Lithium Grim Dirty Little JCM Instruction Manual

Dirty Little JCM
Building instructions
v1.0

Dirty Little JCM v1.0
Manufacturers and product names are mentioned solely for circuit identification, and where applicable their trademarks are the
property of their respective owners who are in no way associated or affiliated with the author. No cooperation or endorsement
is implied.
2
Table of contents
PCB layout ............................................................................................................................................... 3
Components ............................................................................................................................................ 4
Bill of Materials........................................................................................................................................ 5
Power section.......................................................................................................................................... 6
Modifications........................................................................................................................................... 7
Build sequence ........................................................................................................................................ 8
Off board wiring ...................................................................................................................................... 8
Potentiometers.................................................................................................................................... 8
(Foot)switch......................................................................................................................................... 9
Troubleshooting .................................................................................................................................... 10
Schematic .............................................................................................................................................. 11
Read this entire manual thoroughly before you start building the effect! There are some available
options and you should choose which one you want to incorporate before starting your build.
Last update: 24-04-2017

Dirty Little JCM v1.0
Manufacturers and product names are mentioned solely for circuit identification, and where applicable their trademarks are the
property of their respective owners who are in no way associated or affiliated with the author. No cooperation or endorsement
is implied.
3
PCB layout
Dimensions: 50 mm x 61 mm
1.97 inch x 2.4 inch

Dirty Little JCM v1.0
Manufacturers and product names are mentioned solely for circuit identification, and where applicable their trademarks are the
property of their respective owners who are in no way associated or affiliated with the author. No cooperation or endorsement
is implied.
4
Components
All parts must be rated 25V+
Name
Value
Comment
Name
Value
Comment
Name
Value
Comment
C1
220n
R1
470k
D1
1N5817
C2
1n
R2
33k
D2
1N5817
C3
680n
R3
820R
D3
1N5817
C4
2n2
R4
1M
IC1
ICL7660S
Or LT1054
C5
2u2
R5
1M
P1
A1M
GAIN
C6
22n
R6
1M
P2
B25K
MID
C7
470p
R7
470k
P3
A1M
BASS
C8
47p
R8
470k
P4
B250K
TREBLE
C9
470p
R9
560R
P5
B10k
PRESENCE
C10
680n
R10
100k
P6
B250K
VOLUME
C11
2u2
R11
1M
Q1
MPF4393
C12
470p
R12
1M
Q2
MPF4393
C13
22n
R13
56k
Q3
MPF4393
C14
22n
R14
1k
Q4
MPF4393
C15
22n
R15
1k
Q5
MPF4393
C16
220n
R16
47k
C17
100n
R17
2M2
C18
220p
R18
2M2
C19
470p
R19
4k7
C20
47u
R20
1k
C21
22u
R21
33k
C22
270p
R22
1M
C23
10u
R23*
4M7
C24
10u
SW1
SPDT
Voltage
C25
100n
SW2A
SPDT
C26
100u
SW2B
SPDT
C27
Not connected
SW2C
DPDT
C28*
10n
SW2D
DPDT
* R23 and C28 are part of a mod. Do not place them if you do not want to use the mod!

