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No generative AI was used in any way, shape, or form during the
composition of this post. See the Site-wide
Generative AI Statement for details.
Preamble
Ah yes, the venerable EDIROL SD-90. The legendary (but weird) combo
of a ROMpler and an audio interface in a box[1] used by
the mastermind behind the Touhou Project.[2] Released more than two decades
ago, surely there can’t be anything new to learn about this thing out in
the wild, right?
Turns out, that is not the case. I’ve never found an electronic copy
of the service manual for this machine online. I’ve had my SD-90 for
nearly three years at that point (prior to that I was using my SD-80), but I have still yet to
figure out how to boot into its test mode despite having systematically
exhausted all possible three-button combinations. So when I saw a
listing on ebay for a physical copy earlier this year, I knew I just
have to get it.
As soon as the service manual arrived, I was shocked to find out that
the correct button combination for booting into test mode is among the
first few combinations I tried – I just didn’t wait until the boot
animation finished playing because I simply didn’t have the patience for
that: there are a lot of three-button combinations to try when
you have 19 buttons!
But I didn’t stop there: I flipped through the entire 50 pages of the
service manual, making comparisons against its little brother SD-80’s
service manual throughout the way. In the process I found a lot of
curiosities about the design of this machine that clearly indicates its
transitional and experimental nature. And the purpose of this blog post
is to share these curiosities (mostly design details of the
PCB[3], as well as a few other interesting things) with the
world.
And of course just a few months after me paying the ransom, a scanned
version of the service manual popped up on archive.org.
Sigh.[4]
[5]
As usual, this article will be written in a way such that readers
with little knowledge in electronics will hopefully not find themselves
totally lost. However, please do keep in mind that the author of this
article is not a professional either. Corrections are always
welcome.
Firmware Revisions
My SD-90 seems to be a pretty early specimen. Its main board was
manufactured on 2001-10-27, still fairly early into the product’s life
cycle: some official documentation of the SD-90 was dated later than
that, e.g. the MIDI Implementation version 1.02 was dated 2001-12-12,
and the service manual was dated 2001-11. The MIDI Implementation
document shipped in the driver CD of my SD-90 is however version 1.00,
and dated 2001-10-11. Earliest snapshot of SD-90’s Japanese product
information page on the Wayback Machine is dated 2001-10-31. Mine came
to me with firmware version 1.02, which I assume is the version it was
shipped with and the previous owner never bothered to apply the
1.03 update which is available on Roland’s website.[6]
However as other people started checking the firmware version of
their SD-90, news of units on odd firmware versions started pouring in:
A few people’s units are running version 1.05. One even has a unit
that’s running 1.06. Unsurprisingly, these units were all manufactured
later than mine. But I could find no information on these newer firmware
versions online[7], and
they apparently do not provide any new functionality. So I’d assume that
these are factory firmware versions for later hardware revisions. And as
you will see later, there are actual hardware differences
between early and late units. So these newer firmware revisions might
have been made to accommodate these hardware differences.
Since I updated the firmware of my SD-90 to 1.03 before I knew how to
check the build information, I would never know when was version 1.02
built. However archived supported pages for the SD-90 on the Wayback
Machine indicates that version 1.02 was made public on 2001-12-10. The
same page has a reference to version 1.01 which I have never seen
running on an actual unit. The service manual shows version 1.00 in what
the version check would look like in test mode, however there is no way
for me to tell whether that information is accurate or just a
placeholder for demonstration purposes.
If you want to check the firmware version of your SD-90, you might
want to try the following button combinations (hold these buttons while
powering on the unit):
- inst/drum set + exit + preview
- mic/guitar + inst/drum set + system
All SD-90 firmware versions that I was able to personally confirm are
listed below:
|
Updater info
|
Ttl :---- [1655] 1.02
Prog:00FA [00FA] 1.02
Boot:AA1D [AA1D] 1.02
Updt:1284 [1284] 1.01
|
Ttl :---- [05A5] 1.03
Prog:1F50 [1F50] 1.03
Boot:AA1D [AA1D] 1.02
Updt:4B60 [4B60] 1.03
|
Ttl :---- [8488] 1.05
Prog:01D2 [01D2] 1.05
Boot:AA1D [AA1D] 1.02
Updt:4B60 [4B60] 1.03
|
Ttl :---- [11E9] 1.06
Prog:DAD7 [DAD7] 1.06
Boot:A9E6 [A9E6] 1.03
Updt:FAE5 [FAE5] 1.04
|
|
Build Number
|
?
|
0038
|
0041
|
0042
|
Build Time
(YYYY/MM/DD HH:MM)
|
?
