TubeDepot JTM45+ User manual
This manual was developed and
published by:
TubeDepot.com LLC, Memphis, TN
Written by:
Robert Hull
Edited by:
Robert Hull
Josh Phelps
Design and Artwork by:
Robert Hull
Christia Magee
Special thanks to following for their design help:
Joe Austi Bria Overstreet Da iel Yakel
Matt Kirby Mike Taylor Aaro Coppage
He ry Lum Be Siler
Special thanks to the following for their excellent amp building and proofreading skills:
Matt We dt Brad Jo es Michael Wa g
Terry Gayle Richard I gold Scott McMilli
Copyright © 2011
TubeDepot.com LLC
1686 Barcrest Dr.
Memphis, TN 38134
(877) 289-7994
REGARDING THESE BOOK MATERIALS
Reproductio , publicatio , or duplicatio of this booklet, or a y part thereof, i a y ma er, mecha ically,
electro ically, or photographically is prohibited without the express writte permissio of the publisher.
The Author, Publisher or Seller assume o liability with respect to the use of the i formatio co tai ed herei .
For permissio a d other rights u der this copyright, co tact TubeDepot.com.
Acknowledgements
ii TubeDepot.com
Preface …...........................................................................................................
Chapter 1
Safety ….........................................................................................................
Chapter 2
Tools a d Supplies .........................................................................................
Chapter 3
Parts I ve tory …...........................................................................................
Chapter 4
Cabi et Preparatio …...................................................................................
Chapter 5
Chassis Preparatio , Assembly a d Wiri g .......................................…......
Chapter 6
Turret Board Co structio …........................................................................
Chapter 7
Turret Board / Chassis a d Wiri g …...........................................................
Chapter 8
Testi g …......................................................................................................
Chapter 9
Fi al Assembly ….........................................................................................
Chapter 10
Schematic ….…..................…......................................................................
Appe dix
A) Resistor a d Capacitor Codes ...............................................................
B) Solderi g Hi ts .......................................................................................
C) Amplifier Care a d Feedi g ....................................................................
D) Mods …...................................................................................................
Table of Contents
iv
1
2
3
28
6
10
24
35
38
30
33
34
TubeDepot.com iii
40
41
Marshall amplifiers have always bee the forefro t i the sou d of rock ' roll.
Si ce the early 1960's, Marshall has take simple circuits a d tur ed them i to
extraordi ary, amplifiers that to this day, co ti ue to defi e great to e.
I the early 60's, the JTM45 established Marshall as the ew leader i guitar
amplifiers. While all the other amplifier ma ufacturers were desig i g their
amps to be clea er, Marshall took a differe t path. With a simple circuit (from
the Fe der 1959 4x10 Bassma ), Marshall “cru ched” it full of harmo ically rich
to e a d built a amplifier that set the sta dard for everyo e to follow.
This British JTM45+ kit is our od to the origi al JTM45 a d MkII 50W
amplifiers. With turret board, poi t-to-poi t co structio , quality compo e ts,
a d just a touch of America upgradi g, this kit is ready to become your sou d.
U like previous assembly ma uals, we have desig ed this ma ual for the
more adva ced builder i mi d. This ma ual is lite o step-by-step i structio s,
but filled with detailed drawi gs a d photos. We are leavi g these drawi gs a d
photos to speak for themselves. If you have previous amp buildi g experie ce,
you will e joy the challe ge that this kit provides.
But before we get started, a safety review …
Robert Hull
Director of Tech ical Services
TubeDepot.com
Before continuing, PLEASE READ the following:
We are continually making improvements to this assembly manual in
an effort to provide the best instructions possible. Therefore, when
the manual's instructions differ from the video, I recommend following
this written manual as this will be more up-to-date and accurate.
NOTE
iv TubeDepot.com
Preface
!!! Read these safety precautions before continuing !!!
ALL tube amplifiers co tai LETHAL VOLTAGES, ofte several hu dred volts which WILL
leave bur t e tra ce a d exit wou ds i ski if accide tally touched. These voltages have the
pote tial to cause permanent physical damage and death. These voltages are prese t
whe the amp is tur ed o a d also for some time after the amp has bee tur ed off. You
can still get shocked with a tube amp turned off and disconnected from AC power.
