We’ve been posting about these old Digitech PDS series pedals for years both as restoration projects and overhaul mods to make the pedal function better than new. I think we have a good sampling of the delay pedals shown above – all fully restored with various modifications performed depending on what we were experimenting with at the time.

Since these pedals are now approaching 30+ years old we like to do the basic maintenance of cleaning, replacing hardware, install a standard “Boss style” 2.1mm DC jack, new mechanical foot switches, upgrade aging components or just low quality op-amps. The goal is the improve the analog section of the pedal while keeping the original digital circuitry all original when possible. We want the pedal to be reliable but we’re not trying to reinvent the sound. The biggest sonic change that we recommend would be installing a high-cut knob to roll off the treble and give a much more ambient sounding delay.

Other nice-to-have options include replacing the LEDs with something a bit brighter or to just match the color of the pedal. For the PDS 20/20 above we installed a foot switch to bypass the modulation effect making it even more versatile. We’ve also experimented with adding modulation to the PDS 1002 but at the end of the day decided to keep it simple.

Experimental mods listed above are not necessarily available to be ordered. Please check out our modifications page for what’s currently available on the PDS series pedals.

We love the old Roland AP7 Jet Phaser and have seen a few in over the years for modifications and repairs. Warm Audio’s clone is fairly accurate to the original which means it benefits from our modifications to separate out the Phaser and Fuzz circuit into two separate foot switches that can be activated independently. We also break out the goofy 6-position Mode switch which combines the bypass switch for the fuzz, tone control for the fuzz, and depth control for the phaser.

It’s interesting to note that the pedal is being marketed as true bypass, however the two units we’ve reviewed absolutely are not true bypass and use the same FET bypass system found on the pedal this was copied from. The first one we received also had a defective power supply that sounded considerably worse than battery power. A bit concerning for quality control on an otherwise beautiful pedal.

Mods include:
1. Install additional center footswitch so Phaser and Fuzz can be activated separately.
2. Convert pedal to true bypass.
3. Install status LEDs for phaser, fuzz, and fast footswitch.
4. Install fuzz Tone knob in place of the Mode 6-position rotary switch.
5. Install phaser Depth 3-way toggle switch: Low, Medium, and High settings.
6. Install volume boost circuit to increase the output of the phase circuit. This can be adjusted internally

This pedal has a unique design with a thick, aluminum plate on top of a steel enclosure. That makes it time consuming to drill and requires special hardware with a longer shaft. For those reasons the mods on this page will not be offered in this form as an Overhaul mod. We expect to have a more practical overhaul mod available in the near future which utilizes the two existing footswitches to act as bypass for fuzz and phase circuits.

Don’t own one already? Purchase a stock Jet Phaser and have it modified.

Our Boss CE-1 power conversion bypasses the internal power transformer and allows the pedal to be powered by an 18V DC power source rather than plugging into a 120V AC power source. This can be helpful for people that live in areas with different voltage standards or just for making the pedal pedalboard-friendly as it’ll be compatible with an isolated 18V DC power supply.

We’ve found that the Dunlop ECB-004 is a great option for our mods as it’s readily available and high quality. However, any quality power supply can be used if it’s:
1. 18V DC
2. Tip Negative
3. 2.1mm Barrel Jack
4. 100mA or higher
5. Isolated (no daisy chains or Y cables)

Another consideration for this project was the value of the pedal and preventing any permanent modifications to the pedal. This mod is entirely reversible with the stock transformer remaining untouched, the power switch wiring isn’t modified, the new power circuit (small, purple rectangle seen above) is mounted using pre-existing holes in the chassis, and the DC jack fits in the stock power cable hole.

Our Boss CE-1 Modification page has pricing information. This is a modification service and not available as a kit or with DIY instructions.

As a company that repairs vintage electronics we often run into the problem of finding quality replacements for discontinued ICs. Third-party companies will often make reproductions for popular chips but for the less common chips we’re on our own to find a suitable replacement. The NE5554N is a dual polarity voltage regulator used in older EHX pedals like the Micro Synthesizer and Memory Man. We made a PCB replacement using surface mount voltage regulators and utilize the PCB as a heatsink. This provides better heat dissipation as the stock chip (and suitable replacements) will heat up under use. These boards are NOT for sale; we exclusively use them in our repairs.

