ebay for sale
July: 2014
Boss (Roland) GP-10: New page on the amazing GP-10. Video demo of the 100 factory patches posted on YouTube.

GK-20: 13-pin Guitar Synthesizer Input Switcher: $199. $198.88 (buy on ebay here). Last one!

IMG2010 Magazine Advertising: Steve Howe (YES) added!.

IMG2010 Update: New photos, expanded videos and more!

Roland GR-700 Programmable Analog Guitar Synthesizer

Features and Specifications:

6 voice, Dual Oscillator Synth Engine Based on the Roland JX-3P/MKS-30
3 - Selectable Octave Settings for Each Oscillator, 2’, 4’ and 8’
Choice of Square, Sawtooth or Pulse Waveform, plus Noise for Oscillator 2
Cross Modulation Between Oscillators
Frequency Modulation with Envelope and/or Modulation
VCF Low-Pass Filter with LFO, Envelope and Pitch Modulation
Variable High-Pass Filter
Four Stage Envelope Generator
Low Frequency Oscillator for Vibrato Effects
Selectable Dynamic Control Over Pitch, Filter and Amplifier per string
Selectable Pitch Bend, Hold and Voice On/Off per String
Lush Analog Chorus Mode
Programming Via Foot switches or with optional PG-200 Programmer
Dimensions: 27 3/16" (W) 14 3/4" (D) 6 1/8" (H)
Power Requirements: 45 watts
Response Time: 29.88 ms

John Abercrombie (see YouTube for video)

Introduction to the Roland GR-700:

The GR-700 is classic Roland 1980s analog synthesizer technology. Released in late 1984, the GR-700 is the pinnacle of early Roland guitar synthesizer design. The distinctive and futuristic GR-700 features both a digital CPU for guitar tracking and a warm, fat hybrid digital/analog synthesizer engine for lush sounds.

A look at articles written about the GR-700 in Guitar Player, Guitarist, and other magazines, plus the synthesizer's appearance on television shows like The Tonight Show (US) and the Rock School series (UK), demonstrate the enthusiasm in the belief that the long anticipated age of the guitar synthesizer had finally arrived. The GR-700 launched just as the MIDI standard was being introduced, and musicians were entering a brave new world of electronic music where relatively inexpensive CPUs made possible instruments like the Prophet 5, Simmons drums, and the GR-700, instruments unimaginable a decade earlier.

Generally speaking, the GR-700 has not held up as well as its 24-pin brethren, like the GR-100 or GR-300. But for a guitar player in 1985, the GR-700 offered an astonishing range of sounds that could never have been triggered from a guitar: strings, basses, electronic effects, synths, and more. It was assumed that guitar players eventually would become fluent in GR-700 programming, and that the great silver box could become as ubiquitous as the wah-wah pedal.

Like the current generation of Roland guitar synths, the GR-700 controls the internal synth engine directly for faster response. But, make no mistake about it, when it comes to tracking the GR-700 is not a GR-300. Of all the products Roland has ever made, the GR-700 has the trickiest and most erratic tracking. The GR-700 is certainly better than equivalent products made by other manufactures at the time, but it is inferior to the GR-100, GR-300, GM-70, Korg Z3, or the Ibanez MC-1. The GR-700 has a MIDI out port for controlling other MIDI modules, but the MIDI output is erratic and unreliable. In addition, no pitch bend information is sent via MIDI.

Stand alone converters like the GM-70 became more popular toward the end of the eighties. They were faster and more accurate than the GR-700, plus via MIDI the range of sounds available to guitar players expanded considerably. The GR-700's combination of clunky pitch tracking, married to a limited synth engine, boxed up inside a huge, heavy foot pedal crammed with complex electronics made it more of a curiosity than a must-have piece of gear for the gigging musician. Still, for those who love the GR-700, nothing else sounds or responds quite like this unique guitar synthesizer.

The GR-700 was played and recorded by such prominent guitarists as Al Dimeola, Robert Fripp, Chuck Loeb (video), Jimmy Page and Andy Summers. The GR-700 was the top-of-the-line guitar synthesizer system in the mid-eighties. Retail price on a GR-700 was almost two-thousand dollars. More recently, Amir Derakh has used the Roland GR-700 extensively on several records.

The GR-700 Synth Engine:
Roland GR-700

The GR-700 has six, independent, analog synth voices, two oscillators on each voice. Roland digitally clocked these oscillators and called them "DCOs", as a response to the fact that the earlier Roland oscillator’s pitch had a tendency to drift in performance. The DCOs on the GR-700 generate classic analog waveforms: sawtooth wave, square wave, and pulse width modulated wave, as well a noise for special effects.

