sammichFM Build Guide v1.0 0. Introduction Check
sammichFM Build Guide v1.0
0. Introduction
This build guide tries to explain every step of the build process so that even those people inexperienced in
electronics can follow the guild closely and achieve success. However, if you are so inexperienced that
you have never done any soldering at all, you can look at guides aimed at teaching you this. I recommend:
Even if you are an experienced electronics guru of many years, please read through the guide fully before
beginning to solder parts. The parts list alone is not sufficient in describing everything. Pay particular
attention to:
Mounting the power socket
Mounting the heatsinks and voltage regulators
Soldering the male/female headers that join the two PCBs and LCD
Soldering the LEDs
I don't assume anything is obvious; instead I expect that if there's a wrong way to do something, at least
one person in a hundred will probably do it the wrong way (including myself). So please:
Check twice, solder once!
Check the Mount Notes for every part!
Leave the backing paper on the panels and use this as a mask while you
paint the engraving!
Don't remove the clear acrylic window from the top panel!
You can build the entire sammichFM with the backing paper still on the panels, and then paint the panel
engraving after you have finished. This allows you to play with your new MIDIbox FM synth while you
paint the panels (a slow process).
1. Soldering Techniques
These are the techniques I use when soldering through-hole components. These could be obvious,
common-sense things to do, but in case you have no idea, here they are:
The “Upside-Down PCB” Technique
Early in the build process, it's possible to insert several components which have the same height and then
flip the PCB upside-down and put it flat on the work surface so that the components are held in position.
Typically I do this only with the resistors and IC sockets, and only if I can guarantee that components will
definitely be held flat against the PCB.
This technique sometimes fails if there is not enough weight holding the components close to the PCB.
Some components like IC sockets and switches will “snap-in” and be held in place. In these cases, make
sure the part isn't moved while soldering the pins. It is better to solder one pin first and check the
component is flat against the PCB before proceeding with the other pins.
The “Tacking” Technique
“Tacking” is a term used in other crafts, essentially meaning “temporarily attach”. By holding the
component onto the PCB with one hand (and optionally holding the PCB as well), you can tack one or
more leads/pins in place by carrying a blob of solder on the soldering iron and wiping it into the joint.
The solder joint formed is bad and should not be left like this, however, it should hold the component in
place while making proper solder joints for the other leads/pins, and then the tacked leads/pins can be
resoldered using proper soldering joint technique. For IC sockets, pins on either side should be tacked, so
the part is held flat. Pads connected to the ground plane (i.e. no dark circle around the pad) are hard to
solder normally and even harder to tack, so choose another pad when tacking.
Please note that good soldering joints are formed by heating the pin and the pad simultaneously and
feeding solder into the point where they meet, on or near the tip of the soldering iron. Do not normally
carry solder blobs on the soldering iron to the joint. Only do this for the tacked joint.
BTW... if you don't burn your finger occasionally using the Tacking Technique, you're doing it wrong :-)
Tip: Adding flux to pads will make “tacking” much easier and often the joint will be good enough and
won't require resoldering. If it has a cone shape (i.e. good “tenting”), it should be good enough.
The “Add Flux To Every Pad” Technique
In case you didn't know, flux is so essential to soldering that solder has flux inside it already.
Since your kit contains a tube of CHIPQUIK No Clean Paste Flux and you need only a tiny bit on the
surface mount ICs, there's plenty spare to use on all the other pads on the PCB. I highly recommend it for
pads that are difficult to solder (ground pads, socket pads) or which you want to solder quickly to avoid
overheating the component (diodes, transistors, voltage regulators, LEDs) and there's nothing wrong with
using it on all pads to make soldering every joint easy and looking perfect.
Squeeze out a blob of flux paste onto a non-porous surface (e.g. blister pack plastic) and use a toothpick
to smear a tiny bit on the pad. It doesn't have to be even or cover the whole pad, as it will liquify during
soldering and mingle with the molten solder. You can do this before or after you insert the component.
After soldering the surface mount ICs, start using it on the resistors, so you can learn how much you need
and how it affects the soldering. At the very least, use it on ground pads, as the direct connection to the
ground plane will dissipate the heat from the iron making soldering difficult.
Note: be sure to clean your soldering iron tip regularly (after every 4th joint) to avoid burnt flux
getting into the joints, making them look brown. This is a good thing to do even if you don't add more
2. Base PCB Soldering Walkthrough
This walkthrough suggests mounting and soldering parts in the order they are presented in the Parts List.
I recommend attaching the 20mm spacers to the bottom of the base PCB so the PCB can sit above the
work surface. This allows parts with long leads to be inserted.
Step 0: Check if 5V and GND are shorted/connected.
In the unlikely event that your PCB has a manufacturing fault, it is a lot easier to fix if you know the PCB
is at fault and not your soldering or the components.
Note: Since the 5V supply to the audio and OPL3 section is isolated by two headers, in which you use
shunts to connect to the 5V supply, you need to test for possible 5V/ground shorts in two places, inside
the audio/OPL3 section (e.g. at C50, C51, C52, C53, C54, C55) at and outside it (e.g. at J4:Vd/J4:Vs)
Step 1: Solder surface mount ICs.
Here is a good instructional video of soldering surface mount ICs:
You don't need all the equipment they show there. I use a cheap temperature-controlled soldering iron,
some flux paste applied with a toothpick, and copper braid/solder wick,
Your kit includes CHIPQUIK No Clean Paste Flux and 12” of copper braid/solder wick. USE IT!
