Sanity check for Dunlop 535Q Mods

[duck_arse]

on your cap and resistor switch schem, you can remove 1 of those 5M resistors. I leave it to you to work out why.

that dime wah leds business - all that extra gunk you have circled is a fairly standard boss/dod style soft bypass and flip-flop, using the fets to switch the audio. some more reading for you there, and you might need to redraw that circuit snippet.

do your cores have any markings on? can you show a photo of? I've got some saved data on odd/old ferrite parts might help. do you know how many turns you put on for those indutances you posted earlier? - they make v. good data points.

about them beers - I've been a non-beer drinker for a while now, took up (pear) cider instead. but, line up a few flavours of beers, and I might take a swing at them.

[PRR]

> SWG - gah!

Antique gauge systems are the BEST. Three cheers for three (different) Imperial Yards!

> only managed 400uH. 400mH is a long way off.

You need 1,000 times the Henries, so you need sqrt(1000) or 31.6 times as many turns.

If the core is getting full, you need wire of 1/32 the area, 0.18 times the diameter.

> 25 SWG wire
> 32 SWG wire

SWG is not-quite AWG but IIRC they are close.

#25 AWG is 0.018" diameter.

#32 AWG is 0.008" diameter.

By the calculation above, if #25 gives 400uH and you want 400mH, 0.018" * 0.18 = 0.003,2" is the diameter you want.

Smaller than #32.

#40 AWG appears to be just-right (0.003,1").

You will not find #40 in motors, power transformers, or even relays. The best source may be guitar pickups.

[navin]

on your cap and resistor switch schem, you can remove 1 of those 5M resistors. I leave it to you to work out why.

that dime wah leds business - all that extra gunk you have circled is a fairly standard boss/dod style soft bypass and flip-flop, using the fets to switch the audio. some more reading for you there, and you might need to redraw that circuit snippet.

do your cores have any markings on? can you show a photo of? I've got some saved data on odd/old ferrite parts might help. do you know how many turns you put on for those indutances you posted earlier? - they make v. good data points.

about them beers - I've been a non-beer drinker for a while now, took up (pear) cider instead. but, line up a few flavours of beers, and I might take a swing at them.

oops yes we can short the 5Mohm resistor between 3.8nf and 1.2nf.

I think I will have to wait till I get the 535Q in hand to check if I can boot-strap these components on to the PCB. There seem to several versions of the 535Q and at least one of them shares a common PCB with the Dimebag wah.



I don't know if one can really add (using a vero board) the on/off schematic (green LED) to an existing wah. It is all a bit complicated with the BJT and FETs used just to indicate if the wah is on or off.  The boost indicator (red LED) scheme is simpler. Maybe I can vero-board that and accommodate that (replacing the single pole SW2 with a double pole SW2).
Any idea where on the 535Q PCB is the Udd (100 ohm resistor and 220uf cap)?
Also where can I find a 2pole 2 way switch similar to the boost switch used on the 535Q? Dunlop wont sell them will they?

meanwhile I found this thread and some fantastic work by various members. Too bad so many pictures have broken links especially all of Güero's work.
http://www.diystompboxes.com/smfforum/index.php?topic=93036.60
and this one
http://stamp.zakupka.com/p/3517516-wah-wah-dunlop-crybaby-original-gcb-95-stamp-mod/

Thank you PRR on the 40SWG tip. Sorry about using SWG and not mm or AWG. I'll convert next time.

There are a few more tips here
http://www.wah-wah.co.uk/diy.html
To compensate for true bypass mod loss they say we can try this:
1. Replace 470 ohms resistor in emitter of Q1 with 330 ohms to increase gain and bass a little
2. Replace 68k input resistor with 47k (or 51k) resistor to increase output slightly

[duck_arse]

let me also say - AWG - gah! it is only my opinion, but when a wire is specified as 0.00001 mm, I know it is a smaller diameter than one specced 0.31415926 mm.  and if specced in inches, odd tho they are, I still know a number to use in the conversion to mm.

navin - your resistor string - if you short your nominated resistor, 1n2 and 3n9 will be permanently 5n1. those switch spots will be no difference ie wasted. we are looking to remove one of the string.

as for Udd, it is more often called Vcc, as in Volts for the collectors. and seeing as the resistor connects hard to 9V, internal and external, you only need to follow the positive supply wire to the board, find what the first parts connecting to it are, and if it is 100R, that's probably the one you want.

the on/off green led is not the purpose of that switching junk. all that stuff controls/remembers state for the fets, to direct the BP or FX_out to the output buffer, thence out. you get the led indication extra free. kinda. you could probably just use another dpdt switch to select buffer or not AND switch the indication led.

what does that boost switch look like?