Roland PG-200 Programmer Map
Click on image for larger view.

The oscillators on the GR-700 can also be synced with cross modulation for hard, biting analog sounds or with ring modulation for metallic sounds. The GR-700 has a sweet Low Pass Filter with Resonance on each voice, with an additional High Pass Filter. And of course there are complete LFO and Envelope controls. To top it all off, the GR-700 adds a classic Roland analog Chorus circuit! If you like that expansive Roland Chorus found on early 80s products, you will love the Chorus on the GR-700.

The synth engine in the GR-700 is the same synth engine found in the Roland MKS-30 and Jupiter JX-3P. And, like these synths, the Roland GR-700 can use the PG-200 as a programming tool.

Roland GR-700 Block Diagram (click to view on a new page).

Links to more information:

John Themis in-depth GR-700 system review from Guitarist magazine, May 1985.

GR-700 and GR-77B System Review and Details Guitar Player, June 1986.

Steve Carnelli article on three favorite GR-700 patches, with performance and programming tips.

Mark Wood article guitar synthesizers, featuring the Roland GR-700.

Vintage Guitar Player Magazine Interview with John Abercrombie highlighting the Roland GR-700.

Vintage Guitar Player Magazine Interview with Steve Morse highlighting the Roland GR-700.

Jimmy Page Roland GR-700 page at the Achilles Last Stand Zed Zeppelin website.

Download the GR-700 Owner's Manual (pdf).

Download 64 GR-700 Alternate Sounds (Alternate Patches #2) (pdf).

Download 64 GR-700 Alternate Sounds (Alternate Patches #3) (pdf).

Version History Hardware and Software:

Click on image to enlarge

Generally speaking, the Roland GR-700 shipped in two different versions. There is an early, and later, version of the hardware, an early and later version of the factory patches, and early and later versions of the owner's manual.

I have not had the chance to see if the changes in manual, patches, and software are related to each other. The cosmetic changes to the GR-700 manual seems to be related to achieving uniformity with other Roland products from the same period.

Hardware Versions:

The early hardware versions are immediately recognizable for the open, metal frame trim pots. The later versions replaced these with more durable trimmers using a sealed plastic enclosure. This is shown in the first two photos at right.

Also, test points were added to reflect the calibration procedures outlined in the service manual. The bottom picture shows the "poly output" test point. In the early version, there is an analog ground test point, but no test point to easily attach your scope probe to analyze the poly out waveforms. In the later version a poly test point was added by moving the ground test point just a bit to the right.

Software Versions:

I have been able to document five different versions of software for the GR-700. At some point the in the production run, Roland also changed the factory patches for the GR-700 as well (see below). The most common version in my experience is version 4. The GR-700 service notes explain the differences for versions 1, 2, 3 and 4. I have seen a few GR-700s with version 5 software.

Original manual
Later manual

As noted, the GR-700 does not come with a MIDI input. While there was never a formal "factory retrofit" from Roland to add a MIDI input to the GR-700, a MIDI input upgrade was available from former Roland technician Mark Tsuruta. I understand Mark had come from Roland Japan to work at the Roland headquarters in Los Angeles. The software necessary for the MIDI input is the rare version 5 software.

What version software does your synth have? This is easy to check! Power up the GR-700 while holding down the STRING SELECT NO. 4 button. The display will show the software version, 1-4 means version 4. 1-2 indicates version 2 software. Incidentally, the patch corresponding to the software version will selecting when doing this procedure.

  • Version 1:Initial software release, with the original GR-700 patches.
  • Version 2: Version 2 allows the changing of the Chromatic circuit equal temperament pitch. In Version 1, if you are in chromatic mode, and play an "A" you will hear a note pitched at 442Hz. While A=440Hz for most Americans, some European orchestras use A=442Hz, and A=445Hz in Germany, Austria and China. With version 2 software, you can press 4 - 8 while in edit mode and adjust the chromatic pitch of "A" from 438 to 446Hz using the EDIT (resonance) knob.
  • Version 3: The GR-700 can fail to maintain sustain level is the EDIT (resonance) knob is turned to maximum when the SUSTAIN LEVEL is being edited. The software address this problem.
  • Version 4: In earlier versions, the frequency range which is covered and defined as the note "B" is narrower when compared with that of other notes. As a result, a note in the lower "B" range would be recognized as "A#" Version 4 fixes this problem.
  • Version 5: MIDI input, plus improved speed and tracking. Version 1.5 is, on average, about 1.5 milliseconds faster than version 4. The MIDI input requires extensive hardware revisions to the GR-700, in addition to the new software.

