Helloooooo,
I checked the connections twice and also double-checked the values. The numbering doesn't follow the PCB at all because the PCB numbering is buried under the components.
Here the voltages, all measured against circuit ground (not DC adaptor ground), pedal on, switches off, knobs at 12 o'clock
U1
1 4.73
2 4.73
3 4.67
4 0
5 3.88
6 3.90
7 3.90
8 7.77
U2
1 3.82
2 3.82
3 3.79
4 0
5 4.51
6 4.74
7 4.74
8 7.77
U3
1 3.88
2 3.88
3 3.87
4 0
5 3.81
6 3.83
7 3.83
8 7.78
Q1 J175 Pedal ON
D ~0.3V
G ~6.2V
S 0
Q1 J175 Pedal OFF (side loop on)
D 0
G 0.047V
S 0
Q2 1616A Pedal ON
E 0
C ~6.2V
B 0
Q2 1616A Pedal OFF (side loop on)
E 0
C 0.047V
B 0.564V
I built this on vero and the voltages there are the same. I'll post the layout next. I used the side loop on the vero pedal to A/B against the Fat Rock. To me they sound the same. Sometimes I hear a slight difference, but then I just twiddle with the knobs a little bit and I get the same sound again. Putting the knobs to their extremes also sounds the same. So to the best of my knowledge this is a good trace.
Amptweaker - Fat Rock [traced]
Thanks, glad you like it!
Anybody knows what kind the pale/white resistors R8 and R9 (330R & 47R) on the secondary PCB are? I suppose they have a higher Watt rating. I used 2W for the 47R on the vero on a hunch.
Anybody knows what kind the pale/white resistors R8 and R9 (330R & 47R) on the secondary PCB are? I suppose they have a higher Watt rating. I used 2W for the 47R on the vero on a hunch.
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karul
- Cap Cooler
2W seems too big for me. Probably 1/2 or 1W. There are some charts with dimensions for different power ratings, but don't expect values to match exactly.
https://www.electricalengineering.xyz/r ... ing-chart/
Hello again,
Curiosity won and I dismantled the PCBs. I measured all components and I retraced the pedal once more, following the actual traces. Did not find any difference to the schematic from first post. To get at least a little win/value out of destroying the pedal I changed the numbering in the schematic below to the actual PCB numbering and also added the components that were omitted in the FR. Also measured the transistors after I took them off, although for this build it shouldn't matter much as they're just switching. BOM below.
Curiosity won and I dismantled the PCBs. I measured all components and I retraced the pedal once more, following the actual traces. Did not find any difference to the schematic from first post. To get at least a little win/value out of destroying the pedal I changed the numbering in the schematic below to the actual PCB numbering and also added the components that were omitted in the FR. Also measured the transistors after I took them off, although for this build it shouldn't matter much as they're just switching. BOM below.
Code: Select all
Pots
VR4 Volume pot,B10k
VR3 Tone pot,B10k
VR1 Tight,C100k
VR2 Gain,A500k dual
Resistors
R1,1M
R2,15k
R3,1M
R4,47k
R5,470k
R6x,1k5
R7,22k
R8,100k
R9,150k
R10x,15k
R11x,4k7
R12x,22k1
R13,10k
R14x,470k
R15,150k
R16,100k
R17x,1k5
R18,10k
R19,4k7
R20x,220k
R21,47k
R22,47k
R23,330r
R24,47r
R25,15k
R26,18k
R27,47k
R28,100k
R29,3k3
R30,1k5
R31,1k
R32,100k
R33x,470k
R34,3k3
R35,3k3
R36x,3k32
R37,1M
R38,47k
R39,100k
R40,150k
R41,470k
R42,220k
R43x,100k
R44x,150k
R45x,68k1
R46x,omit
R47,33k
R48,33k
R49,10k
R50,150k
R51,3k3
R52,68k
R53,10k
Caps
C1,100nF
C2,220nF
C3x,33nF
C4x,47nF
C5x,100pF
C6,100nF
C7x,560pF
C8x,omit
C9,100nF
C10,33nF
C11,100nF
C12,100nF
C13,220nF
C14x,4n7
C15,100nF
C16,220nF
C17,100nF
C18,22uF
C19,100uF
C20,22uF
C21,47pF
C22,3n3
C23x,22uF
C24x,47nF
C25,22nF
C26,22pF
C27,4n7
C28x,100nF
C29x,3n3
C30x,22nF
C31x,omit
C32,22uF
C33x,47nF
C34,22uF
C35,22uF
C36,2u2 BP
C37x,omit
Diodes
D1,ON 1N4007 Vf 0.58
D2,ON 1N4007 Vf 0.57
D3,Fairchild 1N4148 Vf 0.56
D4,Fairchild 1N4148 Vf 0.56
D5,Fairchild 1N4148 Vf 0.56
D6,Fairchild 1N4148 Vf 0.56
Zener diodes
ZD1,Fairchild 4733A Uf ~5.0V
ZD2,Fairchild 4733A Uf ~5.0V
ZD3,Fairchild 4733A Uf ~5.0V
ICs
U1x,TL072CP
U2,TL072CP
U3,TL072CP
Transistors
Q1,"D1616A hFE=392, Ic=3.7mA, Ube=602mV"
Q2,"Fairchild J175 Idss=40mA, Id=2.5mA @Vg=1.71V, Id=0.00mA @Vg=2.60V"
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I made another vero layout that is a bit smaller and has less links (from 30 down to 24). See pic below for size comparison.
