I need this pedal done today, the circuit is not completely dead when connected, but the volume is low with almost no gain, like clean sound. Voltages:
Q1 q2 q3 : 4.4v 0.14v 0.8v
Q4 : 4.8v 1v 1.4v
Diodes: 0.8v 0.6v
NYC Big Muff pi ec3003, 2n5088 trans, 1n4148 diodes
Layout : http://2.bp.blogspot.com/-dhrzj6JgnAQ/VDkrfpxRgZI/AAAAAAAAIpk/H-6aMtpt0CQ/s1600/EHX%2BNYC%2BBig%2BMuff.png
Schematic : http://4.bp.blogspot.com/-uYM0v6H2q-s/VDlz5ZgvKVI/AAAAAAAAIp0/N33_ifLfqf0/s1600/Big_Muff_PI_Ec-3003_ver_C_.png
I already ran a knife through the rails. Where should i look at?
Your Base voltages on Q1, 2 & 3 are very low. The expected base voltage would be somewhere near 3.6 V. Check the values of the 470K resistors going from the Collectors to the Bases on those transistors.
Make sure that you have the transistors orientated correctly.
Some pictures would be very helpful too.
Edit: I am an idiot. The base voltages should be near 0.6V not 3.6V Your emitter voltages seem to be a bit higher than expected, 0.05V is to be expected. Sorry for the error.
I write quickly. Check all the orientations. Check the value of the resistors. Check the position of the component, wires, cut track and jumpers.
Did you flip your transistors? The pinout is different on the 5088s compared to the BC550 on the vero layout.
Failing that, photos would help.
I checked everything and didn't find the solution, but putting a ts9 in front of this sounded soo good and unique. So i'm just keeping this board and i'll build another one from scratch. Thanks everybody!
Post some photos of your board!
(Closer solder side )
Ok now i really need some help. I built the second board and got the exact same results: there's almost no gain, only with the sustain at maximum i do hear some fuzz, it's like a warm overdrive. I replaced the 2n5088 with 2n5089 assuming it was just that the transistors had low gain; same thing. I have double checked the orientantion and soldering and its all right. What should i look for?
Here's the copper side, looks terrible because i replaced the transistors, but i ran a knife through the rail so they're not touching: https://s13.postimg.org/q0f2op913/image.jpg
Here's my normal soldering job from the previous board: https://s13.postimg.org/3pr7oaoh3/image.jpg
Component side: https://s13.postimg.org/mgt4yyqwn/image.jpg
Component side from previous board: https://s13.postimg.org/qr7suftdz/image.jpg
I've also double checked resistors and pots values
Quote from: seadi123 on January 16, 2018, 08:17:00 AM
Component side: https://s13.postimg.org/mgt4yyqwn/image.jpg
I'm seeing the diodes in the centre of the board. I guess them should be in anti-parallel.
^ me too.
just for the educational value - can you measure the resistance of all your 120R resistors, and all your 10k resistors? and, funny colours/light, can you also measure the resistance of the 27k in the middle of the board?
Quote from: Elijah-Baley on January 16, 2018, 09:18:52 AM
Quote from: seadi123 on January 16, 2018, 08:17:00 AM
Component side: https://s13.postimg.org/mgt4yyqwn/image.jpg
I'm seeing the diodes in the centre of the board. I guess them should be in anti-parallel.
Nice catch! Will flip one now
Flipped the diode, now i hear fuzz only with all knobs turned up full. The volume is low, with volume in half i almost cant hear anything. Tone pot is ok, fuzz also works but there is no aggressive distortion whatsoever.
Quote from: duck_arse on January 16, 2018, 09:28:42 AM
^ me too.
just for the educational value - can you measure the resistance of all your 120R resistors, and all your 10k resistors? and, funny colours/light, can you also measure the resistance of the 27k in the middle of the board?
Also measured 120ohm and 27k resistors, everything is fine. It's also intriguing that i have the same problem on both the boards i've built, it's like i've done the same mistake twice
Additional info: I've used the upper ground rail of the muff as a ground point for everything. This is a 2 in 1 pedal, the other effect works fine and true bypass also works fine
Solved. Besides the diode which was in the wrong direction, one of the cuts was made in the wrong place
Hello, I have almost the same problem. Sustain pot kills the volume. It sounds only with sustain pot from middle range to full open. I used the same schematic and vero board as seadi123.
What could it be ?
(https://s13.postimg.org/z1lw85lqr/IMG_6763.jpg) (https://postimg.org/image/z1lw85lqr/)
(https://s13.postimg.org/youi1ziwj/IMG_6765.jpg) (https://postimg.org/image/youi1ziwj/)
(https://s13.postimg.org/rznylectv/IMG_6772.jpg) (https://postimg.org/image/rznylectv/)
(https://s13.postimg.org/dggtjz49f/IMG_6773.jpg) (https://postimg.org/image/dggtjz49f/)
<Sustain pot kills the volume. It sounds only with sustain pot from middle range to full open.>
Is sound volume constant or does it rise in accordance with pot wiper setting..??
Volume rises whilst the sustain pot is anywhere between middle and full range; but if i close the sustain pot, then everything is muted.