How to check the GR-700 Software Version:

Power up the GR-700 while holding down the STRING SELECT NO. 4 button.

The display will show the software version, 1-4 means version 4.

Photos:

Click on any image for larger view.

Videos:

Original and Alternate GR-700 Patches:

Broadly speaking, there are two sets of internal sounds for the GR-700. The most common set is programmed into the EPROM chips for version 1.1 through version 1.4 software. This is the list of sounds included in the Roland GR-700 brochure. With version 1.5 software, Roland changed the internal sounds.

Patch list from Roland GR-700 brochure. Version 1.1 - 1.4 patches
Later patches from Version 1.5 software
Cartridge sounds listed with version 1.5.
Click on any image for larger view.

For me, the most distinctive GR-700 patches are the special effect sounds. Sometimes it is a little hard to distinguish a GR-700 brass patch from a poly synth patch, but the sound in the first list above, 1-8, "FX" is very cool. It features inverted filter resonance modulation, and I use it quite a bit.

Download 64 GR-700 Alternate Sounds (Alternate Patches #2) (pdf)

Download 64 GR-700 Alternate Sounds (Alternate Patches #3) (pdf)

Reinitializing Patches:

It is possible to reinitialize the first four banks of patches for the GR-700, banks 1 though 4. There is no way to recover patches in banks 5 through 8 if they have been lost.

It is possible to reinitialize the first four banks of patches for the GR-700, banks 1 though 4. There is no way to recover patches in banks 5 through 8 if they have been lost.

To reinitialize patches in banks 1 - 4, turn on the power switch while pressing down the WRITE (copy) button.

Be sure to set the rear panel memory protect switch to the off (middle position) to have the memory protect circuit turned off. Since the GR-700 only restores the contents of banks 1-4, banks 5-8 may contain random data after reinitialization.

Modifications - GR-700 MIDI Input

Roland GR-700 Turbo PLUS

I frequently receive emails from people asking about adding a MIDI INPUT modification to the GR-700. In fact, there is a MIDI INPUT modification for the GR-700!

The GR-700 MIDI Input modification is credited to Mark Tsuruta, who I understand had come from Roland Japan to work at the Roland headquarters in Los Angeles in the 1980s.

As recently as 2005, Mark Tsuruta is listed as the executive vice president with Roland System Solutions. In any case, adding a MIDI input would have required a talented engineer with access to the original, commented, uncompiled operating system code for the GR-700.

The MIDI input requires both a change in the operating system, plus additional hardware and processing to convert the MIDI signals into the proper format for the GR-700’s computer. A look inside the GR-700 shows quite a few modifications made to support the MIDI input.

Overview:

I have probably seen six of these rare birds for sale on ebay in the last ten years. Not surprisingly, most have been located in Los Angeles, where I got this GR-700. This is the only MIDI IN GR-700 that I have personally worked with, and the unit did not come with any additional documentation, so what I do know about the features of the rare GR-700 comes my personal experimentation, or trial and error.

First, a basic tip-sleeve, latching (not momentary) on/off foot switch is needed to toggle between regular guitar mode, and MIDI operation. Without the foot switch, the GR-700 always operates in standard guitar synthesizer mode. Plug in the foot switch and you can toggle between MIDI and guitar mode. The GR-700 does not respond to MIDI controller 7, volume. In fact, even in MIDI IN mode, the GR-700 volume is still controller by the volume knob on the guitar, and all editing parameters are controlled by the guitar. If you do not have guitar connected, you will not get any output.

New MIDI Parameters

Here are the new MIDI parameters added to the MIDI input: MIDI Channel, Program Change (on or off), Sustain (MIDI #64 on or off), Pitch Bend response (on or off), and Modulation (MIDI #1 on or off).

To change these parameters, press and hold down the Chorus switch. Pressing either switches 3, 4, 5 or 6 will show the status of the four MIDI controller settings. Just like the standard GR-700 editing mode, if a block is in the lower position, the function is off, and if it is in the upper setting, it is on.

MIDI Channel:

Pressing foot switch 7 decrements the MIDI input channel, and foot switch 8 increments the MIDI channel.

Program Change:

Program change status, on or off is controller by foot switch 3. Pressing foot switch 3 will enable or disable program change commands to the GR-700. The GR-700 responds to program changes 1 through 64, corresponding to the 64 patches in the GR-700. With a memory cartridge installed, program changes 65-128 calls up patches on the memory cartridge. So program change 65 equals patch 1-1 on the memory cartridge, and program change 128 call up patch 8-8 on the memory cartridge. Without a memory cartridge, sending program changes 65-128 cycles through the original 64 patches, so sending program change 65 calls up internal patch 1-1, and sending program change 128 calls up internal patch 8-8.

