Roland Juno-6 & Juno-60 Key Assigner CPU Chip 8049-380

Description

A common failure with the Juno 6 and Juno 60 are the Mask ROM CPU Chips.  Unfortunately because these Mask ROM CPUs have the firmware on the chip, you can’t just pop in a generic MCS-48 (8049) CPU chip and be up and running.  This replacement chip is a drop in CPU replacement with the firmware on board for the main key assigner CPU found on the CPU board of the synthesizer.  All Juno 6 and Juno 60 owners would be wise to keep one of these on hand as part of a “Survival Kit”.  Installation of this CPU requires desoldering/soldering the old chip which is not socketed.

Please note: This chip has the later revision firmware (“380”) and can replace the 8049-238 chip found in Juno 6 and early Juno 60 synthesizers.  The firmware is essentially the same, but the 238 version has a bug where the lowest C sometimes fails to sound.  If replacing a “238” chip with a “380” chip, you will need to modify the reset circuit by replacing a 1uF capacitor with a 10uF capacitor and adding a diode (neither are provided with the chip, details are in the Juno-60 service manual).