Roland S-220 12-bit Sampler

Introduction In October 2018 I bought a 31-year old Roland S-220 sampler for £70, with no photo of it working this was a bit of a risky purchase! Why buy one in the first place, given it only manages 4.4 seconds of sample time at 30 kHz and 12-bits? Even the disk drive is horribly unreliable and impossible to replace or even find blank QD diskettes for.

Well its that 12-bit lo-fi sample sound that I am after, so I can sample some modular synth sounds and create bass lines and strings. I also want to develop a Quick Disk drive replacement using a microprocessor, which will store 100 sample banks in memory.

Worn Out 16×2 LCD

History The Roland S-220 was introduced in September 1987 as an upgraded 16-voice version of the S-10/MKS-100 but with the same limited 256k byte RAM. It lasted about a year in production before the improved S330 was launched with 756k byte of RAM, so its a relatively rare sampler. The S-220 received a new operating system with a lot of improvements over the S-10 including 4-part multi-timbrality and up to 4 audio outputs and a good auto loop. There is an external trigger and arpeggiator, so it plays nicely with modular synthesizers.

My S-220 I bought a new mains lead and carefully powered it on, after checking there were no internal issues such as damaged power caps. It booted successfully but the LCD screen was extremely worn out and barely visible, so a new green 16 x 2 OLED display from Raystar Electronics (Part Number: REC001602AGPP5N) was bought for £22. You can buy the OLED in different colours, all part numbers start with REC001602A and they are the correct 80mm x 36mm size.

New OLED

New OLED Display It is a simple swap, the new LCD is the same size as the new OLED, and the EL back light power can be disconnected from the power supply. The front panel has to come out to gain access to the LCD, and the interface wiring has to be desoldered from the old LCD and re-soldered to the new LCD without pin 3 connected (no need for contrast).

This is easy to do as the wiring unplugs from the motherboard. The OLED needs careful alignment with the front panel bezel so all the top and bottom of the characters can be seen. The character size of the new display is slightly larger, notice the tight fit of the lettering.

Roland L-109

Sample Disks I also bought a set of new Roland sample diskettes, the L-109 Synth & Organ, as it has a rather nice Jupiter 8 and VP-330 sample bank. This loaded successfully on the second attempt after I cleaned the disk head and felt pad. Amazingly the QD drive works, although it is easy to do sample bank transfers over MIDI using the S-10 Manager software.

Second S-220 A couple of weeks later I bought a second S220, but this was in much worse condition . The electronics seem okay but the QD motor was permanently on and whining loudly, and the drive belt had melted. I did manage to reduce the whining and improve the head tracking but the Motor will not stop when powered on. So this S-220 will be the “mule” for the QD drive replacement project.

Maintenance The lithium batteries were replaced in both samplers, they keep power to the 8k bytes of Performance Data held in SRAM. A symptom of the battery failing is that the Bender range setting needs to be input at power on. Don’t believe the voltage measured on the battery, even if its above 3V replace it. The old battery legs can be cut away and the new one soldered in place without removing the PCB.

The PSU and Main boards were refreshed with new electrolytic capacitors, especially the 4700uf and 2200uf reservoirs as they have been working for 30 years, along with a lot of cleaning out of dust from the casing! The audio path capacitors were upgraded to Nichicon UES types. I also installed a proper 3 pin IEC socket and earth connection to the chassis, which means the non standard 2 pin cable can be dispensed with. I also replaced all 30x push button switches on the front panel which took a long time, but was worth it! They are ALPS SKHHBSA010 part number.

Outcomes The first S-220 was moved from the workshop into my studio in August 2019 and hooked up with MIDI for sample transfer and audio. The second S-220 remains in the workshop for the QD replacement project. Incidentally the S-220 uses a nice Burr Brown 16-bit DAC chip the PCM54HP, typically used in high end CD players around 1988, but not the best DAC ever made..

QD Drive Replacement  Part of the reason to buy a Roland S220 was to design and produce a QD drive replacement. The QD drive uses a single spiral track recorded onto each side of the diskette, and is half like a cassette and half like a 3.5″ floppy drive. It transfers data slowly at 100 kHz and is encoded in MFM format with 64k bytes each side taking about 5 seconds to load. Samples can be loaded and saved but also the disk can be read to provide the sound name and bank setting.

The drive replacement will use a micro-controller to read and write the data, a small OLED display and a SD card for storage. This project will take place in 2Q19 and it has its own dedicated web page here.

UPDATE: Some clever folks are already modifying the Flash Floppy software for the Gotek SD Floppy Emulator, so I have cancelled my project and will test the software once it is available. This post explains the technical details of the Roland QD diskette drive and the test outcomes.