The above stateme t is a bit scary, but we wa t to stress that every piece of electro ic
equipme t must be treated with respect. Whe AC power is applied, there is always a cha ce
for i jury or death. With tube amps, eve whe the AC power is ot applied there is still
da ger. Bei g shocked with high voltage is very pai ful a d we do ot wa t a yo e fi di g
out the hard way.
Whe buildi g this kit, we wa t your experie ces to be both e joyable a d safe. There are
more kits to assemble a d we wa t you to e joy buildi g a d playi g them all.
Throughout this ma ual at key poi ts i the co structio , we have a otated importa t
steps with the below alerts. For your safety a d to improve co structio quality, It is importa t
that you become familiar with each of these alerts a d adhere to a y safety recomme datio s
whe they appear.
Explanation of Alerts
Safety
1
- DISCLAIMER -
TubeDepot.com, it's employees, officers, shareholders, investors and
subsidiaries accept no liability for any damage s), injury s) or death incurred
from or while building or using this kit.
WARNING
CAUTION
NOTE
MOD
sed when identifying an action that may cause physical injury or death.
sed when identifying an action that may cause damage to components
and/or equipment.
sed when identifying general points of interest.
sed when identifying potential modification point(s)
TubeDepot.com 1
As with a y co structio project, there are certai recomme ded tools a d supplies. The
followi g are the tools a d supplies NOT provided with the kit but are eeded for completio .
These are expected to be provided by the builder.
TubeDepot.com
The following is our recommended list part number
Phillips screwdriver, #1 a d #2 TL-VTSCRSET8
Slip joi t pliers
Needle ose pliers TL-VT33
Wire cutters, diago al TL-VT33
Wire strippers, for 18 a d 20 awg wire TL-VT5021
Electric Drill (cordless recomme ded)
Drill bit, 1/8” - AC receptacle i stallatio ; turret board wire routi g TL-DB-40125
Drill bit, 5/32” - turret board mou ti g TL-DB-40156
Drill bit, 9/32” - Chassis mou ti g i cabi et
Drill bit, 5/16” - i set ut i stallatio i to chassis
Drill bit, 7/16” - impeda ce selector i stallatio
Drill bit, 1/4” - shock mou ted tube socket mou ti g holes
Cou tersi k bit
Maski g tape, 2” or 3”
Ruler or scale, 12” w/ 1/16” marki gs
Perma e t marker, fi e tip
Solderi g iro , 25W – 40W (35W recomme ded) TL-WP35
Solder, electro ics safe (60/40 w/ rosi core recomme ded) TS-24-6040-0027
Flux, electro ic – liquid or paste (must be safe for electro ic work) TS-83-1000-0186
De-solderi g pump / solder extractor TS-384-1000
Solder wick or desolderi g braid TS-1817-10F
Spo ge or solderi g iro tip clea er TL-TIP-CLEANER
The following are tools that really nice to have on hand
Solderi g statio w/ temperature co trol TL-WTCPT
Multimeter w/ DC ra ge of at least 500V TL-DVM850BL
Variable AC supply (Variac® style)
Curre t Limiti g AC source (dim bulb tester) – self built
Needle ose pliers – small size, for electro ics work TL-NN7776
Wire cutters, diago al – small size, for electro ics work TL-170M
Ce ter pu ch – a automatic ce ter pu ch is great
Nutdrivers - 5/16”, 11/32”, 7/16”, 1/2”
Square, 9”
Scratch Awl
De-burri g tool TL-DB-1
Fi ger ail polish (for holdi g uts a d screws i place)
Step drill bit (1/8” - 1/2”)
Ora ge wood stick – for movi g compo e ts a d wires i to place TS-OWS
2Tools and Supplies
2 TubeDepot.com
Make sure the followi g items are i cluded with your kit. Let us k ow if there are a y missi g
items or if you have a y questio s regardi g a particular part(s).