Sustain:

Sustain on or off is controlled by foot switch 4.

Pitch Bend:

Pitch bend on or off is controlled by foot switch 5. Pitch bend range can the changed at anytime, it is not necessary to hold down the chorus switch. Press the pitch bend switch, and the pitch bend range is displayed. Now pressing the VOICE switch increments the range, up to seven semitones, and pressing the HOLD switch decrements the range. Pressing pitch bend again exits pitch bend range.

Modulation (LFO):

And modulation, or LFO on or off is controlled by foot switch 6.

With all four blocks in the up position, the GR-700 responds to program change, sustain, pitch bend and modulation. You will notice that when you enter MIDI Input mode, the dynamics LEDS turn off. In MIDI mode, the dynamics are always on. For example, factory patch 2-7, Bell, does not respond to dynamics in guitar mode, so how hard to pick the string does not effect the loudness, or brightness, or the sound. And the patch has chromatic mode enabled, so it does not respond to pitch bends. In MIDI input mode, the sound responds to both velocity. changing the loudness and brightness, and pitch bend as well.hat a Roland M-64C can be used to hold four banks of GR-700 sounds. Additional delay and ambience has been added during mix down.

Extended Operational Range:

The GR-700 MIDI input extends the range of the GR-700. Normally, the lowest note on the GR-700 is low E on the guitar, and GR-700 extends this to the A below low E on the guitar, adding another fifth to the lower range of the synth. If you play below the A, the octave repeats. On the high side, the GR-700 will respond to the highest possible MIDI note, more than two octaves above what is possible on the guitar. The highest note on a 88-key synth is C7. The GR-700 will respond to G8, or a fifth above the last note on a keyboard.

Can the MIDI INPUT modification be done today?

For all practical purposes, the answer is "no." While the version 1.5 software, which implements MIDI INPUT can be found, the additional technical details on the extensive wiring and additional electronic hardware are not documented. Even if you had all the details to do this, and knew how to make the additional hardware for the buffered MIDI output, etc. there is a good chance the GR-700 would not survive.

GR-700s are pretty fragile now, and use lots of parts that are no longer available. When the unit sold for thousands of dollars, and MIDI units were rare, this modification made sense. However, there is a ready-made GR-700 with a MIDI-IN: the Roland MKS-30. The MKS-30 has the exact same voice board as the GR-700, and the exact same parameters. Even better, it has built in MIDI implementation and is a better MIDI sound module than than a GR-700 with MIDI IN will ever be.

GR-700 with MIDI Input Videos:
GR-700 MIDI Input - Version 1.5 Software

The GR-700 Turbo PLUS adds the sound of the GR-100 hexaphonic polydistortion to the Roland GR-700, with all the original features of the GR-700 Turbo.

This includes a modern 13-pin input, top panel controls for string level and filter cutoff and EDIT parameters. The PLUS also adds a latching sustain input.

The GR-700 Turbo PLUS has the ability to blend analog distortion with synthesizer tones for new synth sounds never heard before.

GR-700 MIDI Input - Bach 2- Part Invention

What can you do with a GR-700 that has this modification?

I use Digital Performer to play a sequence of Bach's 2-part invention in E minor, incorporating program changes to call up various patches.

The internal sounds are the original GR-700 factory patches, and the cartridge sounds are the second generation factory patches.

GR-700 with MIDI Input Interior Photos:
Click on any image for larger view.

Modifications - GR-700 With 13-Pin Output

Roland GR-700 Turbo PLUS

The standout feature of this GR-700 is the custom printed circuit board installed to buffer the internal guitar synth signals, and provide a modern, 13-pin Roland synthesizer output.

When the Ibanez IMG2010 is connected to this GR-700, you will be able to access both the classic analog sounds from the GR-700, plus the latest in cutting edge Roland guitar synth tones, using the Roland GR-55 or VG-99. It is like using a GR-700 with a Roland US-2 and BC-13.

The active circuitry is part of a DB25 input card, which frees the GR-700 user from searching for hard-to-find, expensive 24-pin cables. This GR-700 can use data-grade, shielded 25-pin cables which offer improved performance over the original Roland cable, at a fraction of the price.

Full Support for all Modern 13-pin Synth Controls:

The modern GK 13-pin controls have been integrated into the GR-700. The master volume control on the guitar controls the volume of the 13-pin synthesizer as well. There are two 1/4" jacks added for the controlling the 13-pin synth, both are TRS (tip-ring-sleeve) jacks. This first is for muting either the GK Volume (synthesizer volume) or the Guitar signal (hex fuzz), and this circuit works best with latching switches. The other TRS jack is for a momentary foot switches to send GK S1/S2 commands. Both the switches are basic on/off switches, connecting to ground. I like to use the Roland FS-6, a versatile pedal with latching or unlatching capability, and LED status indicators.