One of the great things about the large EHX casings is that there is plenty of room to add knobs on the pedal. This pedal was one of our own to experiment on. Our mix knob has been popular on flanger and phaser pedals so we decided to add it to this chorus pedal. Chorus is simply a dry signal mixed with a pitch shifted (vibrato) signal so this mix control allows you to make the chorus effect a bit more subtle by mixing in some clean guitar or more intense by mixing in more of the vibrato sound. Turning the knob entirely clockwise will give a full vibrato effect.

We added a Depth Knob which affects how wide the LFO sweeps.Since adding a Depth knob makes the Depth switch redundant, we decided to rewire it as an Intensity Switch. When pushed up the pedal is at it’s stock tone, when slid down it is a more subtle shimmer effect.

Other mods include a Volume knob to help the pedal boost the signal an appropriate amount and a Boss style barrel jack to replace the stock ⅛” phone jack. Overall a very versatile pedal with an entirely analog circuit path which should cover a wide variety of tones.

There’s a long history of pedal manufacturers using PCB mounted switches and a spring actuator. This system is very cost effective for manufacturers but leads to problems in reliability as the switches are often cheap and unreliable. Some other pedals with a similar switching scheme include the Line 6 modeler series pedals and the newer TC Electronics pedals such as the Flashback X4. What we do is replace the spring actuator (as shown below) with a standard “soft touch” switch which is a favorite of many musicians these days. This mod works on most pedals that have room for the new, larger, and more durable switch and will withstand the rigors of the road.

The Digitech Whammy has been around forever and the latest revision– while very nice– still doesn’t address the issue of not being able to change presets without leaning over and turning the knob. While some guitarists choose to use a MIDI box to make changes our solution has always been to install a second footswitch so you can cycle through the presets. This was a great hands-free solution but may be tedious for quick changes in the middle of a song.

The box above allows you to remotely control the Whammy and uses the same rotary control as the stock pedal. This box can be mounted on a mic stand or left on a table for easy access. We also offer LED color swaps so you can quickly identify your favorite settings from a distance.

Whenever I talk about modernizing pedals that refers to maintaining and improving vintage pedals without changing their tone. Sometimes this involves converting the pedal to true bypass, adding a status LED, replacing old and aging components like electrolytic capacitors, and in this case: converting the pedal to run on a standard power supply / pedal power unit.

This may sound confusing to some people. Why doesn’t changing the power supply change the tone? In this example, the MXR 117 uses a 15V regulator. That means it will take a higher voltage and always outputs 15V to power the audio circuit. Our modification removes the internal transformer and power cable and inserts a jack in its place to allow you to power the pedal from an 18V power supply. This is also a great option for pedals where the internal transformer has failed. Removing the internal transformer also allows this pedal to be rehoused, but that’s a post for another day.

The only difference is that this King Vox Wah has an electrolytic capacitor where the Cry Baby has a tantalum of the same value. This is due to the fact that the circuit boards were manufactured a few years apart and would not change the tone in any way for this application.

Adding an expression pedal jack to control the rate of an effect is a common request that we get for a variety of pedals. The Phase 90 is mentioned quite a bit but unfortunately it uses an uncommon potentiometer value which isn’t found in any expression pedals on the market. Our solution was to build a custom expression pedal from an old wah pedal. A few key features of this setup:

• The slowest phaser rate (heel down) is set by the Speed knob on the Phase 90 itself.
• The fastest phaser rate (toe down) is set by a Rate knob on the opposite side of the expression pedal.
• The maximum rate can go even faster than when the pedal is in stock form.
• Unplug the expression pedal and your Phase 90 is back to working like normal.

The only downside to a setup like this is the added cost of building a custom expression pedal. Our future builds will be using a Roland EV-5 expression pedal which is readily available, easily replaced in the event of failure, and is less expensive. Unfortunately the expression pedal jack occupies the battery compartment so this pedal requires an external power supply.