(Not after 2001/12/10)
|
2002/06/06 10:00
|
2002/12/12 21:35
|
2005/03/17 14:00
|
Main board mfg. date &
Specimen courtesy of
|
2001-10-27 (me)
|
(No confirmed units shipped with this version)
|
2004-12-09 (Palto)
|
2005-01-24 (Eason20000)
|
PCB Madness
Even before obtaining my copy of the service manual, I was already
fairly familiar with the internals of the SD-90: I disassembled mine as
soon as it arrived to photograph its internals, noticing striking
similarities to the SD-80 in the power supply section, and later
performed a partial recap to address its noisy synthesizer output.
However, getting my hands on the full schematics and the parts list has
definitely revealed a few very interesting things about this
machine.
To buffer, or not to buffer
While we were trying to figure out the firmware versions, Palto
noticed that there is a chip missing in a PCB photo of my SD-90 while
the same position is populated on their board. This got me deeply
hooked, because this confirms the existence of different hardware
revisions.
Determined to figure out what is going on, I asked for more PCB
photos from Palto. Here is a list of differences I spotted:
IC30, IC31, IC32,
IC33, IC34, IC35 and supporting
components for these chips (mostly output resistors) are not populated
on my board. These are populated on Palto’s board.RA41, RA42, RA44,
RA46, RA47 are not populated on Palto’s board
while these are populated on my board.
RA41/IC30,
RA44/IC31,
RA42/IC32,
RA46/IC35, RA47/IC34
have overlapping footprints on the PCB so they cannot be populated at
the same time. These are all 0 Ohm resistor arrays (0 Ohm links).
All but one of the chips mentioned above are bus transceiver chips
(74LV245). The exception is IC33, which is four 2-input AND
gates in a single package (74LV08).
As a bus transceiver, the 245 connects 8 pairs of inputs and outpus
together. It allows the signals to flow in a set direction, which can be
flipped on demand with the DIR pin. More specifically, it
has two “ports” A and B, each with 8 pins A1-A8 and B1-B8. Depending on
the setting on the DIR pin, signals are allowed to travel
from port A to its corresponding pin on port B or vice versa. It can
also “disconnect” the ports altogether. This is controlled by the pin
marked /OE. When /OE is set to high, signals
are neither allowed to travel from port A to port B, nor from port B to
port A regardless of the setting on the DIR pin. This
effectively disconnects the ports.
Beside being used as a bus transceiver, some variants of the 245 chip
is also often used as a logic level shifter, especially in older
electronics that has mixed logic levels[8]. Initially this sounds like a
plausible reason why these 245 chips were put there: the XV chip is
powered by both 3.3V and 5V, therefore it might have used mixed logical
levels; and in the schematics the ports connected to these 245 chips are
named WA/3WA (for the wave memory address bus)
or WD/3WD (for the wave memory data bus), as
if it’s converting between 3V logic and a certain other logical level.
However, this is where the variant of the chip comes into play. The “LV”
in its part number 74LV245 is the variant. In this case,
the LV variant is not suitable for use as a level shifter. This is
rendered even less possible by the fact that in earlier production units
that lacked these 245 chips, signals that would pass through these 245
chips are connected directly through 0 Ohm links. If logical level
shifting is in fact required, that would be a bad design and might even
damage the XV and / or the wave memory chips.
Now here is the fun part: 3 of these 5 245 chips have their enable
pins and direction pins tied to the ground as well! This means that they
are always enabled, and fixed to a specific direction, which means they
are connecting each output to its corresponding input all the time, as
long as the chips are powered. These chips are all on the wave address
bus, which means the two designs are not that different as far as the
address bus of the wave bus is concerned[9].
The other two 245 chips are on the wave data bus and have their
enable pins connected to the /WOE (likely stands for “wave
output enable”) pins of the XV chips. This means that the XV chips in
late revision SD-90 units would have the ability to disconnect the data
output of the wave ROM chips from them. Why it would need to do that is
something I couldn’t answer: the /WOE pins of the XV chips
are also connected the the /OE pins of all the wave ROM
chips as well, meaning the same signal already have direct control over
the output right at the source. Their DIR pins are
controlled by the XV chips’ /WWE signal, which means
besides receiving data on the wave data bus from the ROM chips, the XV
chips would also be able to send data to the wave data bus. This would
only make sense if the flash memory (more details later) on the wave bus
is used, as that would be the only occasion where the XV chips need to
write to the wave bus.
IC33 implements glue logic for these two bus transceiver
chips on the wave data bus, as well as the unused flash memory on the
wave bus.
