StewMac 57 MINI TWEED Assembly Instructions Manual Download Page 2

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Contents

About this iconic amp

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

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Parts list

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Tools and supplies

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Amp voltages are

seriously dangerous!

. . . . . . . . . . . . . . . . . . . . . . . . . . 6

How to use a snuffer stick

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

How to read resistor values

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Capacitor values

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Complete wiring diagram

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Prepping the cabinet

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Prepping the boards

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Installing the chassis-mounted components

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How to wrap and solder the eyelet board

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Tips for great soldering

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Wrapping parts onto the eyelet board

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Soldering and installing the boards

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Installing the eyelet board and insulator board

. . . . . . . . . . . . . . . . 22

Connecting the eyelet board and chassis components

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Final assembly

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Testing and troubleshooting

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Learning more: secrets revealed in the schematic

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5F1 circuit schematic

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Mounting hole template

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Tube replacement chart

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This material is protected by copyright and has been created by and solely for the purposes of StewMac .

You may not sell, alter or further reproduce any part of this material, or distribute it to any other per-

son . Where provided to you in electronic format, you may only print from it for your own private use .

Failure to comply with the terms of this warning exposes you to legal action for copyright infringement .

How to build this kit!

Summary of Contents for 57 MINI TWEED

Page 1: ... 57 MINI TWEED 5W CO MB O AMP KIT ORIGINAL 5F 1 CIRCUIT ASSEMBLY INSTRUCTIONS One knob titan of tone With loads of helpful tips ...

Page 2: ...rd and insulator board 22 Connecting the eyelet board and chassis components 22 Final assembly 25 Testing and troubleshooting 26 Learning more secrets revealed in the schematic 28 5F1 circuit schematic 29 Mounting hole template 33 Tube replacement chart 35 COPYRIGHT WARNING This material is protected by copyright and has been created by and solely for the purposes of StewMac You may not sell alter...

Page 3: ... while you build this kit StewMac ICON KITS bring classics that are no longer made or are simply unaffordable within reach And the best part is you get to build them with your own hands We give painstaking attention to parts selection authentic materials and instantly recognizable details everything that makes the originals so sought after Build it with StewMac These immersive instructions walk yo...

Page 4: ...hematic but it s fun See how your guitar s signal gets processed into sound on page 28 Sort your components by type using the parts list Quick look 10730 2018 StewMac 57 TWEED 5W 5F1 CIRCUIT SCHEMATIC Resistor Capacitor Ground Jack Transformer Potentiometer Diode tube plate cathode Triode tube plate grid cathode Pentode tube grid plate cathode screen Power Gain Negative Feedback Processing Output ...

Page 5: ... locknut r 2 8 32 machine screw 1 4 r 6 8 32 locknut r 2 6 32 machine screw 1 2 r 2 6 32 locknut r 4 4 40 machine screw 3 8 r 2 4 40 machine screw 1 4 r 6 4 40 locknut r 1 Black wood screw r 1 Strain relief for power cord r 1 Cable clamp for power cord r 2 Rubber strain relief grommet Capacitors r 1 047μF 600V Orange Drop r 2 022μF 600V Orange Drop r 1 25μF 50V Sprague Atom r 2 8μF 475V electrolyt...

Page 6: ...5Y3S r 1 Fuse socket r 1 Fuse 1 amp slow blow r 1 Pilot lamp socket r 1 Pilot lamp lens r 1 Pilot lamp bulb 47 Terminals knobs and cords r 1 Control pot with switch 1M r 1 Chicken head knob r 2 Three lug ground terminal r 1 Power cord Transformers r 1 Power transformer r 1 Output transformer Wire r 1 Yellow wire r 1 Green wire r 1 Speaker wire two leads 6 4 32 19 8 7 5 4 3 2 1 8 7 6 5 12AX7 6V6 5Y...

Page 7: ... for mounting chassis to cabinet 5 32 for mounting eyelet board to chassis Ruler Item 4905 StewMac Shop Rule Digital multimeter Item 3618 Fieldpiece Pocket Multimeter Snuffer stick bleed resistor Item 1552 Snuffer Stick Copper shielding tape Item 0028 2 Conductive Copper Tape Pencil Wooden chopsticks Glue Wood glue white glue or contact cement for gluing a paper label inside the cabinet Helpful Ro...

Page 8: ... to call 911 can be a lifesaver How to use a snuffer stick To discharge a capacitor clip the snuffer stick lead to ground preferably a mounting bolt on the power transformer Hold the tip of the stick to the cap s positive lead and use your multimeter to watch the voltage drain to less than 18V Take breaks and stop when you re tired Fatigue leads to mistakes and no one can afford mistakes when work...

Page 9: ...o large for use in an amplifier Caps for amps are rated in millionths of a farad called microfarads μF or trillionths of a farad picofarads pF The voltage spec for a cap refers to how much DC voltage it can handle at any given time A unique property of capacitors is that they don t allow DC current to flow past them only AC current This is important in parts of an amplifier circuit such as the pat...

