Italian Jen Cry Baby - Drop in Volume and Bass when engaged

[sohosteve]

Hi there
My Jen Cry Baby pedal, which has been modded to true bypass has seemingly just developed a fault.
First the switch seemed to die, so I replaced it.
Now it seems to suck all the bass out of the tone when engaged and there is a noticeable volume drop - not massive - but enough to take my sound from big and fruity to thin and slightly lack lustre.
Any helpful suggestions?
I must mention that though I am not electronically literate (I can't read a circuit diagram and don't know a micro farad from a kilohertz) I can meticulously remove and substitute components if pointed in the right direction and I can usually recognise the difference between a resistor, cap or diode.
If anyone can help me restore my much loved Wah to it's former glory I'd be very grateful.
Here is a shot of it's circuit

[Jazz P Bass]

Any chance that you repositioned the rack while repairing it?

It makes no sense that changing the switch goofed with the tone.

[52 Bill]

It makes no sense that changing the switch goofed with the tone.

Unless the switch is bad or dirty. Try cleaning it with some DeoxIt.

[sohosteve]

Unless the switch is bad or dirty. Try cleaning it with some DeoxIt.

No I didn't move the rack - though I have since tried that to see if having a different sweep would help.
It's a brand new good quality switch but I'll try some Deoxit just in case.
Actually I wonder if a component is dying as I had it wired to True Bypass before and as I didn't have a battery I taped up a connection to my 9v psu.
And it was working great like that for several hours.
Then suddenly, when I switched on the wah to use it the signal disappeared.
So I switched it off - nasty crunching with signal cutting in and out. Then the signal came back briefly - clicked the switch again and it totally died - whether it was switched on or off.
When I opened it up the connection of the 9v across the battery clip had come adrift. So I reconnected it. Still dead.
So I figured the switch had died.
Put in a new switch and now it seems like some of the guts go out of the sound when the wah is on - so I wonder if my amateur 9v connection hurt a component when it became disconnected.
But when I researched Wah Volume Drop - a Google search threw up loads of info about how wiring a vintage style wah often causes a volume drop and it either needs a different value cap or a different value input resistor.
Or possibly both...
So I figured I would try a mod to see if that resolves the problem....

[52 Bill]

So I figured I would try a mod to see if that resolves the problem....

Modding a broken pedal, may or may not fix it. What it will do is confuse the issue and make the actual repair more difficult.

If it was working fine before, then fix it to make it sound that way again. Then you can mod it to see if it gets even better.

[Mick Bailey]

What it will do is confuse the issue and make the actual repair more difficult.

The man who chases two rabbits catches neither.

[Jazz P Bass]

Flip the circuit board over & have a look at all of the connections.

Solder connections that look suspect can be reflowed at this time.

[sohosteve]

Thanks for all your advice.
Just got back from having it checked out by an engineer and apparently it's 'working as it should'.
There are no dry solder joints, the switch is clean and there are no burned out components.
He seemed to think my problem is 'caused by changing the design' in making it true bypass
I was certain it sounded better before but maybe I'm suffering from a case of 'the past always being better' syndrome - now I'm starting to doubt my own judgement...
Anyway, it definitely has a slight drop in volume and has absolutely no bass when engaged - I've been using Wah pedals for forty years so am aware that the frequency is changed but this seems far too extreme at present.
So can someone lead me (graphically as I can't read a circuit board) to which is the input resistor to change (with suggested values) to fix the volume drop and which capacitor (with suggested replacement values) to help counteract the lack of low frequencies?
Thanks

Modding a broken pedal, may or may not fix it. What it will do is confuse the issue and make the actual repair more difficult.

If it was working fine before, then fix it to make it sound that way again. Then you can mod it to see if it gets even better.

[52 Bill]

Just got back from having it checked out by an engineer and apparently it's 'working as it should'. There are no dry solder joints, the switch is clean and there are no burned out components. He seemed to think my problem is 'caused by changing the design' in making it true bypass

Well, logically that makes absolutely no sense. Making the switch true bypass would not change the way the effect circuit worked unless the switch was wired horribly incorrectly. The input still connects to the input and the output still connects to the output. Did you add bleeder resistors to the circuit? If you did, what value did you use?