My surface mount soldering process is fairly similar to that in the video above:
Step 1.1: Apply some flux to the pads using a toothpick.
Step 1.2: Put IC on the pads, align carefully. The flux should keep it in alignment.
Check orientation of IC with part outline on PCB, the dot on the corner of the IC should match the dot on
the PCB (left of the “notch”).
Step 1.3: Apply a tiny bit of solder to iron tip and touch only the blob onto the joint. Don't touch the pin
with the iron tip and move it out of alignment!
Consider this joint just “tacking” the part down while you do the other pins properly. It doesn't matter if
it has slightly too much solder, or has a “horn”, you can fix this easily later.
Step 1.4: Check alignment again. If it requires adjustment, reheat the corner pad and move the IC while it
is hot. This is tricky to do with tweezers. Use a finger.
Step 1.5: Repeat Step 1.4. Srsly. Check the orientation as well! Dot to dot!
Step 1.6: Apply more flux to the pads and pins.
Step 1.7: Solder the corner pin/pad diagonally opposite to the pin/pad already soldered.
My technique is to hold the solder vertical, touching the end to the low point of the pin (where it touches
the pad), and pushing the soldering iron tip into the solder. This will instantly melt the solder and it will
naturally fall into the joint. If there is too much solder in the joint, immediately remove it with solder wick
before proceeding. You don't want to create solder bridges behind the pins, which might happen while
soldering the next pin.
Step 1.8: Check alignment again. If it requires adjustment, reheat the pad and move the IC while it is hot.
With the other corner already soldered, you can only do rotation adjustments, but that might be enough to
get pins in alignment.
If you are not 100% happy with the pin alignment, desolder these two pins and start again. If you solder
any more pins, desoldering becomes very difficult.
Step 1.9: Solder all the pin/pads not already soldered.
Step 1.10: Resolder the corner pin/pad you did first, it might be a poor joint, i.e. just “tacked” to hold the
IC while you solder the other joints.
Step 1.11: Use solder wick to remove any excess solder or solder bridges between pins. By “excess” I
mean obvious blobs. If the solder joint is no wider than the pin/pad, it's OK. If you use just the right
amount of solder per joint, you don't need to use the solder wick at all.
Step 1.12: Do continuity testing between all adjacent pin pairs. (Note: IC53 and IC54 each have four
pairs which are supposed to be connected by tracks on top layer.)
Step 1.13 (Obsessive Completion Distinction): Do continuity testing between the top of each pin (the
unsoldered part) and another pad/via on the same track, to test the solder joint is perfect.
Here is an example of the YMF262 and YAC512
soldered with “good” solder joints, IMHO.
Observe how the solder fills the space behind the
pin, between the pin and the pad, and a little bit
stuck to the inside bend on the top of the pin. This
may be more solder than what you might see in a
factory assembled PCB, because they use tiny
amounts of solder paste and cook it in an oven.
You could remove some of this excess with solder
wick, but it's not necessary.
Step 2: Solder resistors, diodes, IC sockets, ferrite bead, crystal, small
Diodes must be oriented correctly. The stripe on the diode matches the stripe on the part outline.
IC sockets are oriented with the notch of the socket matching the notch on the part outline.
IC sockets in IC5-IC9 are best soldered together as a group so they align nicely.
Resistors do not have a correct orientation, but look nicer if oriented consistently. As you can see in the
photo, I orient them so the value can be read left to right or bottom to top.
You can use the “tacking technique” (see above) for all small two-lead components, but it is more
common to insert components and bend the leads outward just enough so they stay in place.
If you do the “bending leads” technique, I highly recommend cutting leads short (around 5mm) prior to
soldering. This will make soldering easier, as there will be less heat dissipated through the leads, and
easier to get the iron tip onto the pads.
I also recommend adding a bit of flux to ground pads (pads that are directly connected to the ground plane
and are missing the dark ring around them) and starting with a blob of solder on the iron tip first, that will
get the heat into the pad quickly and then feed more solder into the joint until it sucks into the hole.
Tip: Don't try to do too many components at one time!
Even if you can get all the components to stay in place while you soldered the bottom side, it's not a good
idea. It's much safer, easier and probably quicker to solder all parts of one type, then trim leads before
starting on another type.
Step 3: Solder small electrolytic capacitors, transistor, 78L05 voltage
regulator, trimpots and header pins.
Electrolytic capacitors must be oriented correctly. The lead identified by a black stripe (with “-” inside) is
the negative lead. The other lead must go in the positive pad, identified with a “+” on the part outline.
Tip: You can solder one lead of electrolytic capacitors from the top side to hold them all in place.
The transistor (T1) requires bending out of the middle lead to fit the holes. Bend it away from the flat side
at 45º angle, then bend it another 45º to be parallel to other leads.
The voltage regulator (IC3) requires bending out of the outer leads to fit the holes. Bend it away at 45º
angle, then bend it another 45º to be parallel to other leads.
Solder transistor/voltage regulator quickly! Do not heat the joint more than 3 seconds, and allow 20
seconds to cool between soldering transistor leads. Add flux to help solder the pads quicker.
Only solder the required headers, all others are for using this PCB in other contexts.
Do not solder the big voltage regulator (IC4) now, only the little one (IC3).
Step 4: Solder DIN sockets, audio sockets, DC power socket, rocker switch,
bridge rectifier, crystal oscillator, big fat 2200uF electrolytic capacitor.
