Thomas Organ Cry Baby / UPDATE:

[plexi50]

It arrived this afternoon. I hooked it up and played with it for about 5 minutes before my phone went nuts again

Sounds nice. I like it. It has the CentraLab pot. Some numbers on the caps and board. As far as dating this all i know it is either earlier 70's or a little earlier

[plexi50]

I have noticed having more time to use this cry baby that it is horribly noisy. Scratchy when using the pedal function

Could this be attributed to the carbon comp resistors? I measured them and many are out of value by quit a margin

The Clairostat is Central lab and sealed  / Has anyone made any changes to theres to make it a smoother and less trebly pedal?

[sluckey]

You need to replace the pot. That's a common failure with a 40 year old wah. Even if you open it up and clean it, it will still be noisy. The pot is wore out, not dirty.

[plexi50]

Thanks. I saw it was sealed and opened it up enough to get cleaner inside a bit. Made no diff like you say. What about the paper foil caps? Should i leave well enough alone to retain its original spice? If i think about it with the pot being scratchy the way it is now i can not truly make any judgments about it's tone

Think i might try the fulltone pot. Not sure about anything just yet / Does Doug sell these?

[Bickster]

Plexi,

I have the same pedal.  I used Doug's wah pot and wired it true by-pass.  They are tone suckers without it!  It's butter now.  Won't leave home without it!

Bob

[plexi50]

Yeah i will have to do the bypass in the future when i get time. I cant wait to hear it with a new pot

[plexi50]

Got the new pot today. It is a supposed copy of the ICAR but this one has 200K value. Sorry i mean it has the 100K value.  / So far i dont like it.  Not as intense on the treble as the old pot. The Cry is not the same. But there is more adjusting to do on the gear travel so it may pan out later. For now it is installed and working much quieter. Still i have a slight wisp of noise. I didnt have time to use it with just a 9 volt battery to ruel out the PS as the source of the wisp. Got interupted. Could be the power supply i am using. It is one of those daisy chain PS off ebay rated at 2 ma. My Vibe and BD-2 are slighty noisy as well. I have to get back on that Radio Shack 3 amp power supply build

[plexi50]

I replaced 3 resistors checked out of circuit that were bad and also the caps were leaking like crazy

I went Rad Shack and got the (2).22 & .01 polyester film caps i needed / Man this wah is getting much better (SWEET)

I could not find a 3.9uf Tant to put in place of the black diode thingy

Very mellow with just the right amount of treble peak. No longer muddy at the heal position either

This is as close to Cream (The Band) as it gets for me. White Room is dead on

[Bickster]

Plexi,
I played around with the gear to get it in the range I liked.  The pot has more travel than the pedal.  Mine hates anything but 9v batteries.  It loves those!  I unplug it between sets.  I imagine that it has some leaky caps but I hate to mess with it's originalty.  Hopefully I can put a BYOC kit in a trashed wah I have and can leave the vintage one at home.  Just got to find the time.

Bob

[plexi50]

Time? Whats that? I wake up and before i know it it's 12:45 AM. Some thing is wrong. Father time needs to slow it down. I put the polyester film caps in and what a difference. It was so bad before with the original caps you could wave your hand over or touch the caps and it would hum like crazy. I may put the Panasonic caps in it it later but i am happy for sure with the tone it now has. Yeah my Wah prefers batteries too. But after i finish building a new power supply i expect it to be hum free. We will see.

[alerich]

I just bought my third Thomas Cry Baby this morning off of Craigslist. A nice Thomas Int'l Chicago pedal for $35. Now I have two of those (the other I have had since the late 70s or early 80s) and a Thomas Organ Sepulveda model which is what I am thinking yours is. Honestly, I could barely tell the difference between them totally stock. The Chicago pedals have the 03 "stack of dimes" inductor and the Sepelveda pedal has the TDK inductor like yours.

I had wired Grandpa (my old pedal) to true bypass some years ago and just tonight I got in it and changed a few resistor to increase the gain a touch and change the Q of the wah circuit. It sounds fine but now after reading your posts I may pickup some new caps and replace those, as well.

The pedals made in Sepulveda predate the ones made in Chicago. What is the serial number on the bottom plate?

[plexi50]

I just replaced the Central Lab pot because it was wore out and it is dated 1972. I have to do or get some more info on the best caps to use in this Wah. I again am not happy with the new Rad Shack film caps i put in last week. I am going back and forth on this but sooner or later i will get exactly what i want.  I am wondering if i should put the old paper and foil caps back in. I have a bunch of them so i can choose different ones other than the ones that came out of it. I dont know if the caps were actually bad. All i know is that if i touched them the signal would be interfered with and was noisy. Is this normal for these caps?

