Serviced ARP Quadra Synthesizer with MIDI & New Sliders

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Vintage ARP Odyssey Mk I White 2800 - Serviced w/ New Sliders

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video upload by Synthchaser

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Vintage Moog Modular Synthesizer Repair - Synthchaser #167

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"In this video I troubleshoot a dead vintage Moog Modular Model 12 and bring it back to life with a 3 cent part!"

Vintage ARP 2600 Synthesizer w/ 3620 Duophonic Keyboard

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via this listing, also on eBay

"Really nice vintage Orange & Black late model ARP 2600 with the 3620 Duophonic keyboard. This particular synthesizer is in great shape and was on display at NAMM 2020. The keyboard controller was serviced by Synthchaser in 2020 and the main unit was tested and calibrated by Synthchaser in February 2025.

There are some scratchy sliders on the main unit, and the tolex inside the main unit's lid is coming up on one edge (can easily be re-glued). Includes an original style oval power cord."

Nice R2-D2 on screen.

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Arp Omni String Synthesizer w/ LED Sliders

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"Arp Omni String Synthesizer. Fully working. I recapped all of the boards except the power supply because the power supply is outputing the correct voltages. All sliders have been replaced with lighted sliders and work smoothly. Synthchaser master oscillator module installed to insure good tuning. Power cord is missing the ground pin. This was a diy project, when got this it did not work at all. After the recap and replacement of sliders it now fully works and sounds good. The next owner can play it as is but may want to consider replacing the power cord, recapping the power supply and replacing the keybushings. Cosmetically this unit is nice. There are a few scratches from normal use and storage and some keys that have marks on them but nothing major."

Pics of the inside below.

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ARP 2600 Grey Meanie Synthesizer with Matching 3604 Keyboard - One of 34 Made!

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Arp Quadra Serviced Keyboard Synthesizer

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Additional Retro Gear Shop Listings

"Rare vintage Arp Quadra synthesizer keyboard that just got back from a full servicing by Synthchaser. Work included a complete re-cap, new slider pots (which can be led activated at a later stage if desired), new touch panel membrane and keybed refurb. It's fully functional and good to go. We have a long demo video made by Synthchaser we can share on request. The only issue worth mentioning is the lower transpose button is not working, but the upper transpose button does work and performs the same action. We have sold Arp Quadra's in the past for $12k - $15k and it's been a couple years since we last listed one for sale. These are very cool vintage analog synths."

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ARP QUADRA w/Synthchaser MIDI + LED upgrade + more

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"This synth has been fully serviced and upgraded, making it IMO the best and most musically usable Quadra you'll likely ever come across. Modifications installed are the Synthchaser Quadra MIDI kit (very few of these kits in existence, I believe there were only around 20 of them made/sold, and it is no longer available), the Synthchaser Quadra LED slider upgrade kit, as well as a custom modification which routes the external audio input through the Quadra's glorious stereo phase-shifter effect (normally the external input is simply there to mix in an external audio source, and isn't routed through any of the Quadra's processing signal path). For info on the Synthchaser kits, you can read up on them and watch video demos via their website: synthchaser [dot] com.

Additional notes:
(1) the Midi Out can alternately be switched to Midi Thru, via a switch on the board.
(2) I also had my tech install an on/off switch for the LED lights on the sliders, as seen in photo#9, under the "la tosca INC" sticker.

This thing sounds absolutely glorious, and everything, including keyboard aftertouch, is working perfectly. It was fully serviced at the same time as the Synthchaser kits were installed."

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Serviced ARP Omni 2 Synthesizer with Synthchaser MIDI Adapter

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Sequential Circuits Prophet 600 Synthesizer w/GliGli Upgrade SN 4589

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"The Prophet 600 is a good synthesizer, but with the GliGli CPU upgrade installed it becomes a great synthesizer! One of the best vintage synth values out there today.

This Prophet 600 is in good working order and has been upgraded with the GliGli mod running the 2.0992 firmware revision (GliGli's final version), a new membrane panel, a new set of Synthchaser key contacts, and a new set of knobs. All 6 voices are tuning, scaling and sounding great.