NOTE: Rear panel sockets must be soldered perfectly aligned so that the rear panel will be aligned
with the bottom panel. Read Step 4 instructions entirely before you start soldering.
All rear panel sockets (and switch) are soldered flat against the PCB. There should be no gap between the
component and the PCB. In particular, the audio sockets and power socket (since they protrude through
the rear panel) will cause rear panel misalignment if there is a gap. (By “no gap” I mean pushed into the
PCB as far as possible, the audio sockets might have a very tiny <1mm gap between the plastic and the
Solder only one pin of each socket to hold it in place, then you can check for correct alignment before
soldering the other pins.
Use a “tacking” method – i.e. while holding the socket/PCB together with one hand, apply a blob of
solder to one pin. This is a temporary joint – be sure to solder the joint properly after soldering the other
Solder both DIN sockets (MIDI In, MIDI Out) at the same time to ensure they are both level with the
PCB edge.
After soldering one pin of each audio socket, attach the rear panel using the plastic nut on the audio
socket. Tighten so it is touching the PCB edge. This helps align the DC power socket, which has a tight fit
in the panel and is loose in the PCB's pad holes. It should stick out 0.5mm because when the case is fully
assembled, there is a gap of 0.5mm between the PCB edge and the rear panel. You can now solder one
pin of the DC power socket using the “tacking” method.
After “tacking” all the sockets, you can now check for correct alignment by placing the PCB onto the
base with screws/nuts attached and adding the corner spacers (see Case Assembly section) and then
attaching the rear panel. You should check that the power socket and audio sockets are not causing the
rear panel to have a gap where it joins the bottom panel. If they do, you can heat up the “tacked” joint
while you realign the socket.
Solder the other pins of each socket with proper solder joints (not “tacking”), before resoldering the
“tacked” joint. Don't be shy with the solder, these joints can take a lot because they are big, and they are
the ones that will receive stress from plugs going in and out.
Follow the same process for the power switch, “tack” it on, check for alignment, solder the other pins,
resolder the “tacked” pin. You may need to bend the leads slightly to make it fit. Solder it as far towards
the rear panel as possible (as well as centered and aligned with the outline on the PCB).
Now solder the bridge rectifier, crystal oscillator and big fat 2200uF electrolytic capacitor.
Here's what you should have when you finish. Everything soldered to the base PCB except the voltage
regulator on the right and the female headers on the left.
Now is a good time to check for shorts between 5V and GND before you solder the voltage
regulator, so you can rule out the voltage regulator as a cause (removing it later is painful!)
Step 5: Assemble voltage regulator and heatsinks.
This step is fiddly and requires long-nose pliers and a philips screw driver. It is important not to
overtighten the screws holding the voltage regulator to the heatsinks.
NOTE: Avoid using conductive heatsinking compound like Arctic Silver or some other fancy stuff
that PC power users use between their PC's CPU and their custom CPU heatsink with all the fins
and fan with LED bling etc. Conductive heatsink might cause shorts between pins of the voltage
regulator, which might cause blue smoke, sparks, fried voltage regulators, fried power supplies, and
a trip to the local electronics shop to buy more parts.
NOTE: Don't use heatsinking compound between the PCB and big heatsink. There is not much to
gain from using it here and it will only make a mess due to the holes in the PCB.
Step 5.1: Mark where to bend leads of the voltage regulator and then bend to fit. Ideally, voltage regulator
should have leads all bent exactly the same, so it will easily “fall into” the holes and also have the tab's
hole aligned with the hole on the PCB.
Step 5.2: Practice assembling the heatsinks and voltage regulator without using heatsinking compound!
i.e. do steps 5.3, 5.5, 5.7, 5.8, 5.9, 5.10, disassemble and repeat using heatsinking compound.
Step 5.3: Place big heatsink onto PCB
Step 5.4: Apply non-conductive heatsinking compound to bottom of small heatsink.
Step 5.5: Place small heatsink onto big heatsink, align holes.
Step 5.6: Apply non-conductive heatsinking compound to back of 7805 voltage regulator (IC4)
Step 5.7: Place 7805 voltage regulator (IC4) onto small heatsink.
Step 5.8: Screw together 7805 and heatsinks using 9mm screw coming from the bottom side. This is
easiest done by holding screw in position with a finger while attaching and tightening nut using long-nose
pliers, until the nut is on the screw. Thereafter, use a screwdriver on the screw while stopping the nut from
turning with a finger, and then later, with pliers.
Step 5.9: While nut is firm but not tight, you can move the heatsinks and voltage regulator to be neatly
aligned. Ensure big heatsink is not touching the pads of the voltage regulator.
Step 5.10: Tighten nuts, but don't overtighten nuts :-)
Step 5.11: Cut leads of 7805 (on the bottom side) to be 2mm.
Step 5.12: Solder 7805. Allow 20 seconds for part to cool between soldering leads. The middle pin is
connected to the ground plane and will be harder to solder. Starting with a blob of solder already on the
iron tip, and holding the tip at a smaller angle to the PCB (i.e. more horizontal).
Step 5.13: Clean up any excess heatsinking compound
Step 5.14: Check that you did not create any shorts between any of the pads you just soldered (or from
using conductive heatsinking compound even though I told you five times already not to use it.)
Step 6: Attach LCD to Control Surface PCB
To achieve “perfect” alignment, first attach loosely on two diagonally opposite mount holes, then move it
until the hole underneath is centered in the hole above.
