Colorsound Wow-Fuzz Layout Part 2

[rocket8810]

After having some confusion in the thread I started previously, it was suggested that I start a new one. So the deal is this: there are 2 different schematics floating around for the colorsound fuzz-wah, and as far as i can tell neither have been verified for the wah section.

The one below seems to be have the right schematic for the wah section as it matches the one posted at FuzzCentral, which as far as I know only has accurate/verified schematics.



Also, after even more searching, I found on FSB someone who traced their normal colorsound wah from '77 and created a schematic which is nearly identical to the wah section in the above fuzz-wah schematic.



As far as the fuzz section, the input/output caps in the D*A*M reissue are 100nF, which makes more sense then 10nF, which just seems way too low.

From the new information I have created a layout for the fuzz section, and the wah section (see below), which is unverified, and untested at the movement.



Before it is built it still needs to be reviewed and compared to the schematic.

[rocket8810]

ok, finally sat down and built this based on a layout someone i know put together so this is all on one board, but i have both good news and bad news.

here's the original layout.


the good news is that when the fuzz is engaged it works, and sounds incredible. the bad news is that when the wah is engaged it sounds like i just went underwater, no wah effect at all, and there's a massive volume drop. i did find a problem with the layout, there is a 22nF cap connected to Wah2 that should be 220nF. i changed the cap, but that did not correct the problem.

also, i got my hands on original bc164b's and bc184l's, and the inductor i had a layout of 4x4, so i added 2 cuts and 1 link. here's the changed layout.


i haven't had a chance to take any pictures cause my camera is acting up, but will post some ASAP. Any idea what could be happening?

[rocket8810]

here's some build pictures:






any help would be amazing. i need to get this beast up and running. it's driving me nuts that half of the layout is golden, and the other half doesn't work. i was also thinking maybe there is a way to change a known verified crybaby layout into the colorsound wah, that way i could just disconnect the wah section and make a 2nd board or get a pcb and put it in.

[duck_arse]

well, now, you found the 220nF//22nf cap. from that cap, the third resistor to the right is marked 470R. what value did you use? other than that, there is a cut under the 100k of the 100k//10nf input pair, but I think you saw that.

that resistor is all I can see diff in the wah section.

[rocket8810]

its 470r, i checked the bands and double checked with my multimeter and that cut under the 100k is there. this is the first wah i've built so i have no idea what could go wrong or cause something like this.

[duck_arse]

the 470R should be 470k

[rocket8810]

i'll change it and see if that fixes it. i know that the layout was put together based on the schematic and the perf layout from sinner, since supposedly it's verified. i'll report back in a bit.

Edit: not i get volume and but it acts like a volume pedal rather then a wah. i'm thinking its the polarize 4.7uF cap....

[joegagan]

hard to tell from the photos, but i can't see where the inductor is tied to the 4.7 u.  that would definitely cause the wah part to act as a volume.

looks like you cut 2 legs of my inductor - are you sure you still have the two live legs there? according to how i normally install the top piece, you have it oriented correctly, but it never hurts to doublecheck.  lacking an inductance meter, you can tell if you have the two good legs if the reading is approx 42 ohm, if you have the two connected legs, you will have 0 ohms. you may have to pull it from the board to know for sure , there could be shorts elsewhere on the board giving a false reading.

but verify you have your 4.7u connected to the inductor first. make sure the - is grounded as well.

side note: i see problems with layouts this dense, too much going on in such a small space. this whole thing would be so much better if it was 25 to 40% larger. ( just a note for future vero layout/build artisans)

[rocket8810]

ok, so update:

changed the 4.7uF cap to 10uF just like the original colorsound wah - no change.

see photo for where the inductor connects to the board.


the positive side of the polarized cap connects to the top lug of the inductor, negative connects to ground and is parallel to the 100k resistor 2 over on the left.

i checked resistance across the inductor and got a reading of 43.3k, so it should be good. i checked the both on the pin where they are soldered, and on the open tracks right next to it.

[joegagan]

ok, that sounds correct. i know you might not want to hear this, but go over your circ from in to out again.  2 times. one time, verifying that every single connection is getting a full connected reading on your meter. ( audio continuity helps) 2nd time, run your meter leads to surrounding pads that are nOT supposed to be connected, looking for bridged soldering or slightly connected vero. i still suspect something around the 10u to ground, but there are other ways this thing could be exhibiting this behavior.

what are your  voltage readings at the wah transistors?

