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BYOC Classic Brit 50 Instructions Manual

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Build Your Own Clone
Classic Brit 50
Kit Instructions
(Revision 1.0)
WARNING!!! HIGH VOLTAGE!!!!
Tube amplifiers contain high voltage that can cause injury and even death. Please use extreme caution and common sense when
building this kit. Do not attempt to do anything to your amp while it is plugged in other than take voltage readings as necessary or
actually playing an instrument through it as it was intended.
Don't just turn the power off!!! Always unplug the power cord from the socket before working on your amp!!! The mains supply can
still electrocute you AND the power filter capacitors can still retain a charge powerful enough to kill you. Always unplug the power
cord from the socket before working on your amp.
1

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  • Page 1 Build Your Own Clone Classic Brit 50 Kit Instructions (Revision 1.0) WARNING!!! HIGH VOLTAGE!!!! Tube amplifiers contain high voltage that can cause injury and even death. Please use extreme caution and common sense when building this kit. Do not attempt to do anything to your amp while it is plugged in other than take voltage readings as necessary or actually playing an instrument through it as it was intended.
  • Page 2 DISCLAIMER Build at your own risk!!! BYOC, Inc. is not liable or responsible for any damages, injuries, or deaths that may incur from or while building this kit. It is your own responsibility to follow proper safety precautions. Never attempt to build, modify, repair, or perform any sort of maintenance on your amplifier while the power cord is plugged into an AC power source.
  • Page 3 That being said, we will do our best to help you as much as we can. Our philosophy at BYOC is that we will help you only as much as you are willing to help yourself. We have a wonderful and friendly DIY discussion forum with an entire section devoted to the technical support and modifications of BYOC kits.

  • Page 4: Table Of Contents

    CLASSIC BRIT 50 KIT INSTRUCTION INDEX Parts Checklist…………………………………………………page 5 - 8 Chassis Assembly………….………...…………………….…...page 9 - 20 Wiring (Power Section)…………….………………………….page 21 - 50 Populating the Circuit Board……………..…………………..page 51 - 66 Wiring ………………………………………………………….page 67-75 Wiring(Tube Side)……………………………………………..page 76 - 93 Wiring (Potentiometer Side)………..…………………………page 94 – 111 Wiring Layouts/Diagrams……………………………………..page 112 - 113...

  • Page 5: Parts Checklist

    Parts Checklist for Classic Brit 50 Kit Resistors: 1/2watt (4 color band will either be silver or gold): 1 – 470 ohm (Yellow/Purple/Brown) 2 – 820 ohm (Gray/Red/Brown) 1 - 2.7K (Red/Purple/Red) 1 – 10K (Brown/Black/Orange) 1 – 15K (Brown/Green/Orange) 1 –...
  • Page 6 Diode: 5 – 1n4007 (or byv26ev) Capacitors: 1 – 47pF (Red or black with ‘47’ on the body) 2 – 500pF (Red or black with ‘500’ on the body) 2 – 0.1uF axial leaded polyester film 7 – 0.022uF axial leaded polyester film 2 - .68uF axial leaded polyester film 2 –...
  • Page 7 6 – ¼” Shorting Mono Jacks 1 - Indicator Lamp 1 - 6' 3-conductor power cord 1 - Power cord socket 2 – black screws for power cord socket 1 - Panel mounted fuse holder 1 - Flat-Mount Fuse Holder 1 - Mains Fuse (3A Slow-Blow for 120V, 2A Slow-Blow for 220V or 240V) 1 - HT Fuse (500mA) 3 - Rubber Grommets...
  • Page 8 Save the wire you clip from the transformers as well. This will provide you with more than enough wire to complete your kit. Tubes: 3 – ECC83 2 – EL34 Transformers: 1 – Power Transformer (Classic Tone 40-18033) 1 – Output Transformer (Classic Tone 40-18025) 1 –...

