January 2020
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Pedulla XJ-S

Pedulla XJ-S Guitar Synthesizer Controller

Features and Specifications:

  • Body:Maple
  • Finish: Polyester
  • Neck: Through-body maple
  • Fingerboard: Ebony
  • Frets: 22
  • Bridge: Schaller fixed and Tremolo
  • Nut: Brass
  • Tuning machines: Schaller
  • Pickups: Bartolini two sing-coils and a humbucker
  • Scale:25 1/2"
  • Truss Rod: Single, Adjustable
  • Neck Width: 1 5/8"
  • Body Width: 14 1/2"
  • Body Depth: 1 1/2"
  • Overall Length: 38"
  • Weight: 8 lbs 6 oz
Pedulla XJ-S Black

Introduction to the Pedulla XJ-S:

With the introduction of the Roland GR-700, the guitar world was convinced that the age of the guitar synthesizer had arrived!

The Pedulla XJ-S was one of a number of third-party guitars mass produced with vintage Roland 24-pin electronics guitar included. By and large, these tended to be more higher-end guitars. Some folks are suprised to learn that the heralded bass manufacturer Pedulla produced guitars with the vintage Roland 24-pin electronics included.

Based on the availibility of these guitars in the used market, ebay, etc. it appears that Pedulla may have built more of these guitars than other builders such as Gibson, whose 24-pin guitars remain fairly rare.

The XJ-S is the Roland equipped version of the Pedulla XJ guitar. Presumable the "S" stands for synthesizer. The guitar shipped in two versions, with aSchaller fixed bridge or tremolo bridge. The guitar also sported Bartolini pickups, and Bartolini pickups are still found in Pedulla basses.

The synthesizer electronics package in the XJ-S is the LPK-1 kit, based on the G-303/G-808 guitars, which includes the hex fuzz circuit.on the XJ-S as well: filter cutoff, resonance, LFO depth, mode switch, and touch pads to activate/deactivate the LFO feature.

Pedulla XJ-S Various Finish
Click on image for larger view
Eric Fischer helped me out with these photos, and John Senior provided the Red XJ-S.
Links to more information:

Photos - Various Finishes:

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Pedulla JXS
Pedulla XJS Pedulla XJS Pedulla XJS
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Pedulla XJS Pedulla XJS Pedulla XJS
Pedulla XJS Pedulla XJS Pedulla XJS
Click on image for larger view


YouTube Playlist: Pedulla XJ-S

Schematics - Repairs - Service Bulletins:

There are no known service bulletins from Roland addressing any XJ-S problems

Repairs - Roland G-202/303/505/808 Opamp Failure

You suddenly notice that one string on your guitar synth system stops working. The first thing you want to do is try another cable! Cable failures are the most frequent GR-system problem. If you do not have a spare cable, try jiggling either end of the connector, though the problem is most likely to be the end that plugs into your guitar. If the sound comes and goes, then you need to fix your cable. If not, then you most likely have a problem with an op-amp inside the guitar electronics. A more remote possibility is that you have a damaged pickup.

If you have a GR-700, an easy way to determine if you cable is working correctly 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.

Unless you have been moving the synth pickup around a lot, they usually do not fail on their own. Instead of a synth pickup failure, you possibly could have a problem with the electronics. Inside every GR guitar are a lot of small, integrated amplifiers called "op-amps." These due tend to fail over time. If you have a G-303, G-505 or G-808, you are in luck! These guitars are easy to test, and easy to repair. The other models of guitar synths are a little bit more difficult to troubleshoot, since they do not have hex-fuzz. While the G-202 has hex fuzz, it actually uses the same circuit for both the fuzz and clean signal, so the hex fuzz test will not work.

To find out if you have an op-amp failure, listen to the hex-fuzz output only. If all six strings work in hex-fuzz mode, and you know your cable is good, your pickup is working fine, then your op-amp is most likely bad. If you get all six stirngs to output a synthesizer signal, but one string looses the hex fuzz sound, then it is almost certain that you have a bad op-amp.

The GR guitars use 4558 op-amps, available at any decent electronics shop, and they typically cost just a dollar or less.

Typical replacement part: STMicroelectronics 4558 operational amplifier at Mouser.com.

Here are some photos of a op-amp replacement I did on a G-303. Notice I installed an IC socket on the G-303 circuit board, to make future repairs or upgrades easy.

opamp repair opamp repair opamp repair
G-303 Electronics interior, the arrow points to the failed op-amp. Underside of the electronics. Arrow points to the pads to de-solder. The new 4558 was mounted inside a socket, for easy replacement in the future.
Repairs - Roland G-202/303/505/707/808 Divided Vintage GR Synth Pickup

If you remove the guitar electronics for repair, it is quite possible to crack the divided hex synthesizer pickup ribbon ever so slightly. These ribbons become very brittle as they age. The conductive metal traces are layered on to the plastic ribbon, and are fragile. Fortunately, there is a possible fix for this problem, but be forewarned, this is the most difficult and tedious vintage Roland repair.