Dirty Little JCM v1.0
Manufacturers and product names are mentioned solely for circuit identification, and where applicable their trademarks are the
property of their respective owners who are in no way associated or affiliated with the author. No cooperation or endorsement
is implied.
5
Bill of Materials
Capacitors
Resistors
Amount
Part
Type
Amount
Part
Type
1
47p
Ceramic
1
560R
1% metalfilm
1
220p
Ceramic
1
820R
1% metalfilm
1
270p
Ceramic
3
1k
1% metalfilm
4
470p
Ceramic
2
4k7
1% metalfilm
1
1n
MKT
2
33k
1% metalfilm
1
2n2
MKT
1
47k
1% metalfilm
1
10n
MKT
1
56k
1% metalfilm
4
22n
MKT
1
100k
1% metalfilm
2
100n
MKT
3
470k
1% metalfilm
2
220n
MKT
6
1M
1% metalfilm
2
680n
MKT
2
2M2
1% metalfilm
2
2u2
Electrolyte 25V+
1
4M7
1% metalfilm
2
10u
Electrolyte 25V+
1
B10k
16 mm Alpha
1
22u
Electrolyte 25V+
1
B25K
16 mm Alpha
1
47u
Electrolyte 25V+
2
B250K
16 mm Alpha
1
100u
Electrolyte 25V+
2
A1M
16 mm Alpha
Semi conductors
Other
Amount
Part
Type
Amount
Part
Type
3
1N5817
3
SPDT
5
MPF4393
1
DPDT
1
ICL7660S
Or LT1054
1
3PDT
Footswitch
1
LED
1
Jack
Mono jack
1
Jack
Stereo jack
1
Box
Hammond 1590B/BB
1
DC
2,1mm DC jack
4
Spacer
Plastic PCB spacers
1
DIL-8
Socket for IC

Dirty Little JCM v1.0
Manufacturers and product names are mentioned solely for circuit identification, and where applicable their trademarks are the
property of their respective owners who are in no way associated or affiliated with the author. No cooperation or endorsement
is implied.
6
Power section
The effect has been designed to be able to operate on 9V or 18V. SW1 enables you to switch
dynamically between these settings. If you do not want to use the switch then do not forget to solder
a jumper between the middle pad and the desired voltage pad. NEVER let the outer 2 lugs of SW1
tough each other and also never connect all 3 pins of SW1 together. If your IC gets hot then there is a
short in the power section and you must disconnect the effect immediately from the adapter and
find the fault.
You can choose between 3 options for the power section:
1. No charge pump:
Do NOT install: C23, C24, D2, D3, IC1, J1, SW1
Extra jumpers: SW1 on 9V pad and middle pad
The effect can now be used with a standard 9V adapter or a 18V adapter
2. Charge pump using a ICL7660S:
Place all components as stated on the PCB and
connect a jumper between leg 1 and 8 of IC1.
Do not forget to place the jumper before placing the
DIP-8 socket of the IC.
NB. Only use the 7660S and not other
versions without the S.
The effect can now only be used with a 9V adapter and you can switch it internally to 9V or
18V.
3. Charge pump using a LT1054:
You can place all components as stated on the PCB just do NOT connect pin 1 and 8 of IC1!!
The effect can now only be used with a 9V adapter and you can switch it internally to 9V or
18V.

Dirty Little JCM v1.0
Manufacturers and product names are mentioned solely for circuit identification, and where applicable their trademarks are the
property of their respective owners who are in no way associated or affiliated with the author. No cooperation or endorsement
is implied.
7
Modifications
The effect can be perceived as dark and wooly. If you experience this, I recommend the following
mod (thanks to John Kallas & lvlark on tagboardeffects):
C4: 220n
C17: 22n
C28: 10n
Q1-Q5: 2N5457 (or J201)
R9: 1k
R15: 220R
R20: 220R
R23: 4M7
These parts are extra and not in the bill of materials (except for R23 and C28 which are on the BOM).
Switching between the “Super Lead” and “Super Bass” can be done by either soldering SW2A-D on a
single 4PDT or as mentioned in the off board wiring by 2 SPDT (SW2A and SW2B) and one DPDT
(SW2C and SW2D).
The MPF4393 are hard to find and expensive. You could replace them with PN4393, 2N5457 or J201.
I advise the 2N5457 for the pure subjective reason that I like the sound.