The SD-80 doesn’t have design variants when it comes to how the wave
ROM chips are attached to the DSP (i.e. its PCB does not have
unpopulated positions for alternative designs). It’s consistently using
the design of later SD-90 hardware revisions.
Those are all the differences we’ve spotted between our production
SD-90 units. Below are a few other interesting components marked “Not In
Use” in the schematics, but they were never populated on any production
boards that I’ve seen.
IC37 and IC45 are simple OR gates that
would allow the SH3 CPU (in addition to the XV chips) to control whether
the effect RAM chips’ output are enabled. These seem to be still missing
from later units, and are completely absent in XV-5080 and SD-80’s board
designs. In those models, only the XV chips control whether the outputs
of its effect RAM chip are enabled.
IC38 is an AND gate that connects the WBACK
and WBREQ pins of the XV chips together, but exposes one of
its inputs as a test point with a pull-up resistor that’s also not
installed. If this block is functional, the WBACK and
WBREQ pins of the XV chips would be effectively
disconnected when the test point is shorted to ground. This is possibly
just a leftover for internal testing. In production units, which lack
this chip on its board, a 0 Ohm link is installed to connect them
directly. In XV-5080 and SD-80’s design, all this extra testing
circuitry is completely absent and said pins are linked directly by
circuit board traces.
IC19 and CN7 seem to be related to an
additional encoder that’s removed in the final design. It was referred
to as ENC0 in the design while the 3 encoders that are
actually present on the SD-90 are referred to as ENC1 to
ENC3.[10] This seem to suggest
that the SD-90 was initially designed with a single value knob (like the
SC-8850) instead of 3.
Q13 and Q14 (close to the LCD backlight
power socket) are used for driving the LCD backlight with a PWM signal
from the XV chip. This suggests the SD-90 is designed with adjustable
backlight brightness (not just contrast, as available in production
units), but was scrapped before it reached production.
Robbed memory
There are footprints (IC42, IC43) for two
additional memory chips that are on the wave bus. These two chips are
never populated in any of the SD-90 specimens that I’ve seen.
IC42 is just another 128 Mbit Mask ROM chip, very much
like the two that are installed on all SD-90 units (IC40
and IC41). This position is not reserved as a simple
substitute for either IC40 or IC41, as it has
its own, distinct chip select line. Therefore its capacity would be
added to the total wave ROM capacity were it installed. The only notable
difference is that the part number designated for IC42 is
23C128000LGY, while IC40 and IC41 has the part
number 23C128040LGY. The difference between these two parts is that
000LGY does not have the page access mode that 040LGY
has.[11] I’ve never seen Roland
using the version of this ROM chip that doesn’t have page access
mode.
This chip does not have its “mask code”[12]
printed in the service manual. This could mean the content of this chip
was never finalized and passed on to the mask manufacturing process.
If IC42 was used alongside IC40 and
IC41, the SD-90 would have 48 MB of compressed samples (96
MB uncompressed using Roland’s calculus). Roland never released a
sample-based synth that came with 48 MB of compressed samples (that I’m
aware of). Update 2026-04-28: Actually, they did. Both the VA-7
and VA-5 had 48 MB of wave ROM. These models are extremely interesting
in their own right[13], but I
don’t have the time to go too deep into that right now. Now back to your
scheduled programming: although they did release ones with 24 MB of
compressed samples, which include the SC-8820 and its relatives. In
later sound modules with bigger wave ROMs, they jumped straight to 64 MB
of compressed samples.
Imagine what they could have done with 16 MB of additional space for
samples. They could probably squeeze the entire RD-700 piano in there
(equivalent to the piano found in SuperQuartet), alongside possibly not
crippling a few sample sets (e.g. keeping all velocity layers of the XV
acoustic guitar samples). Oh the missed opportunities!
The specific parts used for IC40 and IC41
had changed throughout the production too. In fact, there are at least 3
equivalent set of ROM chips used seemingly interchangeably through the
entire lifespan of the Studio Canvas product line (The R-number is
Roland’s internal part number):
| SD-90 Parts List & Schematics |
UPD23C128040LGY-529-MJH (R02678601) |
UPD23C128040LGY-535-MKH (R02678612) |
My SD-90
(MB mfg. 2001-10-27) |
R02678601 23C128L-529J 0127E7001 |
R02678612 23C128L-535K 0127E7002 |
Palto’s SD-90
(MB mfg.
2004-12-09) |
R03010612 23C128AL525J 0419E7001 |
R03010623 23C128AL526K 0420E7001 |
Eason20000’s SD-90
(MB mfg.