[PRR]

> my opinion, but when a wire is specified as 0.00001 mm, I know it is a smaller diameter than one specced 0.31415926 mm.

I'm working with #2, about the size of a pencil. With that and any other wire number, the trend is clear.

Bigger number is smaller wire. The number is (or was) literally the number of times the rod was hammered-down (or pulled through a die) to make the wire. Classic gauges start from roughly 1/3" copper rod, the smallest standard copper-mill product. It takes 40 to 44 pulls to get down to 0.003" hair-wire.



You can only draw-down wire so-much in one pass. This varies little with size. The result has to be strong enough to carry the stress of the area being drawn-down. So the percent increment between numbers is fairly constant.

But SWG uses a piecewise approximation, #30 to #38 all 0.000.8" per step. AWG has been formalized to use 1.1229322 as the ratio one size to the next. A couple close-approximations fall out of this: twice diameter is 6 gauge numbers, 10 gauge numbers is 10X resistance.

> using SWG and not mm or AWG.

I looked. AWG and SWG go the same way in nearly the same amount, but not quite the same. AWG40 is similar to SWG44. SWG became a British Standard, so of course was used in much of her Empire. 1964, the UK made metric sizes standard in most fields, but SWG hangs-on in a few fields and in other lands.

[navin]

navin - your resistor string - if you short your nominated resistor, 1n2 and 3n9 will be permanently 5n1. those switch spots will be no difference ie wasted. we are looking to remove one of the string.

as for Udd, it is more often called Vcc, as in Volts for the collectors. and seeing as the resistor connects hard to 9V, internal and external, you only need to follow the positive supply wire to the board, find what the first parts connecting to it are, and if it is 100R, that's probably the one you want.

the on/off green led is not the purpose of that switching junk. all that stuff controls/remembers state for the fets, to direct the BP or FX_out to the output buffer, thence out. you get the led indication extra free. kinda. you could probably just use another dpdt switch to select buffer or not AND switch the indication led.

what does that boost switch look like?

Thanks PRR and duck_arse,

Yes we can remove the 5M between 1.2 and 3.9uf. Cant we? In fact I think someone used 10M resistors instead of 5M resistors.

I am sending a pic of another ferrite core I sourced yesterday. 2 of these will fit in the slot provided for the 9V battery. I managed to get 20H using 2mm/0.008" dia. wire. Resistance also was a bit too high @ 500ohms.

So I am going to re-try with a variety of wire I have on hand and see how close to 1H / 50ohms I can get. Then I can split the coil 3 ways (at about 400mh, 650mh, and 1H) and tap it. How does that sound?


The boost switch on the 535Q (circled in orange). I believe the part number is ECB233
http://store.jimdunlop.com/p/ecb233-switch-pcm-ea


Similar boost switch on the CAE MC404  (also made by Dunlop - circled in blue)


Meanwhile I could use some help on getting an LED to light if the boost switch on the 535Q is engaged. Thanks in advance.
I assume I can use the 3PDT switch scheme to switch the LED on when the pedal is on. Can we use a single bi-colour LED for both the boost and the 3PDT scheme? I assume we can.

PRR,
I understand both SWG, AWG, and mm. I live in India where we use both LPS and MKS systems together ( for example we measure a person's height in feet and inches and length or distance in meters or km go figure).

[duck_arse]

thanks Paul, with the history, it does make stickable sense - without it, it's just a load of B&S (which I forgot to add). and, as it happens, my father worked for AWI, a subsidary of BHP, and made wire and nails. well, they made it, he accounted it.

navin - 10H? really? have those cores any part # marking we can look at?

from this distance, those switches look like schadow/alps/many other makers standard "banked" switches. I'm not sure who/where they might be found, tho. I might have misled you on the switch wiring/operation as well, it's hard too squint at the full circuit, and you only posted a snip latest.