Page 10: ...E JACK 2 JACK 2 4 3 2 1 8 7 6 5 4 3 2 1 8 7 6 5 6 4 3 2 1 9 8 7 5 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 2 1 3 4 5 6 7 8 9 10 11 25μF 022μf 8μf 8μf 16μf 022μf Complete wiring diagram Our diagrams show a flat view of the metal chassis Here s the complete 5F1 wiring When you ve finished the kit you ll have connected all the parts shown in this wiring diagram If it looks complex now don t worry...

Page 11: ... about to drill line up with holes on the chassis to the right and left of the print control area Compare this template to the mount ing holes in the chassis and you ll see how these holes line up Cut out the gray area and fold the template on the dotted lines Center it over the control panel cutaway aligning it with the back edge Tape it in place Press a sharp awl through the tem plate at the scr...

Page 12: ...ide Then snug the third nut and fourth Repeat this criss cross pattern of quarter turns until all four nuts have had one full turn This will give proper tension to compress the speaker gasket Overtightening canwarptheframe damagethecone and cause unwanted distortion STEP 4 Solder the speaker plug Push the insulation back 3 8 at the other end of the leads Insert the white positive lead into the cen...

Page 13: ...ing Position the taped boards inside the chassis as shown above with a gap of roughly 1 4 between the boards and the top of the chassis The ends oftheboardsareflushagainsttheside of the chassis Holding the boards in place turn the chassis so you can see the two mounting holes Using a sharp pen cil through the holes mark the hole locations onto the insulator board Prepping the boards Drill the 5 32...

Page 14: ...the chassis mounted components STEP 12 Install two rubber grommets Squeeze these into the two holes as shown These provide strain relief for the transformer wires that will pass through the metal chassis STEP 13 Mount the output transformer The output transformer has red blue and yellow leads Thread the red and blue leads through one rubber grom met as shown and the yellow lead through the other g...

Page 15: ...amp toward the fuse STEP 21 Install the volume pot A small metal tab protrudes from the face of the pot Bend and snap this off so the pot can mount flush to the surface of the chassis Mount the pot so its three lugs face out toward the chassis opening STEP 22 Install two jacks 1M resistor Add the two input jacks Turn the jacks so the right lug of jack 1 is close to the center lug of jack 2 as pict...

Page 16: ...former green leads Run the two green wires from the power transformer to the lugs on the pilot lamp socket either wire can go to either lug Trim these wires to length and wrap them onto the lugs Don t solder these connections yet STEP 26 Power transformer red yellow lead Trim the power transformer s red yellow lead to an appropriate length and solder it to the 3 lug terminal strip along with the g...

Page 17: ...ound the volume pot Cuta3 pieceofgreenwireandsolder it to the left lug of the volume pot as pictured Wrap and solder the other end of this wire to the three lug grounding strip near the pilot lamp A wire between two parts like this is called a jumper Don t cut this piece toolong becausethere sjustenough green wire to create all the jumpers you re going to need STEP 32 Inspect and double check This...

Page 18: ...ap How to wrap and solder the eyelet board Put the lead through the eyelet or lug Bend it tight against the opposite side Solder after all the parts are in place Trim excess wire Tips for great soldering n Wrap the leads tightly for good electrical contact before soldering n Melt a small amount of solder onto thetipoftheiron tinning theiron Hold the tip against the connection until the connection ...

Page 19: ...r and wrap it ontoeyelet9 Wrapa4 yellowjumper onto eyelet 10 Turn the board over and add a 5 yel low jumper from the back at eyelet 13 Run this jumper to the front of the boardthroughhole25andpullittight to keep it in place STEP 35 Install a 022μF cap one jumper Wrap one of the 022μF Orange Drop capacitors between eyelets 8 and 24 This cap is not polarized so it can be installed in either directio...

Page 20: ... stays in place STEP 40 Add a 22K resistor one jumper Attach a 22K resistor between eyelets 21 and 12 Add a 1 1 2 yellow jumper to eyelet 21 STEP 41 Add a 1 5K resistor one jumper Add the other 1 5K resistor between eyelets 6 and 12 Flip the board and add a 5 yellow jumper to eyelet 12 Run the jumper up through hole 23 and pull it tight STEP 42 Install a 25μF cap a 470Ω resistor soldered together ...

Page 21: ...ween eyelets 2 and 3 These wires make the ground bus for the three filter capacitors u STEP 44 Add one 8μF capacitor Wrap the leads from one of the 8μF electrolytic caps through eyelets 5 and 18 Take care to match the polar ity shown on the wiring diagram the negative lead connects to eyelet 5 When electrolytic capacitors do not show a positive or negative symbol look for the arrow design which po...

Page 22: ...hrough holes 4 and 23 Pull at least 2 1 4 of this jumper up through hole 4 and at least 2 up through hole 23 Cut two 10 green jumpers and twist them together Twisting these wires reduces unwanted hum and noise Run them behind the board and pull them to the front through hole 1 and 15 Leave 2 1 2 of lead coming through hole 1 and about 3 1 2 at hole 15 Now all the components and wires are on the ey...