2005-01-24) |
R03010612 23C128AL525J 0451E7001 |
R03010623 23C128AL526K 0451E7002 |
| SD-80 Parts List & Schematics |
UPD23C128040ALGY-525-MJH
(R03010612) |
UPD23C128040ALGY-526-MKH
(R03010623) |
My SD-80
(MB mfg. 2004-08-27) |
R02678601 23C128L-529J 0224E7007 |
R02678612 23C128L-535K 0222E7005 |
Palto’s SD-80
(MB mfg.
2005-07-25) |
R03010612 23C128BL832J 0525K7002 |
R03010623 23C128BL833K 0525K7003 |
My SD-20
(unknown mfg. date) |
R03010612 23C128BL832J 0620K7002 |
R03010623 23C128BL833K 0620K7005 |
Palto’s SD-20
(unknown mfg.
date) |
R03010612 23C128AL525J 0229E7005 |
R03010623 23C128AL526K 0229E7006 |
… what a mess.
Keep in mind that a different mask code for chips in a slightly
different series does not necessarily translate to different data
stored. This can be back by the fact that the BLGY-version of the chips
and ALGY-version have different mask codes, but identical Roland part
numbers, which indicates that Roland saw them as exact equivalents and
should therefore have identical data.
It’s plausible that the last line of the engraving on these ROM chips
is a date code in the format of
<last two digits of year><week> (which seems
consistent with other lines of evidence). If that’s the case we can
easily reconstruct a time of these parts: they started production using
the LGY-version of the chip, switching to the ALGY-version and then the
BLGY-version later. But they definitely grabbed whatever was available
on their production lines at times too.
If that already sounds wacky, I have more in store for you: the story
of IC43 might be way more interesting, because it’s a 32
Mbit (4 MiB) flash memory chip directly connected to the wave bus!
If this sounds crazy, it’s because it is: No other Roland
sample-based synth from this era that I’ve seen has a flash memory chip
directly hooked up to the main synthesizer DSP chips. All models with
sample playback / sampling capability that I’m aware of must first load
the samples into some form of RAM first. The flash chip they had chosen
however, does seem fast enough to behave like all the other ROM chips on
the wave bus. The write enable input of the flash memory chip is
connected to the /WWE pin of the XV chips through some
trivial logic, so this chip can definitely be written to, making it
unlikely that it’s just a factory configuration vessel that is only
written once when the product leaves the factory.[14] The same /WWE signal
is also used to flip the direction of the transceiver chips on the wave
data bus so that the XV chip can send data to the flash chip. In the
XV-5080, the /WWE pin of the XV chips are connected to pin
47 (/WE) of the RAM socket, although the way it control the
signal direction on its wave data bus is much more complicated. This
/WWE pin is completely unused in all other Roland devices
that use the XV chip that I’m aware of (XV-5050, SD-80, FA-76 and
MV-8x00), with the notable exception of the Fantom-S/S88 and MC-909. In
these two models the /WWE signal would go into a 74LV245
chip (used in the same way as those always-enabled unidirectional level
shifters in later SD-90 units), and then seemingly vanish right there.
Coincidentally both the Fantom-S and the MC-909 do support sampling into
a wave RAM, but they use a dedicated “BA” chip as their memory
controller.
One plausible explanation of why this existed in the design is Roland
wanted to make the SD-90 their response to Yamaha’s MU2000, which also
has sampling capabilities, and coincidentally has 4 MiB of temporary
sample storage[15]. Despite having multiple audio inputs, the
MU2000 does not serve as a USB audio interface. In addition Roland’s
design would have made the SD-90 a completely self-contained solution:
no additional storage would be required to permanently retain the
samples. Sounds like the SD-90 would be a all-around winner if had this
chip, right? Unfortunately their design also makes loading samples a
pain: it would probably involve some kind of proprietary communication
over MIDI or USB. So maybe the MU2000 would still have a chance if the
SD-90 was released with sampling capabilities[16].
But at the end of the day this would be pretty useless, just
like MU2000’s sampling feature: 4 MiB of storage is not even
enough for one minute of 44100 Hz single channel audio.
The way the chip select lines for these wave memory chips are
connected is interesting when compared against the XV-5080. In the
XV-5080, the two built-in wave ROM chips are selected first as a single
entity using /WCS0, then selected between these two using
WA23 with a small 2-to-3 line demuxer. In the SD-90, a
similar approach is implemented with a 3-to-8 line 74LV138 demuxer. The
SD-80 uses yet another different design, but it is basically a
simplified version found in the XV-5080. This commonality between these
different approaches is that this way the XV chip could treat the two
built-in wave ROM chips as one big 32 MiB chip, rather than two
individual 16 MiB chips.