Anyway, it definitely has a slight drop in volume...

A slight drop in volume is fairly normal with this circuit. Before the failure was the volume drop a problem? Many people will change the emitter resistor of the first transistor from a 470R to a 390R value. This is the first resistor at the lower left hand corner of your photo (yellow-violet-brown).

...has absolutely no bass when engaged - I've been using Wah pedals for forty years so am aware that the frequency is changed but this seems far too extreme at present.

When you first switch on the pedal and the treadle is in the downward position the pedal is in the brightest mode, which will attenuate the low frequencies and give a sound similar to a treble booster. As you sweep the pedal backwards, the sound should thicken up as the high frequencies are phase canceled out via the feedback from the pot. Is the pedal too bright when first switched on or too bright when the pedal is swept back or both? When you sweep the pot back, do you hear a change in the sound?

If the problem is always there, the caps to check are the input cap or the LCR filter cap. If the problem is with the sweep range, then the cap to check is the feedback cap. The input and feedback caps are both 0.01uF caps and if they have drifted low in value, they can change the frequency range of the pedal. The LCR filter cap is the 4uF non-polarized electrolytic.

The two 0.22uF coupling caps could also cause a problem, but they would really have to change value to make a big difference in the tone of the pedal.

[Audiotexan]

Then suddenly, when I switched on the wah to use it the signal disappeared.
So I switched it off - nasty crunching with signal cutting in and out. Then the signal came back briefly - clicked the switch again and it totally died - whether it was switched on or off.
When I opened it up the connection of the 9v across the battery clip had come adrift. So I reconnected it. Still dead.
So I figured the switch had died.
Put in a new switch and now it seems like some of the guts go out of the sound when the wah is on - so I wonder if my amateur 9v connection hurt a component when it became disconnected.

A strong possibility (which throws me given what you wrote further below).
Depends on where the connection was, and how it 'flopped around' while it was loose inside (and most importantly, what it happened to conact while being moved and a 'live circuit'/engaged)
Was the fix for a bad 9v wire in the middle of the wiring (near the circuit board?) or closer to the battery, or AT the battery connector itself? Is there a battery holder? Was it in the battery holder when you removed the cover and found the loose connection?

Given that you later stated that you had the engineer check it out...I'm guessing that nothing was damaged since he said it was "working as it should".
If that's the case, you got extremely lucky!!

Just as an FYI, I'd recommend finding a local electronics hobby shop, and investing a small amount in some heat shrink tubing!
It's not uncommon to have battery cable issues in stomp boxes, and while that's always an easy fix, NEVER use electrical tape, or wire nuts either, as IMO/IME given the mobility and banging around that most pedals take, eventually those nuts come off, and heat moves the electrical tape. Either way renders a heavy chance of ending up with a live B+ wiggling around waiting to torch your unit.

Just got back from having it checked out by an engineer and apparently it's 'working as it should'.

He seemed to think my problem is 'caused by changing the design' in making it true bypass
I was certain it sounded better before but maybe I'm suffering from a case of 'the past always being better' syndrome - now I'm starting to doubt my own judgement...
Anyway, it definitely has a slight drop in volume and has absolutely no bass when engaged - I've been using Wah pedals for forty years so am aware that the frequency is changed but this seems far too extreme at present.
So can someone lead me (graphically as I can't read a circuit board) to which is the input resistor to change (with suggested values) to fix the volume drop and which capacitor (with suggested replacement values) to help counteract the lack of low frequencies?

Yeah, I can relate to memories getting fuzzy.. and I'm inclined to believe that's (mostly) the case here. Barring an error in your 'true bypass mod'.
It's easy to 'forget a bit' when something's been shelved a bit (whether days or weeks)..even more so the older I get it seems.