I will get you the serial number tommorrow

[alerich]

Since you found the original caps to be leaking they probably needed replaced. I've never had my wah connected while I had the cover plate off to do the touch test. People make a big deal about the different caps in these things. The earlier Vox pedals had these striped capacitors sometimes referred to as fish caps or something - maybe they look like Nemo.

I lowered the input resistor from 68K to 33K and lowered the resistor at the emitter of Q1 from 470 to 330. These mods together increase the gain and bass response a little bit. I guess it's a matter of taste but I like it. It's really not much - just a hint.

I bumped the 33K across the inductor up to 100K. Raising that resistor makes the wah effect a little more vocal and a little less "quacky" or trebly. Anything from 33K to 100K will work. Some of the old Clyde McCoy pedals had 100K there so I gave it a shot. Again, it's a matter of taste. I may tinker with that one a little more. Many players like the quacky tone of the Cry Baby since it cuts through the mix better in live settings.

You can also raise that 1K5 resistor to increase the mid range response a bit. None of these are my own ideas - I copped them from a wah website but so far I like the mods. I A/B'ed this pedal and my new unmodded Chicago pedal side by side and the difference is subtle but I like it.

These are my serial numbers:

Thomas Organ Sepulveda:  1919035
Thomas Int'l Chicago:        2073557  (unmodded)
Thmoas Int'l Chicago:        2078586   (modded)

There is no data available online that I can find that allows you to date the pedal via the serial number. Using component date codes like you did is a good idea. I can't see the pot date codes clearly without removing the pots and I don't want to know badly enough to disturb them.

**Edited to correct my resistor multipliers.**
 

[plexi50]

This is my serial number. I could not see the numbers on the Central Lab pot to date it until i removed it to put a new on in it

Is there a way to test my TDK inductor to see if it is good?

The pedal seems to have lost some of it's gain and the wah effect is not as detailed

[alerich]

If the wah is working I would think that the inductor is operating properly. Could it be compromised? I suppose so. I wouldn't know how to test them except to do a continuity check. Some guy on eBay sells a Dunlop reissue Fasel inductor for $17 shipped. Dunno that the TDK or Stack of Dimes inductors are any longer available. Dunlop also sells a replacement pot. Never tried them. Amazingly all three of mine are quiet.

Short of confirming that all of your component values are in spec and the caps are not leaking (it's a pretty simple circuit) you may want to check this site out:

http://www.wah-wah.co.uk/

That's where I read about those mods. It's under the DIY section. Also has instructions to rewire it true bypass if it has not been already if you wish. Some people call these tone suckers without the true bypass mod but I think the gain is extremely modest. It makes a difference but it's not night and day at least not to my ears. The cumulative benefits of the true bypass mod and the resistor changes I made it a nice improvement. Any of them alone is very slight.

I also change out those el cheapo jacks for Switchcraft jacks.

[sluckey]

Is there a way to test my TDK inductor to see if it is good?

There's nothing to go bad. If it's working, I'd quit trying to 'fix' it.

I did one simple, reversible mod to my pedal. I added a filter stage to the B+ line so it would work well with my pedal board power supply. My pedal is mounted on the board. I didn't drill any holes just in case I may want to sell this thing someday.

[alerich]

Lord Valve on the Usenet alt.guitar.amps newsgroup sells a wah pedal replacement pot. No big deal - lots of folks sell them. One day he was describing the pot to someone in the group who needed a replacement and said "It is guaranteed for 150,000 revolutions or two and half renditions of "The Theme From Shaft" - whichever comes first". It's one of the few times I actually spit a drink on my monitor.

[sluckey]

LV had a style that I liked. He had a lot of funny stuff like that. I really enjoyed his touts with his "bottom feeders and ankle-biters".

[alerich]

sluckey - what is the purpose of the 1N4148 diode in that filter circuit?

[plexi50]

Just put the old caps back in and WOW! again. I quess i should have left them in the Wah and made a tone judgement after changing the pot

My friend concurs the huge and beautiful difference

There is so much crap info on this pedal about what is good and bad about it. At this point i know first hand for my self that it needs to be left alone as working like you said Steve. I can get wrapped up in trying a bunch of different ideas out. In this instance the end result is (If it works leave it alone)

IMO i should have installed the new pot before going on a witch hunt. Am i a witch? Scrap that question:

[sluckey]

what is the purpose of the 1N4148 diode in that filter circuit?

It will protect the circuit from a reverse polarity power supply or battery. It works with the 1K resistor. The diode never conducts if the battery polarity is correct, but will be forward biased if the battery is reversed, dumping all 9 volts across the 1K resistor. The diode is a very fast switching diode, so if someone accidentally tries to connect the battery backwards, hopefully the diode is fast enough to protect the circuit.