This could make sense for the XV-5080, since in a fully expanded
XV-5080, it has to be able to address 2 * 16 MiB + 4 * 8 MiB + 4 * 32
MiB = 192 MiB of wave ROM. It could be important to save a few chip
select lines, as the XV chip only has 8 of them. But in the SD-90 /
SD-80, they might as well treat the built-in wave ROM chips as separate
chips to reduce the complexity of the hardware. The only reason that I
can think of that explains why they did it this way is to maintain some
level of hardware compatibility with the XV-5080 so they can reuse some
of the software code written for the XV-5080.
Which port we using again?
The XV chip seems to have 6 output channels and 2 input channels for
serial digital audio data. They are marked
SDO0, SDO3, SDO4, SDO5, SDO6, SDO7 and
SDI1, SDI2 respectively in service manuals for various
products[17]. Among these, SDO0 and
SDI1 seem to double as part of a 6-bit wide full
duplex communication channel (PO5 and PI5 of
PO[0..5] and PI[0..5]
respectively)[18]
between the XV chips when a pair is used in a design[19], and they are always used this
way. Even in models where there’s only one lone XV chip, these are never
used as audio I/O ports.
The other ports are used in an interesting, consistently inconsistent
fashion, summarized in the table below.
| SD-90 |
(unused) |
INST
(MR3 AD0) |
(unused) |
(unused) |
(unused) |
(unused) |
| XV-5080 |
Coaxial / Optical Output |
Output A
(Analog &
R-BUS)
Front Panel Phones Jack |
Output B
(Analog & R-BUS) |
Output C
(Analog & R-BUS) |
Output D
(Analog & R-BUS) |
Input A
(R-BUS)[20] |
| SD-80 |
Coaxial / Optical Output |
Output A
(Analog)
Front Panel
Phones Jack |
Output B
(Analog) |
(unused) |
(unused) |
(unused) |
| XV-5050 |
Coaxial / Optical Output |
Output A
(Analog)
Front Panel
Phones Jack |
Output B
(Analog) |
(unused) |
(unused) |
(unused) |
| Fantom-S |
To CPU?
(SY-PPC
PPC-SD)[21] |
(unused)[22] |
Output B
(Analog) |
Output A
(Analog)
Phones Jack |
Coaxial / Optical Output |
Analog Input L/R |
| MC-909 |
To CPU?
(SY-PPC
PPC-SD) |
Direct 2 Output |
Direct 1 Output |
Mix Output
Front Panel Phones
Jack |
Coaxial / Optical Output |
Analog Input L/R |
| MV-8800[23] |
Coaxial / Optical Output |
MV8-OP1
Output 1-2
(Analog &
R-BUS) |
MV8-OP1
Output 3-4
(Analog &
R-BUS) |
MV8-OP1
Output 5-6
(Analog &
R-BUS) |
MV8-OP1
Output 7-8
(R-BUS) |
MV8-OP1
Coaxial / Optical
Input
R-BUS Input 1-2 |
Power supply
As already mentioned, the SD-90 has an extremely similar power supply
section to the SD-80, even just by looking at the circuit board. In fact
they are built around exactly identical core components.
I find the design based around a buck regulator used in the SD-90 and
SD-80 much more reliable than the linear regulator design used in, say,
the XV-5080.
Display module
When I was looking for display modules for an unrelated project, I
realized displays that are almost identical to the one used in the SD-90
are still being manufactured, for example NHD-C12864WO-B1TMI#-M.
This particular one seems to be a drop-in replacement. In fact, it seems
to be possible to rewire any 128×64 LCD display that can use the
parallel 8080 interface into the SD-90.
Although the SD-90 does indeed have a terrible display, I’m not in a
rush to buy one of these to replace the factory LCD. Primarily because
all drop-in replacements are also STN displays, so it’s likely that they
are going to look equally terrible. Replacing it with an OLED module
would be an interesting idea and will certainly look much nicer, but
would also require rewiring, and right now I simply don’t have time for
that.
“Emurator”
There is an unpopulated D-SUB connector[24] near
the CPU, which the SD-80 also has. In SD-90’s service manual, it is
marked “Emurator”[sic]. Signals connected to this port directly
correspond to those used by the Hitachi User-Debugging Interface from
the CPU. The datasheet of the CPU describes the Hitachi User-Debugging
Interface as a JTAG-compatible interface. The section on the H-UDI does
mention an emulator, as well as Advanced User Debugger (AUD), which
appears in the names of multiple signals going into the port, confirming
this port is used during development of these products. Hitachi’s E10A
emulator kit (both the hardware and software) is the official tool used
with this port.