At any rate, I wouldn't go redesigning the circuit before triple checking the bypass mod.
It's easy to look at something a few times, and still miss the trees for the forest.
Then you look at it that third or fourth time, and go "WOW. How'd I miss that??"
(Recent cases in point, a '75 script logo...or in my own backyard: an Ibanez AD9 delay) lol

Well, logically that makes absolutely no sense. Making the switch true bypass would not change the way the effect circuit worked unless the switch was wired horribly incorrectly. The input still connects to the input and the output still connects to the output. Did you add bleeder resistors to the circuit? If you did, what value did you use?

Given his admitted level of experience in electronics, I doubt he applied (or even knows about bleeder resistors) -no slight to soho whatsoever...just trying to keep it 'inexperienced friendly'!

But I wanted to note, changing to true bypass can definitely affect "the way the circuit worked"...
(and rather than put my own wording since Mark covered it so nicely

Note that not all vintage pedals take to true-bypass equally well. Many DO, but often the output stage (which is what is switched in the pre-1980's type pedal) is predicated on how much passive loss there will be due to the input of the effect always being connected to the input jack. The result is that bypass (when converted to TB) can be louder than effect mode. That's not such a problem when the effect itself provides some gain and an output level control, as is true with the Dynacomp, but for many things like phasers (which rarely come with an output level control), there may be a need, following TB conversion, to mod the output stage in order to achieve bypass/effect volume balance.

And I'm betting this is where soho's thinking spawned from, which would be a reasonable leap (given the volume change). A straight one to one switch exchange would NOT change the audio frequency (tone) aspects of a pedal. Which is what I believe 52 Bill was trying to convey. That is another issue altogether.

First question, was the switch identical (at least mechanically)? (pinout)
-Most TB are 3x3 layouts, and orientation is critical!
Were the wires done one at a time to the exact same locations? (ideally*)
Or were they 'drawn out' on scrap paper, the old switch removed, and the the new one installed according to the notes.? (always leaves room for errors, either in the drawing or wiring itself)

The * method seems to reduce chances of errors orders of magnitude FWIW!

When you first switch on the pedal and the treadle is in the downward position the pedal is in the brightest mode, which will attenuate the low frequencies and give a sound similar to a treble booster. As you sweep the pedal backwards, the sound should thicken up as the high frequencies are phase canceled out via the feedback from the pot. Is the pedal too bright when first switched on or too bright when the pedal is swept back or both? When you sweep the pot back, do you hear a change in the sound?

I'm with 52Bill here... if the thing is currently working, but the frequency has shifted (to being more treble)..I'd check the black plastic piece going from the treadle to the potentiometer, and perhaps reposition that (the interaction between the toothed piece, and the receiving teeth on the pot is what sets the 'Q' point [or frequency target]). Perhaps it jumped some teeth during the previous work session(s) and is now in a sweep position in the higher frequency range (hence the loss of bass).

Regards,
Audiotexan

[sohosteve]

Phew!!
I'm taken aback by the responses here - you are a fantastic bunch!
Thank-you everybody for your input - please excuse me not replying to each of you personally - there is a hell of a lot for me to take on board but I will try to cover all the questions - sorry if I don't manage them all though!