[rocket8810]

Transistor readings

Q3:
B: 0.601V
C: 3.779V
E: 0V

Q4:
B: 8.82V
C: 9.53V
E: 8.82V

i ran a check for bridges, and didn't come up with anything, and checked to ensure continuity where there should be, and everything seems ok.
i just took my multimeter and did 2 things. i checked to see the voltage change going across the inductor while changing the sweep and voltage doesn't change from .599V. also when i change the sweep of the pot there is no change in voltage. the way the pot is wired is 3 to ground 2 to board where indicated in the layout and 1 where the layout indicated 3. i checked the pot and there is a change in resistance between lug 2 and lug 3, lug 2 and lug 1, but not lug 1 and lug 3 it stays 65.3k. please tell me that this is all because the pot is miss wired. btw, the way i'm thinking of the numbering is lug 1 is closest to the enclosure and lug 3 is the one closest to you when looking into the enclosure.

Edit: i corrected the wiring and still the same problem.

[rocket8810]

good news!!!!! i randomly thought, why what if i change the transistors to something with higher gain then the bc184L's? i popped in some bc108's i had that i know have hfe around 450, rotated the pins, dropped them in place and stomped on the switch and BAM!!!! everything works. holy sh*t, it should incredible. i think i'm going to see what other transistors i can put in to alter the tone and both of the effects. btw, both transistors in the wah section are good, and the hfe is around 200, but i guess it's just too low ti engage the inductor. i might have to change the position of the pot when the treddle is fully forward there's so much bass that it sounds almost muffled.

thanks for all the help.

BTW, completed build:

[joegagan]

that is AWESOME

[rocket8810]

thanks joe. i still have to put it up on your facebook page. i love the tone of this wah, by far its #1 on my list. i still think i have to adjust the pot sweep because at full forward i think it sounds too muffled. i don't know why i thought about putting higher gain transistors into it, but it worked. i think i just got so pissed off that i couldn't get the wah to work that i was like, " phhh why not? what bad could it do?" and it worked. i swear sometimes its the dumbest things that you think of that solves the most frustrating problems in a build. why can't they be the first thing you think of 

[duck_arse]

now that it is working, can we have transistor volts again? your posted Q4 suggests shorted B-E. did you end up with a bad transistor? those blasted "L" series!

nice work.

[rocket8810]

so duck, i went back and checked the original bc184l's i had in there with my dca55 and both actually gave me a good reading. so i put them both back in checked the voltages and got the same thing i posted before. so i pulled out the one that according to the voltage readings was shorting, and put in another bc184l and the freaking wah works. so that transistor must have been bad, despite what the dca55 read, what a bummer. but in any event here are the correct voltage readings you should get at Q3 and Q4

Q3
B: 0.603V
C: 3.821V
E: 0V

Q4
B: 3.328V
C: 9.40V
E: 2.851V

[duck_arse]

as rg recently said .......

pinout...pinout...pinout...pinout...pinout...pinout...pinout...pinout...pinout...pinout...pinout...pinout...pinout...pinout...pinout...pinout...pinout...pinout...

staring at the voltages and some scribbles and some datasheets, I decided that the Q4 volts don't show a short B-E, but transposed pins. if I've got this right, that would mean two PN junction conducting in two directions, so 9V53 - 0V7 = 8V82. and so, to the datasheet, and it's all there.

IF the transistor is an "L" series, it will have legs in-line, and E-C-B pattern. if however, it has a cranked middle pin, it is not an "L" series, and has the C-B-E pattern of a bog-standard BC transistor. this according to the "MICRO ELECTRONICS" "BC184 BC184L BC214 BC214L" datasheet.

http://pdf.datasheetcatalog.com/datasheet/MicroElectronics/mXyztqtw.pdf

I can't see clear enuff in yr pics, whether cranked, marked L, both or neither. and, of course, there is the dreaded spectre of the counterfeit transistor, which is marked L but not L-pinned, cranked but L pattern. whatever, you may well find that by assuming your not-working transistors are BC pattern, bending the pins to the L pattern and re-trying them will prove one way or another.

I wonder how many people have things built and non-working that include a BC184 or BC184L .....

[rocket8810]

Oddly enough it's marked as an "L" so my guess is then that internally it isn't correct. I just tossed it, and put in another one that is right, cause if I kept it then it would be an issue later if I grabbed it again. The center pun was not cranked, just straight accross. My guess is with some vintage parts they are not as reliable as we may hope, I mean think about it. I put in another transistor, same model number, from the same group, and it's fine. I think the important thing here is if you use a dca55 make sure you pay attention to the pinout it gives you, don't just assume it is as it should be on the data sheet if it's 30+ years old.