UralTone Deluxe Reverb AB763 - Build Guide

UralTone Deluxe Reverb AB763 - Build Guide

UralTone version of the classic. The Deluxe Reverb has been chosen as the best amplifier of all time many times, at least if you judge by pure sound quality. If you could only bring one guitar amplifier to a desert island, this would not be a bad choice at all.

As with all our kits, we spare no expense when it comes to the quality of the parts—we use only the best and most reasonable parts that are built to last and sound good.

In this article, the stages of construction are outlined. Note that not all details are reviewed, and the architects' idea is mainly to familiarise the builder with its main features. The assembly is done by using the layout picture and BOM. The pictorial guide works as additional help to understand the assembly process and as well the correct order of it.

When building, always follow the layout picture and parts list. These are always the most up-to-date versions and are connected to the parts kit provided. Component availability, etc., may cause changes over time, along with improvements or adjustments. The layout picture and the parts list included with the kit are always the correct ones to follow and the most recent versions.

Deluxe Reverb - Layout

Deluxe Reverb - BOM - BILL OF MATERIALS

Schematics (google linkki)

Instructions for measuring and startup

Soldering instructions

Identifying components

First, always check that all parts are included in the delivery. If you find any deficiencies, please get in touch with us by e-mail or via the "contact us" form on the pages. Please note that the components may look slightly different from the photos. Also, note that the voltages of the parts may be higher than what is written in the list. We try to keep the models of the components 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, don't panic; each component has the necessary values ​​marked on the side of the component. Read the notes on the part list carefully.

Building the amplifier involves three stages. Installation of the parts to be attached to the chassis and their incomplete wiring, laying of components and soldering of the PCB board, and installation of the PCB to the chassis and its wiring. You can do the first two in the order that suits you. However, we recommend that you follow the order of the images below.

Start by fitting all components and parts attached to the chassis. Mount the small parts first; this makes the work a bit easier when the heavy transformers are fitted last.

Fasten the small parts of the bottom face of the chassis:

• 6x spacers which four on the sides are fasteners with M3x6 screws (some kits may use M3X5) and two in the middle with M3-10mm male-female spacers.
• 4x rubber grommets
• 6x Noval-sockets (preamp tubes) - Note the orientation, space between pin 1 / pin 9 points towards two o'clock. Fastening by M3x6 screws.
• 3x Octal-socket (output and rectifier tube) - Note orientation, the guide pin with slot on center of the socket (between pin 1 ja pin 8) points towards four'o clock. Guide the ground wire in the solder lug 8. (See picture below:) Fastening by M3x6 screws.

Cathode-ground wires guided in the solder lugs.

Same as above, seen from the outside of the chassis.

Fasten the parts to the back panel. The panel is attached to the parts.

Rear panel parts:

• Panel
• 4x RCA-connector.
• 2x Jack.
• Mains and stand-by switches
• 2x Fuse holders

Same as above seen from inside of the chassis.

Fasten the front panel parts. As well as on the rear, the panel is attached to the components.

Mount:

• 9x potentiometers. Note: Alpha potentiometers are fitted with the guide pin for locking them in the right position. This pin is a bit too tall, so cut approximately half of its length. Make sure the guide is flush with the front panel. The pin is made of cast aluminum, so it breaks easily.
• Pilot light. This is a bit tricky and tight with the space to assemble. If the pilot light is supplied with the large star washer, fit this one between the chassis and the body of the light. This way tightening the nut is easier. Try to secure the nut well: if the nut is loose and the jewel is tightened too much, replacing the bulb will be easier. With a loose nut, the jewel won't come off, and the nut opens instead. This then requires opening the amplifier. Keeping the nut tight and the jewel loose, switching the bulb can then be done without opening the amplifier.
• Leave the jacks uninstalled for now

When the light parts are done, continue with the transformers. First, check the mains transformer screws for proper tightness. The tolerances over here are quite large, so you may need to reopen the screws to make the transformer to go through the chassis. If needed, reopen the trouble corner and reposition the screw. Note: The mains transformer is fastened by separate M4 nuts and large washers. (check the picture below)

Attach the transformers and choke on top of chassis and guide the wires through the rubber grommets. These transformers are secured with M4 screws and nuts, except the reverb transformer, which uses M3 screws.