You can also check if the LCD's PCB edge is parallel with the edges of the ground plane gap of the
control surface's PCB (i.e. the darker red shape on the bottom which is the exact size of the LCD).
When you have all the screws tightened, check alignment again. The LCD can move on the mounts
during tightening of screws.
Good alignment is critical in making the control surface PCB easily “plug into” the base PCB.
Step 7: PCB Interconnection Stage
Now here comes the fun bit!
You are going to attach the two PCBs together so they're perfectly aligned while you solder the male and
female headers to both PCBs.
Step 7.1: Prepare the male and female headers. The shorter end of the male header goes into the female
Note: depending on the LCD type, the 16 pin male header goes into the “upper” or “lower” 16 pins of
the 18 pin female header. Most of the time it will be the “upper” 16 pins, as shown by the white outline
on the base PCB. As far as I know, only the Optrex STEP LCDs require it in the “lower” 16 pins,
because the backlight pins are at the other end of the header.
Step 7.2: Attach 32mm screws and 20mm spacers to base PCB corners
Step 7.3: Attach 9mm screws and 20mm spacers to base PCB side midpoints
Step 7.4: Insert female headers (with male headers inserted) into base PCB.
Note: as described above, for most LCDs, the male header will be in the “upper” 16 pins of the female
header (i.e. on the left side, as shown in this photo). If using an Optrex STEP LCD, it will be in the
“lower” 16 pins (i.e. on the right side). There's only one way your LCD can align and fit (when
mounted to the control surface PCB) so don't worry too much about it unless you plan to connect the
LCD while it is not mounted to the control surface PCB.
Step 7.5: Slowly and carefully place control surface PCB onto corner screws and lower down so male
header pins go through holes in LCD and control surface PCB. Attach with 10mm spacers at corners and
3mm screws at side midpoints.
Step 7.6: Solder two diagonally opposite pins on each header on the top side, ensuring female header is
flat against base PCB.
Step 7.7: Have another look from the side. Everything looks good? Female headers are still flat against
base PCB? Good. Finish soldering the headers on the top side.
Step 7.8: Solder all the pins of the female headers on the bottom side..
Step 8: Congratulate Yourself for Finishing Soldering of the sammichFM
Base PCB!
3. Control Surface PCB Soldering Walkthrough
Step 0: Check if 5V and GND are shorted/connected.
In the unlikely event that your PCB has a manufacturing fault, it is a lot easier to fix if you know the PCB
is at fault and not your soldering or the components. Check between J1:Vd and J1:Vs.
Step 1: Solder the resistors, small capacitors, IC sockets, resistor networks
Insert and solder parts in the order they are presented in the Parts List.
NOTE: Pay attention to the orientation of resistor networks! Match the dot on the resistor network
with the dot on the PCB.
Tip: I use a small piece of card (i.e. business card) between the resistor network and the IC socket to
keep it vertical while “tacking”.
Step 2: Solder electrolytic capacitor, transistors, tactile switches
Insert and solder parts in the order they are presented in the Parts List.
As with the base PCB, check orientation the electrolytic capacitor before soldering.
NOTE: The leads of some switches (see arrows on bottom side of PCB) might touch the heatsink.
You should cut only the leads indicated by the arrows as short as possible before soldering, not all
of them!
Step 3: Soldering LEDs
Now here comes another fun bit!
The objective here is to solder all the LEDs at exactly the same height above the PCB. If any of them are
shorter, it is very noticeable, as our brains notice tiny differences in regular patterns. Take things slowly.
Step 3.1: In the corners, mount 20mm spacers to bottom, 10mm spacers to top, using 32mm screws.
Allow enough thread in the top of the 10mm spacers so you can screw on the top panel (i.e. 5mm)
Step 3.2: Place switch caps on the switches. This helps ensure you have the panel aligned with the PCB
in a later step. They require a good bit of force to snap onto the switch, so don't be concerned about this.
Step 3.3: Insert the LEDs and push them all the way to the PCB. Align the flat side of the LED with the
flat side of the part outline. The flat side is the cathode, which is also the shorter lead. The other side is
the anode which is the longer lead. So alternately, place the longer leads into the left hole when the PCB
is facing you the right way up (i.e. with LEDs at top, buttons at bottom).
Step 3.4: Attach top panel to PCB using black screws. Check alignment by looking at the switch caps.
Step 3.5: Turn PCB upside down. Carefully and gently push LEDs into the holes as much as possible.
Step 3.6: Look underneath at the LEDs and check they all protrude the same amount. If any do not, it
could be that a LED is stuck because the hole is slightly smaller or the LED is slightly bigger.
Disassemble PCB and panel and check that LED individually. It is possible that a LED has a little bit of
excess plastic from molding imperfections, which can be scraped away using a craft knife.
Step 3.7: Solder all the shorter leads of one row of LEDs. Push down on the longer lead with your middle
finger while soldering, if you have one. Work quickly! No more than 3 seconds per joint! If you must
resolder a joint, allow LED to cool for 20 seconds.
Step 3.8: Look underneath at the LEDs and check they all protrude the same amount. If not, heat up a
joint and push down on the longer lead (there's a reason I told you to solder the shorter lead first!)
Step 3.9: Solder all the longer leads of that row of LEDs.
Step 3.10: Cut all the leads of that row of leads, as short as possible. This gives you room to solder the
other row.
Step 3.11: Repeat steps 3.7 to 3.10 for the other row of LEDs.
