Updates: July 2016
Roland M-16C

Roland M-64C Memory Cartridge

Features and Specifications:

Memory Backup for Roland Products: Alpha Juno 2, GR-700, GR-77B, MKS-10, MKS-20, MKS-30, MKS-70, MKS-80, TR-707, TR-727, TR-909, JX-3P, JX-8P, JX-10
Switches: Memory Protect On/Off
Dimensions: 66 mm (W) 54 mm (H) 14 mm (D)
Accessories: Labels
Weight: 41 g

Introduction to the Roland M-64C:

The M-64C is the "big brother" to the more common Roland M-16C memory Cartridge. This cartridge can be used with the Alpha Juno 2, GR-700, GR-77B, MKS-10, MKS-20, MKS-30, MKS-70, MKS-80, TR-707, TR-727, TR-909, JX-3P, JX-8P, JX-10.

The M-64C was part of a trio of memory cartridges. Along with the M-64C there is the very rare M-32C, and the M-16C. Inside the M-64C are four Toshiba TC5517AFL 8 x 2K static RAM chips with a lithium battery to power the chip and protect the memory contents.

The original projected life span of the battery was five years, but many of these batteries are still at work twenty-five years later. However, I have seen a few M-64Cs, with dead batteries. Replacing the battery is a bit of work, you will need some desoldering tools, and patience getting the pins lined up when installing the new battery.

M-64C - Compatible with Synths and Drum Machines Designed for the M-16C:

My experience has been that while the M-64C has four times the memory capacity of the M-16C, it is "backwards" compatible. You can use a M-64C in a synth that accepts the M-16C. However, you do not get any additional memory. The synth still "sees" the M-64C as a M-16C. The additional memory capacity of the M-64C remains unused.

Another interesting example is the Roland JX-10. It has a modest on-board sequencer. Using the M-16C, 400 notes of sequencer data can be stored. Using the M-64C, 1600 notes can be stored, or four times the amount of note data.

The M-64C can also be used with a modified Roland GR-700 to increase the external memory by means of a switching circuit.

Links to more information:

Download the M-64C Owner's Manual (pdf).

Download the M-64C Schematic (pdf).

Website with detailed instructions on converting the M-16C to a M-64C.

Photos:

Roland M-64C Roland M-64C Roland M-64C
Roland M-64C Roland M-64C Roland M-64C
Click on any image for larger view.

Photos - Battery Replacement:

M64C Battery Replacement M64C Battery Replacement M64C Battery Replacement
M64C Battery Replacement M64C Battery Replacement M64C Battery Replacement
Click on any image for larger view.

Converting a Roland M-16C Cartridge into a Roland M-64C Cartridge:

The Roland M-61C cartridge can also be converted into a Roland M-64C cartridge by changing the internal 2K memory chip into an 8K chip. This requires some good soldering skills and an 8K chip.

I purchased 8K memory chips for $5 each in November of 2009, from Surplus Electronics. These chips were 8K (8192-word) x 8 CMOS SRAM chips, 5 volt operation. Check out the link below for more details on the specs of the memory chip required.

I have done this modification on several M-16C cartridges with great success. The photos below show a modification I did to a M-16C. You will notice that when I did this conversion, I also replaced the backup battery. The size of the 8K chip is slightly larger than the 2K chip, so I used a Dremel tool to slightly enlarge the area inside the M16-C case. Full details of M-16C to M-64C conversion.

Click on any image for larger view.

Converting a Roland M-16C Cartridge into a Roland M-64C Cartridge.

Videos:


Schematics - Repairs - Service Bulletins:

The M-64C service notes recommend changing resistor R1 from value of 10k to 3.3k for electrostatic discharge protection.

Replacement battery for M-16C.

Download the M-64C Schematic.