Note: The amplifier kit includes screws, nuts, and straps for mounting the chassis to the case. The nuts belonging to this set have the largest diameter of all in the set. Do not use these nuts to install transformers, etc. The thread of the nut is UNC 8-32, which can be made to fit millithread screws with sufficient twisting. Since the threads are not compatible, the nut cuts into the screw threads during installation and the nut cannot be removed anymore.

Chassis seen on inside. On the main transformer, the nuts holding the core and end bells are on the outside of the chassis, and the transformer is mounted with a second set of four M4 nuts and large washers.

Prepare the mains wire: Peel off the outer insulator within 25-30cm so the blue wire can be soldered to the mains switch. Do the estimation with the help of the chassis. Be generous; removing clipped-in strain relief without the proper tools is difficult. Over here, a few extra centimeters is a good investment; excess wire can be clipped off later on with less effort.

Cutting the mains wire is exact work. Don't cut the insulator of the inner cables, by bending the wire in tight angle and cutting carefully the outer insulator usually tears open without of getting too deep. Going round the wire, the insulator is then finally cut. If you cut the inner wire insulators and expose the copper, cut the cables and shorten the wire another 30cm. Do not use wire with damaged shielding.

The strain relief is usually fitted with a tool made for this purpose but can be done with standard tools: link to guide

The project is progressing for starting soldering. In the following, the wires from all transformers, choke, and mains wire are soldered to chassis mount parts. Try to keep the wiring similar as seen in the picture.

• Red (thin wire) pair to the rectifier tube socket pins 4 and 6.
• Yellow (thick wire) pair to rectifier tube pins 2 and 8. Use the excess wire from the previous step to continue the wire to the fuse holder side pin. Solder the rest of this wire to the top connection of the fuse holder. The end of this wire is connected to the circuit board later on.
• Yellow (thin wire) to the common negative pin of can capacitor.
• Blue (thin wire) is left as is for now. It's later soldered to the circuit board.
• Green (thick wire) to pilot light solder lugs (see picture below). Use the inner pair of holes, and make sure there are no solder bridges too short to the light body.
• Black and white (mains in) wires to mains switch to the center pair of the solder lugs (see picture below). Insulate the soldering joints with shrink sleeves.

Green wires soldered on the pilot light holder.

• The blue wire of the main cable is soldered to the main switch, and the brown one to the solder lug on the side of the fuse holder. Use a shrink sleeve on the lugs of the main switch.
• Solder a brown wire between the main switch and the main fuse holder. Insulate the switch end.
• Solder the black and white wires from the main transformer. Insulate.
• The blue and brown wires are soldered to output tube sockets pin 3.

Note: the wiring of the fuses is routed towards the back. The fuse holders are covered with shrink sleeves, and this routing enables covering the fuse holders without removing the wires. (this is done later, not now)

Solder the speaker output wires of the output transformer. The layout picture doesn't have the black wire between the jacks, but you may solder this. This ensures the ground connection if the nut of the jack gets loose. Note the jumper on the switching jack. The wiring is done by using the excess wires cut from the transformer wiring. This reusing of wires keeps the colors and gauges of the wires uniform. The solder lug of the green wire of the external speaker can be left unsoldered now. There's another wire to be soldered here later.

Solder the wires of the reverb transformer: Green and black are soldered to the rear panel RCA, and blue to pin 6 of the V6. Continue with the same wire to pin 1.

Next, the circuit board for the filter capacitors is assembled. This board is installed on the cover of the amplifier.