I checked the continuity, the holes and the rails. Actually there is some difference between the schematics and the vero board design if you look on the seadi123 attachment. In the schematics C5 is placed before the R15, but if you track on the vero board design you will notice that from sustain 2 goes first to R15 and after that to C5. Would that make a difference ? I mean is a verified built on that tagboardeffects web page.
You pobably mean R19 (R15 in schematic is the feedbck resistor of Q3..)
The order of C5 & R19 doesn't mind as far as they are set in series..
That Sustain pot behaviour seems to me like a Log pot (not Linear) without R1..
(mute at full CCW with very "low" responce a about 1/3 of initial wiper travel..)
Quote from: antonis on February 01, 2018, 06:02:26 AM
That Sustain pot behaviour seems to me like a Log pot (not Linear) without R1..
(mute at full CCW with very "low" responce a about 1/3 of initial wiper travel..)
Exactly, but I'm pretty sure that sustain is a 100K Linear pot (see attachment). Only the volume pot is a 500K Log Pot. I'll change the sustain pot, who knows, maybe it has some manufacturing issue.
(https://s13.postimg.org/jf8ezqow3/IMG_6777.jpg) (https://postimg.org/image/jf8ezqow3/)
Befor Pot change try to "simulate" its lower settings with a resistive voltage divider of same total resistance value..
(i.e. for an about 20% adjustment use 82k & 18k respectively, for 33% use 68k & 33k, etc.)
a slap on the wrist for antonis! why didn't you say "why have you left-right mirrored your build?" or "what transistors are you using?" and you didn't even mention the curse of the purple wire.
and, antonis, no welcome?
welcome to the forum Cenzoru.
:icon_eek: :o :icon_redface: :icon_redface:
Is there any amount of apologies enough for excuse, Stephen..??
(written by hand - not copied-pasted, of course..)
it is not for me to say, Antonis. you are at the mercy of Cenzoru.
Quote from: antonis on February 01, 2018, 07:18:50 AM
Befor Pot change try to "simulate" its lower settings with a resistive voltage divider of same total resistance value..
(i.e. for an about 20% adjustment use 82k & 18k respectively, for 33% use 68k & 33k, etc.)
I'm a total noob on electronics and this is my first pedal.( also this being the explanation about mirrored vero board).
I tried some measuring: resistance between pin 1 and 2 = for example at 1/4 of a full turn and it shows 25k and between pin 2 and 3, 75k at the same position, and so on.
Is that what you meant by "simulate" ?
I did the measurements without connecting the pedal to 9v. Is that ok ?
Got it ;D. All the transistor were reversed :-[ :-[ :-[ . Maybe because of the mirrored built.
I read the debugging section and found that NPN transistor must have its base higher than its emitter. In my case was the reverse. So I reversed the position of the four transistors.
Thx a lot to all of you.
Cenzoru - wait, don't go just yet. it is often we get people misinterpreting vero layout convention. they are most often shown looking down on the top of the components, imagining the board is transparent. and then if the underside of the board is shown for the cuts placements, the builder needs to be aware of whether it is looking at the copper side, or still looking thru the transparent board from above.
and so we get mirrored builds. most common is the left-right mirrored, which in general doesn't affect transistor orientation, but makes a real mess of IC's. so, to my point - you transistors should not have been reversed. what transistors did the build specify, and what transistors did you build with? [the 2nxxx series transistors are backwards to the BCxxx series.]
and, because we always ask, can you post the transistor voltages now that the board works, please?
Quote from: duck_arse on February 03, 2018, 08:37:30 AM
what transistors did the build specify, and what transistors did you build with? [the 2nxxx series transistors are backwards to the BCxxx series.]
and, because we always ask, can you post the transistor voltages now that the board works, please?
The part list of the scheme specifies (see scheme below):
Q1 - BC550C
Q2 - BC550C
Q3 - BC550C
Q4 - BC550C
I used BC550C in every position (see photo below).
Transistor voltages:
Q1
C =4.24
B =0.66
E =0.06
Q2
C =4.22
B =0.66
E =0.06
Q3
C =4.28
B =0.66
E =0.06
Q4
C =4.88
B =0.66
E =0.06
Is that ok ?
Anyway thx a lot. I feel so enthusiastic with this. For sure you remember your first pedal.
(https://s18.postimg.org/4mrprakid/EHX_NYC_Big_Muff.png) (https://postimg.org/image/4mrprakid/)
(https://s18.postimg.org/mpksiio2t/Big_Muff_PI_Ec-3003_ver_C.png) (https://postimg.org/image/mpksiio2t/)
(https://s18.postimg.org/m1bxzgmr9/IMG_6894.jpg) (https://postimg.org/image/m1bxzgmr9/)
You should probably name it after the Duck's Arse :icon_lol: :icon_lol: :icon_lol: never forget...
QuoteQ4
C =4.88
B =0.66
E =0.06
well now, see those two resistors, R7 (470k) and R3 (100k) on the base of Q4, we would expect to see about 1V5 on the base there.
also, are those tayda transistors, by any chance?
@ mth - you might be thinking of elephants.
this is the transistor info from the local store I bought:
NPN 45V 0,1A 0,5W B:420-800 TO92
Technical Specifications
• Collector Emitter Voltage At Open Base: 45V
• Collector Current: 0.1A
• Power Dissipation: 0.5W
• Transition Frequency: 100MHz
• DC Current Gain: 420...800
I don't think they are tayda transistors.