Shared lineage with SC-D70
The SD-90 shares two major ICs with the SC-D70, which can be
considered a weaker predecessor of the SD-90. They are both sound module
/ audio interface combo devices. The shared major ICs are all in the USB
/ Audio interface section.
| M37641M8-106 |
IC48 |
IC21 |
Mitsubishi 7600 series microcontroller
with 32KiB ROM, used as USB controller |
| TC203G08AF-1017 (“KD chip”) |
IC47 |
IC25 |
Roland ASIC made by Toshiba, 6 in / 6 out
USB audio interface |
Note that this USB controller chip runs code stored in its built-in
mask ROM, the 106 in its part number being the mask code. This means the
USB controller in the SC-D70 and SD-90 are running exactly the same
firmware.
The USB audio interface seems an overkill for both. 4 inputs and 4
outputs are simply wasted, making me speculate it might have been used
in other Roland products. However I couldn’t find such a product.
The SC-D70 is interesting in its own right. Besides the obvious
shared components with the SC-8820 and SC-8850 (as its tone generator
section is essentially a SC-8820), it somehow also has an ESP4 chip
inside, making it the earliest Roland product to use this chip to my
knowledge. This chip is also used as a secondary DSP inside Fantom-S,
MC-909, and MV-8800. It’s the primary DSP chip in the V-Synth. As I
don’t own one to test how is the ESP4 connected to the other chips, nor
do I have access to its service manual, I currently do not have any idea
what this chip is used for in the SC-D70.
SC-8850 expansion
Speaking of the SC-8850, here is something I must address despite it
being completely off-topic for this post. As soon as I saw the circuit
board of SC-8850’s main board, I noticed a big, unpopulated 50-pin
header near one of its XP6 chips. It’s only marked as CN8
on the circuit board. But its proximity to the DSP section and one of
the wave ROM chips made me speculate that it might be some kind of
expansion slot.
Turns out, that is exactly the case. The component is labelled
“50P-Header Expansion-Slot (NIU)”, and is a Molex 52411 plug, which is
the same series of socket used for the SR-JV80 expansion boards. However
SR-JV80 expansion boards use a narrower version of the socket that only
has 40 pins.
This got me interested in comparing Roland’s sound expansion formats
used over the years …
|
SN-U110
|
34
|
1
|
19
|
8
|
512 KiB
|
U-110 & U-220
|
|
|
SN-R8
|
34
|
1
|
19
|
8
|
512 KiB
|
R-8
|
Electrically identical to SN-U110 cards
|
|
SO-JD80
|
40
|
1
|
21
|
8
|
2 MiB
|
JD-800/990
|
|
|
SO-PCM1
|
40
|
1
|
21
|
8
|
2 MiB
|
JD-990, JV-80, JV-880, most JV-series
|
Electrically identical to SO-JD80 cards
|
|
SR-JV80
|
40
|
4
|
21
|
8
|
8 MiB
|
JD-990, JV-80, JV-880, many others
|
|
|
“SC-8850”
|
50
|
4
|
21
|
16
|
16 MiB
|
Never released
|
|
|
SRX
|
80
|
8
|
23
|
16
|
128 MiB
|
XV-88, XV-3080, many others
|
Theoretical max capacity never reached.
Commercial releases all had
32 MiB ROM or less.
Has additional serial EEPROM, likely for board
identification purposes
|
|
ARX
|
70
|
Not a simple ROM expansion.
|
Fantom-G
|
Has a full synth engine built into it.
Connects to host CPU via UART
(likely based on MIDI protocol), and I2S-style serial digital
audio.
Akin to Yamaha’s PLG-100 / PLG-150 boards.
|
The theoretical max capacity is calculated using the formula 2(#
of address signals)×(# of data signals)×(# of CS lines)÷8. The
result is the theoretical max capacity in bytes.
So Roland apparently attempted to develop a new expansion format just
for the SC-8850 eh? Seems a weird thing to do for a product category on
its way out … Oh that’s probably why it was scrapped.
Again this excellent
article from Edward D-tech has more details on the actual content of
these expansions.
IC listing
See below for a list of all ICs as installed on the main board (as
well as select ICs installed on the analog board) inside my SD-90.
Please note that this information is NOT from the service manual.
It’s read off actual PCB of my SD-90. Some remarks contain information
derived from my reading of the schematics. If you skipped straight to
this section, you may want to refer back to early sections where
unpopulated chips are discussed in more detail.
