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ARP 2600 + 3604-P Keyboard
For sale is a very rare vintage Tonus logo of the Arp 2600 semi-modular analog monophonic synthesizer, most likely a 2600P V2.0 based on internal components. This is one of the more desirable sounding Arp's to get with the 4027 Oscillator and 4012 Filter than the later G-clef and orange/black models.

Very good condition, with some wear as expected for its age but overall still nice shape. Most of the wear is on the outside tolex, the front panel face and keyboard itself are in great shape. Includes both lids to unit and keyboard along with keyboard connecting cable. Comes with original manual. We've had many 2600s pass through our shop over the years and we found this particular unit to sound fantastic. It's 100% fully functional, just back from full professional servicing.

Servicing included
- VCO modules are 4027 (2nd generation between 4017 and 4027-1)
- Confirmed output of VCOs and general operation
- Full recap, replacing all tantalum caps with proper electrolytics
- Cleaning and restoration of all sliding potentiometers
- Adjustment necessary
- Cleaned boards
- Performed adjustment procedure
- Completed reassembly and tested for proper operation 

3604-P
- Complete disassembly
- Replaced tantalum capacitors
- Replaced poly caps for greater stability
- Removed all keys
- Straightened keybed chassis and replaced all bushings
- Cleaned key contacts
- Lubricated and replaced all keys
- Cleaned all potentiometers and switches
- Adjusted and set CV output
- Performed final play tests