Solder:

• 3x resistors. These do not have polarity for mounting.
• Five electrolytic capacitors. These have polarity. The body of the capacitor has a groove on the positive terminal side. The circuit board has an outline of the capacitor with an equivalent groove marked on it. (Don't mind the C32 markings; these are valid if the board is used with other circuits.)
• Jumper wire between C31 and C32 positive terminals. Use, for example, the excess wire from the capacitors.
• Wiring from the top left corner clockwise: Red (10cm), Brown (19cm), Green (30cm) + Red (17cm) - shared pad, Red (29cm), Black (19cm), Black (bottom left corner, 12cm).

Do not solder any shared pad until all components and wires are fitted in. Filling the pad with solder makes inserting wire or components more difficult. Twist and solder the ends of the wires before actually soldering them to the pad.

Attach the circuit board to the cover and insert the wires through the grommets. The circuit board is attached with screws to the two mounting sockets and with plastic mounting posts. First attach these to the board and remove the protection from the tapes. Align the plate and press the posts. Later version of kit uses four metal stand offs and screws for fastening.

Leave the cover for the capacitor board unattached for now.

Chassis preparations are now done, and this can be set aside for a while.

The next phase of the assembly is laying the components on the circuit board of the amplifier.

It's possible to assemble the circuit board per component type or low components first order. The latter is better because the parts are pressed against the board when it's turned around for soldering. In the following pictures, this technique is used. To keep on track the build, mark the parts used to print BOM.

In the picture above, most of the resistors are set on the circuit board. These resistors don't have specified mounting directions. However, these all have been laid in the same reading direction as the part numbering on the PCB. This makes the boars somewhat easier to read afterward with the uniform direction of the parts.

Note: Some of the pads are shared, so solder only those that aren't populated later with another component or wire.

The cathode resistors of the preamp tubes with capacitors have been added to the board. These electrolytic capacitors have a specific polarity. The plus pole is marked with a groove corresponding to the connection plate print. In the picture, the grooves are all pointing downwards.

In addition to the above-mentioned parts, ceramic capacitors are now soldered to the board. These have no installation direction. The value of the parts is marked in such a way that the first two digits indicate the first two digits of the value and the third (if the capacitance is large enough) shows the number of zeros to be added after the number. For example: 471 is 470pF and 10 is 10pF.

Proceed yet a bit taller components: The bias supply electrolytic cap is on the left. Mind the polarity of it. On close on the right of this is the diode for the bias supply. The diode has polarity. The package of the diode has a stripe on the cathode end. The PCB has a corresponding marking on the printing.

The yellow polyester capacitor doesn't have polarity.

Note the C18 with the body is shorter than the other 100nF capacitors.

Finally, solder the tremolo circuit capacitors. The one on the bottom is different in value, 22nF, marked as 223. Solder the bias trimmer and optoisolator as well. The optoisolator has a dot on the lamp end of the package, and this is aligned towards the bottom of the picture. If there are no markings, the lamp end can be determined by feeling through the sleeve/package. The lamp is cylinder chaped, where the LDR is a round disk.

Finally, shave off the connecting wires of the components on the solder side of the board. The component wires on pads sharing wires, which aren't soldered yet, are cut short. These parts won't drop off if the connecting wire is bent a bit under the board or the component is soldered on its other end.

Fasten the board to the chassis by six M3X6 screws. Guide the four ground wires in the eyelets on top edge of the board.

Solder the four ground wires. The second from the right has the black wire from the cap board soldered, too.

Be careful when soldering the uninsulated wires. Check that no other wires are touching this wire while soldering so the hot wire won't cut through the insulation of the other wire. Mind especially the second grounding point from the left.

A detailed picture of the grounding

Solder the wires on the left end of the circuit board (wires from the cap board, fuse holder, output transformer, choke, and mains transformer).

Solder the rest of the wires from the capacitor board and the red wire of the reverb transformer.

Note: as different as on the layout picture, the red wire of the reverb transformer is soldered directly to the same pad as the wire coming from the cap board. Some reverb transformers have short cables. This can be solved by using a board jumper and secondary pad on the PCB if needed, as in the layout picture. If the wire is long enough, wiring can be done as in the image.