IC listing
|
Label
|
Engraving
|
Remark
|
|
IC1
|
62292 071
|
Voltage regulator with dual output
|
|
IC2
|
SH-3 1E3 F100B HD6417709A JAPAN
|
CPU, SH7709A
|
|
IC3
|
LH28F320BFE-PBTL80 SHARP JAPAN 0132 32B
|
Flash memory, 4 MiB
|
|
IC4 IC6
|
SAMSUNG 120 K4S161622D-TC80 T7D049A3 KOREA
|
CPU SDRAM, 2 MiB
|
|
IC5
|
7W04F 1E
|
Inverter
|
|
IC7 IC8 IC9
|
P14A0 VT245A
|
Bus transceiver
|
|
IC10 IC13
|
01 42 H LVXC3245
|
Bus transceiver
|
|
IC11
|
(illegible)
|
OR gate
|
|
IC12
|
0134H VHCT139A
|
Demuxer
|
|
IC14
|
VHC T04A 130
|
Inverter
|
|
IC15
|
(illegible)
|
AND gate
|
|
IC16 IC49
|
1C26 LV 00A
|
NAND gate
|
|
IC17
|
E1
|
NAND gate
|
|
IC18
|
1D36 LV 04A
|
Inverter
|
|
IC19
|
(Not installed)
|
DQ flip-flop for additional encoder knob.
|
|
IC20
|
1G26 LV 14A
|
Schmitt trigger inverter
|
|
IC21 IC23 IC24
|
0M16 LV 74A
|
DQ flip-flop
|
|
IC22
|
(Not installed)
|
DQ flip-flop in encoder circuitry. Bypassed in production units.
|
|
IC25 IC27
|
1D16 LV 08A
|
AND gate
|
|
IC26
|
BOSS R02565501 RA0B-B01 JAPAN 0130EPI F0006ZA8
|
DSP (“MR3”). Found in many BOSS effects (BF-3, DD-20, etc.), EDIROL
portable recorders (R-1,
R-4,
etc.), among other things (SP-404 etc.).
4 pairs of
I2S-style digital serial audio I/O (8ch in, 8ch out).
Curiously does not require external RAM despite many effects implemented
with it typically require a buffer.
|
|
IC28 IC50
|
1A4S LV 138A
|
Demuxer
|
|
IC29 IC39
|
Roland R01455956 RA08-503 JAPAN 0124EAI F0013ZBB
|
DSP (“XV”)
|
|
IC30
|
(Not installed)
|
Bus transceiver on wave address bus. /OE and
DIR tied to ground. Present in newer units.
|
|
IC31
|
(Not installed)
|
Bus transceiver on wave address bus. /OE and
DIR tied to ground. Present in newer units.
|
|
IC32
|
(Not installed)
|
Bus transceiver on wave data bus. Present in newer units.
|
|
IC33
|
(Not installed)
|
AND gate. Glue logic for unused bus transceiver chips on the wave data
bus, as well as the unused flash memory on the wave bus. Present in
newer units.
|
|
IC34
|
(Not installed)
|
Bus transceiver on wave address bus. /OE and
DIR tied to ground. Present in newer units.
|
|
IC35
|
(Not installed)
|
Bus transceiver on wave data bus. Present in newer units.
|
|
IC36 IC44
|
ESMT M11B16161A- 45T DZW1H8929 0126
|
XV EDO DRAM, 2 MiB
|
|
IC37
|
(Not installed)
|
OR gate. Lets CPU disable the effect RAM of the first XV chip.
|
|
IC38
|
(Not installed)
|
AND gate. Presumably used during development.
|
|
IC40
|
Roland R02678601 23C128L-529J 0127E7001
|
Wave ROM, 16 MiB. Later units used mask ROM of a slightly different
series (23C128AL525J, Roland P.N.
R03010612).[25]
|
|
IC41
|
Roland R02678612 23C128L-535K 0127E7002
|
Wave ROM, 16 MiB. Later units used mask ROM of a slightly different
series (23C128AL526K, Roland P.N. R03010623).
|
|
IC42
|
(Not installed)
|
Third 16 MiB wave ROM.
|
|
IC43
|
(Not installed)
|
4 MiB flash memory connected directly to the wave bus.
|
|
IC45
|
(Not installed)
|
OR gate. Lets CPU disable the effect RAM of the first XV chip.
|
|
IC46 IC51
|
129100 M5M5256DFP -55LL
|
SRAM, 32 KiB
|
|
IC47
|
Roland R02234767 203G08F1017 JAPAN 0052EAI B0196DAB
|
USB Audio Interface ASIC. 3 pairs of I2S-style audio I/O (6ch
in, 6ch out).