1 chassis, alumi um Marshall style JTM45 CH-MARJTM45
1 pa el, fro t a d back, Marshall style JTM45, plastic CH-MARJTM45-FP
1 TR-PW-05
118025
118058
1 JJ-GZ34
1 JJ-EL34
3
xfmr, power, 45W Marshall style w/ rectifier tap
xfmr, output, 50W Marshall style by Classictone
choke, Marshall style 3 HY, 250mA by Classictone
GZ34 JJ dual-diode rectifier
EL34 beam power tetrode (sold i pairs) 12AX7 /
ECC83 dual triode preamp tube JJ-ECC83
7 k ob, Marshall style w/ set screw P-MAR-1-4-BRASS
1 k ob, chicke head, vi tage w/ set screw P-VSCH
2 fuse holder, low profile screwdriver cap, 3AG P-FH-LOWPRO
2 fuse, 3AG 500mA slow blow (HT fuse) P-BK-MDL-.5A (o e spare)
2 fuse, 3AG 3A fast blow (Mai s fuse) P-BK-AGC-3A (o e spare)
1 I dicator lamp, 6.3V i ca desce t P-PL-MARSHALL-1
1 push ut-flat rou d 5/16" stud (i cluded w/ above lamp)
6 jack, 1/4", Amphe ol mo o P-ACJM-IHS
2 washer, chassis grou di g for above jack GW-CL1442
1 switch, toggle SPST; Carli g P-110-63
1 switch, toggle DPST, Carli g P-2BK62-73
2 washer, lock 1/2", i ter al tooth LW-IT-1-2
2 switch, mi i toggle, DPDT, (o -o ) P-108-MINI-2
1 switch, mi i toggle, SPDT (o -off-o ) P-108-MINI-3
1 switch, 3 positio rotary P-ROTARY-SWITCH
1 plug, AC chassis mou t, press fit P-IEC-1
1 power cord, with IEC co ector P-12PWI
3 diode, 1N4007 D-1N4007
2 diode, GP02-30-E3/73 D-R3000
3 socket, tube, mi iature 9 pi SK-B-VT9-ST-C
3 shield, tube socket, mi iature 9 pi SK-PCP
3 socket, tube, octal chassis mou t SK-B-VT8-ST
3 grommets, rubber 1/2" chassis hole P-GROMMET-1/2
4 bolt, metric, M6x30mm, stai less steel MS-M6X30MM
4 flat washer, metric, M6, stai less steel BP-M6-WASHER
4 captive uts, M6 BP-M6-CAPTIVENUT
3Parts Inventory
TubeDepot.com 3
qty description TD part number
4 screw, zi c plated 6-32 x 1/4", phillips pa head BP-632-1/4
18 screw, zi c plated 6-32 x 3/8", phillips pa head BP-632-3/8
2 uts, sta dard 6x32 BP-632
12 uts, KEPS 6x32 BP-632-KEPS
4 sta doff, alumi um hex, #6 threaded, 1/2" lo g BP-ALSTDOFF-6-FF-1/2"
7 uts, KEPS 8x32 BP-832-KEPS
3 uts, 8-32 sta dard BP-832-NUT
6 screw, zi c plated 8-32 x 3/8", phillips pa head BP-832-3/8
4 solder lug, locki g, #8 screw P-TERMLOCK-8
4 solder lug, locki g, #6 screw P-TERMLOCK-6
10 ft. wire, 20 AWG, stra ded, hi-temp PVC - yellow HTPVC-20-STR-YELLOW
10 ft. wire, 20 AWG, stra ded, hi-temp PVC - red HTPVC-20-STR-RED
10 ft. wire, 20 AWG, stra ded, hi-temp PVC - black HTPVC-20-STR-BLACK
10 ft. wire, 20 AWG, stra ded, hi-temp PVC - white HTPVC-20-STR-WHITE
10 ft. wire, 20 AWG, stra ded, hi-temp PVC - blue HTPVC-20-STR-BLUE
10 ft wire, 20 AWG, stra ded, hi-temp PVC - violet HTPVC-20-STR-VIOLET
10 ft. wire, 20 AWG, stra ded, hi-temp PVC - ora ge HTPVC-20-STR-ORANGE
10 ft. wire, 18 AWG, stra ded, hi-temp PVC - black HTPVC-18-STR-BLACK
2 ft wire, 20 AWG, solid bare buss wire, ti ed copper BW-20
2 ft wire, 16 AWG, solid bare buss wire, ti ed copper BW-16
2 ft shielded wire, i terco ect IW-2330
5 ft alumi um tape, 2" width, self adhesive P-TAPE-ALUM
1 ft double stick tape, 1" wide ( ot listed i stock – applied to back of plastic back plate)
1 heat shri k, 1/8" - BLACK, 6" piece TS-HS-1-8
11 i . G10 glass epoxy board (11”x 3-1/8”) BP-125BOARD-RED
68 turret, hollow Keysto e 1540-4 BP-TURRET
1 470 / 1/2W, 1% metal film R-273-470
2 820 / 1/2W, 1% metal film R-273-820
2 1.5K / 1/2W, 1% metal film R-273-1.5K ← mod.