  • Page 9: Chassis Assembly

    Chassis Assembly Step 1: Add grommets...
  • Page 10 Step 2: Mount the transformers. Orient the power transformer so that the side with the green wires is towards the “tube side” of the chassis. Orient the output transformer so that the side with the black/yellow/purple/orange wires is towards the “tube side” of the chassis.
  • Page 11 Step 3: Add the tube sockets (red arrows)
  • Page 12 3a: Adding the 9 pin sockets - First crimp pins 4 & 5 of the 9-pin sockets. You don’t really have to do this. When you hook up the heater wires, you will need to connect pins 4 & 5. Some people think crimping these two pins together makes it easier, but if you don’t want to do this, you can just use wire to jump the two pins together.
  • Page 13 Only add the ring terminal to the power tube sockets. Do not add a ring terminal to any other tube socket Use M3 screws and M3 nuts. See next page for exploded diagram.
  • Page 15 Step 4: Mount the two 32uF x 32uF capacitors to the outside of the chassis. Use the mounting rings to mount to chassis. Use M3 screws to mount to chassis of the left capacitor (Green arrow). Use M3 screw and nut to tighten clamps. Use M3 screw, M4 flat washer, and M3 nut to attach mounting ring of the right capacitor (Red arrow).
  • Page 16 Step 5: Add flat mount fuse holder. Use 1 x M3 screw and 1 x M3 nut.
  • Page 17 Step 6: Add the rear plexi panel and rear panel mounted parts !!!!The plexi panels are EXTREMELY DELICATE!!!! 6a: Mount the AC Power Cord Receptacle. Use black flat head screws for power cord receptacle.
  • Page 18 6b: Mount the rotary switch. Bend the rotary switch tab flat before mounting to the panel. 6c: Mount the two speaker jacks and the panel mounted fuse holder. After these are in place, use an M3 screw to secure the far end of the rear plexi panel.
  • Page 19 Step 7: Add the front plexi panel and panel mounted parts 7a: Add the Switches and lamp. Orient the toggle switches so that the “ON” arrow is pointing in the same direction as the “ON” label on the plexi panel. The lamp is not mounted with any nuts or bolts. You simply push it through its hole and it will lock in place. The lamp may be loose fitting.
  • Page 20 7b: Mount all the potentiometers and the four remaining ¼” jacks.

  • Page 21: Wiring (Power Section)