Years ago when I was modding my pedal to work with my 9 volt power supply, I had to add a pi filter to kill the hum from the pedal when operating on the power supply. There is no filter cap in the stock pedal, and that's fine for battery operation, but it needed something extra to be hum free on the power supply. Anyhow, I ran across a couple schematics (see attachments) with the diode and 1K on the B+ line and decided to incorporate into my mod.

EDIT... BTW, my pedal is model 95-910511, sn 1923744. I bought it new in late '71 or early '72 along with a Walnut Gibson 335.

[plexi50]

Sluckey have you seen this pic before? They have replaced the diode all together with this 3.9 Tant cap. It is said to further improve the tone. No specifics

[sluckey]

Sluckey have you seen this pic before? They have replaced the diode all together with this 3.9 Tant cap. It is said to further improve the tone. No specifics

That component was never a diode. It's always been a cap. My cap is a black, bullet shaped plastic encased cap, just like the one in the very first pic you posted in this thread.

[alerich]

As sluckey said that position has always been 4uf capacitor. The diode is not part of the circuit in Thomas pedals. Never was. That's something that was added to the design after Dunlop began manufacturing them. Both of my Chicago pedals have the orange cap. The Sepulveda pedal has a small silver cap. Both of your pedals have the black bullet style cap. I've seen Dunlop boards with the added diode/1K resistor as part of the circuit. Dunlop also added a buffer stage at the input of the pedal. A Dunlop board has 3 transistors.

I think the diode/1K was added by Dunlop because Thomas pedals never had a 9VDC adapter jack and it's kinda tough to install a 9V battery backwards. With the advent of the 9VDC adapter jack the diode/1K was probably added for protection by Dunlop. Good idea.

[sluckey]

and it's kinda tough to install a 9V battery backwards.

That's true. But, on a dim lit stage it's very easy to touch a battery to the connector the wrong way before you finally get it to snap in correctly. And if your guitar is plugged in, the battery hits the circuit. It doesn't take long to do damage to a ss device.

[plexi50]

I keep forgetting to post this but i still have a problem with wispy noise while rotation of the NEW pot occurs.

I am using a 9 volt battery.  Any clues?

[sluckey]

That may be normal. You don't notice it when you are playing guitar thru it, do you?

[plexi50]

Ok let me revise the noise i am hearing. It is not noise from the pots rotation or the carbon wiper. It is white noise when i reach the treble peak position on the pedal. If i leave it at that position it sounds like and amp just hissing. Like some amps sound when turned up all the way with no signal input. Hissssssss Maybe this is normal but it is annoying. Yes while i play the guitar there is more hiss at the toe positon that comes through with the guitar signal

I wonder if those foil caps are shot. They sound great but if you pass your hand over them you get a humm
Maybe there picking up some frequency some where inside the pedal. No radio interference

[plexi50]

Ok let me revise the noise i am hearing. It is not noise from the pots rotation or the carbon wiper. It is white noise when i reach the treble peak position on the pedal. If i leave it at that position it sounds like and amp just hissing. Like some amps sound when turned up all the way with no signal input. Hissssssss Maybe this is normal but it is annoying. Yes while i play the guitar there is more hiss at the toe positon that comes through with the guitar signal

I wonder if those foil caps are shot. They sound great but if you pass your hand over them you get a humm
Maybe there picking up some frequency some where inside the pedal. No radio interference
[/unquote]

Dont know if i can unquote myself but im trying. You know me!

Ok after 20 minutes of nit picking the crybaby the hiss is normal. But there is definatley a spot on the pot right on the edge of the treble peak where there is in FACT a scratchy position. Dam this pot is new too.

I just sprayed some cleaner in the pot and the scratch is gone.!

[tubenit]

Ironically, I just discovered this thread this recent week.  AND ............ I have the exact model  Crybaby as Sluckey does.

I am going to add a 9 volt supply jack and a true bypass to mine also.

I am attaching some more info about this pedal to this thread.  One of these photos showing the power supply jack and filtering is Sluckeys.

With respect, Tubenit

[alerich]

Since my last visit to this thread I have built a Weeping Willow wah pedal kit from Mammoth Electronics. Bomber Orange paint job. I have three pre-Dunlop Thomas Organ Cry Baby pedals. An early 70's Sepulveda pedal and a late 70's and and early 80's each from Chicago. I bought the early 80's pedal new and it had been my go to pedal for years. I had added true bypass and a few minor mods to increase the gain a touch and make the pedal less "quacky" and more vocal. Personal preference on both of those and the changes are very subtle. I also added true bypass to the Sepulveda pedal.

