LAL GM2 Green Monster (Lastgasp Art Laboratories) [traced]
- Gila_Crisis
- Resistor Ronker
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I recently got a LAL Green Monster, a super rare fuzz and long discontinued pedal by LAL.
Since I opened it to clean it a bit, I decided to take also some gut pictures.
Some notes to the pictures:
True bypass 3PDT footswitch
Pots: Vol 10kB, Sens1 10kB, Sens2 10kB, Sens3 50kB
Wiring: Green GND, Yellow OUT, White IN, Red +9VDC
Opamps are both UA741CP, and there are only 2 components which maybe are a bit tricky to track.
These look like 2 diodes: the black one in the middle of the board (I guess is a 1N400x for 9VDC polarity protection?), and the second is a black-yellow one (marked 4Z and something else I wasn't able to read: zener for LED power?).
The other diodes look like normal 1n4148 or 1n914 (clipping diodes I suppose).
Capacitors are marked 103, 104 and 56.
The RED +9VDC wire goes to one pins of the 3PDT switch and from there to the +9VDC power plug! That means when the pedal is bypassed (OFF) the power is killed on the whole circuit!
Enjoy and have fun with the tracing!
Official LAL website: https://lalweb.com/gm2/gm2-e.html
Since I opened it to clean it a bit, I decided to take also some gut pictures.
Some notes to the pictures:
True bypass 3PDT footswitch
Pots: Vol 10kB, Sens1 10kB, Sens2 10kB, Sens3 50kB
Wiring: Green GND, Yellow OUT, White IN, Red +9VDC
Opamps are both UA741CP, and there are only 2 components which maybe are a bit tricky to track.
These look like 2 diodes: the black one in the middle of the board (I guess is a 1N400x for 9VDC polarity protection?), and the second is a black-yellow one (marked 4Z and something else I wasn't able to read: zener for LED power?).
The other diodes look like normal 1n4148 or 1n914 (clipping diodes I suppose).
Capacitors are marked 103, 104 and 56.
The RED +9VDC wire goes to one pins of the 3PDT switch and from there to the +9VDC power plug! That means when the pedal is bypassed (OFF) the power is killed on the whole circuit!
Enjoy and have fun with the tracing!
Official LAL website: https://lalweb.com/gm2/gm2-e.html
Zwischen Ordnung und Chaos fangt die Musik an
- ppluis0
- Diode Debunker
WOW !!!
There is a new ways to send unsuspecting readers to a commercial site:
Thanks for sharing...
I draw a layout...
Here is a veroboard for this schematic, etc. etc
- Manfred
- Tube Twister
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I made a layout copy for tracking.
I found other positions of the potentiometer names.
I suspect that the D1 is a 1N4001 diode and D2 is a 5.1V Zener diode.
The clipping diodes looks like Zeners or Schottkies
Can you measure them with the multimeter.
Some multimeters have a measurement mode for diodes where the threshold voltage is displayed.
If no measurement is possible, it could be Zener diodes. In this case there should be an imprint with the Zener voltage. Ready-to-Print PDF-files: SprintLayout6.0-file´:
I found other positions of the potentiometer names.
I suspect that the D1 is a 1N4001 diode and D2 is a 5.1V Zener diode.
The clipping diodes looks like Zeners or Schottkies
Can you measure them with the multimeter.
Some multimeters have a measurement mode for diodes where the threshold voltage is displayed.
If no measurement is possible, it could be Zener diodes. In this case there should be an imprint with the Zener voltage. Ready-to-Print PDF-files: SprintLayout6.0-file´:
- karul
- Cap Cooler
My initial guess was that 50k pot is the one on the output too. But one photo (there was a link somewhere for bigger gallery with 40 photos and a note) shows 50k pot above the 10k resistor and two diodes. Also the position of the green and yellow wires is clearly visible.
LAL Green Monster:
True bypass 3PDT
Pots: Vol 50k, Sens 1-2-3 10k
Wiring: Green-GND, Yellow-OUT, White-IN, Red-9VDC
Opamps are 741
Last edited by karul on 21 Apr 2022, 19:51, edited 1 time in total.
- karul
- Cap Cooler
Z4. visible marks for the diode. 4.1V, 4.3V, .... 4.x ?