    Wiring (power section)
  • Page 22 Step 1: Solder the High Voltage Center Tap (red/yellow) and Heater Center Tap (green/yellow) wire to ground via the lower lock washer w/ solder tab.
  • Page 23 Step 2: Cut the orange, gray, white, and both yellow wires. Cut the brown wire if you are using 120V. Cut the black wire if you are using 240V. These are you mains wires for the power transformer. Leave them long enough so that you can switch them if you need to at a later date.
  • Page 24 Step 3: Connect the OFF side of the MAINS switch to the center lug of the panel mounted fuse holder.
  • Page 25 Step 4: Attach the remaining terminal on the panel mount fuse holder to the ‘L’ terminal of the AC receptacle.
  • Page 26 Step 5: Attach the Black wire from the transformer (Or brown if using 240V) and one lamp wire to the ON side of the MAINS switch.
  • Page 27 Step 6: Connect the remaining lamp wire and the blue wire from the transformer to the “N” terminal of the AC receptacle.
  • Page 28 Step 7: connect the OFF side of the STANDBY switch to the red lug of the first 32 +32 capacitor. At the same time, make a jump connection between the positive lugs. Only solder at the green arrows, not the red arrow yet.
  • Page 29 Step 8: Connect the silver lug of the first 32 + 32 capacitor to the silver lug of the second 32 + 32 capacitor. Connect the “E” terminal of the AC receptacle to the silver lug of the second 32 + 32 capacitor, and then connect to ground.
  • Page 30 Step 9: Connect ON side of the STANDBY switch to one end of the flat fuse holder.
  • Page 31 Power Wiring Drawing...
  • Page 32 Step 10: Add bus wire to the speaker jacks. Solder on the green arrows, not on the red arrows yet.
  • Page 33 Step 11: Connect the black wire from the OT secondary (Common) to the Sleeve bus and solder.
  • Page 34 Step 12: Connect the yellow, orange, and purple wires to the rotary switch as shown.
  • Page 35 Step 13: Using a piece of white wire, connect the tip bus to the pole terminal of the rotary switch as shown. Solder the tip bus.
  • Page 36 Step 14: Connect the Output Transformer primaries to their respective sockets. Blue to pin 3 of the V5 power tube, which is closest to the power transformer. Red to pin 3 of the V4 output tube as shown.
  • Page 37 Step 15: Connect a 1 ohm 1 Watt resistor from pins 1 & 8 of the V5 power tube (tube closest to the power transformer) to the terminal ring (page 13) and solder. It is difficult to see in the picture, but one end of the resistor is threaded through both pins 1 &...
  • Page 38 Step 16: Repeat the previous step for the V4 power tubes, but this time, also add a black wire to the terminal ring. Connect the other end of the black wire to the remaining unsoldered lug on the speaker jacks. You should now have all of the lugs on the speaker jacks soldered.
  • Page 39 Step 17: Connect the 6.3V heater wires from the power transformer to the filament pins of the power and preamp tubes. Start with the power tubes. One green wire goes to pin 2, the other to pin 7 of each power tube. It does not matter which green wire goes to which pin.
  • Page 40 Continue daisy chaining the heater wire to the pre amp tubes. Pre amp tube filament pins are 9 and 4/5. Step 18: You will need to jumper pins 4 and 5 if you elected not to crimp them together earlier.
  • Page 41 Step 19: Connect 1k 5W resistors between pins 4 and 6 of V4 and V5 as shown. Only solder on pin 4 of both sockets for now.
  • Page 42 Step 20: Using a length of brown wire, make a jump between pins 6 of each power tube. Only solder pin 6 of V5 (closest to the transformer).
  • Page 43 Tube Side Wiring...
  • Page 44 Step 21: Connect a bare bus wire to the back of the potentiometers as shown. We will refer to this as the “ground bus”. If you are having trouble connecting the bus wire to the back of the potentiometers, you can rough up the backs with some emery cloth or a file, this should help with solder adhesion.
  • Page 45 Step 22: Connect a .1uF capacitor between lugs 1 and 2 of the B25K Presence potentiometer. Thread the extra lead through lug 1 and solder it to the back of the potentiometer as shown.
  • Page 46 Step 23: Prepare the bottom row of input jacks. Connect a 1M 1/2Watt resistor between the tip and sleeve terminals of each jack, threading the extra lead through the sleeve terminal to the tip disconnect terminal as shown. Connect a 4” piece of black wire to each sleeve terminal. Solder the sleeve terminal only. They should look like the picture above.
  • Page 47 Step 24: Use ¾” of bus wire to connect the sleeve terminal of the other input jacks to the tip disconnect terminal as shown. Only solder the terminals with green arrows.
  • Page 48 Step 25: Mount the input jacks and connect the black wires to the ground bus at the green arrow.
  • Page 49 Step 26: Connect the ground bus to the last terminal washer mounted to the power transformer and solder at the green arrows.
  • Page 50 Chassis Wiring Layout...