I suspect that what was meant by 'changing the design of the circuit' was including the switch as part of the circuit.
Which is the principle reason people want to add true bypass to these pedals - they 'tone suck' so badly when sticking to the original (non true bypass) circuit that you compensate by adding volume and juicing up the tone at the amp to counteract the treble/bass/volume drop to the dry signal.
With this original (un-modified to TB) circuit - when the pedal is engaged it gives more of a balanced changeover.
By bypassing the circuit altogether when in the 'off' position you can set your amp in your usual way.
However when the circuit is engaged you are suddenly made fully aware of the inadequacies of the circuit's design - volume drop and 'guts' missing from the sound as this is NOT how the pedal was originally designed.
Trawling the internet there are countless comments to be found verifying this - so at least I am comforted to find out that it is not just me or my pedal.
When I said 'using a wah for forty years' I was trying to convey that I have a good idea of how a wah usually sounds (yes, I know they all have their own characters dependent on their pot/how the treadle is set/which year/fasel or if Coloursound, Vox, or Morley etc etc etc) and that I'm not on my first wah and shocked to find out that it's full treble when all the way down! ;-)
I have made numerous adjustments to the treadle to find a 'sweet spot' that suits my preferred foot movements and the pot is one of the excellent McCon-O-Wah pots - the best replacement I've found so far.
My dodgy PSU lash up was a temporary measure to use the wah on a home recording as I didn't have a battery handy - it didn't do any travelling and is not the way I would wire anything up for a professional engagement!
It was sitting in the same position on my carpet for the duration of it's use and I had taped the output from a 9v Boss style PSU across the battery clip connections to record with it. When it stopped working (probably due to the switch wearing out - cheap Chinese rubbish) I opened up the pedal and discovered that the tape had lost it's grip (due to rare sunny weather in London no doubt) and the PSU connection had become detached from the battery clip. However, this may have happened when I actually opened up the pedal - & not while it was in use as I feared - I have no way of finding out but it would appear the components are fine and I'm just suffering from the same affliction that countless others have encountered when wiring one of these vintage wahs to TB - They were not designed to be wired that way. I suspect that if they designed it as TB from the off they would have used some different component values to fix the volume drop and allow a little more weight through.
So....
Back to my original question, 52 Bill has already kindly pointed me in the right direction for the resistor change.
Now could someone please describe (in graphic terms) which cap to change to which value to allow more bass through?
I did find this on another forum but haven't a clue (due to being electronically challenged) where to find this component
"Looks like you could change the first capacitor on the input side to a .1uF or maybe a bit larger to let more bass pass through the circuit." - this was referring to a Jen Super Cry Baby - probably a slightly different design - though I'd guess, fairly similar

52 Bill also suggested "If the problem is always there, the caps to check are the input cap or the LCR filter cap. If the problem is with the sweep range ((The problem is NOT with the sweep range)), then the cap to check is the feedback cap. The input and feedback caps are both 0.01uF caps and if they have drifted low in value, they can change the frequency range of the pedal. The LCR filter cap is the 4uF non-polarized electrolytic.
The two 0.22uF coupling caps could also cause a problem, but they would really have to change value to make a big difference in the tone of the pedal."

I'm not sure if some of these suggestions are similar to the chap on the other forum with different terminology or totally different ideas.

Could someone please help with a "change the sky blue pink capacitor that is third from the left to either an 11, 1.3 or 13 nano farad myxomatosis-minor" kind of description so that I can order the new values and swap them out?

Thanks again for being such a wonderful helpful bunch and I apologise for my lack of electronic nous and dreadful sense of humour!

This is the True Bypass wiring

And this is how is connects to the circuit

[52 Bill]

Phew!!

I've been pondering how to reply to your last post. Up until now, I have been trying to get you to give us all of the information that we need to help you repair your pedal and to explain how the circuit works, so that you could figure out where the problem might be.

Let me ask this, did this pedal ever sound right to you? If the answer is yes, then the pedal is broken and needs to be repaired. If the answer is no, then the pedal needs to be modified to make you happy.

Did it ever sound right to you after you installed the true bypass switch? If the answer is no, then there is a problem with the switch or wiring that needs to be repaired. If the answer is yes, then there is a problem with the circuit on the pc board.

Not having memorized all of the different circuit board layouts of all of the wah pedals made in the last 45 years, I find it difficult to directly advise you as to which component to replace. The first stage emitter resistor is the only one of that value, so I could go out on a limb and guess which one it was.

The fast solution to your problem will probably be to replace all of the coupling caps on the pc board. So get 2-0.22uF and 2-0.01uF film caps and replace the ones on the board and see if the pedal works correctly again.

Good luck.

