Roland MC500 Refurb
- At May 19, 2020
- By amsynths
- In Sequencer
17
Overview I bought an original 1986 MC-500 in May 2020 for a nice low price but sold as a repair job. It turns out to be in very good condition and the issue was a damaged OS floppy diskette, which refused to boot and gave I/O ERROR 3. Once I had powered it up with a brand new DS/DD diskette with Super MRC-500 software it works perfectly. The LCD had faded after 35 years and needs an OLED replacement and the diskette drive is rather loud and clunky but I will keep it until it fails.
The MC-500 was way out my budget in 1986 at £999 and I bought an Atari 520STFM (£299) in 1987 and used it with MasterTracks Pro for many years until it was struck by lighting one night and exploded.
I had added a 20MB hard disk to the Atari to enable a large collection of songs to be built up. The price of hardware sequencers has of course fallen significantly, so I can now experience and use this approach in my studio.
OLED Display This is an easy plug and play replacement using the Newhaven 2×20 NHD-0220D2W-AB5, which is a nice blue on black OLED. The EL backlight connections are not needed and can be removed along with the EL transformer, which is on the PSU PCB.
My transformer has a slight wine so I removed R1 and R2 from the PCB to cut the power to the transformer, which avoided the need to take the PCB out. The display is hand wired to the 14-way cabling rather than using a plug and socket. I removed the old LCD from its metal frame and then carefully peeled the metal frame from the display bezel which has some doubled sided tape.
Diskette Drive The drive works ok and uses 3.5″ DS/DD diskettes which are a bit expensive to buy these days. The sensible approach is to install a Gotek drive but I rather like using floppy diskettes as I can write stuff on the label about the song. So whilst the drive still works I will keep it in place. I also have a MC-300 and MC-50 (sold), so I can swap songs between them.
Power Supply Recap I decided against a recap of the power supply, as the main electrolytic caps were in good condition and it meant quite a bit of dismantling and desoldering cables. In the future I will do a full power supply refurb along with the regulators, but for now no changes, If you do want to replace them us high quality Panasonic EEU-FC’s with the same diameter and height:
- 4,700uF 16V – EEU-FC1C472SB
- 2,200uF 25V – EEU-FC1E222SB
Technology The MC-500 is based around an enhanced Z80 micro processor manufactured by Hitachi as the HD64180 with integrated memory management and on chip peripherals. It was launched in 1985 and initially Roland used the DIP64 pin version the R0, before moving onto the 80-pin SMD R1 version for the MC-500 Mark II launched in January 1988. The R0 DIP version can only address a maximum of 512KB, with just 256KB fitted in the MC-500 using 8x 32KB RAM chips.
The MC-500 Mk II uses the R1 micro processor which can address 1 MB of RAM, with 756 KB fitted, and the subsequent MC-50 and MC-50 Mk II also use the same microprocessor giving the this micro composer a life span of nearly ten years. The MC-50 versions use onboard memory for the OS to live in, so its faster to use and boot, but not as classic in style!
Memory Upgrade My MC-500 was manufactured in July 1986 only a few months after the launch in January, and it uses the original PCB layout with 256 KB of RAM and the R0 version of the HD64180 which has 19 address lines. This limitation means the early MC-500’s can not be easily upgraded to 786 KB of memory. The processor and RAM need swapping out and the extra address line added. Roland did offer the OM-500 upgrade, which must be a main PCB swap, and the resulting sequencer is called a MC-500B by Roland..
Software Options & Versions In 1986 the MC-500 was launched with an initail software release (MRC-500) which was upgraded with more detailed features as Super MRC in 1988 along with a wider range of software to enable SysEx storage, chained songs for live performance, MIDI file conversion and a set of rhythm tracks. Here are the various software releases, click on the titles to download the .OUT file:
- MRC-500 Midi Realtime Recorder V1.00
- Super MRC Midi Realtime Recorder V2.00
- Super MRC Midi Realtime Recorder v1.01
- MRB-500 Bulk Librarian System Generator
- MRP-500 Performance Set
- MRM-500 Midi File Converter
- MRD-500 Rhythm Track Disk
I use the MRB-500 to store MKS-80 Patch Banks as it performs the correct handshake and MRM-500 to transfer MIDI files to Cubase and back. V2 of the MRC software results in a lot of diskette loading to get the various parts of the software in as the features are used. For a faster workflow stick to V1 and the 4 tracks.
Recreating the Software The MRP and MRB software cannot be downloaded from Roland and the original boxed software is expensive at £50 – 100, when you can find it secondhand. Fortunately 20 years ago R. Kevin Grannum archived the files onto his web site in .DAT format using obscure uCopy software. The web page exists but the links are all broken, but with Wayback Machine I found the files and downloaded them.
With some careful hex editing and byte level comparisons I was able to trim the start of the files and add extra bytes at the end to make them into binary 720 KB files in .OUT format that SDISK (or WDISK) can write to a 3.5″ DS/DD floppy diskette. The diskette must be pre-formatted by the MC-300/500/50.