Step 4: Solder rotary encoder
You solder this last so that the shaft doesn't get in the way while soldering LEDs (i.e. it can sit flat). Now
you need it to sit flat while soldering the rotary encoder. To avoid bending LEDs (and if you don't have a
vice), invert the spacer/screw combos so the 20mm spacer is now on the top side.
NOTE: The leads of of the rotary encoder might touch the heatsink. You should cut the leads as
short as possible before soldering.
Step 5: Congratulate Yourself for Finishing Soldering of the sammichFM
Control Surface PCB!
4. Jumper Configuration
MIDI Routing Jumpers
Headers JMI and JMO control whether the MIDI In and MIDI Out ports are connected to either the
PIC18F4685 or the “expansion port” pads below it.
Insert a shunt in JMI and a shunt in JMO where the thick white line indicates the default (i.e. connected
to the PIC).
Backlight Voltage/Current Jumpers
Header JR4A controls whether the backlight current is limited to 25mA (open) or approximately 250mA
(closed). The header actually shorts resistor R4A, which is an 81K resistor in series with R4 in the
traditional MIDIbox Core backlight circuit. Thus, leaving this header open will enable R4A and reduce
the current, a shunt in this header will disable R4A and the current will be higher.
Low-power Backlight LCD (i.e. Edge-lit)
If you are using a low-power backlight LCD that requires only 25mA, then do not put a shunt in JR4A!
High-power Backlight LCD (i.e. LED array)
If you are using a high-power backlight LCD that requires 250mA or more, then put a shunt in JR4A to
increase current. Turn brightness trimpot to half-way (12 o'clock), this gives the optimal current for a
high-power backlight LCD.
Audio/OPL3 Power Jumpers
The two headers to the right of IC51 (YAC512) are for supplying 5V power to the audio and OPL3
sections of the PCB. These headers are protect the surface mount ICs until you're confident there are no
problems elsewhere on the PCB, i.e. voltage tests pass, you can upload the firmware, etc.
5. Power Supply
sammichFM contains two 5V voltage regulators (7805 and 78L05) A typical LCD backlight at 50%
brightness (a good setting for good contrast) draws 100mA. The rest probably draws less than 100mA.
The voltage regulators should receive at least 7V for good regulation. If supplied with DC power, going
through the bridge rectifier will drop voltage by approx. 1.2V.
Thus ideally, you should provide sammichSID with regulated 9V DC (500mA+) supply. That would
ensure that the voltage going into the voltage regulators is good (approx. 7V), keeping the heat dissipation
down to absolute minimum (7V - 5V = 2V, 2V x ~200mA current = 0.4W)
If you can't get a regulated 9V DC supply, then you can also use unregulated DC or AC, but suitable
voltage/current ratings can vary. For example, a 9V AC 200mA supply would be good, but a 9V AC
500mA would be loaded so lightly that the voltage going into the regulators might be 15V or higher,
which would be bad. Also, something like a 5V AC 500mA or higher might work, since it is loaded so
lightly that the voltage would be over 7V at the voltage regulator inputs.
Avoid switchmode power supplies! They generate far too much noise in the audio. I have yet to find one
that works for sammichFM. Aim to get a transformer based (linear) power supply.
Test voltage going into the voltage regulators! You should do this while sammichFM has the control
surface attached. Measure between IC3 input pin (or pins of MS1) and ground pin of C7 (left side),
which is accessible from the right side when PCBs are connected.
6. Voltage Tests
Before inserting any of the ICs for the first time, you should perform some basic voltage tests.Step 1:
Voltage Tests on the Base PCB
Once you've tested 5V between one pair of pads (such as J4 at bottom), you can leave the black probe on
GND at J4 while you test 5V at other points marked with pink dots. Inversely, you can leave the red
probe on +5V at J4 while you test for 5V at other points marked with green dots.
Alternately, you can test voltages once at J4, etc. and then with power unplugged, use your multimeter's
“continuity tester” (i.e. multimeter beeps when probes touch). Test continuity between one point and all
other points that should be connected (i.e. all green dots).
NOTE: “Audio 5V” and “OPL3 5V” are supplied via shunts in the Audio/OPL3 Power headers,
which in turn is supplied by IC3 and IC4. After putting the OPL3 shunt in, “Digital 5V” is
connected to “OPL3 5V”.
Step 1.1: Test for NO continuity (no shorts) between “Audio 5V” and Ground (with power off)
Step 1.2: Test for NO continuity (no shorts) between “OPL3 5V” and Ground (with power off)
Step 1.3: Test for 5V on IC3 pin marked
(with power on)
Step 1.4: Insert both shunts in Audio/OPL3 Power header.
Step 1.4: Test 5V on pins marked with
not exactly 5V but close (5V ± 0.05V).
. They may be slightly different to each other and both
Step 2: Voltage Tests on the Control Surface PCB
You can now attach the control surface PCB and perform voltage tests while it is connected.
Step 2.1: Check JR4A is set correctly for your LCD (See Jumper Configuration)
Step 2.2: Disconnect power.
Step 2.3: Assemble the case with the base PCB and control surface PCB attached (see Case Assembly
Step 2.4: Turn the contrast trimpot fully anticlockwise. Turn the brightness trimpot fully anticlockwise.
Step 2.5: Connect power and turn power on. You should see the backlight on the LCD and a row of black
Step 2.6: Perform voltage tests on the control surface PCB.
