Roland S-750 Refurb
- At August 13, 2019
- By amsynths
- In Sampler
12

Overview I bought a used S-750 in May 2018 for £85, which is a bargain, especially as it has an expanded 18 MB of sample memory, and was from Air Studios. It was manufactured in February 1993 and is a fairly late model although it does have wire kludges to the main PCB. Whilst it is rather large and heavy I plan to upgrade the sampler and use it with 7 Roland sample CDROM’s permanently attached on a SD card in the casing.
New LCD The back light of the blue and original LCD had faded. Rather than just replace the back light EL I decided to replace the complete LCD with a new grey and white one which I bought off eBay to ensure it worked.
It does work and look great, but its a few millimeter higher than the original so the perspex screen has to be fitted back in 2mm proud rather than smooth to the front panel. It is a very nice LED screen. It is not easy to remove the perspex bezel from the old LCD as the double sided tape had hardened over the years.
SCSI Drive I wanted to fit a SCSI2SD V6 drive inside the case rather than having it taking up space outside. The S-750 main board has the connection for the external SCSI 25-pin connector and an unused 50-pin connector. In fact its just the bare PCB holes with no socket. On investigation this proved not to be a 50 pin SCSI connector or even the 40 pin socket on the S-770 which is used to connect a hard drive internally. It is a IDC 2mm pitch 50 pin connector wired as follows:
Pin Function
16 Data 0
18 Data 1
20 Data 2
22 Data 3
24 Data 4
26 Data 5
28 Data 6
30 Data 7
32 PARITY
35 ATN
36 BSY
38 ACK
39 RST
40 MSG
42 SEL
43 I/O
44 C/D
46 REQ
Its a completely non-standard proprietary Roland pin out, but it does have the SCSI bus on it with power. My plan is to put a 50 pin socket onto the Main PCB and cable it to a new PCB that maps this to the correct 50 pin SCSI pin out and attaches to a SCSI2SD drive with a 50 pin socket. This will provide 7 SCSI drives which I will load with sample CDROM’s. The only down side is that I cant swap SD cards without opening the case and getting the sampler out the rack., but that doesn’t worry me given I will have 7 drives to play with.
This new PCB has two 50 pin sockets and space for the SCSI2SD drive to be mounted to the PCB. The S-750 has a convenient set of 4 hols in the chassis to mount the 90 x 100 mm PCB.
Gregoris
My friend i have the same scenario as you
and i want to install an internal SCSI2SDV6 inside my S750
i will use the front 3.5 slot where the floppy drive sits
but i don’t know how to do the internal scsi socket
let me know if you have anything on this
thanks in advance.,
Gregoris.
Mattias Cedergren
Hi. Did you complete the S-750 SCSI issue? I’d like to do exactly same thing with my S-750, so any piece of advice, part numbers and so on are very welcome. Best regards, Mattias
amsynths
Hi, I have not completed the S750 SCSI changes as I have focused on getting SCSI2SD working on my S-760 and W-30. But its next in the back log and I will post details. Thanks Rob
Matt
I have an S-770 with a V6 SCSI2SD mounted internally. I’ve been struggling trying to get CD-ROM images onto the virtual drives for weeks now. It doesn’t seem to be very straightforward!
If you or anyone else ever figures it out let me know!!
Good luck with the renovations!
Lux Voltaire
Hi Matt,
You will have to burn a CD ROM ISO image directly with a Mac, using terminal and DD command. This is the only way I got my Emu’s to read CD ROM images directly from an internal SCSI2SD. The E-mus can also read Roland disk images, so this should apply to the Roland S-770.
Bram
Oi,
i want to re new my s770 (lcd) display. Does it need the black (k) and gray (a) wires for power or is powered from the flat cable.
any help would be appreciated.
thank you and succes with you project
amsynths
Only needs the flat cable if you use led or oled display.
Tony Espinoza
would love to hear how this turned out!
is there a particular firmware/OS version that is required to run SCSI2SD on the S700 series?
amsynths
The SCSI2SD drive plugged straight into the S760 and worked perfectly. It was formatted and loaded with 2 sample cdroms by a third party.
M
I was on the same quest with an S-750, to install the SCSI2SD (v5.1) in place of the floppy drive. I found those same, open 50 pads on the motherboard, and found that they were matched with the 25 pin connector on the SCSI bus. I matched all 18 of the pins, and directly soldered a 50 pin ribbon to connect the new drive. After testing, it didn’t work! I checked all the connections I made, and measured continuity through the drive, and to the DB25 connector. It should have worked!
On start up, it will either get stuck on the initialization message, or will move passed that and get stuck after the Wave Memory check. The only way I’ve been able to get it going again with the SCSI2SD is by reinstalling, and powering, the 3.5” floppy drive with no disk. It will then appropriately map the drive and fully boot up. I also have to connect the DB25 to the SCSI2SD. It doesn’t want to work with the new ribbon I installed.
I’m curious what else I could try? While I’m glad I was able to get it working again, I’m kind of bummed I couldn’t install the new drive in place of the floppy drive.
I haven’t removed any of the new wiring. My guess is that the problem has to do with termination, or drive mapping.
I’m open to any suggestions!
Thanks!!
Obsoletemachines
Do you need the turbo rom?
amsynths
Hi, no the S750 has 18MB of RAM. But many thanks for the offer of help! Rob