OPL2 Audio Board Assembly Instructions


Before we begin to assemble the OPL2 Audio Board let's make sure that all the parts you need are accounted for.

OPL2 Audio Board PCB
R1Resistor1 MOhm (    Brown, Black, Green)
R2Resistor200 Ohm (    Red, Black, Brown)
R4Resistor100 Ohm (    Brown, Black, Brown)
R5Resistor10 kOhm (    Brown, Black, Orange)
RV1Potentiometer1 kOhm
C1, C2, C13Ceramic Capacitor10 pF (100)
C3, C4, C5, C6, C7, C10Ceramic Capacitor0.1 uF (104)
C8, C12Electrolytic Capacitor10 uF
C9, C11, C14Electrolytic Capacitor220 uF
Y1Clock Crystal3.579 MHz
24 Pin Socket
IC2Digital to Analog Converter
8 Pin Socket
IC3Operational Amplifier
8 Pin Socket
Pin Socket
14 Pin Socket
IC6Shift Register
16 Pin Socket
J1Angled or Straight 7 Pin Header
J2, J33.5 mm Audio Jack


To assemble the OPL2 Audio Board yourself you need some basic tools:

The following additional tools may come in handy as well if you have them, but are not required:

Assembling the Board

Let's assemble the OPL2 Audio Board. We'll assemble the components from shortest to tallest.

1. Volume Potentiometer

We'll start with the 1 kOhm volume potentiometer RV1 since it's the shortest component. Insert it into its footprint (you may have to bend some of its pins slightly to make it go in easily). Flip the board over and solder the five pins.

2. Resistors

Next are the resistors. Start by bending their leads as shown so you can insert the resistors into their footprints. The orientation of the resistors does not matter, but your work will look neater if the gold bands are facing the same direction, to the right or down. Bend the leads outward slightly so the resistors will not fall out when you flip the board over.

Now solder the leads and clip the leads as close to the solder joint as possible.

Be careful when clipping component leads, because they can fly everywhere and you don't want to get hit in the eye by one! The safest way to clip off leads is to hold the lead that you're clipping or to put your finger on it so it can't go flying.

3. Angled Pin Header

This step is optional. If you rather use the straight pin header to connect the OPL2 Audio Board then you can skip this step and we'll solder the pin header last in step 9

Insert the header into its footprint at J1 and solder one of the header's outer pins.

Then check your work to make sure that the header is sitting flat on the board as shown in the image.

If the pin header is not sitting flat then you can correct its placement as follows. Put one finger on the pin opposite to the one you soldered and heat up the pin that you already soldered. When the solder starts to flow gently push down on the pin to move the header in place. Putting a little pressure on the plastic part will help. Once the solder has cooled a bit, check your work again.

When the header is positioned correctly solder the remaining pins

4. Clock Crystal

The next part we're going to solder is the 3.579 MHz clock crystal at Y1. Stick its leads through the holes and bend the leads out sighly. The clock crystal has no strict orientation, you can orient it however you like. Solder pins and trim the leads.

Be careful when trimming the short leads of the clock crystal! To prevent leads from flying everywhere, put one finger on the lead that you're trimming.

5. IC Sockets

We continue with the IC sockets one by one. When you place them on the board, have a look at the notch on the top of the socket and the notch drawn on the board. The notch on the socket should match with the notch on the board so that later you know in what orientation to insert the ICs.

Start with soldering one pin and inspect your work. The socket should sit flush on the board on the corner that you soldered. If this is not the case then put a little pressure on the middle of the socket with your finger and reheat the pin. Be careful not to touch the area you're heating up. You should feel the socket move into place.

Now solder the pin diagonally opposite of the first and again inspect your work to make sure that the socket is now sitting flat on the board.

When the socket sits well on the board you can solder the remaining pins and repeat the process for all sockets.

6. Ceramic Capacitors

Now come the ceramic capacitors, starting with the six 0.1 uF (104) ones: C3 ... C7 and C10. Stick them through the holes and slightly bend the leads out to prevent the caps from falling out when you flip the board over. The ceramic capacitors can be oriented either way. Solder the pins and clip the leads.

Finish off the ceramic capacitors by soldering the three 10 pF (10) capacitors: C1, C2 and C13. When trimming the leads of these make sure to put a finger on the lead you're clipping to not have the fly everywhere.

7. Audio Jacks

Up next are the line out and headphone jacks J2 and J3. For these, again first solder one pin, inspect your work to make sure the sockets are sitting flat on the board and solder the remaining pins.

If a socket is not sitting flat then reheat the pin and carefully rock the back of the socket with your finger until it's sitting flat.

8. Electrolytic Capacitors

When soldering the electrolytic capacitors take care of putting them in in the correct orientation. On the body of the capacitor there is a bright band on one side that marks the negative lead. When you insert the capacitor into its footprint make sure that the band on the label matches with the marked side on the board.

We will start with the two 10 uF capacitors C8 and C12. We'll use the same trick to make sure that the capacitors are sitting flat on the board: first solder one leg and inspect if the capacitor is sitting flat before soldering the second leg. If you need to adjust the positioning of the capacitor then reheat the soldered pin and gently push on the top of the capacitor to move it in place.

We finish with the three remaining 220 uF electrolytic capacitors C9, C11 and C14. Make sure they are oriented correctly, solder, and trim the leads.

9. Straight Pin Header

If you decided to use the straight pin header then we will solder it now at J1, otherwise you can skip this step.

Solder one of the outside pins of the header and make sure that the header is sitting straight on the board. If this is not the case then heat the soldered pin up again and with your finger on the pin on the opposite side of the header move the component until it sits correctly. Now solder the remaining pins

10. Tidying Up

After clipping off component leads some of your solder joints may look a bit rough. For a neater look you can clean up the solder joints by heating them up with your soldering iron to make the solder reflow. Sometimes a tiny bit of extra solder is needed to make the solder reflow nicely.

You may also consider cleaning off solder flux residue from the bottom of your board with some isopropyl alcohol and an old toothbrush.

11. Putting in the Chips

For the final step we will insert the ICs into their sockets. Look at the markings on the board and match them with the markings on the chip

Make sure that the pins of the ICs are bent straight before putting them into the sockets. If the pins are not straight then you can bend them into shape by laying the chip on its side with its legs on a flat surface and very gently bending the body of the chip to straighten the legs. Don't overdo it! It's better to bend the legs little by little than to risk over bending them and risking a leg breaking off when you need to correct.

Push the ICs into the sockets and be sure to align the notch on one side of the chip with the notch on the socket and PCB. Some chips may have a dot in one corner instead of a notch cutout to indicate their orientation. When a chip has a dot then the chip should be put in the socket such that the dot is on the same side as the notch in the left corner.

Make sure that when you insert the chips that they are all the way in the sockets. Try putting some gentle force on the body of the chip, but don't apply too much force as you may risk bending or snapping off legs. If the chip does not go in you may need to further straighten its legs. Carefully remove the chip from its socket with an IC puller tool or with a flat-head screwdriver by slowly wiggling it out one end at a time.