Very good physical condition, some wear/chips on the side panels (see photos)."

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Oberheim OB-Xa 8 voice w/ Magic Box (MIDI) SN 812130

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"OBXa in near-mind condition, with Magic Box external midi adapter and custom hard case (orange colour). I say near mint because there's some TINY cosmetic blemishes on the top edge, literally just paint thats been scraped off. No dents, even the paint is still flawless.

many many many hours and $$$ went into restoring the absolute beast of a polysynth. If you think plugins can even come close to this, you've never actually heard one.

-MIDI interface that didnt destroy the case or wood panels ($600USD) ()

-Power supply restored with new capacitors and bridge rectifiers.

-All voice cards completely restored, capacitors (electrolytic and film) replaced, and upgraded with multi turn trimpots.

-Keybed bushings replaced and keys straightened.

-Battery-less storage module installed (synthchaser.com), so no potential for leaky component destroying battery anymore...

Completely calibrated and ready to play. All kinks were ironed out one by one. It is, and I don't say this lightly, the most formidable synth I've ever played.

note - the knob caps are off in some of the pictures for cleaning - they're included :)"

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ARP Pro/DGX Mk I (Pro Soloist) SN 27200407

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video upload by Synthchaser

via this auction, also on Reverb

"vintage ARP Pro/DGX Mk. I, aka the Pro Soloist III. This is the model to get! It has the same sounds and fat ladder filter as the Pro Soloist, but with more reliable and more performance friendly pushbutton voice selection switches. This keyboard is the sound of 1970's Genesis.

This synthesizer has just been serviced by Synthchaser, the top ARP specialist - recapped, new key bushings, new LED sliders, new aftertouch sensor, new Synthchaser linear power supply, fully functional, calibrated and sounding great.

Here is a video demo of the actual keyboard being sold"

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Moog Polymoog Repair - Dead/Incorrect Sounding Keys - Synthchaser #162

video upload by Synthchaser

"In this video I show how to repair the 2 most common causes of a very frequent Polymoog problem--dead or incorrect sounding keys."

Serviced Rare Original 1971 ARP Soloist Model 2700 (Pre Pro Soloist!)

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video upload by Synthchaser

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Vintage ARP Odyssey Mk I 2800 Pro Serviced w/ New Sliders

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video upload by Synthchaser

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"This vintage ARP Odyssey has just been fully serviced in October 2023 by Synthchaser, the top ARP specialist - recapped, new key bushings, all new LED sliders, fully functional, tuned and calibrated, and sounding awesome! The Odyssey was ARP's answer to the Minimoog, a feature packed scaled down version of the legendary ARP 2600.

A video functional demonstration of this synth that is for sale is at the end of the pictures list.

The synth is in great condition. This synth comes with illuminated LED sliders that correspond to the colors of the original slider caps. I can disable the illumination for the buyer before shipping, upon request at the time of purchase.

Work just completed on the synth included:

Synthchaser Precision LED slider upgrade - All 34 of the old original sliders have been replaced with new, smooth, high precision LED illuminated sliders. The difference in the way these sliders feel and perform compared to the originals is a huge improvement. LEDs run off their own power supply mounted inside the synth.
Illuminated slider caps - Slider caps with a translucent plastic stripe that allows the LED illumination to shine through, while giving you something substantial to grip onto. They look and feel awesome!
Power supply rebuilt - All tantalum and electrolytic capacitors in the power supply have been replaced, and high quality, high temperature 105 deg C capacitors have been used for the power supply filter capacitors.
All tantalum capacitors replaced - The tantalum capacitors in ARP synths are ticking time bombs.All tantalum capacitors in this synth have been replaced with electrolytics to help provide stable operation for years to come.
Synthchaser 4023 Voltage Controlled Filter Submodule - This is a very fat 2 pole dual OTA filter. Synthchaser modules are true to the original designs and professionally built using premium components with superior performance and reliability to those found in the original modules.
Keyboard rebuild - New key bushings installed, keys removed and ultrasonically cleaned, bus bars removed and polished, bellcrank caps cleaned and lubricated.
Oscilloscope calibration - Calibrated & tuned using oscilloscope and frequency counter.
1/4" output made High - ARPs of this era had an RCA jack as the high output and the 1/4" jack as the low output. As today RCA jacks are an inconvenience for most, the 1/4" jack has been made to a second high output.
New rubber feet"

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Original 1971 ARP Soloist Model 2700 ex Dennis P. Colin

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video upload by Synthchaser

via this auction

Some pics of the inside bits below.