Continue the wiring between the tube sockets and the circuit board. In the (slightly out of focus) picture, all the blue wires coming to the cathodes of the pre-amp tubes are soldered. Run the wire along the surface of the chassis.

Solder the grid wires (white). The wires on the leftmost tubes are routed through the board.

Solder the return line and foot switch input of the reverb as part of the grid wiring. Note the 220k resistor soldered on the connector.

Output tube sockets have 1.5k grid stopper resistors on the grids. First, solder the wire on the bottom eyelet of the tube, and then solder the resistor. It's a tight space, so doing the wire and resistor at the same time is a bit difficult when the resistor is blocking.

On the last round of the tube socket wiring, solder the brown wires of the anodes. (Note: the second tube from left is missing the wire on pin 6. Solder this wire as well now.)

Route the anode wires either close on the chassis if possible or lift these bit above the wires soldered previously.

Switch to front panel side wiring. Input jacks are easy to prepare outside the chassis, using the chassis as a bench. Fasten the jacks as in the layout and solder the resistors. (Note: If the solder you use has plenty of flux and spits this all over, cover the panel before soldering.)

When done, install the jack packet on the right side of the chassis.

Solder the white wires as shown on layout picture.

Solder the jumper wires/resistors on the back covers of the potentiometers.

Note: The layout picture has the 47pF bright cap drawn, but we don't recommend using this. The cap is drawn on the layout to follow the original layout. The bright cap may cause unwanted oscillation on the circuit, making the vibrato channel sound bad. Omitting the cap is the easiest way to solve this.

The Alpha potentiometers have a grease layer, and this makes soldering difficult. To successfully soldering clean the backs of the potentiometers with degreaser, such as isopropanol or similar. Then, sand of file the area where the solder is applied. Use the cut legs of the components or a piece of single-core wire as a jumper.

Solder the wires across the tone potentiometers. Leave the end where the other wire is inserted later unsoldered.

Solder the brown and blue wires between the potentiometers and the circuit board.

Note: Route the wires of the INTENSITY potentiometer (on the left side) above the wires from the capacitor board. In this way, the audio cables of the tremolo is protected by cap board wires from the wire of the SPEED potentiometer, which may leak interference into the signal. Similarly, position the REVERB potentiometer wires away from the SPEED wire.

Note: the second REVERB wire is missing from the picture. Also, install this.

Same as previously, from a bit altered angle.

As last, solder the output tube screen wires and resistors, feedback wire from the external speaker jack, and tremolo foot switch connector wire to the circuit board.

As the last wiring task, the heater wiring is made. This wire runs in the same line of the tubes above the sockets.

Cut the green single-core wire for a filament that came with the kit in half into two parts. Sold the wires' ends to the socket of the first stage tube to pins 4+5 (bridged) and 9. Braid the cables into a neat pair. A good braid prevents interference from the heater wire from being transferred to the signal. Cut the wire to bend its ends to the next socket.

Solder a new pair of wires to the same pins 4+5 and 9. From the previous point of view, it is enough that the wire only goes to pin 5; bridging can be done with another wire. Alternatively, you can fold the ends of the wires (pin 4 and pin 5) over the solder lug and solder the ends together.

Continue in the same way, proceeding to the sockets of the output tubes. When the heater wiring is done in these parts, apply a shrink-wrap to protect the fuse holders. As before, the holders' wiring is routed towards the panel so the sleeve can be installed without removing the wires.

From the output tubes, continue the wire till the pilot light socket.

Install the pair of the 100ohm resistors between the lugs and chassis and solder the heater wiring.

The amplifier is almost done. Attach the front panel knobs, pilot light, and its cover and fuses.

Note: here's the routing of the heater wire above the tube sockets seen the best.

The amplifier installation work is complete. Next, following the layout image, check that all the wiring has been done right and that the parts have been laid out correctly. Go through the circuit wire by wire, part by part, and mark the checked part on the layout picture.