Page 23: ... your power supply Don t solder eyelet 16 yet Wait until you ve installed the eyelet board to the chas sis because you ll be adding the red wire from the output transformer to this eyelet After all the joints are soldered clip theexcessleadsonboththebackand the front of the board Check all your solder joints to make sure they re shiny and to make sure you didn t miss one u STEP 51 Install the eyel...

Page 24: ...thetwistedgreenjumpersfrom hole 1 onto the pilot lamp socket lugs along with the resistor leads and greentransformerleads Solderthese connections Trim the excess lead wire and inspect the pilot lamp lugs to be sure there is no contact between them u STEP 55 Solder two volume pot connections Solder the jumper from hole 4 to the center lug on the volume pot Solderthejumperfromeyelet8tothe right lug ...

Page 25: ...rim the red wire from the output transformer to an appropriate length and solder it to eyelet 16 along with the other wires wrapped there Trim the blue wire from the output transformer to an appropriate length and wrap it onto pin 3 of 6V6 socket Don t solder this connection yet u STEP 60 Solder the 6V6 tube socket Wrap one of the two green jumpers from hole 15 onto pin 2 of the 6V6 socket Add a s...

Page 26: ...elet22topin 6 of the 12AX7 socket Wrap the jumper from the volume pot coming through hole 23 to pin 7 of the 12AX7 socket Wrap the jumper from eyelet 12 coming through hole 23 to pin 8 of the 12AX7 socket Connect one green jumper from the 6V6 socket from either pin 7 or pin 2 to pin 9 of the 12AX7 socket Wrap it but don t solder it yet Wrap the other green jumper from the 6V6 socket from either pi...

Page 27: ...Never use a fuse rated above 1 amp in this amplifier Final assembly u STEP 65 Install the pilot lamp Insertthepilotlampbulbintoitssock et from the front of the chassis and twistuntilitlocksbackinplace Screw the red jewel lens over the socket u STEP 66 Install the volume knob Turn the shaft of the volume pot to zero and install the chicken head knob so that the indicator line points to number 1 u S...

Page 28: ...e 5Y3 rectifier tube Use one hand to open the tension clip while while you put in the tube with your other hand Any multimeter will work fine for the two types of tests we re about to do checking continuity and reading voltages The instructions that came with your meter will be helpful Continuity testing is simply mak ing sure current flows between two points successfully Touch the meter s red lea...

Page 29: ...rrect plug a guitar in and begin playing at low volume If the amp is behaving as itshould keepincreasingthevolume It should start to break up nicely as you increase the volume If there are any strange oscillations squeals ortheampseemsatallunsta ble use a wooden chopstick to probe for loose connections n from the input jacks to the eyelet board n from the tube sockets to the eyelet board n from th...

Page 30: ...because there s no tone control on the 57 Tweed With this amp players fine tune their tone by varying the volume and tone controls on the guitar The power supply stage provides power to the other circuit stages as well as the tube heaters and pilot light ThiscircuitreceivestheACpowerfromyourwallandpassesitthroughthepower transformer to create higher voltage The electricity then goes to the rectifi...

Page 31: ...ube plate cathode Triode tube plate grid cathode Pentode tube grid plate cathode screen Power Gain Negative Feedback Processing Output Power 4 Ω 2 68K 22K 10K 2W AC switch To tube heaters and pilot light 022 µF 25 µF 25V 470 1W 8 450 8 450 16 450 022 µF 1 MEG 1 MEG 100 K 1 5 K 220 K 1 5 K 100 K 22 K 68K 1 12AX7 6V6 GT 5Y3 GT 1 amp slow blow fuse ...

Page 32: ...ean with enough guts to gig Perfect for recording as well as performing the D Reverb produces stinging clarity that absolutely refuses to get lost in the mix One of the most popular designs ever this amp lives in the happy middle between bright clarity and rich distortion It excels in the studio and on the stage While capable of crystal clear tones at good volume you can push this one into beautif...

Page 33: ...00 50W AMP KIT This hairy monster lives to shred The defining British circuit that dominated the 80s This 50W giant created your favorite heavy rock and metal albums Used by Slayer and Pixies and recorded on early Metallica albums this circuit produces that screaming guitar tone that your mother despises With solid state rectification there s no sag and the distortion created by this circuit is wa...

Page 34: ...stewmac com 32 2018 StewMac ...

Page 35: ...wmac com 33 2018 StewMac 7 7 8 1 3 8 1 3 8 Cut out shaded area Fold template on the dotted line and center over the cabinet s control panel cutout 10730 2018 StewMac 57 MINI TWEED 5W MOUNTING HOLE TEMPLATE ...

Page 36: ...stewmac com 34 2018 StewMac ...

Page 37: ...S Speaker jack 57 MINI TWEED 5W O R I G I N A L 5 F 1 C I R C U I T StewMac I C O N K I T S Use only 1 amp slow blow fuse DANGER Unplug the amp before changing tubes Tube locations from left to right 5Y3 6V6 12AX7 5Y3 6V6 12AX7 ECC83S Speaker jack Cut this label on the dotted line with a razor knife and metal straightedge Fasten it to the bottom of the cabinet using thinned wood glue or contact ce...

Page 38: ...stewmac com 36 2018 StewMac ...

Page 39: ...stewmac com 37 2018 StewMac ...

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