  • Page 51: Populating The Circuit Board

    Populating the Circuit Board Step 1: Run bus wire along turret lugs as shown. Solder the bus wire jumps.
  • Page 53 Step 2: Insert trimpot so that one wiper is not inserted into a turret lug as shown.
  • Page 54 Step 3: Insert all components into circuit board except for the large 32uF + 32uF capacitor, and two large .68uf capacitors. Insert leads into openings of turret lugs. DO NOT solder the red arrows for now. Solder all the other turret lugs and bus wires.
  • Page 55 Drawing of component placement so far. DO NOT solder the red arrows yet.
  • Page 56 Step 3a: Add the large capacitors that were left out of the previous step, and solder all connections.
  • Page 57 Completed Board Component Placement Picture...
  • Page 58 Step 4: Make bare bus connection on underside of board between the “potentiometer side” of the 8.2k 2W and 100K/82K junction. Make a 2 connection between 82K/100K and “potentiometer side” of the 10K 1W. Make a connection between 820Ohm/220uF/2.7k/.68uF junction and 820Ohm/100K/.68uF junction as shown.
  • Page 59 Step 5: Make a jumper connection on the underside of the board between the 15K/10uF junction and the 200k/200k junction. Add a 2 jumper connection between the “potentiometer side” of the 47K and the 10K/.1uF junction. Add a 3 jumper connection between the left 10K 2W/33uF + 33uF capacitor and the 100K/100K junction as shown.
  • Page 60 Top-side picture with component values and the underside wires. Top of pic is the potentiometer side. Bottom of pic is the tube side.
  • Page 61 Example of wire connections to top tier of turrets.
  • Page 62 Step 6: Connect off-board wires to top tier of turret lugs on the board. Start with the “potentiometer side”. Use 10” of red wire off the 8.2K 2W resistor. Use 8” of brown and yellow wires off each 200K/.022uF junctions. Use 8” of white wire off the 10K/.1uF junction.
  • Page 63 Step 7: Connect off board wires to the two 68K/68K junctions and 500pF/470K/470K junction. Thread the wires through the board as shown at the red arrows use 6” of wire for these connections.
  • Page 64 Step 8: Add the rest of the off-board wires to the “tube side” of the circuit board. Use 7” of red wire from the currently unused turret lug. Use 7” of green wire off the “tube side” of the 8.2K 2W resistor. Use 6” of orange wire from the “tube side” of the 47K resistor.
  • Page 65 Step 9: add the 3 hex standoffs at the red arrows. Use M3 screws.
  • Page 66 Top-side component picture showing the location of the standoffs in green.
  • Page 67 Step 11: Mount the circuit board. 11 a: Run the brown and yellow wires from the two 220K/.1uF junctions under the board so they stick out on the “tube side” (red arrows). Also run the red wire coming from the “potentiometer side” of the 8.2K 2W resistor under the board. (green arrows) 11 b: Make sure you can get to the remaining choke wire and 1K 2Watt resistor (blue arrow), and the remaining white OT primary wire (orange arrow)

  • Page 68: Wiring

    Wiring Step 1: Connect the red wire from the empty turret lug to the previously unsoldered lug of the first 32uF + 32uF capacitor. Solder the capacitor lug. (shown at green arrows).
  • Page 69 Step 2: Twist the red wires from the transformer together and attach to the rectifier diodes as shown. Solder both connections. WARNING!! A: DO NOT make wires/leads so long that they go through the turret lug and out of the other side. They may touch the chassis and cause a short.
  • Page 70 Step 3: Attach the green wire from the “tube side” of the rectifier diode junction to the remaining lug of the flat fuse holder. (green arrows)
  • Page 71 Step 4: Connect the red wire from the “potentiometer side” of 8.2K 2W resistor to the YELLOW terminal of the 32uF+32uF electrolytic capacitor (red arrows). Also connect the green wire from the “tube side” of the 8.2K 2W resistor to the RED terminal of the 32uF+32uF capacitor (green arrows) Solder both connections.
  • Page 72 Step 5: Connect the remaining white OT wire and one of the choke wires (it doesn’t matter which choke wire) to the previously empty turret lug. (green arrow) solder.
  • Page 73 Step 6: Using a short piece of brown wire, connect the unsoldered pin 6 of V4 to the “tube side” of the 8.2K 2W resistor. At the same time, connect the remaining choke wire to the same turret lug (green arrows). Solder all the connections.
  • Page 74 Step 7: Prepare the 5.6K 1W resistors as shown. The straight piece will go into pin 5 of V4 and V5 in the next step.
  • Page 75 Step 7a: Attach the brown and yellow wires from the “potentiometer side” of the 220k/.022uF junctions to pin 5 of V4 and V5 using the 5.6K 1W resistors prepared in the previous steps. Attach the brown wire to V5, and the yellow wire to V4 (shown at green arrows).
  • Page 76 Step 8: Attach the orange wire from the ‘tube side” of the 47K resistor to the orange OT wire that is already attached to the rotary switch (green arrows).