1 2.7K / 1/2W, 1% metal film R-273-2.7K
2 5.6K / 1/2W, 1% metal film R-273-5.6K
1 22K / 1/2W, 1% metal film R-273-22K
1 27K / 1/2W, 1% metal film R-273-27K
2 33K / 1/2W, 1% metal film R-273-33K
1 47K / 1/2W, 1% metal film R-273-47K
1 51K / 1/2W, 1% metal film R-273-51K
1 56K / 1/2W, 1% metal film R-273-56K ← mod.
4 68K / 1/2W, 1% metal film R-273-68K
1 82K / 1/2W, 1% metal film R-273-82K
5 100K / 1/2W, 1% metal film R-273-100K
4 TubeDepot.com
qty description TD part number
2 220K / 1/2W, 1% metal film R-273-220K
2 470K / 1/2W, 1% metal film R-273-470K
4 1M / 1/2W, 1% metal film R-273-1M
2 1.0 / 1W metal oxide R-273-1
3 10K / 1W, metal oxide power resistor R-273-10K
1 15K / 1W, metal oxide power resistor R-273-15K
1 220K / 1W, metal oxide power resistor R-273-220K
2 470 / 3W metal oxide R-282-470
1 1K / 3W metal oxide R-282-1K
2 10K / 3W metal oxide R-282-10K
1 22K / 3W metal oxide R-282-22K
1 47pfd / 500V; silver mica CP-SM-47-500V
1 100 pF / 500V; silver mica CP-SM-100-500V
1 250pfd / 500V; polystyre e CP-PFC-250-500V
1 500pfd / 500V; polystyre e CP-PFC-500-500V
1 .0022ufd / 630V; Mallory 150 CP-M150-0022-630V ← mod.
7 .022ufd / 630V; Mallory 150 CP-M150-022-630V
2 .1ufd / 630V; Mallory 150 CP-M150-1-630V
2 .68 / 100V, Mallory 150 CP-M150-68-100V
2 50ufd / 50ufd @ 500V CP-JJ-50X2-500V
2 capacitor clamp, small CP-CLAMP1
1 16ufd / 475V CP-FT-16-475V
1 47ufd / 500V CP-FT-47-500V
1 330uF / 16V CP-ST-330-16V
2 10uF / 160V CP-ST-10-160V
1 5K li ear RV24A-10D2-15R1-B-5K
1 25K li ear RV24A-10D2-15R1-B-25K
1 250K li ear RV24A-10D2-15R1-B-250K
4 1M audio RV24A-10D2-15R1-A-1M
1 50K trimmer pot BP-BIASPOT-50K
1 Turret setter kit DIY-PFT-KIT
The following additional parts are particular to your choice of head or combo kits:
head kit -
1 cabi et, small box black tolex Marshall style CAB-MAR-SMBOX
combo kit -
1 cabi et, 1x12 combo Marshall style CAB-MAR18
1 speaker, 12",(various 75W speakers) our secret hidde stock
1 1/4" pho e plug, Switchcraft P-280 P-280
1 ft. techflex, yellow TS-PTNO-1-4
2 ft. wire, 18 AWG, stra ded, hi-temp PVC - white HTPVC-18-STR-WHITE
TubeDepot.com 5
qty description TD part number
This chapter deals with prepari g the cabi et for i stallatio of the completed chassis. But
first, we eed to take i ve tory of the parts that came i stalled with the cabi et.
Cabinet Inventory
Combo Cabinet
1. Handle w/ mounting hardware – There should be a si gle flat black ha dle with two
gold e d covers mou ted to the top of the cabi et.
2. Feet, rubber – There should be four rubber feet attached with screws.
3. Back panels, upper and lower with screws – There should be two back pa els. The
top back pa el should be secured with four pa el screws, the bottom pa el should be
secured with five pa el screws. All pa el screws should have a fi ishi g washer.