[navin]

thanks Paul, with the history, it does make stickable sense - without it, it's just a load of B&S (which I forgot to add). and, as it happens, my father worked for AWI, a subsidary of BHP, and made wire and nails. well, they made it, he accounted it.

navin - 10H? really? have those cores any part # marking we can look at?

from this distance, those switches look like schadow/alps/many other makers standard "banked" switches. I'm not sure who/where they might be found, tho. I might have misled you on the switch wiring/operation as well, it's hard too squint at the full circuit, and you only posted a snip latest.

Sir, yes 20H! Well actually the impedance bridge I got measured 19.2H! When I removed the ferrite core and measured it without any ferrite core I got around 160mH. Do you suspect the impedance bridge I am using is faulty?

I could not find any markings on these cores but will ask the supplier if he knows anything about them.

Dunlop sells spare switches and I found them on Amazon too.

Which switch wiring are you referring to? The inductor wiring or the capacitor wiring?

I posted complete schematics for the 535Q and Dimbag Wah earlier on page 1 of this thread. Is there another schematic you need?

Thanks again for all the help

[duck_arse]

navin - did you wind the coil shown, all 20H of it? impedance bridges I''l leave well and truly alone, maybe PRR can help you on the rightness and rongness.

if you go back to your earlier wire, the size smaller than the 0.5mm/24B&S, and fill a boobin while counting the turns, and then do the inductance measures with and without cores, it will give us some base numbers on the cores to work with.

yes, that complete circuit from page 1, but it's a bit hard (for my eyes) too read, is all. I meant the boost switch wiring, as to whether there is 2 poles or only one.

[navin]

navin - did you wind the coil shown, all 20H of it? impedance bridges I''l leave well and truly alone, maybe PRR can help you on the rightness and rongness.

if you go back to your earlier wire, the size smaller than the 0.5mm/24B&S, and fill a boobin while counting the turns, and then do the inductance measures with and without cores, it will give us some base numbers on the cores to work with.

yes, that complete circuit from page 1, but it's a bit hard (for my eyes) too read, is all. I meant the boost switch wiring, as to whether there is 2 poles or only one.

No I did not wind the 20H coil. I had the person who supplied me the ferrite core do that. I have asked him to wind me 5 coils with 5 different gauges (20, 24, 28, 32, and 36). I have also asked him to give me the turns used for these 5 coils. It may take him till Monday or Tuesday to do this as he will do it when he has time. Let's see what the results are.

As far as th boost switch wiring goes, in the 535Q schematic there is only 1 pole (SW2) but in the Dimebag schematic there are 2 poles (SW2a and SW2b). Let me see if I can simplify this schematic. I don't have great drawing skills.

In the Dimebag schematic SW2a is at the volume control end (just as in the 535q schematic) and SW2b turns on the red led to indicate the boost is on. Hope this help.

Thanks for all of this. I don't know where I would be without your patience and help.

[navin]

navin - did you wind the coil shown, all 20H of it?

duck_arse, PPR,

I had some more cores wound.
0.254mm (33SWG) gave me 600mH at  380 Turns
0.234 (34SWG) gave me 600mH at 400 Turns
then I got another coil wound but with a different core
0.193 (36SWG) gave me 1.2H at 650 Turns

It seems that there is a huge variance from core to core and I would have to experiment with various cores. I am trying to get 4-5 values between 300mH and 800mH. Does this range seem correct? Should I attempt to use values larger than 800mH?


Meanwhile I got the 535Q and when I opened it, it has a PCB that looks similar to the one used in the Dimebag Wah.


At the foot of the wah are 3 diodes (I presume these are LEDs) along with some associated components are missing


Also I see that a third pot and some associated components are missing near the trim pots. Where can I buy these pots?


Can I convert my 535Q into a Dimebag Wah? If so what will I need to do this? see picture of a Dimebag wah with LEDs and trim pot



So this is my intention.

1. Trace FX on / off LED and Boost LED and add these LEDs to the 535Q
2. Build 2 inductors and use the battery space to house these 2 inductors with taps at 300mH, 550mH for L1 and 400mH, 650mH, 900mH for L2. Use a 6 way (2 pole) rotary switch to choose between existing red fasel and the 300mH, 400mH, 550mH, 650mH, 900mH of my home brew inductors (the second pole will turn on a RGB LED to indicate which inductor is in use)
3.   Add a 5M (pop reducing) resistor in the switch and change maybe 3 of the caps.
4.   Trace the components missing for the 5K trim pot in the Dimebag wah and add that to the board
5.   Replace existing 6 way capacitor switch with 6 way 2 pole switch and use second pole to turn on different LEDs. (optional)


optionally if I can access the components
1. Remove 1k pot in series with inductors and replace 33k resistor with series combination of 22K pot and 10K resistor.
2. Replace 470 ohms resistor in emitter of Q1 with 330 ohms to increase gain and bass a little
3. Replace 68k input resistor with 47k (or 51k) resistor to increase output slightly

Any pointers?
Where can I find the small pot used in the Dimebag wah (and 535Q)?
Anyone know what other components are missing on the 535Q board?
There is a SMD IC CD4049 missing from the 535Q. Can this be hand soldered?