J on the other one. It's for polarity protection so 1n400x would be fine.
link for the bigger gallery 140Mb zip file
https://mega.nz/file/Ct8ABApD#Zc2nYzH4e ... C6HB9e-eLo
J on the other one. It's for polarity protection so 1n400x would be fine.
link for the bigger gallery 140Mb zip file
https://mega.nz/file/Ct8ABApD#Zc2nYzH4e ... C6HB9e-eLo
- Gila_Crisis
- Resistor Ronker
Information
Sorry for the mess with the pots.
I confirm Sens3 is 50kB all others (Vol, Sens1+2) are 10kB!!!
The "power diodes" diodes: the zener is the LED protection only, the other polarity power protection and looks like a 1N400x.
Note the wiring: when you bypass the pedal you also remove the electrical power from the whole circuit.
Ths said a normal true-bypass switch shall work as well.
The clipping diodes looks like 1N4148 or 1N914. These are used very often in LAL designs.
I confirm Sens3 is 50kB all others (Vol, Sens1+2) are 10kB!!!
The "power diodes" diodes: the zener is the LED protection only, the other polarity power protection and looks like a 1N400x.
Note the wiring: when you bypass the pedal you also remove the electrical power from the whole circuit.
Ths said a normal true-bypass switch shall work as well.
The clipping diodes looks like 1N4148 or 1N914. These are used very often in LAL designs.
Last edited by Gila_Crisis on 30 Apr 2022, 06:00, edited 1 time in total.
Zwischen Ordnung und Chaos fangt die Musik an
- Manfred
- Tube Twister
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Here the corrected documents according your review. Ready-to-print file: Sprint Layout6.0 file:Gila_Crisis wrote: ↑29 Apr 2022, 20:49 Sorry for the mess with the pots.
I confirm Sens3 is 50kB all others (Vol, Sens1+2) are 10kB!!!
The diodes: the zener is the LED protection only, the other power supply protection looks like a 1N400x.
Note the wiring: when you bypass the pedal you also remove the electrical power from the whole circuit.
Ths said a normal true-bypass switch shall work as well.
The clipping diodes looks like 1N4148 or 1N914. These are very often in LAL designs.
- Gila_Crisis
- Resistor Ronker
Information
Note that Deadend FX released a PCB for the Green Monster, called 'Zilla, with an additional switch for more gain and devastation!
https://www.deadendfx.com/product/zilla
https://www.deadendfx.com/product/zilla
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- digi2t
- Degoop Doctor
Please note that the resistor that is 47R is actually 470K. If you look closely at the picture of the resistor, you can see that the black band has been deceptively hand painted. Not only are the edges not crisp, but you can see the yellow bleeding through.
Besides... there's no way you'll get enough gain out of it with a 47R, but 470K sounds just right. The DEFX board adds a toggle that switches between the original 470K and 4M7, which will totally flatten Tokyo. Again.
And great big thanks and flying high five to gila for the chance to trace out these gems. Muchos gracias amigo!
Besides... there's no way you'll get enough gain out of it with a 47R, but 470K sounds just right. The DEFX board adds a toggle that switches between the original 470K and 4M7, which will totally flatten Tokyo. Again.
And great big thanks and flying high five to gila for the chance to trace out these gems. Muchos gracias amigo!
- Manfred
- Tube Twister
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Ready-to-print PDF-file:
SprintLayout6.0- file:
- karul
- Cap Cooler
yep
- Jarno
- Resistor Ronker
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That is very creative, and also a potential headache for someone looking to repair one of these products, unless a service manual is available (probably not). Also, it adds no value to the product, so yeah, idiotic.
"It crackles....., but that's ok"
- digi2t
- Degoop Doctor
I prefer that to gooping. At least you can still get at it with a multimeter. Besides, it sort put my sleuthing skills to the test, and a decade plus of staring at schematics finally paid off.
- Gila_Crisis
- Resistor Ronker
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I've built a Green Monster clone following digi2t schematic and using his Deadend FX board: I compared it with the original LAL, and it totally nails the original GM!
Plus the Deadend FX has an additional switch to increase the gain in the IC1 stage, which is a nice addition to this noise maker.
Plus the Deadend FX has an additional switch to increase the gain in the IC1 stage, which is a nice addition to this noise maker.
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