GR-700 with 13-pin Output Video:
GR-700 with Modern 13-pin Output - 4x Memory Expansion - Version 1.5 Software - New End Panels - Full Factory Calibration

The standout feature of this GR-700 is the custom printed circuit board installed to buffer the internal guitar synth signals, and provide a modern, 13-pin Roland synthesizer output.

A vintage Roland guitar connected to this GR-700 will be able to access both the classic analog sounds from the GR-700, plus the latest in cutting edge Roland guitar synth tones, using the Roland GR-55 or VG-99. It is like using a GR-700 with a Roland US-2 and BC-13.

GR-700 with 13-pin Output Photos:
Click on any image for larger view.

Modifications - GR-700 Turbo PLUS (GR-100):

Roland GR-700 Turbo PLUS

The GR-700 Turbo PLUS is an expansion of the original GR-700 Turbo. The primary feature of the original GR-700 Turbo is the modern 13-pin input, installed in place of the older 24-pin input, allowing a GK-2 or GK-3 equipped guitars to play the vintage Roland GR-700.

The Turbo PLUS goes one step further, integrating a vintage Roland GR-100 polyphonic distortion hex fuzz circuit with the processing power of the GR-700. It is like building a GR-100 inside a GR-700.

Each string has an input switch to select from the output of DCO-1, or from a hex fuzz signal. Parameter 18, Source Mix, controls the balance between the hex fuzz signal and DCO-2.

With the Source mix set at “00”, the GR-700 sounds much more like the earlier Roland GR-100, with vintage Roland analog low-pass filters and rich analog chorus output. Sources can be mixed, with some strings outputting a blend of the two digitally controlled, analog oscillators, and some strings a mix of the polyphonic distortion hex fuzz, and the oscillator tone.

DCO-2 can be tuned independently of the hex fuzz signal, and oscillator synth and cross synchronization between DCO-1 and DCO-2 is still available, even when the string output is set to polydistortion, rather than DCO-1. The GR-700 improves on the feature set of the GR-100, with a four-stage envelope and LFO modulation, plus a high-pass filter.

Latching Sustain/Hold Pedal and LFO Depth Input

Another new feature of the GR-700 Turbo PLUS is a latching sustain switch. The Roland GR-700 sustain feature only works when the pedal is depressed. Once the foot is removed, the sustain stops. A custom built sustain foot switch can be plugged into the Turbo PLUS, for infinite sustain. Synth parameters can be edited while the sustain is engaged, and strings can be switched between DCO-1 and polydistortion, with control over the blend of synth and normal guitar sounds using the GK S-Volume and conventional volume control on the guitar.

Like the original GR-700 Turbo, the Turbo PLUS has a foot switch input for LFO depth, designed for a Roland EV-5, plus a 4x memory expansion input, so that a Roland M-64C can be used to hold four banks of GR-700 sounds. Additional delay and ambience has been added during mix down.

Roland GR-700 Turbo PLUS (GR-100) Video:
01 - GR-700 Turbo PLUS (GR-100)

The GR-700 Turbo PLUS adds the sound of the GR-100 hexaphonic polydistortion to the Roland GR-700, with all the original features of the GR-700 Turbo.

This includes a modern 13-pin input, top panel controls for string level and filter cutoff and EDIT parameters. The PLUS also adds a latching sustain input.

The GR-700 Turbo PLUS has the ability to blend analog distortion with synthesizer tones for new synth sounds never heard before.

Roland GR-700 Turbo PLUS (GR-100) Photos:
Click on any image for larger view.

Modifications - The Original GR-700 Turbo (2011):

GR-700 Turbo (2011)

In place of the proprietary and awkward 24-pin input, the GR-700 Turbo has been retrofitted with a modern, 13-pin Roland-Ready input jack. Now you can directly play a vintage Roland guitar synthesizer without having to search for a costly vintage Roland guitar, and the expensive and rare 24-pin connecting cable.

4x Memory Expansion

A stock Roland GR-700 has 64 memory locations for storing synth patches. If you insert a Roland M-16C memory cartridge into the GR-700, the memory expands to 128 patches. However, the GR-700 Turbo has the ability to store an astonishing 320 patches with a Roland M-64C cartridge! How is this possible? A special 4-position switching circuit has been added to the GR-700 Turbo, which basically divides a stock Roland M-64C (64K) memory cartridge into four individually addressable 16K memory banks!