[sohosteve]

As previously stated, I'm now starting to wonder. It may just be my failing memory playing tricks with me regarding it not sounding as good as I thought it 'had'.
It could well be because I'm using it with an amp that I'm less familiar with that has less pre-gain - so the sound is not so compressed.
Maybe the more distorted and compressed sound of my old amp masked the volume and tone drop - it is, as already mentioned, not huge, though currently noticeable.
It switches on, it 'wahs' as I use the pedal - it sounds exactly like a wah pedal should. Except when I compare it to the bypassed tone.
The innumerable posts on the web of other wah users with the self same problem lead me I believe that it could sound better.
ie without a level drop when engaged. And with a little more 'weight' to the sound when rocked backward.
I'm pretty sure that if I reverted back to the original switch, the transition between on and off would be similar - the obvious downside to that 'fix' is that it gave me a rubbish so

As for it needing to be repaired - I took it to a tech to do just that - he works repairing amps and pedals for pro musos on a daily basis and he's the one who told me that it's working fine. Which is why I've come to the conclusion that it needs modifying in the self same way so many others have modified theirs - different value input resistor to fix the volume drop and possibly the "Looks like you could change the first capacitor on the input side to a .1uF or maybe a bit larger to let more bass pass through the circuit. That's a cheap and easy" modification mentioned by a chap on another forum.

If I actually knew which was the 'first capacitor' I'd order a couple and try that - though I also have no reference point to know what beyond a .1uF I'd need to order to make it 'a bit larger'...

I've been pondering how to reply to your last post. Up until now, I have been trying to get you to give us all of the information that we need to help you repair your pedal and to explain how the circuit works, so that you could figure out where the problem might be.

Let me ask this, did this pedal ever sound right to you? If the answer is yes, then the pedal is broken and needs to be repaired. If the answer is no, then the pedal needs to be modified to make you happy.

Did it ever sound right to you after you installed the true bypass switch? If the answer is no, then there is a problem with the switch or wiring that needs to be repaired. If the answer is yes, then there is a problem with the circuit on the pc board.

Not having memorized all of the different circuit board layouts of all of the wah pedals made in the last 45 years, I find it difficult to directly advise you as to which component to replace. The first stage emitter resistor is the only one of that value, so I could go out on a limb and guess which one it was.

The fast solution to your problem will probably be to replace all of the coupling caps on the pc board. So get 2-0.22uF and 2-0.01uF film caps and replace the ones on the board and see if the pedal works correctly again.

Good luck.

[52 Bill]

I guess you didn't get my subtle hint about not knowing the parts layout of your particular wah. And being a lazy sot I didn't want to have to search the web to find a photo, so I have pulled out my own Jen made Cry Baby and have pulled the board to find out exactly which cap you should change.

The blue green Arco cap that is to the left side of the inductor (the big red round thingie that is marked FASEL), is the input cap. Try replacing that one with one that has a larger value than the original 0.01uF.

[sohosteve]

Actually I did see that and have been trawling the net to try to find a suitable schematic that matches the exact design of my circuit.
Though you didn't need to drag out your Cry Baby as there is a high resolution photo in my initial post if you scroll to the top of this page
I'm not sure if this is totally accurate but it's the 'best' I could find

Also just saw this on the diyguitarist site

"When it comes to vintage wah pedals, they almost always show a major improvement when true bypassed since the "tone sucking" is pretty bad in a typical non-true bypass vintage wah pedal. It can be a little tricky to match bypassed and effected levels after true bypassing, but a little tweaking of the input resistor, and if required, the resistor on the emitter of the first transistor will usually resolve that problem without changing the tone too much. The tone will usually change somewhat after true bypassing. 
"

I guess you didn't get my subtle hint about not knowing the parts layout of your particular wah. And being a lazy sot I didn't want to have to search the web to find a photo, so I have pulled out my own Jen made Cry Baby and have pulled the board to find out exactly which cap you should change.

The blue green Arco cap that is to the left side of the inductor (the big red round thingie that is marked FASEL), is the input cap. Try replacing that one with one that has a larger value than the original 0.01uF.