

However, I have some experiences you may want to take note of. I used to provide Mouser part number lists for effects buildit writeups. I quit that because Mouser changes its suppliers and parts numbers on an ongoing basis as their stock shifts. I still get emails about Mouser not carrying this or that part number, since they've changed it since I did the listing. Sometimes these emails are for lists put together years ago. Nothing dies on the internet - it just becomes misinformation and lives on.

I concluded, sadly, that the only real answer was for people who build to learn to order whatever part number parts are available *now*. Maybe there ought to be warnings and expiration dates on ordering parts lists. That would still get you emails in a year or two saying that Mouser doesn't have X or Y, and could you look up the current number. 

[pinkjimiphoton]

lol....

rg....you're killing me. ordered stuff from mouser to build a clone(d) theory, right? went thru and tediously checked and shopped and bought the best stuff i could find.
made SURE it was STOCKED, and they had some...and paid electronically.

the stuff shows up a couple days later, and even THEN some of it ended up backordered.   

arrrrrrrrrrrrrgh...

but...

ya go thru the process, it gets easier, ya definitely learn more, and can find way better deals....i buy stuff for 6 cents that would cost a buck at rat shack.
these days, that's important.


now if only their computer could keep up with my mouse clickin'...lol

[R.G.]

OK, I got those bugs checked out.  We have definitely proved that I can't type and can't process lists. 

The parts list has been updated and the changes are on line at geofex.

The PCB problems are harder. For this board rev, they are what they are, so builders will have to cope with the hole sizes for Q6 and the capacitor body size for C12. They can be fixed on any hypothetical future PCBs (which might or might not ever be ordered).

For the Q6 holes: all the connections to the transistor are on the bottom/copper side, so through-PCB connections are not an issue. I recommend drilling out the holes a little to fit the transistor you get. Do this gently: don't drill away the pads.

For C12: The top/component side of the PCB is very tight there. That's probably why I didn't change the size. There are three options here.
1. Get a 47uF/50V cap in a 6mm or 6.3mm x 11mm long package; Mouser stocks several that fit. This cap is inside the 35V regulator, so the voltage won't go over 50V, and it'll work fine. I always put more voltage on the inputs of power supplies because of possible voltage transients on the supply. I don't know for sure that's what I was thinking (it was longer ago than yesterday  ) but it makes a good story, doesn't it?
2. Get a 47uF/63V cap in the 6.3mm x 11mm package. Mouser has fewer, but still several of these, notably:
647-UFW1J470MED
647-UVZ1J470MED
3. Use the 8mm size package and mount it on the bottom/copper side of the PCB.

[theehman]

For C12 I used the same 8mm size as the others mounted on top.  It fit fine, just a little narrow on the lead spacing.

[UKToecutter]

All

Please note:
There is an unmarked, unused resistor position next to and in parallel with RF33.

Andy

[UKToecutter]

R18, 120k 0.25W missing from BOM