Having said all of that, in side by side A/B testing of the Mammoth pedal with each of the Thomas pedals I could discern little if any difference between them i.e. the kit pedal sounds just as good as the originals. I have since retired my vintage Thomas Organ Cry Baby pedals and Big Orange is now my go to pedal. The kit pedal includes a DC power jack which is a big plus.

[tubenit]

Useful links:

http://customguitarprojects.co.uk/?page_id=1034

http://www.geofex.com/article_folders/wahpedl/wahped.htm#basicmod

http://www.freestompboxes.org/viewtopic.php?f=19&t=24760

Input jack is easily understood.  Input circuit means where the input jack attaches to the input board.

So you instead send the input jack to the 3DPDT in the "middle".  There is sort of a pole/prong where the input jack attaches to the board.  And on that same prong, the wire goes to the 3DPDT on the "top"

[tubenit]

This is "sort of" my original crybaby.  Obviously, I replaced components on the board and had to put in a new 9 volt battery wiring.

Compare this with Sluckey's original crybaby which is the same model.  The wiring colors are a little different in appearance.

On the original switch,  white= output jack,    green =  input jack,    blue = to pot

[shooter]

I have a '78 Thomas on the bench, all original, the input jack is shot, the pot is questionable, I surfed and read, and get the sense this is a band pass filter *tuned* about 800hz.
The question I have;
when I play through it, it wah'zd, but it is mono-tone boring, like a history prof with NO inflection in their voice, is this a normal thing?

Thanks

[tubenit]

Not sure what you are describing with mono-tone?   

My pedal has a pretty wide bandwidth of vowel tone from quite trebly to a muted bass sound.

With respect, Tubenit

[sluckey]

when I play through it, it wah'zd, but it is mono-tone boring, like a history prof with NO inflection in their voice, is this a normal thing?

Let Mike Scaggs kick it a bit. I bet he can get it talking right.   

[shooter]

pretty wide bandwidth of vowel tone

It's up next, hopefully this weekend.  I want to scope it through a range of freq's because there is NO trebly, No bass, just this flat, lifeless wah sound.

Let Mike Scaggs kick it a bit

If Mike can squeeze good sound from this pedal, I might ask if he can walk on water also

[sluckey]

That rack and pinion gear does not drive the pot from one extreme to the other. Maybe just a slight mechanical adjustment is needed?

Try this... Totally disengage the gears. Now manually turn the pot shaft from end to end. Do you have a usable range of tones anywhere between rotation extremes?

[shooter]

usable range of tones

I was thinking just that after talking with the customer, he said tone wasn't an issue, and when I was initially testing things I did mark the pot, dis-engage it and sweep it with a meter hooked up.  It did have jumps n bumps as I moved it end to end.  I did get approval to order parts, including a pot.  probably be 5or6 days til I get parts, I will be stealing the true bypass from this thread  

Thanks for your help

dave

[shooter]

Got the pedal working, I guess.  Swapped both in and out jacks, pot, and changed switch to DPDT, wired per Doug’s *true-bypass*, which works.

Started with a sine wave, the circuit kept it very clean, moved to sin swept, from 200 to 2K, here’s my #’s;

Pedal in the *toe* position;
Input 120mVrms
200hz 70mVrms
800hz 1.4Vrms  (signal out max)
2Khz 100mVrms

Pedal in *heal* position
Input 120mVrms
200hz 100mVrms
480hz 1.7Vrms  (signal out max)
2Khz 30mVrms

Sine wave stays clean throughout the sweep.  So until the customer gives it a test drive I’m done, unless someone here see’s something that I’m missing, since I’m clue-less on *normal*  WAH (ya, I hear wahwah).

I did, for fun, change to sawtooth swept, the circuit did a nice job of converting to sin-wave, as it swept, though the leading edge would fold in about 80% up the slope, then start painting the downslope *early* while the original wave continued on also, creating 2 waves, shifted in time by 10% or so.  When I changed to square wave sweep, things got way hinky!

[super&plexi]

I thought I replied to this awhile back but I was just rereading and... doesn't anybody use a stereo Jack on the input and run power on the ring? You may have to make a connection from +_--  battery clip inside, but that's easy enough with another  battery clip with its Leads tied together, then clipped in place of the battery for continuity

Oh and for anyone new to wahs, and nodding  and adjusting them, one of the most important things to watch out for is not breaking a tooth off once you've adjusted the travel. If you adjust it for maximum travel but it's not depressed all the way ( past the on off click) when you step on it you'll probably shear a tooth off. The gear attached to the pot usually holds out but the vertical gear shaft that attaches to the treadle will probably lose a tooth at least maybe two. At least if you do make the  mistake you'll remember the rest of your life. I know I have.