4. Baffle screws – There should be eight black oxide coated screws with matchi g
black fi ishi g washers holdi g the baffle i the cabi et.
5. Speaker bolts – There should be four black oxide coated bolts for securi g the
speaker to the baffle board.
Head Cabinet
1. Handle w/ mounting hardware – There should be a si gle flat black ha dle with two
gold e d covers mou ted to the top of the cabi et.
2. Feet, rubber – There should be four rubber feet attached with screws.
3. Back panel w/ screws – The back pa el should be secured with four pa el screws.
With either cabi et, i spect all screws. I've fou d screws that were 't fully tighte ed duri g
assembly. These loose screws will buzz whe vibrated by the speaker or speaker cab.
Drilling the Four Chassis Mounting Bolts
4.2.1 Combo Cabinet
Step 1 – Remove the back pa el a d lay the pa el o
the work table with the vi yl coveri g faci g dow .
Step 2 – With the alumi um chassis, ce ter the chassis
o the back pa el with the co trol pa el side of the
chassis flush agai st the back pa el cutout (photo 4.2a).
Step 3 – Make a mark through each of the four mou ti g
holes of the chassis o to the back pa el (photo 4.2a).
Step 4 – Drill a small 1/8” pilot hole i the ce ter of each of these marks.
Step 5 – O ce the pilot holes have bee drilled, drill the fi al 5/16” hole dow the ce ter of
each of these holes.
Step 6 – With a hobby k ife, clea the edges of the holes by cutti g off a y excess vi yl
coveri g left from the drilli g operatio .
4.2
4.1
CAUTION The following steps call for drilling the mounting holes in the cabinet for the chassis. Make
sure to review, reread and remeasure at each step to reduce potential drilling errors.
Because (as the wise old amp builder's saying goes) what is drilled, cannot be undrilled.
photo 4.2a
4Cabinet Preparation
photo 4.2b
6 TubeDepot.com
4.2.2 Head Cabinet
Step 1 – Place the cabi et
upside dow with ha dle
agai st the be ch a d fro t
of cabi et faci g you.
Step 2 – Lay two strips of
maski g tape o each e d
just o the i side of the
feet.
Step 3 – O both strips of
maski g tape, make marks
1-3/8”, followi g the curve,
from the outside edge of the cabi et (photo 4.2b).
Step 4 – Locate the fro t of the chassis (the fro t has the four
i put holes). Now, alig the fro t of the chassis mou ti g lips
o the 1-3/8” mark (photo 4.2b). Visually ce ter the chassis
over the fro t ope i g of the cabi et. (photo 4.2c).
Step 5 – Make a mark through the four chassis mou ti g holes
o to the tape. Move the chassis to the side. (photo 4.2d)
Step 6 – Drill a 5/16” hole i each of the four marks. Remove
the maski g tape. (I crease this hole size to 3/8” if eeded).
Step 7 – With a hobby k ife, clear the holes of a y remai i g
vi yl coveri g.
Installing the Shielding Tape
4.3.1 Combo Cabinet
Step 1 – Place the cabi et back pa el with the vi yl side dow toward the desk.
Step 2 – Cut three le gths of shieldi g tape, each 20” lo g.
Step 3 – Remove the backi g from the first of these 20” shieldi g tape strips.
Step 4 – Apply the alumi um tape to the
back of the pa el ce tered betwee the
chassis mou ti g holes.
Step 5 – Apply the seco d strip of tape alo g
the lower edge of the previous tape,
overlappi g about 1/8” the e tire le gth
(photo 4.3b).
Step 6 – Apply the fi al shieldi g tape strip
alo g the upper edge of the first tape,
overlappi g about 1/8” (photo 4.3b).
Step 7 – With a hobby k ife, Clear the
mou ti g holes of shieldi g tape.
4.3
CAUTION Once the backing is removed from the aluminum tape, the tape will have a tendency to curl.
Be sure to keep the tape straight to avoid having the tape stick permanently to itself.
photo 4.3a
photo 4.3b
TubeDepot.com 7
photo 4.2c
photo 4.2d
photo 4.2b
4.3.2 Head Cabinet
Step 1 – Place the cabi et with the back ope toward you.