  • Page 77: Wiring(Tube Side)

    Tube Socket Wiring...
  • Page 78 Step 1: Attach the first white wire from the 47pF/100K/.022uF junction to pin 6 of V3.
  • Page 79 Step 2: Attach yellow wire from 47pF/82K/.022uF junction to pin 1 of V3.
  • Page 80 Step 3: Attach brown wire from .1uF/1M junction to pin 7 of V3.
  • Page 81 Step 4: Attach the white wire from the 470Ohm to pin 8 of V3. Make sure you either strip enough to make a jump to pin 3, or use a piece of bus wire to make the jump. Shown with green arrows, solder both pins of V3.
  • Page 82 Step 5: Connect the 2 yellow wire from the 1M/.022uF junction to pin 2 of V3.
  • Page 83 Step 6: Add the 100k resistor and jumper to V2. Thread one end of a 100K 1/2W resistor through pin 1 of V2. Bend the lead around and thread through pin 7. Insert the other end into pin 6. Solder pins 1 & 7 (Green arrows) DO NOT solder pin 6 (red arrow).
  • Page 84 Step 7: Connect brown wire from 10K 2W/32uF+32uF capacitor to pin 6 of V2 (green arrow) solder pin 6 of V2 now.
  • Page 85 Step 8: Attach white wire from the 100K/33K/500pF junction to pin 8 of V2.
  • Page 86 Step 9: Connect yellow wire from .68uF/820Ohm junction to pin 3 of V2.
  • Page 87 Step 10: Connect brown wire from 470K/470K junction to pin 2 of V2.
  • Page 88 Step 11: Connect white wire from .022uF/100K junction to pin 6 of V1.
  • Page 89 Step 12: connect yellow wire from 68K/68K junction to pin 7 of V1.
  • Page 90 Step 13: Connect brown wire from .022uF/100K junction to pin 1 of V1.
  • Page 91 Step 14: Connect white wire from 68K/68K junction to pin 2 of V1.
  • Page 92 Step 15: Connect the yellow wire from .68uF/2.7K junction to pin 8 of V1.
  • Page 93 Step 16: Connect remaining brown wire to pin 3 of V1.
  • Page 94 Wiring diagram for Tube Side For high-Res image click here: http://byocelectronics.com/brit50tubesidewiring.pdf...

  • Page 95: Wiring (Potentiometer Side)

    Wiring (Potentiometer Side) Step 1: Attach the first black wire to the ground bus (green arrows).
  • Page 96 Step 2: Connect the white wire from the .1uF/10K junction to lug 3 of the PRESENCE potentiometer (green arrows).
  • Page 97 Step 3a: Make a jump between lug 1 of the BASS pot and lug 3 of the MIDDLE pot (green arrows). Solder both lugs. Step 3b: Make a second jump between lug 2 of the BASS pot and lug 1 of the Treble pot. Only solder on the green arrow.
  • Page 98 Step 3c: Connect a piece of black wire from lug 1 of the MIDDLE pot to the ground bus.
  • Page 99 Step 4: Connect the brown wire from .022uF to lug 2 of the TREBLE pot.
  • Page 100 Step 5: Connect next black wire to ground bus as shown.
  • Page 101 Step 6: Connect yellow wire from .022uF to lug 2 of the MIDDLE pot.
  • Page 102 Step 7: Connect white wire from .022uF to lug 1 of the TREBLE pot. Solder the connection now.
  • Page 103 Step 8: Connect brown wire from 500p to lug 3 of the TREBLE pot.
  • Page 104 Step 9: Attach next black wire to the ground bus.
  • Page 105 Step 10: Connect lug 1 of both LOUDNESS pots to the ground bus.
  • Page 106 Step 11: Connect yellow wire from 470K/500p junction to lug 2 of the LOUDNESS 1/BRIGHT TREBLE pot.
  • Page 107 Step 12: Connect the white wire from 470k to lug 2 of the LOUDNESS 2/NORMAL pot.
  • Page 108 Step 13: Connect the brown wire from .022uF to lug 3 of the LOUDNESS 1/BRIGHT TREBLE pot.
  • Page 109 Step 14: Connect the final brown wire from .022uF to lug 3 of the LOUDNESS 2/NORMAL pot.
  • Page 110 Step 15: Using two 2” pieces of wire, make a jumper between the tip connection of the LOWER input jacks, and the disconnect connection of the UPPER jacks. Solder the LOWER jacks at the green arrows. DO NOT solder the red arrows for now.
  • Page 111 Step 16: Connect the yellow wires to the tip terminals of the upper jacks, and the white wires to the disconnect terminal of the upper jacks. Solder all connections now.
  • Page 112 Diagram for Potentiometer Side Wiring For High-Res image click here: http://byocelectronics.com/brit50potsidewiring.pdf...
  • Page 113 120V Layout Go to http://www.byocelectronics.com/brit50-120layout.pdf for high-res PDF.
  • Page 114 240V Layout Go to http://byocelectronics.com/brit50-240layout.pdf for high-res PDF Note: The difference between 120V and 240V wiring is using the brown wire on the transformer instead of the black, and a 2Amp fuse for the Mains Fuse.