7. Installing ICs
ICs are manufactured with the leads spread out. Before inserting into IC sockets, you will need to bend
the leads so they fit. While holding the IC firmly, use your work surface to bend all leads simultaneously.
Do this a little bit at a time until it looks right, then check to see if it will line up with the middle of the
pins of the IC socket. It is important that all the pins are vertical and parallel, as insertion requires a good
deal of force and if any pins are not aligned correctly, they might bend or break.
Perform voltage tests before installing ICs the first time.
Always install ICs with the power disconnected.
Carefully check orientation of the IC. The notch on the IC must match the notch on the white outline
on the PCB (which should also match the notch on the IC socket, if you soldered that oriented
I recommend installing the “Bankstick” ICs (IC5, IC6, IC7, IC8, IC9) after fully completing both PCBs,
uploading MIDIbox FM firmware and having a fully working control surface. This allows you to watch
the formatting of the Banksticks by the MIDIbox FM firmware.
8. Initial Testing and Firmware Upload
Step 1: Installing MIOS Studio 2 and Testing MIDI
Install MIOS Studio 2 from here:
Connect MIDI cables between sammichFM and PC. Connections should be PC MIDI Out to sammichFM
MIDI In and PC MIDI In to sammichFM MIDI Out.
For the first test, leave sammichFM power off when starting MIOS Studio.
Run MIOS Studio 2. You should see a screen like this:
Set the MIDI IN and MIDI OUT combo boxes (at top) to match the MIDI interface/ports you are using to
connect to sammichFM.
Power on the sammichFM!
You should see a single upload request message in the MIDI In window:
This is because the PIC18F4685 has already been burned with MIOS 1.9g. If you get this message, then
you know the PIC is working and MIDI Out is working. MIOS installation can also be confirmed by the
LCD showing the MIOS startup message.
If you do not receive the upload request, then check the JMO header has the shunt installed, the MIDI
cables are correctly connected and match the MIDI In/Out interface/ports selections in MIOS Studio.
Refer to for more MIDI troubleshooting advice.
Now test if the PIC is receiving MIDI In. Click on the “Query” button.
MIOS Studio will send MIDI SysEx message to the sammichFM, and expect a SysEx message response.
If all is good, MIOS Studio will report that the “Application is up & running!”. This means the PIC is
receiving MIDI and responding by sending MIDI, which is received by the PC.
If you do not see this message, then check the JMI header has the shunt installed, the MIDI cables are
correctly connected and match the MIDI In/Out interface/ports selections in MIOS Studio.
Refer to for more MIDI troubleshooting advice.
Step 2: Uploading the MIDIbox FM application
You can find the latest MIDIbox FM Synth V1 firmware on the website:
For example, the latest version at time of writing this guide is:
Download the ZIP file and extract it.
The sammichFM firmware is in the setup_pic18f4685_sammich_fm.hex file. Only upload this file; the
other .hex files are for different hardware configurations.
Select the file with the “Browse” button and click the “Start” button.
(Yes, I know this screenshot shows setup_sammich_sid.hex but I'm too lazy to do another screenshot. Only use setup_pic18f4685_sammich_fm.hex!)
If there are “ignorable errors” reported (i.e. packets were retried), then try uploading again until you get
no “ignorable errors”.
After the firmware has finished uploading, the sammichFM will reboot and show the MIDIbox FM
bootscreen and main screen.
You can now test if the buttons and knobs are working by referring to the MIDIbox FM User Manual,
which can be found here:
If everything appears to be working, then you can install the “Bankstick” ICs (IC5, IC6, IC7, IC8, IC9)
and watch the LCD while the MIDIbox FM application formats the Banksticks.
If you want, you can try uploading the default patches into the Banksticks now.
The default patches are found in the MIDIbox FM Synth release package (they are in the “presets”
You can try TL's “MidiBox Patch Manager”:
or JSynthLib:
If you have trouble with uploading patches using these patch editors, you can alternately try uploading the
patches using the SysEx dumps, with a delay between each SysEx message (i.e. use MIDI-OX or
equivalent MIDI utility).
9. Testing the OPL3 chipset
You can tell pretty quickly if the sammichFM is working correctly by using the MIDIbox FM application.
I advise uploading the default patch set and scrolling through them, having a listen to each one.
However, if the sammichFM isn't producing any sound, or the sound is not what you expect, then you can
troubleshoot what is wrong by using some test applications. The use of these test applications is explained
in detail elsewhere in the MIDIbox forum, the wiki and the readme.txt files inside the test applications.
If you require help with troubleshooting, just post on the MIDIbox forum and someone will help.
The following links will help you find the other relevant information and assistance:
10. Using MIDIbox FM Synth
Read the user manual!
There are some differences between sammichFM and the “default” MIDIbox FM synth control surface
which should be covered here, but I'm sure you can work it out.
11. Case Assembly
Put the 32mm and 9mm screws into the base panel from the bottom. The 32mm screws go in the corners.
Add the nuts and tighten firmly using screwdriver and long-nose pliers.
Place the base PCB onto the screw shafts. Thread the 20mm spacers onto the screw shafts. You should
not need to tighten these with pliers; tightening just with fingers is sufficient.
Attach the control surface PCB, taking care to mate the headers without bending them.
Thread the 10mm spacers onto the screw shafts in the corners. You should not need to tighten these with
pliers; tightening just with fingers is sufficient.
Add the 3mm screws to the midpoints of the PCB edges. (Leave these out if you think you'll often be
opening up the sammichFM to show off, then you won't need a screwdriver to do this).