Step 2 – Cut three le gths of shieldi g tape, each 18” lo g.
Step 3 – Remove the backi g from the first of the 18” shieldi g tape strips.
Step 4 – Apply the first alumi um
tape strip to the i side of the
cabi et, ce tered dow the middle
betwee the chassis mou ti g
holes (photo 4.3c).
Step 5 – Apply the seco d
shieldi g strip to the cabi et alo g
the lower edge of the previous
tape, overlappi g about 1/8” the
e tire le gth.
Step 6 – Apply the third strip alo g the
upper edge of the first tape, overlappi g about 1/8” alo g the e tire le gth (photo 4.3d).
Step 7 – Clear the mou ti g holes of shieldi g tape with a hobby k ife.
Wiring the Speaker Cable to the Speaker Combo Cabinet)
Step 1 – Measure a 14” le gth of white 18AWG wire, a d a 14” le gth of black 18AWG wire.
Step 2 – Twist these black a d white wires tightly together the full le gth.
Step 3 – At o e e d of this twisted pair, strip the i sulatio back ½ ” from both wires a d ti
these two wires
Step 4 – U screw the barrel of the ¼ ” pho e plug a d solder the
two ti ed wires to the plug; white to ce ter a d black to shield
(photo 4.3a).
Step 5 – Slide the le gth of yellow Techflex over this twisted pair
right up to the ce ter co ductor of the plug (photo 4.3b).
Step 6 – Slide the 3” le gth of 3/8” heat shri k up over the
Techflex up to the ce ter co ductor of the plug (photo 4.3b).
CAUTION Once the backing is removed from the aluminum tape, the tape will have a tendency to curl.
Be sure to keep the tape straight to avoid having the tape stick permanently to itself.
4.4
photo 4.3a
NOTE
The ¼” phone plug was invented for use in telephone switchboards in 1878. And although it
is no longer used for telephone switching, this great plug has become the standard
connection type between musical instruments and outboard equipment.
photo 4.3d
photo 4.3c
To get an even, tight twist, use a handheld drill to twist the two wires together. Place the
loose wire ends into the drill chuck and slowly turn the drill until the wires are well twisted.
NOTE
For hints on improved soldering skills, review Appendix B at the end of this manual.
Additionally, see “How to Solder”, http://www.youtube.com/watch?v=cIDydYIVTq
NOTE
8 TubeDepot.com
Step 7 – Shri k the heat shri k i place with a heat gu (photo 4.3b)
Step 8 – I stall the remai i g 3” heat shri k le gth over the tech flex at the
opposite e d of the twisted pair ear the cut e d.
Step 9 – Shri k the heat shri k i place with a heat gu .
Step 10 – At the opposite e d of the twisted wire pair, strip back the i sulatio
¼” a d ti these two wires.
Step 11 – Solder these wires to the termi als of the speaker; the white wire to the “+” termi al
a d the black wire to the “-” termi al (photo 4.3c).
Mounting the Speaker in the Cabinet Combo Cabinet)
Step 1 – Remove the four speaker mou ti g screws
from the speaker baffle board.
Step 2 – With speaker i ha d, carefully alig the
speaker mou ti g holes to the baffle board mou ti g
holes (I recomme d i stalli g the speaker with
co ecti g termi als o top).
Step 3 – I stall a si gle #8 flat washer o each of the
four mou ti g screws prior to i stallatio .
Step 4 – I stall the four mou ti g screws through the
speaker mou ti g holes i to the baffle board. Firmly
tighte dow .
4.4
CAUTION Be careful when applying heat to the heatshrink, especially at the point where the techflex
and heatshrink meet. The techflex will quickly melt if excess heat is applied.
photo 4.3b
photo 4.3c
photo 4.4a
The speaker that comes with the combo kit could be one of several different speakers
(not just Celestion as shown).
NOTE
TubeDepot.com 9
Installing the Captive Nuts into the Chassis
Step 1 – Locate the four mou ti g holes o the outwardly be t
fla ge edges of the chassis, two o each edge.
Step 2 – Remove the protective white plastic o just
these edges.
Step 3 – With a 5/16” drill bit, e large all four of these
holes a d remove a y burrs.