2021 Postscript It turns out the Newhaven OLED has a minor problem working with the MC-500 Boot ROM. When no diskette is in the drive the Boot ROM should display an Insert Diskette message but the screen goes blank and only after pressing a number of keys does a partial message get to the OLED. It looks like the Boot ROM is failing to handshake with the OLED possibly due to timing problems, whilst the main software works fine.
This probably comes down to the speed of the OLED processor and there is not much that can be done, even swapping out to a different OLED may result in the same failure. The work around is easy – just leave a diskette in the drive. Available Memory also fails and shows a blank screen, press PLAY to exit this.
In late 2021 I purchased an original set of MRP-500 Performance Set diskettes which means I can generate the correct song disks.
Kenny
Hi there,
A very nice article. You’ve inspired me to upgrade my MC500, MC 500 mkii and my MC50 mk1.
I ordered the new oled displays and soldered them in. They seem to be working okay but i have noticed that some of the screens aren’t appearing: ‘Insert disk’ and so on.
There are an extra 2 pcb holes in the new board, so 16 instead of 14 on the old one.
I started the wiring from the bottom holes and left 15 & 16 empty.
Should i have started at the top? I’m reluctant to resolder everything again.
Many thanks
Paul
Did you ever get it figured out? I want to do that to mine.
amsynths
Hi, most 20×2 OLED’s just have 14 pins but Pins 15 and 16 should not be used as they are the backlight power to an LCD and were used on the original LCD. Let me know what model of OLED you used and I can double check. The connection is Pin 1 to 14. If you have OLED displaying characters then the connection is good.
Paul Lanctot
Cool. The one I’m looking at has 16 pins, and the original mc500 one has 14. In my unit the 2 wires that go to the transformer come off the other side of the original lcd.
I’m looking at NHD-0220DZ-FSW-FBW.
So just put pin one to pin one and the rest in order until 14, and leave the 15, 16 empty?
https://www.newhavendisplay.com/specs/NHD-0220DZ-FSW-FBW.pdf
Thanks
Paul
https://www.newhavendisplay.com/specs/NHD-0220DZ-FSW-FBW.pdf
So just don’t hook up pins 15 and 16 on this? Thanks.
Kenny
Many thanks for all your replies, very helpful.
The screens I used are
model No: NHD=0220DZW-AB5
From Mouser Electronics, Inc.
Paul Lanctot
I’m getting ready to try NHD-0220DZ-NSW-BBW and NHD-0220DZ-FSW-FBW will let you know,what happens
Paul Lanctot
Well I just tried mine and I get nothing on the screen at all on power up. I used pins 1-14.
Reading 5 volts at pin 2 of the display board. The weird part is that pin one of the display connects to pin 14 of the connector on the main board, but looking at the schematic it made sense to me.
The data sheet for the display says pins 15 and 16 are power for the backlight- pin 15 needs 5v , pin 16 to ground. So maybe I’ll try that , because the 5volts to pin 2 is for data power, according to the data sheet.
Paul Lanctot
I just tried again with NHD-0220DZW-AB5 – connected pin 3- ( contrast) even though it says it’s not used. the display is working but I have the same problem with “ insert disk “ screen not coming up- I have not yet disabled the transformer that fed the old backlight.
Riva Lima
Great job… What the type of rotary encoder?
Pierre
Hi Congratulations on your willingness to share your experiences with Roland Mc 500, I would like to ask you for advice, I recently bought mc500 even if in the past I had mkII, now I don’t have the sys disk and I don’t even have floppy on pc, i would like to bulk data via midi connection, do you think it is possible if possible
how do you advise me to achieve my goal.
Thanks again
Krystian
Thanks for this post.
So can you just get a standard Gotek drive and slot it in instead of the disk drive (with boot software etc on a USB)?
amsynths
Hi, you will need to configure the Gotek as a standard floppy drive replacement with the correct ID(0) and then its a straight swap.
Krystian
Thanks for your help.
One more question (as you seem to be the only person who knows about this stuff on the internet!) – my MC-500 (it’s not a MKII) uses MRC-500 ‘version 1.10’.
Is that something in between the original MRC software and ‘Super MRC’?
I don’t think it’s Super MRC because once it loads from the floppy disk, it doesn’t need to load anything again (I heard that because of smaller memory of MC-500s vs the MKIIs, it would otherwise need to load from the floppy disk each time you used some function).
Disk drive works fine at the moment and I have a few, but I may just buy a generic floppy disk drive emulator to have in case I need it, as I heard they are the same as the Gotek ones.
Thanks again!
amsynths
No there is no other software version just the MRC and Super MRC. MC500 Mk1’s could be hardware upgraded to a Mk2 but they usually have stickers on them for the new functions. Enjoy!
Krystian
Yeah it’s strange, as it shows up as version 1.10 when I load it. I really like my MC-500 – such a great unit, just finished my first song fully sequenced using it: https://www.youtube.com/watch?v=UL5gZzoKJmU
Mario
MRD-500 Rhythm Track Disk
Hi Would anyone out there know how to put the .sng files on a USB. As the Gotek only reads images.
Thank you in advance