LJUNGGREN 2xVCX User manual

Produced by:
Roll Your Own
ljunggrenaudio.com
Schematic & PCB Design by:
KYMATICA DEVICES
www.kyma ica.com
2xVCX version 1.0
Bills Of Ma erial Bold = PCB1
Calibration instructions can be found on the last page.
12 100nF
C13 C14 2 10uF
CON1 1 IDC 10-pin IDC 10 pin power connector (2x5 pin)
D1 D2 D3 D4 D5 D6 6 1N4148 Sign l diode
D7 D8 2 1N5818 Schottky diode (or 1N5817, 1N5819)
J1 J2 J3 J4 J5 J6 J7 J8 J9 9 3.5mm j ck Thonkiconn 3.5mm j ck socket
PCB_CON1_1 PCB_CON2_1 2 8 pin he der m le PCB connector PCB1 (1x8 pin)
PCB_CON1_2 PCB_CON2_2 2 8 pin he der fem le PCB connector PCB2 (1x8 pin)
Pcv1 Pcv2 2 100k Line r Pot Alph /Song Huei 9mm
Pofs1 Pofs2 2 22k Line r Pot Alph /Song Huei 9mm 20-25k
Q1 Q2 2 BC557B PNP tr nsistor
19 100k Resistor 1/4W 1% c 7mm long
R21 R22 R29 R31 R47 R48 6 10k Resistor 1/4W 1% c 7mm long
R23 R24 R27 R28 4 22k Resistor 1/4W 1% c 7mm long
R25 R26 R30 R32 4 470R Resistor 1/4W 1% c 7mm long
R42 R43 R44 3 1k Resistor 1/4W 1% c 7mm long
R45 R46 2 10R Resistor 1/4W 1 to 5% c 7mm long
R9 R11 R13 R14 R15 R18 R33 R34 R35 R36 10 200k Resistor 1/4W 1% c 7mm long
SW1 SW2 2 on-off-on
TRb l1 TRb l2 2 50R Trimpot Bourns 3296W or equiv lent
TRg in1 TRg in2 2 50k Trimpot Bourns 3296W or equiv lent
3 TL074 DIP-14 qu d op- mp (or TL084)
U4 1 LM13700 DIP-16 du l OTA
1 TL072 DIP-8 du l op- mp (or TL082)
3 DIP14 IC Socket
U4 1 DIP16 IC Socket
1 DIP8 IC Socket
2 PCB sp cer 11mm
4 Knobs
1 16 to 10 pin IDC ribbon c ble
1 P nel
C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12
C p citor byp ss MLCC X7R 2.5-
2.54mm pin pitch
C p citor electrolyte 2mm pin pitch,
5mm di , m x 10mm height. Min 25V.
R1 R2 R3 R4 R5 R6 R7 R8 R10 R12 R16 R17
R19 R20 R37 R38 R39 R40 R41
SPDT on-off-on mini toggle switch.
Mouser# 108-1MS3T2B3M2QE-EVX
U1 U2 U3
U5
U1 U2 U3
U5

PCB pic ures
PCB1
PCB

Assembly ins ruc ions
We start with PCB .
S ep 1
Solder small signal diodes. Diodes are sensitive to mounting direction, make sure the stripe on
the diode match the stripe on the silkscreen.
D1, D2, D3, D4, D5, D6 1N4148 6pcs
S ep 2
Solder resistors. Resistors are not sensitive to mounting direction.
R10, R12, R16, R17, R19, R20 100K 6pcs
R21, R22, R29, R31, R47, R48 10K 6pcs

R23, R24, R27, R28 22K 4pcs
R25, R26, R30, R32 470R 4pcs
R45, R46 10R 2pcs

R9, R11, R13, R14, R15, R18, R33, R34, R35, R36 200k 10pcs
S ep 3
Solder power polarity protection diodes. Diodes are sensitive to mounting direction, make sure
the stripe on the diode match the stripe on the silkscreen.
D7, D8 1N5818 2pcs
S ep 4
Solder ceramic capacitors. Ceramic capacitors are not sensitive to mounting direction.
C3, C4, C5, C6, C9, C10, C11, C12 100nF 8pcs

S ep 5
Solder IC sockets. Match the IC sockets indent (marking pin 1 side) with the silk screens.
If you feel the least uncertain on the IC direction, please search the web for IC orientation.
U2, U3 14 pin DIP sockets (DIP-14) IC's wi be mounted ater. 2pcs
U4 16 pin DIP socket (DIP-16) 1pcs
S ep 6
Solder electrolytic capacitors. Electrolytic capacitors are sensitive to mounting direction. Put
the long pin in the hole marked with a + (anode) on the silkscreen.
The opposite side - (cathode) is marked with fully filled silkscreen.
C13, C14 10µF 2pcs
S ep 7
Solder transistors, transistors are sensitive to mounting direction. Match the curved side on the
transistor with the curved side in the silkscreen.
Q1, Q2 BC557B 2pcs

S ep 8
F ip PCB2 to the bottom side. So der the power header. Make sure the key opening is oriented
in the same way as in the picture be ow. It's easier to avoid bent pins if you attach the power
cab e in the header whi e you are so dering.
CON1 2x5pin
S ep 9
F ip PCB2 to the bottom side. Now it's time to so der trimmers. They are not sensitive to
mounting direction.
TRbal1, TRbal2 50R mu ti turn trimmer 2pcs
TRgain1, TRgain2 50k mu ti turn trimmer 2pcs

S ep 10
Insert the ICs in the sockets. If you feel the least uncertain on the IC direction, please search
the web for IC orientation.
U2, U3 TL074/TL084 2pcs
U4 LM13700 1pcs
Leave PCB on the side with the PCB to PCB connectors not soldered.
Now it's time for PCB1.
S ep 11
Solder resistors. Resistors are not sensitive to mounting direction.
R1, R2, R3, R4, R5, R6, R7, R8, R37, R38, R39, R40, R41 100k 13pcs
R42, R43, R44 1k 3pcs

S ep 12
Solder ceramic capacitors. Ceramic capacitors are not sensitive to mounting direction.
C1, C2, C7, C8 100nF 4pcs
S ep 13
Solder IC sockets and insert IC's. Match the IC sockets indent (marking pin 1 side) with the
silk screens.
If you feel the least uncertain on the IC direction, please search the web for IC orientation.
U1 14 pin DIP socket (DIP-14)
U5 8 pin DIP socket (DIP-8)
U1 TL074/TL084
U5 TL072/TL082

S ep 14
Mount the spacers with the nuts on PCB1. You can have the screw-side on PCB1 as well if you
feel that it's more comfortable.
S ep 15
Put the pin & socket strips into each other. Place them between PCB1 and PCB in their
respective places. Take a firm grip wi h a plier around he spacers and screw he
screws in o place. If the nuts gets loose, tighten them again.
Remove them again after the pin & socket strips are soldered.
So der the connectors.