Thanks in advance.

[duck_arse]

some things are becoming a little clearer now. short answer on the conversion to dime is NO. there is a mess of SMD stuff missing from your board, in 2 areas that I can/can't see from your pics.

the 9mm pot (the little green ones) are available from places like tayda, mouser, ?small bear? but you'll have to check the mountings. the pot is a common type, the mounts ??

this winding man - does he have a winding machine and big stock of formers/cores/wire? if so, you should be able to tell him "wind this, interleaved" and he will know what wire for what core and how many winds. Paul would better know what useful % to put the taps at, maybe 500mH with 75%, 100% and 130%, like that?

the switch on your wah "looks" to be a 2pole 6position, and only has 3 wires connecting. you might be able to use this to do all your cap/leds. might. as for your missing/adding leds, let me look at the schems/winding #'s overnight, I'll get back to you.

[navin]

some things are becoming a little clearer now. short answer on the conversion to dime is NO. there is a mess of SMD stuff missing from your board, in 2 areas that I can/can't see from your pics.

the 9mm pot (the little green ones) are available from places like tayda, mouser, ?small bear? but you'll have to check the mountings. the pot is a common type, the mounts ??

this winding man - does he have a winding machine and big stock of formers/cores/wire? if so, you should be able to tell him "wind this, interleaved" and he will know what wire for what core and how many winds. Paul would better know what useful % to put the taps at, maybe 500mH with 75%, 100% and 130%, like that?

the switch on your wah "looks" to be a 2pole 6position, and only has 3 wires connecting. you might be able to use this to do all your cap/leds. might. as for your missing/adding leds, let me look at the schems/winding #'s overnight, I'll get back to you.

Thank you duck_arse,

I was beginning to fear that moving from 535Q to Dimebag would be more trouble than it is worth. There are a bunch of things missing including a CD4049 chip, 2 FETs Q3 and Q4 the kind I have never seen before, and a few jumpers, resistors, caps, etc.

So let's look the reason to consider changing to Dimebag. The reason was to have an LED indicate when he Wah is on (this can be done using a 3PDT switch) and when the boost is on. This second part, I don't know how to do. And lastly to incorporate the 5K trim pot which I think CAN be done using the Dimebag PCB IF I can find a 9mm pot that fits.

The ferrite core guy actually makes low cost simple handheld metal detectors in a sort of cottage industry. He is semi-literate but always willing to say yes. I don't think he knows much about inductors except how to wind what he needs for his detectors. I have to guide him.

The cores he has vary a lot. I saw +/- 25% change in the ferrite cores. Now I don't want him wasting his business time attempting trial and error with his cores so he said he will wind a few multi tap bobbins for me and I will experiment with various ferrite cores till I get the values I need. Maybe Saturday.

At the end of this I should have 6 inductances to use. The existing Red Fasel and home brew inductors of 300, 450, 550-600, 650-700, 900 (approx). So I have asked him to wind me 32 SWG with a 70% tap which I hope gives me 300 and 550mH and 35SWG with 70%, 85% and 100% taps which I hope gets me 450mH, 650mH, and 900mH. Let's see. I guess I will have to experiment with coils and ferrite cores and find a combination that gives me the values I desire.

I am going to have to move the 6 position capacitor switch to make room for a 6 position inductor switch. I guess I will need a small daughter board for the capacitors - I think tagboardeffects has a scheme for one.

http://effectslayouts.blogspot.in/2015_05_01_archive.html

Thanks again duck_arse.