Dirty Little JCM v1.0
Manufacturers and product names are mentioned solely for circuit identification, and where applicable their trademarks are the
property of their respective owners who are in no way associated or affiliated with the author. No cooperation or endorsement
is implied.
8
Build sequence
Soldering this board can be very complicated for some people since the solder pads are very close
together. Use a magnifying glass to make the job easier. The trick to soldering a PCB is to work from
small to big components. My building sequence suggestions in this section are based on the parts I
used myself. Sometimes some components are smaller (or bigger) so always use your own common
sense and change the order. Usually capacitors differ a lot in size depending on their rating.
Note: Do not blow on your solder in an attempt to cool it down. That will possibly result in a bad join
that might corrode!
Start by soldering the resistors, then the diodes and then the ceramic capacitors.
If you want to experiment with other transistors then you could socket them instead of soldering
them to the board. You’ll need a some 20 SIL sockets, break off the sockets and solder them to the
board. Now is the time to solder these sockets on the PCB as well as the socket for the IC. Place the
transistors and IC once you are finished with all soldering and off board wiring!
Now continue by soldering small MKT (<680n) capacitators then the rest of the MKT capacitors and
then the electrolytes.
I suggest you now drill the holes in your enclosure so you can use it during the off board wiring.
Note: Really take some time to determine where to place the pots, switches, jacks and PCB in the
enclosure before you start drilling. Measure twice, drill once.
You are almost ready to rock, well… not really. The difficult part starts now.
Off board wiring
Potentiometers
In the pictures below you see the correct pin numbering of the pots.
Solder the wires accordingly and it is always a good idea to twist the wires together to create a sort
of extra shielding against external noise.
You can break of the pin I marked with the yellow circle with a small pair of pliers.
1 2 3
3 2 1
1 2 3
P1
P2
P3
3 2 1
1 2 3
3 2 1
P4
P5
P6

Dirty Little JCM v1.0
Manufacturers and product names are mentioned solely for circuit identification, and where applicable their trademarks are the
property of their respective owners who are in no way associated or affiliated with the author. No cooperation or endorsement
is implied.
9
(Foot)switch
Ring
Sleeve
Tip
Tip
Sleeve
R led
Cathode (short leg)
Anode (long leg)
Note that this wiring is using a sort of star grounding and the output connector must make good
electrical contact with the enclosure else the grounding will not work properly and the effect might
start to buzz loudly.
Also Note that R led is a 4k7 resistor. You can change this value depending on the type of LED you
use but 4k7 is safe enough for almost all LEDs for both 9V as well as 18V.
As mentioned in the beginning of this manual, you could combine the 2 SPDT with the DPDT switch
of SW2A-SW2D to one 4PDT switch. Make sure you connect all the 4 rows in the same way, making
the square pad always the left most pin on the switch.
It is now time to place your transistors and IC in the sockets if needed. Connect everything, build it in
your enclosure and enjoy your effect!

Dirty Little JCM v1.0
Manufacturers and product names are mentioned solely for circuit identification, and where applicable their trademarks are the
property of their respective owners who are in no way associated or affiliated with the author. No cooperation or endorsement
is implied.
10
Troubleshooting
All PCB’s have been 100% factory e-tested and out of every batch I receive I build an effect to double
check, so there should not be a connection problem on the PCB itself.
The board is not working (at all), what now?
Check if your 9V is plugged in correctly (and/or soldered correctly on the board). Pay special
attention to the polarity.
Check that you oriented the capacitors, IC’s ,transistors and diodes the right way. SMF, MKT
and ceramic capacitors as well as resistors do not need to be oriented. A likely sign of
incorrect capacitors and/or orientation is when an effect is sputtering, rumbling or
“motorboating”.
Check if you used the correct values of the components. For resistors you can look here:
http://www.diyaudioandvideo.com/Electronics/Color/
Double and triple check your soldering! A loose or cold solder can be really bad for your
board.
Replace the IC and/or transistors, one might be defective. Before doing that first unplug the
9V and wait for 5 seconds.
Check that you have good/high grade components. A lot of Chinese sourced parts are fakes
(especially high end opamps, audio capacitors, vintage diodes and transistors) so be careful
that you source your parts from reliable suppliers.

Dirty Little JCM v1.0
Manufacturers and product names are mentioned solely for circuit identification, and where applicable their trademarks are the
property of their respective owners who are in no way associated or affiliated with the author. No cooperation or endorsement
is implied.
11
Schematic