Add the rear panel and loosely hold in place with the plastic nuts for the audio sockets.
Add the other side panels. They should stay in position, but you can temporarily use sticky tape if you
Add the top panel, being careful not to bend the LEDs.
Add the black screws to the corners of the panel. These screws will cause the top panel to clamp the side
panels and hold them firmly in position. You may not need to tighten these with a hex key (Allen key) as
tightening just with fingers is sufficient. Be careful if you use a hex key! Tight enough is good enough!
You will notice that loosening the black screws will allow you to remove the side panels without
removing the top panel, which can be useful for adjusting the LCD brightness and contrast and checking
heatsink/voltage regulator temperatures with a finger.
An extra four 3mm screws are provided should you prefer to use these instead of the black screws on the
top panel.
12. Painting the Panel Engraving
The panels are made from laser-cut acrylic and come with backing paper still attached and the engravings
cut through the backing paper. This paper makes an ideal mask for painting the engraving.
IMPORTANT NOTE: You can build the entire sammichFM with the backing paper still on the panels,
and then paint the panel engraving after you have finished. This allows you to play with your new
MIDIbox FM synth while you paint the panels (a slow process).
My current technique is to apply two coats of enamel paint (i.e. hobby/model enamel paint) by filling the
engraving (the “groove”) completely with paint and then wiping excess away with a “squeegee” made
from a piece of blister pack plastic, i.e. what they use to package things like toothbrushes.
I use Tamiya Color Enamel Paint X-2 White. It is thin but has dense (?) pigment, so you only need two
coats. I suspect many other hobby/model enamel paints will give similar results. Gloss is good! Avoid
So essentially:
Fill a small section (one label!) of engraving with enamel paint
Wipe away wet paint on the paper using the squeegee, leaving paint filling the hole.
Repeat with other labels.
Allow to dry (approx. 1 hour)
Repeat the paint filling as before, again in small sections, wiping away wet paint.
Allow to dry (approx. 8-24 hours)
Do not peel off the backing paper until the paint is absolutely dry and hard, after 8 hours at least,
preferably 24 hours! If you do it while the paint is still soft, the paper will pull it out of the engraving. I
know this from trial and error. After two coats, put it aside and forget about it for a day!
Clean up any imperfections using a craft knife. The matte black acrylic surface is quite tough and won't
be scratched by scraping with the edge of a knife.
13. Parts List
Parts are presented in the preferred order of soldering.
Base PCB part name
Mount Notes
Take off shirt while soldering this part!
IC51, IC52
Shirt optional.
IC53, IC54
Shirt optional.
R50, R51
33 Ohm Resistor
100 Ohm Resistor
R7, R8, R11, R68, R69,
R70, R71
220 Ohm Resistor
R2, R4, R12, R13, R52,
R53, R54, R55
1K Resistor
Very similar bands to 100 Ohm
1K2 Resistor
Very similar bands to 10K resistor!
5K6 Resistor
R3, R9, R10, R56, R57,
R58, R59, R60, R61, R62,
R63, R64, R65, R66, R67
10K Resistor
82K Resistor
D1, D2
1N4148 Small Signal Diode
Very similar bands to 1K resistor!
Very similar bands to 1K2 resistor!
Align with stripe matching PCB.
IC2, IC5, IC6, IC7, IC8, IC9 IC Socket 8 pin
Align with notch matching PCB.
IC Socket 40 pin
Align with notch matching PCB.
ferrite bead
Some magic smoke is emitted while
soldering. Hold your breath!
10MHz crystal (low profile, model
C1, C2
33pF Ceramic Capacitor
C60, C61
68pF Ceramic Capacitor
C56, C57, C58, C59
2.7nF Capacitor
C7, C8, C9, C10, C50, C51, 100nF Monolithic Capacitor (radial)
C52, C53, C54, C55
These mount very close together.
Straighten the leads that will be
closest together.
Mount flat.
330n Monolithic Capacitor
C5, C6, C62, C63, C64,
C65, C66, C67
10µF Electrolytic Capacitor
Align negative “-” (black stripe) lead
with pad that IS NOT marked postitive.
BC337 Transistor
Bend leads to fit PCB, align with flat
side. See guide.
Bend leads to fit PCB, align with flat
side. See guide.
50K trimpot
Marked “503” on back.
10K trimpot
Marked “103” on back.
JMI[3], JMO[3], JR4A[2],
.100" Pin Strip Headers 40P STRT 1
Minimum required headers.
J4[4], J6/J7[5+5], J12, J13,
These are not used in a default
sammichFM construction.
Do not solder them!
Audio Out 1/2,
Audio Out 3/4
Neutrik Phone Jack 3C STEREO 3SPST NC (NMJ6HFD2)
Power Socket
DC Power Jacks PCB 2.1MM
Power Switch
C64-style DPDT rocker switch
Bridge Rectifier 1.5 Amp 800 Volt
Align with flat side
14.318MHz Crystal Oscillator
Align dot/unrounded corner with dot on
PCB (lower-right corner pin).
Use rear panel mounted with audio
socket nuts to check alignment. See
2200µF Electrolytic Capacitor
Align negative “-” (black stripe) lead
with pad that IS NOT marked postitive.
Voltage Regulators and Heatsink Stage
Heatsink TO-220 (big one)
Use heatsinking compound!
See guide.
Heatsink TO-220 (small one)
Use heatsinking compound!
See guide.
5V Voltage Regulator 7805
Bend leads 90º and mount flat.