[duck_arse]

orrl-rite. looking at your cores, they seem to be either "P2616" or "P3019". there are standards for potcore measures you can search up if you like. from your winds/inductance figures, I calculate A_L from 4100 (nH/T²) at 380T to 3500 at 650T. these variations tally with the messing arounds I've done in the past, and the standards rate the A_L tolerance as +/-25%, so your numbers are in the area.

and - that makes a 375mH//500mH//650mH coil about 300/350/400 turns. obviously, with a wide tolerance, on everything, especially my maths. really, just tell him to take the taps out when he reaches the edge of a layer at or reasonably near the turns counts you want.

as for the "when is the boost on?" led indicator, you really only need another pole of switch to turn the led on. is the "boost" the red button switch on yours, the one marked "SW1" on the board? a dpdt push could be hacked-in to replace if that's the one, the pastic tubing makes it even easier.

and, the circuit shows a 1n2 connected parallel to the 10nF in the first position on the cap switch. smart money would be on they fit the 1n2 to all the boards, and then wire the switch boards per version.

[navin]

orrl-rite. looking at your cores, they seem to be either "P2616" or "P3019".

and - that makes a 375mH//500mH//650mH coil about 300/350/400 turns. obviously, with a wide tolerance,

just tell him to take the taps out when he reaches the edge of a layer at or reasonably near the turns counts you want.

as for the "when is the boost on?" led indicator, you really only need another pole of switch to turn the led on. is the "boost" the red button switch on yours, the one marked "SW1" on the board? a dpdt push could be hacked-in to replace if that's the one, the pastic tubing makes it even easier.

and, the circuit shows a 1n2 connected parallel to the 10nF in the first position on the cap switch. smart money would be on they fit the 1n2 to all the boards, and then wire the switch boards per version.

Wow you are good. I called the guy and asked him if he knew if the cores were 2616 or 3019 and he said "oh yes 2616, that's what they are!"

Apparently there is a lot of variation from core to core so I will have to make the time to experiment with a few cores and find values that work.

I will ask him to try 300/400 turns on one coil using 0.274mm (32SWG) to get 300mH and 550mh and maybe make another with 300/400/500 turns with a second coil using 0.213 (35SWG) and get 400mH, 650mH and 900mH. Since the variation in the ferrite cores is +/- 25% I really don't know what the final values I will get. It is going to be trial and error. Fortunately I am modifying only 1 Wah.


The boost switch is the one supplied by Dunlop. I guess it is this one
http://www.stringsdirect.co.uk/effects-recording-c6/effects-spare-parts-c301/jim-dunlop-cry-baby-kick-switch-pcm-replacement-p9302
http://www.ebay.co.uk/itm/NEW-Jim-Dunlop-Genuine-Cry-Baby-Kick-Switch-PCM-Replacement-Effects-Pedal-Part-/181584153997

I suspect that Dunlop used a common switch for the 535Q and Dimebag and maybe even the CAE MC404 just to keep inventory in check. If this is so then the existing switch is probably DPDT shown as SW2a and SW2b in the Dimebag schematic. I believe that this may be the same switch shown as SW1 on the board. If you see the 535Q schematic I posted earlier it shows SW1 to be the DPDT toe switch not the boost kick switch.  The boost switch is labelled SW2 in the 535Q schematic I posted. The labeling on the schematics does not match the board. It leads me to wonder if the schematics we have are accurate.

As far as the capacitor switch is concerned I will have to make a fresh circuit for this. Would using the PCB of the Rotary Cap Switch I posted earlier help? The reason being that I would need to make room to accommodate a second rotary switch for the inductor switching. I am ok with this.

Lastly when I do get started (after I collect all the parts needed) I intend to post the details here so it helps the next guy.

Parts list so far:
2 x 6 position/2 pole rotary switches for the Capacitors and Inductors
1 x 3PDT switch to turn LED on when the WAH is on
6 x  5M (pop reducing) resistor
3.9nf, 6.8nf, 15nf, 27nf, 47nf and 68nf caps
5k and 10k pot (9mm) - I intend to try 10k and see if that swings more
3 RGB LEDs 2 will be used for indicating inductor choice and capacitor choice,  and common LED for 3PDT on/off and boost on/off

Lastly, something to turn the LED on when the boost switch is engaged.

Did I miss anything?

What do you think about the optional changes I listed earlier? I am thinking of trying these two.
1. Replace 470 ohms resistor in emitter of Q1 with 330 ohms to increase gain and bass a little
2. Replace 68k input resistor with 47k (or 51k) resistor to increase output slightly

Thanks again duck_arse.