Step 4 – Place the chassis, fla ge dow , o a flat
solid surface (co crete floor is good).
Step 5 – Place a i set ut o the fla ge directly over
o e of the ewly drilled 5/16” holes (photo 5.1a).
Step 6 – With a few blows from a hammer to the top
of the i sert ut, seat the ut firmly i to the hole a d
flush agai st the chassis fla ge. To assist i maki g
sure the ut is firmly seated, you ca also i sert the
chassis edge a d ut i to a vise a d press together (photo 5.1b).
Step 7 – I spect the ut to i sure it is well seated (photo 5.1c). Repeat step
6 as eeded.
Step 8 – Repeat above for the remai i g three uts.
Step 9 – O ce all the uts have bee mou ted, test fit i the cabi et a d
modify the hole size as eeded.
Drilling New Holes for Mounting Can Capacitors
Step 1 – Measure a d mark appropriate side of chassis with pe accordi g
to (drawi g 5.2a).
Step 2 – Use a ce ter pu ch to mark the poi t to be drilled.
Step 3 – Drill the 5/32” holes at each of these marks a d debur the holes.
Step 4 – Remove all remai i g protective plastic coveri g from chassis.
photo 5.1a
MOD
There are several great modifications that are possible on this amp. I recommend
reviewing these mods prior to beginning the following assembly steps to see if there is
something that interests you.
5.1
WARNING During all drilling and cutting operations, it is important to
wear proper eye protection and follow appropriate safety
precautions.
photo 5.1b
Chassis Preparation,
Assembly, and Wiring
5
5.2
photo 5.1c
10 TubeDepot.com
Installing the Grommets
Step 1 – i stall 1/2” grommets i the appropriate holes o the
top of chassis (photo 5.3a).
Installing the Tube Sockets
Step 1 – Modify the tube shield covers by flatte i g both e ds
of the base so that the mou ti g screws will properly lay flush
agai st the chassis (photos 5.4a a d 5.4b).
Step 2 - I stall the three 9 pi tube sockets i the appropriate
holes i the chassis. Note alig me t of sockets a d which #6
screws are used (drawi g 5.4a).
Step 3 – I stall the three octal
tube sockets i the appropriate
holes i the chassis. Make sure
to i clude the #6 solder
termi als o the power tube
sockets. Note alig me t of
sockets a d which #6 screws
a d uts are used with each
socket (drawi g 5.4b).
TubeDepot.com 11
drawing 5.2a
5.4
photo 5.4a
flatten here
photo 5.4b
5.3
photo 5.3a
Wiring the Filaments
Step 1 – Use a electric drill to twist together 3-1/2 feet of 20AWG black a d 20AWG red
wires. The resulta t dual twisted wire should be about 3 feet lo g.
Step 2 – Wire the filame ts for the preamp a d power tubes. Review the followi g drawi gs
for method descriptio (drawi g 5.5a & 5.5b).
Drawing 5.4a
Drawing 5.4b
9 pin socket installation
Octal socket installation
5.5
12 TubeDepot.com
TubeDepot.com 13
Drawing 5.5a
Drawing 5.5b
T65
T63
Preliminary Wiring of Tube Sockets
Step 1 – Wire a 100K / 1/2W resistor to the back of the
V2 socket as show (drawi g 5.6a). Do ot apply
solder to pi 6 just yet.
Step 2 – Wire a jumper wire across the back of the V3
(pi s 3 & 8) socket as show (drawi g 5.6b). Do ot
apply solder to pi 8 just yet.
Step 3 – Wire a 5.6K / 1/2W resistor to the back of V4
a d V5 sockets as show . Do ot
solder where i dicated (drawi g 5.6c).
Step 4 – Wire a 1.0 / 1W resistor to
pi s 1 & 8 of V4 a d V5 sockets as
show (drawi g 5.6C)
Step 5 – Cut four 3/4” pieces of
recycled 20AWG plastic wire
i sulatio a d place over the leads of
the R3000 diodes.
Step 6 – Wire the two R3000 diodes
to the V4 a d V5 sockets as show
(drawi g 5.6C). Pay careful atte tio
to polarity of diodes.
Installation of Hardware, Transformers and Faceplate
Step 1 – I stall the power tra sformer with the yellow
wires comi g through the chassis cutout toward the rear
of the chassis. Refer to drawi g to determi e the proper
locatio of the four #8 solder termi als (drawi g 5.7a).