The checklist for powering up and measurement point values is found here: 

https://docs.google.com/spreadsheets/d/1CRP6kfBlP8VWHthzhgFmR605qaoRH0X6vjR967P3Yy4/edit?usp=sharing

Follow the instructions on the opening page and look at the measuring instructions on the Princeton tab in the bottom left corner. Turn all potentiometers and the bias trimmer to zero. (Bias zero is the most negative voltage.)

When everything is correct, measure with a multimeter as well as the integrity of the grounding and rule out short circuits in the power source:

• Measure using the resistance range of the multimeter: One probe to any part of the chassis frame and the other to the negative lug of the capacitors C5, C9, C11, C15, C16, C23, C24 and the capacitor board C32, C32, C33, C34 and C35 negative terminal, the grounds of the potentiometers / black wires and the bodies of the jacks. The results should read zero ohms. 
• Measure in the resistance range of the multimeter: one at a time, measure the resistance over the positive poles of the capacitor board capacitors and the chassis. In this measurement, the resistance is small at first, but settles to several hundred kilo-ohms. Make sure to wait for the meter to settle. A small resistance, zero or only a few kilo-ohms can be a sign of a possible short circuit, which should be looked for before connecting power.

When the measurements and checks have been done successfully, you can connect the power to the device. First, install the fuses and the rectifier tube in place; the other tubes are left uninstalled. Measure the voltage from the ground and positive terminal of the capacitor board capacitors. The unloaded voltage is approximately the same at all positive poles and at this stage well above the results of the measurement points marked in the layout image. If there is no voltage on the capacitors, the device smokes, sparks, or does something unexpected, turn off the power.

Before troubleshooting, make sure that the power source's capacitors are de-energized and the device is disconnected from the mains by measuring. The layout picture also shows the AC voltage measuring points. If necessary, these can be measured in the 1000Vac range of the multimeter if there are problems with the device. Of these, those marked with one arrow are measured relative to the ground, and those marked with two arrows are measured between the arrows.

Install the rest of the tubes and connect a speaker or an artificial load to the output. Turn the knobs to zero. Turn on the power. Let the amplifier settle down briefly and measure the voltages at the measuring points. At the same time, make sure that the amplifier does not do anything unexpected.

Measuring points 400V, 325V, etc. are marked in the layout picture / voltage map. The values ​​of these measuring points are measured relative to the ground, i.e., the black measuring head of the multimeter is attached to the body of the device, and the measurements are made with the red one. It is advisable to sit on your other hand while you make the measurements. Use the 1000Vdc setting as the measurement range and allow approx. 10% deviation from the given measurement results. 

The voltages at the measuring points are always affected by the dispersion of the tube parameters and the differences in current consumption. Another factor that changes the results is the magnitude of the mains voltage. This can vary between 220-240Vac, which is easily seen in the measurements. It is better to check the voltages more and allow them to slide in one direction or another. Large deviations in a single measuring point when the others are in place can reveal, for example, the wrong size of the resistor on the PCB. You should also rely on your ears: If the amp sounds bad, something is wrong.

Note: If you measure voltages without tubes, the voltages with the main transformer unloaded are always higher. Except for alternating current measurements of the mains transformer, the voltages should always be measured with the tubes.

When the measurements are done to an acceptable level, install the cover of the capacitor board.

The amplifier is ready to be fitted in the cabinet. The details of this is not covered here, but here are some things to consider:

• Deluxe Reverb kit is supplied with the parts for Fender-style reverb tank wiring. Instructions of the assembly is found here: Fender -style reverb tank wire build guide
• Speaker cable is as well in front of the kit and resembles by the looks of the ones used in Black Face amplifiers.
• The reverse tank needs to be enclosed to the bag intended for the purpose. This prevents the feedback in the cabinet. The bag can be bought as ready or done out of the same tolex as used to cover the cabinets.

We wish you good times with the freshly built amplifier!