Use heatsinking compound!
See guide
Non-Soldered Components
Audio/OPL3 Power
Shunts (jumpers)
See guide for correct jumper
Do not solder! Do not insert until after
voltage checks!
Do not solder! Do not insert until after
voltage checks!
IC5, IC6, IC7, IC8, IC9
Do not solder! Do not insert until after
voltage checks!
Control Surface PCB
part name
Mount Notes
220 Ohm Resistor
R11, R12
1K Resistor
Very similar bands to 100 Ohm
C1, C2, C3
100nF Monolithic Capacitor
Mount flat.
IC1, IC2, IC3
IC Socket 16 pin
Align with notch matching PCB.
RN1, RN2, RN3, RN4
6 Pin Common Bus Resistor
Networks 6PIN 10KOhms 2%
Align with dot matching PCB!!!!!!!
100µF Electrolytic Capacitor
Align negative “-” (black stripe) lead
with pad that IS NOT marked
T1, T2
BC547 Transistor
Bend leads to fit PCB, align with flat
E-Switch TL1100F160Q Tactile
Switches 12X7.3MM 160GF
Some leads might touch heatsink,
marked on bottom side. See guide.
16mm detented rotary encoder
Solder mounting tabs also.
IC1, IC2
Do not solder! Do not insert until
after voltage checks!
Do not solder! Do not insert until
after voltage checks!
LED Standard 3mm round
Mount last! Use top panel to align
LEDs during soldering. See guide.
PCB Interconnection Stage
J16 (on base)
Dual inline header, female (2x9
Solder while control surface PCB
attached to base PCB. See guide.
J8/J9 (on base)
Dual inline header, female (2x5
Solder while control surface PCB
attached to base PCB. See guide.
LCD (on control surface)
Dual inline header with long tail
(2x8 pins)
Solder while LCD attached to control
surface PCB and control surface
PCB attached to base PCB. See
J1 (on control surface)
Dual inline header with long tail
(2x5 pins)
Solder while control surface PCB
attached to base PCB. See guide.
14. Using sammichFM Base PCB Separately
The sammichFM Base PCB can be used separately in an alternative enclosure, with your own control
surface board, a different LCD (i.e. 2x40 character LCD), more buttons and rotary encoders. The base
PCB is essentially a Core8 module (with Banksticks) and an OPL3 module on the same PCB, with its
own power supply circuit (a 7805 for the digital circuits and a 78L05 for the audio and OPL3 circuits).
You can refer to the MIDIbox FM user manual to learn how to connect DIN and DOUT modules (for
your own switches, rotary encoders and LEDs). Here are some specific things you need to deal with:
14.1: Sockets
Alternate (e.g. panel mount) MIDI sockets can connect to J12 and J13, via a 3-pin male header.
Alternate (e.g. panel mount) audio sockets can connect to the pads of the PCB mount audio sockets. There
is no alternate 3-pin headers (sorry, an oversight). Wiring is pretty obvious.
Input power can be supplied to the 2-pin header to the right of the DC power socket.
Alternate (e.g. panel mount) power switch can be used, and connect directly to the power switch pads.
You could alternatively put the switch in series between the power socket and the 2-pin header for input
power, and then bridge the middle and top pins of each 3-pin group of the power switch.
For reference, the power switch for this PCB is DPDT, the middle pin of the 3-pin group is the pole, and
in the “on” position, each pole connects with the top pins (the throw). The bottom pins are not used.
14.2: LCD Header (J16)
The sammichFM base is designed so an LCD with standard pinout can “plug in” to a female header in
J16. This means that even if a male header is put in J16, you cannot connect it directly with ribbon
cable/IDC connectors to a male header in the bottom of the LCD, because the rows of pins will be
Here are some ways to resolve this:
1. Swap each pair of wires in a 16-wire ribbon cable, and mount male header to bottom side of LCD,
male header in J16. You can do this by splitting a ribbon cable into two wire pairs at one end (say
50mm), twisting each pair, reforming into a flat ribbon using some sticky tape, and then clamping
that end into an IDC connector as per usual. (You could also use female header in J16 and a male
header to act as “gender bender” allowing IDC connector to plug into female header).
2. Use a right-angle male header mounted to the top side of the LCD, so the connector mounts from
the side. Use male header in J16 and straight ribbon cable/IDC connectors.
3. Use a connector with crimp pins on one end of the cable, and swap each pair of wires as they go
into the connector. The other end has an IDC connector. Mount male headers in J16 and the
bottom side of LCD.
4. Use female header in J16, solder ribbon cable wires to short end of male header (swapping each
pair of wires), and use IDC connector at other end. Mount male header to bottom side of LCD.
14.2: DIN/DOUT Header (J8/J9)
Header J8/J9 on the sammichFM PCB is identical to the J8 and J9 headers on the Core8 module, so you
can connect it directly to DIN and DOUT modules with ribbon cable/IDC connectors.
14.3: MIDIbox FM Firmware
You will need to recompile the MIDIbox FM firmware with the correct settings of your hardware. The
sammichFM base expects use of a PIC18F4685, and only 4-bit data to the LCD (default MIOS behaviour
for PIC18F4685 anyway). Similarly, alternate PIC pins are used for the 8-bit data bus to the YMF262, this
may already be default behaviour for PIC18F4685 builds of MIDIbox FM. I'm just making note of it here
in case you don't get any sound out of the OPL3 module - this difference might be the cause.
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