Use three sta dard #8 uts o the solder termi als a d
o e KEPS #8 ut o the remai i g mou ti g bolt.
Step 2 – I stall the four alumi um sta doffs to the
chassis with four #6-32 x 1/4” screws.
Step 3 – I stall the output tra sformer with the red, blue
a d white wires comi g through the grommet earest
the fro t of the chassis a d with the remai i g yellow,
ora ge, violet, a d black wires comi g through the
grommet earest the back of the chassis. Secure with
four #8x32-3/8” screws a d four #8 KEPS uts.
Step 4 – I stall the choke with the two black wires
comi g through the remai i g grommet. Secure with
two #8x32-3/8” screws a d two #8 KEPS uts.
Step 5 – Remove protective plastic from faceplate a d rear plate.
Step 6 – I stall faceplate alo g with i put jacks, master volume, volume &
to e co trols, power a d sta dby switches a d i dicator lamp (with rear lock washer). Refer
to drawi g for proper compo e t alig me ts (drawi g 5.15c).
Step 7 – I stall IEC AC power e try co ector i to the square cut out o the back of chassis
5.6
5.7
Drawing 5.6a
Drawing 5.6b
Drawing 5.7a
14 TubeDepot.com
Drawing 5.6c
(before i stalli g rear plate). S ap firmly i to place.
Step 8 – Remove backi g of double stick tape o back of rear plate a d I stall the rear plate
alo g with the two fuse holders a d the two speaker jacks. The impeda ce selector will be
i stalled later. Refer to drawi g for proper compo e t alig me ts (drawi g 5.15c).
Tube / Solid State Rectifier Select Switch Installation
Step 1 – Drill a 1/4” hole through the back pa el a d chassis.
This hole should be ce tered betwee the mai s fuse a d the
IEC AC power e try co ector (photo 5.8a).
Step 2 – Debur this 1/4” hole & i stall the mi i DPDT switch.
Feedback select Switch Installation
Step 1 – Drill a 1/4” hole through the back pa el
a d the chassis. This hole should be ce tered
betwee the impeda ce selector a d the earest
speaker jack (photo 5.9a).
Step 2 – Debur this 1/4” hole a d i stall the mi i
SPDT (ce ter off) switch.
Impedance Selector Installation
Step 1 – E large the impeda ce selector hole to 13/32” with either a
13/32” drill bit or ha d reamer.
Step 2 – Debur this 13/32” hole a d i stall the impeda ce selector
switch. Alig this switch with the switch limit pi closest to the chassis
surface (photo 5.10a).
Power Transformer Wiring,
Step 1 – Wire the power tra sformer primary (black a d brow wires) accordi g to your local
AC mai s supply to the power switch a d the AC IEC co ector. (drawi gs 5.11a a d 5.11b).
Step 2 – Wire the appropriate 18AWG wire betwee the power switch a d i put fuse holder
(drawi g 5.11a or 5.11b).
Step 3 – Wire the appropriate wire (18 AWG black) betwee the AC fuse holder a d the AC
IEC co ector (drawi g 5.11a or 5.11b).
Step 4 – Wire the rectifier filame t (yellow wires) to the rectifier tube (drawi g 5.11a or 5.11b).
Step 5 – With the sta dby switch, i sure the word “MEXICO” o the side of the switch is
faci g the lamp. Wire the HV (red wires) to the sta dby switch (drawi g 5.11a or 5.11b).
Step 6 – Wire the filame t ce ter tap (gree with yellow stripe) to the grou ded solder
termi al G2 (drawi g 5.11a or 5.11b). Save the remai i g wire for future use.
Step 7 – Wire the HV ce ter tap (red with yellow stripe) to the grou ded solder termi al G1
(drawi g 5.11a or 5.11b).
Step 8 – i stall a wire (recycled wire from filame t ce ter tap) betwee the AC IEC co ector
a d the appropriate grou ded solder termi al G3 (drawi g 5.11a or 5.11b).
TubeDepot.com 15
5.8
5.9
5.10
5.11
photo 5.8a
photo 5.9a
photo 5.10a
16 TubeDepot.com
photo 5.11a
Table of contents
