Updates: July 2016
Roland BKA-1 GR Guitar Controller

Roland BAK-1 GR Bass Guitar Controller Assembly

Features and Specifications:

Divided Pickup #22382613
Pre-Amp Board #2292323001
Back Panel #22213490
1 Knob (Large) 6 Knobs (Small)
Touch Plate (with vinyl wire)
Pickup base
24P Connector 2324M-K with Lock Shell 24 L1
Jack SG-7713
Binding screw M3 x 10 (2), Oval-headed screw 3 x 20 mm (2), Self-tapping screw (flat-headed) (6) 2.6 x 10 mm, flat-headed
Washer M3 (4), lock nut M3 (4), Volume Washer (6), Volume Nut (6)
Spring 0.6 x 3.2 x 18 mm (2)
Shielded wire, Vinyl wire (black)
Jack washer

Roland BAK-1 Kit

Introduction to the Roland BAK-1 GR Bass Guitar Controller Assembly:

Roland sought to increase the user base of their guitar synthesizer players with the release of the STK-1, LPK-1 and BAK-1 retrofit kits. Up until this point, the only guitars or basses that worked with the vintage Roland 24-pin synths like the GR-300 or GR-33B were produced by the Fuji Roland partnership.

The BAK-1 is a kit consisting of the electronic components from the Roland G-77 bass guitar synthesizer controller, plus additional knobs, guitar back panel hardware, templates for guitar routing and miscellaneous wiring.

In all my years of searching for vintage Roland GR gear, I have seen only one BAK-1 kit offered for sale on ebay. They are rare.

Links to more information:

Download the G-77 Service Manual (pdf).

Photos:

Click on any image for larger view.

Videos:

Schematics Repairs - Service Bulletins:

There are no known service bulletins from Roland addressing any BAK-1 problems. The BAK-1 shares the same electronics as the Roland G-77 bass. Download the G-77 service manual (belowe) for BAK-1 schematics.

Download the G-77 Service Manual (pdf).