  • Page 115: Turning Your Amp On For The First Time

    Turning your amp on for the first time Step 1: Make sure your AC power cord is NOT plugged in. Do NOT install any of the tubes yet. Do not plug a speaker into the speaker jack. Do not plug any instruments into the input jacks. If at any point in this process, you smell smoke, see sparks, or hear any loud electrical hum noises, immediately pull the AC power cord from the wall socket.
  • Page 116 Step 7: Turn the mains switch off and unplug the power cord from the wall socket. 32uF+32uF EL34 ECC83 Step 8: With the mains switch off and the AC power cord unplugged from the wall, now install the 500mA fuse into the flat mount fuse holder.
  • Page 117 Step 9: Plug the AC cord into the wall socket. Make sure the standby switch is in the “standby” position. Turn the mains switch on. The tubes should start to warm up and glow. Hopefully you know that vacuum tubes get very hot once they are warmed up.
  • Page 118 Step 14: Unplug the AC power cord from the wall and turn the toggle switches to their off positions. Step 15: Install the ECC83 tubes. Plug the AC power cord into the wall. Turn the mains toggle switch on. Keep the standby switch off.

  • Page 119: Biasing

    BIASING Step 18: OK. You need to bias your amp correctly before you start playing. This is very important. If you have it biased too “hot” you can damage the EL34 tubes or burn out one of the resistors. If you have it biased too “cool”, it just won’t sound very good.

  • Page 120: Operating Overview

    Operating Overview Front Panel This should be pretty standard stuff for the most part, but the JTM45 does have some peculiarities. You probably won’t ever want to use the HIGH TREBLE channel unless you are jumpering it with the normal channel. It will typically be much too bright for most peoples’...
  • Page 121 Back Panel Power Cord Socket: Plug your power cord in to this. Fuse Holder: This is where the fuse goes. It says 2AMP, but be sure to use a 3A if you are in a 120VAC country. Impedance Selector: Set this 3 position switch to match the impedance of the speaker(s) you are using. Speaker Jack: Insert speaker cable here.

  • Page 122: Diagrams And Schematic

    Diagrams and Schematic...
  • Page 123 Circuit board (top side)
  • Page 124 Circuit Board Wiring (showing from top side)
  • Page 125 Power Section and Heater Wiring for hi res pdf go to http://www.byocelectronics.com/brit50powerwiring.pdf...
  • Page 126 Schematic For hi res pdf go to http://www.byocelectronics.com/brit50schematic.pdf...
  • Page 127 For technical support, visit www.byocelectronics.com/board Written by: N.W. Kenning & K. Vonderhulls Artwork & Photography by: N.W. Kenning Copyright BYOC, Inc. 2016...

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