These are labeled as banks A, B, C and D. This upgrade does not effect M-16C cartridges! Regardless of the memory switch position, a M-16C will store 64 patches. This auction does not include the M-16C or M-64C cartridge.

Final Release Version 5 Roland Factory Software

There are four documented versions of GR-700 software noted in the GR-700 service manual. Version four (1.4) is the most common software found in the GR-700. However, some of the last GR-700s made by Roland shipped with the rare, version 5 (1.5) software. The GR-700 Turbo has the rare version 5.0 software! Unlike the earlier upgrades, version 5.0 software does not add any new features, but instead improves on the most neglected aspect of the GR-700: faster and more accurate tracking. On average, version 5.0 is 1.5 milliseconds faster than version 4.0. The GR-700 Turbo does not reach the speed and accuracy of modern synthesizers, but it is an improvement over earlier versions, and includes the final revisions of the GR-700 factory patches.

Filter, Edit, Response Controls plus External EV-5 LFO Pedal Input

To take advantage of all cool features and programmability of the GR-700, new controls had to be added to replace the synthesizer controls found on a vintage Roland guitar synth controller like the G-303 or G-707. The GR-700 Turbo has top panel controls for filter cutoff, and edit value. In addition, there is a high/low sensitivity switch. To replace the LFO touch pads and LFO depth control found on a vintage guitar, a Roland EV-5 control pedal input has been added to the back of the GR-700 Turbo. This is a real advantage over the original Roland system, since the touch pads on a vintage Roland guitar were notoriously unreliable.

Final Version Voice Board with NEW Lithium Memory Battery

The GR-700 Turbo also has the final revision of the GR-700 Voice Board, plus a new battery for patch memory backup. The early GR-700 voice boards used open frame trimmers for the adjusting the critical parameters of each voice chip: level, DC balance, filter cutoff and resonance. The GR-700 Turbo has the last revision of the Voice Board with closed trimmers. The later Voice Boards also have additional test points to make testing and adjusting the board easier. And finally the 3 volt lithium memory backup battery has been replaced. This is the battery used to power the memory chip so that patches are retained even when the unit is turned off. This battery should last five years, so the original GR-700 batteries are long overdue for replacement!

GR-700 Turbo Features:
  • 13-Pin Moden GK-2/GK-3 Input
  • Six Top Panel String Input Level Controls
  • Top Panel Filter Cutoff Amount
  • Top Panel EDIT Control
  • Top Panel Sensitivity Response Switch (Hi/Lo)
  • LFO Depth (Roland EV-5) Input
  • 4x Memory Expansion! 320 Patch Memory with M-64C Cartridge
  • NEW! Acrylic Side Panels by California Acrylic Design
  • Final Version Voice Board with NEW Lithium Memory Battery
  • Restored VCF/VCA 80017a Voice Chips
  • Final Version 1.5 GR-700 Software
Roland GR-700 Turbo Photos
Click on any image for larger view.
WATCH NOW! YouTube Video Playlist

Repairs - Service Bulletins:

GR-700 replacement battery for internal memory or M-16C.

GR-700 Foot Switch Repair - Failed Switch or Broken Pin Mechanism.

6-Pin inline connectors for PG-200 and GR-700.

Roland Service Bulletin No. 1000229 - Juno-106/MKS-30/GR-700 December 21, 1984
80017a Chip Failures:

Roland released a service bulletin regarding the problematic 80017a chips in the Roland GR-700. This problem continues to persist for GR-700 users. Perhaps one day one string on your GR-700 suddenly stops working. Or you can hear the string, but it plays very softly, followed by intermittent bursts of noise. Or you turn the GR-700 on, and after a few minutes, it starts making loud noises.

Download the original Roland 80017a chip failure bulletin.

Download the GR-700 Service Manual Schematics.

LISTEN - GR-700 80017a Failure Sample - Intermittent Burst of Noise

LISTEN - GR-700 80017a Failure Sample - Notes Continues Softy in Background

You most likely have a failed 80017a VCF/VCA chip. Here is a list of typical 80071a symptoms:

  • Erratic or sudden loud noise from synthesizer output, particularly after 10 minutes of powering up.
  • Note hang-ups or long sustain
  • One synth voice will not respond to filter or amplifier changes.
  • Unstable operation.
  • One particular voice or string will not sound, "D" string, "A" string etc.

If you are familiar with the eighties Roland synthesizers, then you have likely heard about the dreaded 80017a VCF/VCA chip failure issue. Many synthesizers built by Roland in this period used the 80017a chip: the Juno 106, MKS-30, HS-60 and of course the GR-700. The 80017a is basically a voltage-controlled filter and a voltage-controller amplifier on a single, customized chip made for Roland. The actual components in the 80017a were found as individual elements in the earlier Juno 60 synthesizer: an IR3109 and two BA662 chips. The IR3109 was also used as the heart of the excellent -24 dB low-pass filter in the Roland GR-300.