Before you start this repair, it is important to check that the ribbon is the problem. Remove the ribbon connector from the circuit board, and using a multi-meter, check the impedance between contacts. You should read either approximately 80 or 160 ohms for a "narrow" pickup, or 800 to 1.6K ohms for a "wide" pickup. See the information above on measureing the impedance in your hex pickup.

Since there is no way to repair the ribbon connector itself, you will cut the ribbon connector off the hex pickup, remove the potting wax around the pole pieces, and then solder replacement wires to a new ribbon connector. I have successfully repaired a half dozen pickups this way. It can be done with patience and the right tools. Allow and hour or two for the whole procedure.

  • Dremel Tool with basic attachments.
  • Low wattage soldering iron and solder.
  • Replacement Roland 12-position Ribbon Cable.
  • Masking tape.
hex pickup repair hex pickup repair hex pickup repair
Hex pickup ready for surgery. The ribbon connector has been removed, and tape is placed around the pickup to protect the casing.
Enough potting wax has been removed to allow soldering access to the pole pieces You only need to expose seven poles.
New wires attached to the hex pickup. The top pin is green (common) and the lower row is high E to low E (left to right).
hex pickup repair hex pickup repair hex pickup repair
Close-up detail of wires attached to the pole pieces in the hex pickup. The bottom green wire is the common lead shared by all the elements. The pickup with replacement wires attached, soldered to a spare Roland 24-pin ribbon cable. The original ribbon connector is also in the picture. These are the Dremel attachments I used. The last repair totally destroyed three of my brushes, as the epoxy was very, very hard.

The above photos show the conversion of a "narrow" older-style hex pickup. A Dremel tool was used to remove the epoxy-type potting wax around the pole pieces of the hex pickup. When removing the epoxy-type potting wax, you only want to remove just enough to solder on to the pole pieces. Removing too much will permanently damage the pickup. Also, the Dremel brush can damage the casing of the pickup, so to be on the safe side I taped up the edges of the pickup to prevent damage. I would work a little bit, then closely inspect the pole pieces. When I felt I was close enough, I used a multi-meter to test for conductivity, in a "narrow" pickup, you should read around 80 ohms between the element and the common, or ground. With a "wide" pickup, you should read about 800 ohms.

You will note that one row of six pins are common, or ground. You only need to uncover one of the common pins for this repair. Refer to the photos below to orient your epoxy removal to access the six lead pins and one common pin.

When I was finished with the Dremel tool, I cleaned everything up and carefully soldered seven wires to the pickup, one for ground (the common for all six elements), and one wire for each element. Then everything was tested again. The resistance between two elements (not between the element and ground) should read 160 ohms for the "narrow" pickup, and 1.6K ohms for the "wide" pickup. I have tried different Dremel brushes for this work. The video clip below shows a repair using a nylon brush.


The last repair I did had particularly difficult epoxy. The repair destroyed three of my Dremel brushes, and as the metal brush disintegrated, tiny metal wires went into my face. GR user Peter Kulich reported a similar experience to me, but then he is Canadian. Anyway, when I was done, it was up to my wife pulled these tiny wires out with tweezers. Fortunately, I was wearing eye protection and a breather which covered most of my skin, but it was an important reminder to protection at all times.

hex pickup detail
This is a "wide" hex pickup with new wires attached. The top row of pins are all ground, or common.
hex pickup detail
This is a "narrow" hex pickup with new wires attached. The top row of pins are all ground, or common
Restored Divided Vintage GR Synth Pickup Installed in Pedulla XJ-S:
pedulla hex pickup repair pedulla hex pickup repair pedulla hex pickup repair
This is a photo of a wide pickup set to be installed in a Pedulla XJ-S with Roland electronics. In this installation, the ribbon connector was cut down to seven traces. This ribbon will be used with the remaining ribbon part. New wires attached to the hex pickup ribbon. Refer to the G-303/G-808 schematic for the wiring order.
pedulla hex pickup repair pedulla hex pickup repair pedulla hex pickup repair
Close-up detail both ribbon parts inserted into the ribbon connector on the circuit board. Distant view with wire leads shown as well. In the Pedulla XJ-S the electronics are in a very narrow cavity, with barely enough room. Here is the entire assembly in the guitar, with black masking tape added around the connectors to prevent shorting.
Craig Hara's Excelllent Page on Restoring Divided Synth Pickup