12PPQN Sync Input

There's no sync input on a stock DR-110,  making it virtually useless in a MIDI or DIN-Sync based setup.  Here's a neat mod that I came up with, allowing you to add a 12ppqn sync input.  The mod includes a current-limiting resistor and protection diodes to help avoid damage to the CPU from negative voltages or signals that are too strong.  The best part is I've found an easy way to rewire the "Accent Trig Out"  as the sync input... so you don't need to cut a new jack into the case.  For some reason Boss / Roland decided to install a switching jack at the Accent Output... even though the NC switch contact is unused.  This allows us to disable the accent out, and use this jack as our sync input.

A little overview:  The tempo clock on the DR-110 is on the voice board.  It gets sent to the CPU along conductor 4 of the ribbon cable.  We need to disconnect that wire, and add our new protection circuit in it's place.  You can add a new jack, if you wish, or follow the procedure below to rewire the Accent Output. 

Here's the modification.  All of the links to drawings below are printer-friendly PDF files.

• We'll start out with the schematic.  Nothing tricky here:  The sync input needs to be an 1/8" switching jack with a normally closed contact.  We feed the incoming clock signal through a 470 ohm resistor, and use a pair of 1N914 / 1N4148 diodes to keep the input between ground and V+.    The switching jack allows the 110's internal clock to control the machine when no external sync cable is connected.  Note: When synced internally (no cable attached) the DR-110's clock signal will  pass through the new diodes and resistor, but they have no ill-effects on my machine. 
• This is a view of both circuit boards and the ribbon cable connecting them... you' need to disconnect pin 4 from each end of the ribbon cable. 
• Next is a view of the solder side of the analog board showing the area where you'll perform the mod.  You need to cut a trace and remove a jumper to disconnect the "Accent Trigger Output" jack from the circuit.  These two items are shown in red.   Note that the jumper is on the component-side of the analog board.
• Here's a diagram to show the important solder points that you'll be using to attach the new parts and wires. The internal clock is present on the analog board at pin 4 of the ribbon cable.  V+ and ground are available at the DC input jack.  The stock "Accent Output" uses a switching jack, and the ground, tip and NC contact are identified.
• Finally, you need to put the new components on the circuit board.  Here's a drawing depicting the component layout and below is the procedure for installing them.

1. Run an insulated wire from the CPU board, pin 4 to the point shown on the analog board.   This pad was isolated by cutting the trace and removing the jumper, and  makes a convenient location to tie the new components together.  The new wire should come through the hole from the top side of the board.
2. Install an insulated jumper wire on the solder-side of the analog board.  This jumper connects between the pad for the ribbon cable pin 4 on the analog board (clock) and the "NC" contact of the 1/8" switching jack.
3. Install the protection diodes and current limiting resistor as shown.  Observe the polarity of your diodes, lining up the stripes as shown.

You may need to shave a little plastic off the inside of the bottom of the DR-110 case.   The new diodes seem to hit a tiny little bump on the case.  I shaved the bump off with a Dremel tool, and the case reassembles perfectly.

To use the sync input, you need to have a source for 24ppqn DIN-Sync.  Run the 24ppqn clock signal through a divide-by-two circuit, and then feed it into the DR-110.   When you want the DR-110 to sync, press "Start" on the 110 to prepare it for play.  Next press play on the master sequencer, and the 110 will play along.   After stopping your master sequencer, you'll need to press "Stop"   on the 110 to reset it to beat 1, then "Start"  to prepare it for the next play.

DIN-Sync Input

As I mentioned above, you need a clock divider to convert from 24ppqn (DIN-Sync) to 12ppqn sync. The clock divider circuit is available at AlphA's website, along with his method of getting sync into the DR-110.

I'd like to add that a 5V pulse to the Stop and Start buttons will operate the DR-110... so you can use the Run/Stop connection to control the DR-110 completely. Maek sure you add over/under voltage protection, so you don't cook your CPU.

MIDI Sync Input

Again, I'm not going to get real detailed here: You can add din-sync and use a MIDI to DIN converter. I chose to use the MIDI to DIN-sync IC available from Blacet labs. There are also a few commercial companies that sell MIDI sync kits (See my DR-110 links page) Start and stop are again controlled by a 5V pulse to the buttons.