Why exactly Roland chose to consolidate those three chips (and some surface mounted resistors and capacitors) onto a single ceramic chip dipped in plastic remains a mystery, though Roland seems to have an ongoing policy of creating custom chips that cannot be replaced or replicated. In any case, early in the process there were failures with the chips, and Roland issued a service bulletin and replaced lots of chips. Then, as the chips aged, problems started to show up with again. Third party suppliers started making clones of the original chips using modern equivalents. And I sold quite a few working chips on ebay after gutting GR-700s for parts. I extensively tested these chips, and no one had a subsequent failure from the chips I pulled. But this bothered me: would it be possible to modify a GR-700 in some way that would guarantee against a future 80017a chip failure?

As it turns out, the answer is to remove the problematic resin coating around the components. And this was not my idea, someone sent me a link to a YouTube clip showing how to get the job done. I happened to be working on a GR-700 that needed five (!) 80017a chips. I had five failed chips on hand, and used the Acetone procedure to remove the resin. Each chip was then individually tested in a special socket, running continuously for 12 hours with no failure. As each chip passed the test, I labeled it and replaced it in the GR-700.

The result is flawless operation. I do not know why the resin causes problems, but I am guessing that with aging the resin builds up electronic capacitance, causing the chip to fail once the temperature in the synthesizer warms up. This is the best possible solution to the 80017a problem. You keep the original chips that Roland designed, maintaining the sound of the instrument, and you protect against future failures as well.

If one string does not sound, make certain that it is not your 24-pin cable!

An easy way to determine if you cable is working correctly on the GR-700 is to press the EDIT foot pedal, followed by 4 and 8. This puts the GR-700 in tuning mode. Play each string on the GR-700, and you should see the display change for each string. The displays shows "1" for the high E string, "2" for the B string, down to "6" for the low E string. If the GR-700 responds to all six strings, then your cable is good, and most likely you have a failed 80017a chip.

If you need to have your GR-700 chips repaired, watch the YouTube repair clip and this yourself, or you can also contact Allen Coppock at the website Synth Spa. He can repair and calibrate your Roland GR-700. To restore the chips to factory specification, your really need some test tools, including an oscilloscope.

Failed 80017a chip from lot number 42B, with resin in place. Resin shell removed from the chip by soaking in Acetone. Tested and relabeled chip, ready for installation in the GR-700. The custom Roland IR3109 chip shown in the GR-300. This chip is part of the 80017a assembly.
Click on any image to enlarge in new window.
Locating Specific 80017a Chip Failure:
MKS-30 interior Photo. Summing resistors circled in rear. Detail from GR-700 Interior. Resistors in rear. Summing Resistors Close-up, GR-700. Test side is on left.

There are six summing resistors used to combine each voice in these synthesizers. In the Roland GR-700 and MKS-30 example, shown above, the resistors bridge across the voice section to the output section. If you are not sure which voice is causing a problem, you can use a scope to see the VCF/VCA output by touching the left side of each resistor. If you do not have a scope, then attach a wire to chassis ground, and then touch the wire to the left side of each resistor. This will mute the output of the synthesizer voice. When you mute the output of the bad VCF/VCA, the erratic sound should stop.

Channel and String Identification:

It is very important to correctly identify the failed 80017a chip. The chart below shows how the guitar strings map to the channels inside the GR-700:

  • Channel 1 = High E string
  • Channel 2 = B string
  • Channel 3 = G string
  • Channel 4 = D string
  • Channel 5 = A string
  • Channel 6 = Low E string

Analog Calibration:

Since the GR-700 is an analog unit, it requires calibration from time to time. The many analog components in the GR-700 give it a fat, unique sound. However, with time these functions can drift, and many GR-700s may not sound as good as they originally did from the factory. With some basic test components, such as a multi-meter and oscilloscope, it is fairly easy to re-calibrate the GR-700 to factory specification.

When the 80017a chip is replaced, the small trimmers around the chip may have to be adjusted. These trimmers adjust the level, DC balance, resonance and filter cutoff for each chip. Level controls how loud each chip is, Resonance fine tunes the amount of feedback resonance, Filter Cutoff is a fine tune control for the low-pass filter cutoff. Finally DC Offset adjusts the start and ending output of the chip so that when the sound stops, the amount of voltage is zero.