It uses 3 dual opamps now instead of 1 quad and 1 dual. It's a bit easier to fit, but building it is still painful due to the sheer number of wires
The result is worth it, though. It's got a lot of juice and I find the note decay pleasingly natural, even with the gate on.
The universal loop I don't use right now, but the side loop I do use. No need for an extra loop switcher pedal anymore.
In the new layout I went with a series protection diode. The two LED resistors (in the upper left corner) are marked 4k7 instead of 3k3, but obviously one can use 3k3 like in the orignal. And I left out the diode and resistor connected to the DC ground pin because I think there were just put there for the 4 knob shiners, which I didn't use.
There's 3 100nF ceramics close to the opamps for power filtering. Original uses a 100nF film and a 47nF film. Again, up to you.
It uses 3 dual opamps now instead of 1 quad and 1 dual. It's a bit easier to fit, but building it is still painful due to the sheer number of wires
The result is worth it, though. It's got a lot of juice and I find the note decay pleasingly natural, even with the gate on.The universal loop I don't use right now, but the side loop I do use. No need for an extra loop switcher pedal anymore.
In the new layout I went with a series protection diode. The two LED resistors (in the upper left corner) are marked 4k7 instead of 3k3, but obviously one can use 3k3 like in the orignal. And I left out the diode and resistor connected to the DC ground pin because I think there were just put there for the 4 knob shiners, which I didn't use.
There's 3 100nF ceramics close to the opamps for power filtering. Original uses a 100nF film and a 47nF film. Again, up to you.
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Here's the differences between the Fat Rock and the Tight Rock, both using same PCB revision 04-18-16 REV D:
- C26 is actually called C26x
Refer to the 2nd schematic posted earlier. As no additions are required, the TR can be built on the vero layouts above.
Currently I like the Fat Rock more as it sounds less fuzzy to me, so I'm not sure if I'm going to build the Tight Rock.
The TR I got uses mono switching jacks for the universal loop and stereo switching jacks for the rest. I don't see how that would make a difference, though.
- C26 is actually called C26x
Code: Select all
Component Fat Rock Tight Rock
C3x 33n 22n
C4x 47n 33n
C7x 560p omit
C14x 4n7 22n
C26x 22p omit
C28x 100nF omit
C29x 3n3 omit
C30x 22nF omit
R6x 1k5 3k32
R10x 15k 10k
R12x 22k1 47k5
R17x 1k5 3k32
R20x 220k 150k
R43x 100k 220k
R44x 150k omit
R45x 68k1 omit
Tone B10k A10k
Currently I like the Fat Rock more as it sounds less fuzzy to me, so I'm not sure if I'm going to build the Tight Rock.
The TR I got uses mono switching jacks for the universal loop and stereo switching jacks for the rest. I don't see how that would make a difference, though.
Mmh, can't edit my last post anymore, so have to make a new entry. Sorry for the noise.
Just wanted to add that in the end I built the tight rock vero to confirm it sounds like the original, which it does.
The vero is attached here. It's the same as the previous one, with the tight rock component changes. Cuts are the same.
I think that's it then. Just one last note: If you build any of these I suggest to get the right Zener diodes, Fairchild or Onsemi 4733A. I tried some different Zeners (no idea what brand, but they were 5.1V 1.3W) and they didn't sound right. I also tried a few black plastic Zeners of about the same Zener Voltage and there was no sound at all
Just wanted to add that in the end I built the tight rock vero to confirm it sounds like the original, which it does.
The vero is attached here. It's the same as the previous one, with the tight rock component changes. Cuts are the same.
I think that's it then. Just one last note: If you build any of these I suggest to get the right Zener diodes, Fairchild or Onsemi 4733A. I tried some different Zeners (no idea what brand, but they were 5.1V 1.3W) and they didn't sound right. I also tried a few black plastic Zeners of about the same Zener Voltage and there was no sound at all
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