UralTone MKII assembly instructions

UralTone MKII is now continuing the research into the Tone Bender product family with its third version, the Mk2. It was introduced in mid-1966, immediately gaining prominent users such as Jimmy Page, Jeff Beck, etc. The MN21A from the Soviet production was chosen as the transistor for the Uraltone building kit, which sat in place for circuit smoothly.

MKII offers singing sustain, dynamism and resolution. It works especially with Humbucker guitars, offering a massive Fuzz Symphony.

  1. UralTone Studio Fuzz diy kit
    €70.00 €56.45

UralTone MKII - BOM - Bill of materials

General guidelines to building kits

General guide for pedal builders in PDF format 

Check all the parts

Always check first that all parts are included in the delivery. If you find any problems please contact us by email or through the “contact us” form on the pages. Note that the components may look slightly different than in the photos. Also, note that the voltage specs of the parts may be higher than what is listed. Read all the notes at BOM (bill of material) carefully.

Building the pedal

Follow the order in which the images below are assembled. We try to keep component manufacturers and types the same, but sometimes we have to change the manufacturer or model of a part due to poor availability. So if a part is a slightly different color or higher voltage rating, all is good, each component has the required values marked on the side of the part.

Start building from the footswitch. The current limiting resistor of the LED is soldered first. This resistor is packaged separately in a bag of other parts of the hardware set.

Press the foot switch onto the FS board. Note the installation direction, the hole in the threaded part will come up. The soldering heads on the plate may be narrow, so press the switch with sufficient force. The circuit board and switch will not get hurt!

Cut five-cent lengths from the cord provided with the kit. Peel the insulation about 3mm apart, twist the strands together, and pre-solder the stripped wire ends.

NOTE: The LED will not be installed at this time!

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UralTone MKII pcb. The locations of all parts with their part numbers (designator) are printed on the board. C=capacitor, R=resistor, Q= transistor, D=diode etc.  The values or types of parts corresponding to the designator can be found in the parts list provided with the kit.

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It is a good idea to start with low / smaller parts, so that the parts are pressed against the surface of the pcb when they are soldered to the board and the board is turned over on a table or similar surface. Start by populating the resistors on a pcb. Resistors are marked R1, R2, etc. Resistor values are marked with colored rings. To interpret these, see the table provided with the kit. The correct values can also be measured or compared to the color rings in the image above. It doesn’t matter the direction in which the resistors are installed, but for readability, it’s a good idea to install them in the same direction, depending on the printing on the board.

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Solder the trimmer on pcb.

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Solder the Plastic Film Capacitors (designator prefix C) in place. The values of the ceramic and polyester capacitors are denoted so that the first two digits indicate the value of the first two digits. The third indicates the number of zeros. For example, 471 is 470pF, 472 is 4700pF, or 4.7nF. The installation direction of these parts does not matter.

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Install the electrolytic capacitors on the pcb. Note the mounting direction of the part, the printed stripe on the side of the part marking the negative terminal of the capacitor corresponds to the white semicircular pattern printed on the circuit board. Axial capacitors has goove on the other end of the part. This is aligned according the silkscreen on the pcb.

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Solder the Germanium transistors (Q1, Q2 ...) to the board. Leave about a few millimeters of connecting wire between the housing and the board on the transistor legs. These parts do not withstand hot conditions so work quickly.

The transistors in the KIT have been selected according to the gain and leakage, so install correct part to correct place - Q1 selected to Q1 place etc.

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Same step from another angle

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Solder the potentiometers to the pcb. It is advisable to solder the potentiometer middle foot first and then check that it is on the surface of the plate and straight. When the position is correct, solder the outermost pins.

Solder the footswitch board made at the beginning and the battery clip to the main pcb. The wires of the battery clip are threaded through the pcb and soldered to the pads. This results in strain relief on the conductor. The wires of the clip can be shortened slightly, approx. 5cm. The appropriate length of cord can be measured by temporarily placing the parts inside the case.

Jacket installation in case

Install the Jacks in the case. Not not overtight, since you need to rotate them when the wires are soldered.

DC jacket installation

Insert the DC jack into the mounting hole.

Ledin pujottaminen asennuspaikkaansa

Slide the LED into place. Note the polarity of the LED. The shorter leg / chamfered LED is marked on the pcb. When viewed vertically (wires up), the beveled side / shorter coupling foot comes to the left. Washers are placed in the threaded portion of the footswitch to await installation.

Efektin elektroniikka

This set of circuitry is fitted in the enclosure.

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Install the board in the case. When installing the effect pcb, care must be taken that the DC jack does not fall out of place. (This can be prevented with a non-powered DC cable or plug holding the jack). Install the front panel, if such option has been ordered with the kit. Tighten the nuts with your fingers and fit the plate neatly into place. When everything sits as desired, solder the DC. The LED is installed by pushing it through the front panel and soldering it.

Solder the jacks. The solder lugs of the jacks are pressed inwards before soldering. The jacks can always be rotated for soldering. After soldering, the jacket is twisted for the next wire. Start soldering as seen from the lower lug, so the wired wires move deeper into the housing and are not in front when the next wires are soldered in place.

The UralTone effect kits are delivered with two different types of input jacks. Please refer how to solder instructions found here: https://en.uraltone.com/blog/input-jack/

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Attach the potentiometer knobs and install a 9V battery. Now you are ready to take your guitar / bass / synth and test how does it sounds. If all works, we still have to bias transistors to work as designed.

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You'll need a multimeter and a small precision screwdriver. Adjust the front panel potentiometers to full. Connect plug to input jack and let the device warm and stabilize for some time.

Note the TP1 is not TP1. Right pad to measure the voltage is on right marked with pen.

Insert the black measuring probe into the screw hole on the bottom of the effect housing (this is ground). Measure the voltage at test point on the mid pin of the trimmer. Adjust the trimmer until the voltage is -8.06Vdc.

The values given are recommendations. Always listen and make sure pedal sounds as good as possible. If you pedal sounds best with some other voltages, thats fine, sound quality is the most important thing!