The synth will work without making these fine adjustments, but you may find one voice louder than another, or you may hear soft clicks as a sound decays, indicating some DC offset. While the technical documentation provides specific procedures for setting each chip, most experienced technicians rely on their ears for the final judgment. Also, Roland tends to be cautious with their recommended settings, so users may use these adjustment options to expand the tonal range of their synth.

  • Main board Voltage reference set to 4.7 plus/minus 0.01V
  • DCO-1 reference tuning set
  • DCO-2 and DCO-1 tuning set
  • D/A Offset for maximum output before clipping
  • Level adjustment for each individual voice
  • VCA DC Balance set for each voice
  • VCF filter level adjustment for each voice
  • Final chorus bias adjusted for proper stereo imaging and fattest chorus tone
WATCH NOW! YouTube Video Playlist

GR-700 replacement battery for internal memory or M-16C.

6-Pin inline connectors for PG-200 and GR-700.

2P4T ALPS Selector Switch.

1984 Roland GR-700 G-707 Brochure - "We Design The Future:"

Click on any image for larger view.

Roland 1984 Guitar Synthesizer Brochure:

Click on any image for larger view.

Accessories:

Page six of the 1984 Roland GR series brochure lists several options and accessories for the GR-700.

FV-200 volume pedal: The FV-200 volume pedal could be used to control the filter cutoff on all the vintage Roland synths, GR-100, GR-300, GR-33B and the GR-700. The FV-200 could also be used as a pitch pedal with the Roland GR-700.

And page five lists the Roland US-2 Unit Selector and the C-24D connecting cable.

M-16C Memory Cartridge: These handy-dandy little cartridges double the memory of many Roland devices. Used with a Roland GR-700, patch memory goes from 64 to 128 patches. With a JX8P you add 32 more patches, and it can be used for synth patches on the JX-10 or for sequence memory!

More information on the Roland M-16C Memory Cartridge.


PG-200 Programmer: Roland also made the PG-200 programmer to help program the GR-700, JX-3P and MKS-30. Like other Roland programmers, the base is covered with a magnetic material to allow it to securely attach to the top of the GR-700 or the JX-3P synthesizer.

More information on the Roland PG-200 Synthesizer Programmer


AB-700 GR Guitar System Case: For the heavy and bulky Roland GR-700, Roland made an aluminum case, the AB-700.


Filter and Pitch Pedal:

One of the best features of the Roland GR-700 is the excellent -24 dB per octave filter. The GR-700 shares the same general filter design as the Roland GR-300, based around the custom Roland IR3109 chips.

On the rear of the GR-700 are filter and pitch pedal inputs. You can plug any volume pedal into this jack, and easily sweep the filter or change pitch. You will plug a standard guitar cable from the GR-700 filter or pitch pedal jack to the output of the volume pedal.

GR-700 Filter/Pitch Pedal Recommendation #1 - Korg EXP-2

My favorite pedal is the flexible, versatile Korg EXP-2. With a Korg EXP-2, you do not have to re-wire the pedal, since it also doubles as a volume pedal. Just plug a standard guitar cable from the GR-700 filter/pitch pedal jack to the output of the EXP-2 volume pedal jack, and you will get a wide, musical range of filter sweeps.

GR-700 Filter/Pitch Pedal Recommendation #2 - Behringer FCV-100

The Behringer FCV-100 is a pedal that can function as a dual, stereo volume pedal, or as a control voltage pedal with a 50K pot. However, the FCV-100 cannot be used directly with the GR-300 or GR-700. Since the FCV-100 has an internal PC board, the easiest way to adapt the pedal for the GR-700 is to modify a TRS tip-ring-sleeve cable.

To make the FCV-100 compatible with the GR-700, just reverse the tip and ring wires on one end of a tip-ring-sleeve cable. The other end should be left unchanged. This will reverse the operation of the pedal, resulting in pedal up (dark, filter closed), pedal down (bright, filter opened), as shown in the YouTube clip. I have tested this with both a GR-300, and GR-700. It works with the GR-700 with either the filter or pitch input. It does not matter which end of the cable is plugged into the synth.

Click on image to enlarge

I would note that GR-300 user Joe Bartone, of the band Thelonius Dub, found that the FCV-100 did not hold up well on the gig. By the third gig, the rubber pad came off the pedal. Joe patiently bought some epoxy and took care of that problem...then the bottom of the pedal disconnected from the chassis. Not a big issue, but it meant constantly putting it back together every time he took it out for use. Finally, Joe reported that the pedal went "soft" meaning that it would tilt down when he took his foot off it. It does not stay in position like a quality pedal does. Taking Joe's remarks in hand, I would not give the FCV-100 a strong recommendation at this time.