Pics and video for that one captured below.

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ARP Explorer I SERIAL #1 - Model 2900 Synthesizer - Serviced

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video upload by Synthchaser

via this auction

"The ARP Explorer I (Model 2900) was ARP's first non-preset single oscillator synthesizer, pre-dating the Axxe and the Solus. It includes the same 4027-1 Voltage Controlled Oscillator module found in the ARP 2600, and the same 4034 Moog Ladder Filter Voltage Controlled Filter module found in the ARP Pro Soloist. The oscillator is divided down to suboctaves, and shaped into different waveforms (sawtooth, square, pulse, and fuzz) that can be combined simultaneously for an extremely fat sound from a single oscillator synth, particularly in partnership with the ladder filter.

The synth is in good condition, however the silkscreen is very faded as is common for this era ARP synthesizer. This synthesizer was serviced in September 2023 by Synthchaser, and work completed on the synth included:

Synthchaser Precision slider upgrade - All 12 of the old original sliders have been replaced with new, smooth, high precision sliders. The difference in the way these sliders feel and perform compared to the originals is a huge improvement. The original style slider caps are fitted to keep the look original.
Power supply recapped - All tantalum and electrolytic capacitors in the power supply have been replaced, and high quality, high temperature 105 deg C capacitors have been used for the power supply filter capacitors.
Tantalum capacitors replaced - The tantalum capacitors in ARP synths are ticking time bombs. All tantalum capacitors in this synth (except those in the sub-modules) have been replaced with electrolytics to help provide stable operation for years to come.
Keyboard rebuild - New key bushings installed, keys removed and ultrasonically cleaned, bus bars removed and polished, key contacts cleaned and adjusted.
Oscilloscope calibration - Calibrated & tuned using oscilloscope and frequency counter.
1/4" output made High - ARPs of this era had an RCA jack as the high output and the 1/4" jack as the low output. As today RCA jacks are an inconvenience for most, the 1/4" jack has been made to a second high output. This modification is easily reversible by cutting 1 wire."

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ARP Odyssey MK II Model 2813 SN 0106

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"Here is S/N 0106, an early MK II from around 1976. In nice shape and sounds fantastic! It has new keyboard bushings and plays very smoothly with no key clacks. The sliders were replaced along with the 'lytic capacitors, and has the 4075 VCF module from Synthchaser installed. The colored slider caps were replaced with all black, and the (incomplete) set of original caps is included. Freshly calibrated this spring, and it is rock stable as you would expect."

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Serviced Vintage Moog Polymoog 203a Synthesizer SN 3861

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via this auction, also on Reverb

"Here's a fully functional Polymoog 203a Synthesizer in nice cosmetic condition. This was serviced in August 2023 by Synthchaser. Work done included:

Recapped power supply
Repaired all known functional issues
Replaced panel button LEDs with new, lower current blue LEDs - reduces synthesizer power consumption by over 1/4 Amp, increases LED lifespan, and looks cool.
Cleaned slide pots"

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Moog Minitmoog SN 2262

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via this auction

"Here is an excellent example of the rare Minitmoog synthesizer.

This unit has undergone a full restoration from the top Moog technician in the Midwest, G Dahl in Minneapolis.

New slider kit from Synthchaser, rebuilt key bed, deep cleaning, aftertouch sensor rebuilt, various parts and knobs cleaned and replaced, IEC plug installed, fully functional.

This unit will be packed extremely well and fully insured, arriving to you for studio use.

Only some very minor cracking in some of the preset tabs which is very common with this unit, cosmetically it is an 8 out of 10 easily."

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