Seems to have pins for the ESP bus
too, but are left unused in the SD-90. This chip is also found in
SC-D70.
|
|
IC48
|
Roland R02451356 106 052100
|
USB controller. Also found in SC-D70.
|
|
IC52
|
P145B 74VHC4046
|
PLL/VCO
|
|
IC53
|
0131H 9246
|
PLL
|
|
IC54
|
A E
|
Voltage regulator
|
|
IC55
|
7WU04F 1H
|
PLL
|
|
IC7 @ Analog Board
|
AKM AK4524VF 090A0123N
|
ADC/DAC
|
|
IC11 @ Analog Board
|
PCM1728E L0004E
|
DAC
|
|
IC18 @ Analog Board
|
CS8420-CS EP ZYAFMD0102
|
Digital audio sample rate converter
|
Test Mode
I don’t have much to say about the test mode in the SD-90 except it
does what it’s supposed to do and is in many ways extremely similar to
the test mode in the SD-80.
If you’re wondering what the key combination to enter test mode is
for the SD-90, it’s already referenced at an earlier point in this
post.
A repair that nobody wanted
to do
I daily drove my SD-90 as my primary soundcard for roughly two years,
mainly to combine the sound output of two computers. Later in this
period, the synthesizer portion of my SD-90 started generating noise in
its output, which sounds quite like what
some people have heard from their XV-5080[26]. It was even heard in the USB output, so the fault
has to be in the DSPs.
As I didn’t have a oscilloscope, I couldn’t check the ripple on the
power rails. I didn’t have a replacement for the regulator used in the
SD-90 on hand, but I already had a bunch of capacitors (which were
bought for my XV-5080 repair), and fully convinced that SD-90’s voltage
regulator design is more reliable than the one in the XV-5080, I decided
to try just a partial recap first.
I focused on the main power rails and bypass capacitors close to the
DSP chips first. These are the capacitors I replaced:
C1, C3, C4, C139, C150, C173, C205, C232
I didn’t have access to the schematics when I did the recap. But if I
did, I’d also have replaced C157, C187,
C191, C212, and C219.
The original capacitors taken off the board seem to hold their
original capacitance pretty well (all > 60% their designated
capability), but some had terrible ESR[27] (almost 100 Ω for 16V 10µF ones).
Most SD-90 units are produced during the height of the infamous capacitor
plague. Although all electrolytic capacitors specified in SD-90’s
parts list are made by Japanese manufacturers and therefore
theoretically weren’t affected by the plague, it’s not guaranteed that
they didn’t switch supplier later into the production: Roland is known
to switch supplier for non-critical parts like DRAM chips throughout a
product’s life time. As an example, my SD-90 (early production, mfg.
2001-10-27) was built with DRAM chips specified in the parts list
(Samsung DRAM chips for CPU RAM, ESMT DRAM chips for XV effect buffer).
But Palto’s SD-90 (mid-late production, mfg. 2004-12-09) uses Sanyo DRAM
chips for the CPU and ICSI DRAM chips for the XV chips. I am however not
familiar enough with how surface mount electrolytic capacitors are
marked to tell the actual manufacturer of the capacitors installed in my
unit. What I can tell is that: a) the markings for capacitors
in Palto’s unit seem identical to those in mine, b) I do recognize the
markings on the bigger capacitors I swapped out (“SVP”): those are the
SVP series of Sanyo’s OS-CON capacitors (as specified in the parts
list), and c) of all the capacitors I swapped that had pretty terrible
ESR values, they showed no sign of electrolyte leakage.
I haven’t heard noise from the internal synthesizer since the recap.
I also ceased daily driving my SD-90 as my main soundcard. Be nice to
your obsolete audio equipment, folks!
Driver issues
Starting from a certain insider release of Microslop Windows 11 from
late 2024, the Windows 8 driver for the SD-90 would no longer function
properly on my computer. All audio recordings produced from the device
(regardless of the API used, be it WASAPI, ASIO, or WINMM) were either a
choppy mess, or just complete noise.
I tried a bunch of workarounds, the only thing that worked was
forcing UA-25EX’s Windows 10 driver onto the SD-90. This however leaves
only the primary MIDI port accessible (as the UA-25EX only has one MIDI
port), so it’s not a perfect solution.
I’ve asked around when I first saw the issue, and apparently nobody
at the time had the same issue as me. I suspect that it might have
something to do with me being on the Winblows 11 insider dev channel
(now the canary channel). I haven’t asked anybody since, but now that
ZUN himself is also experiencing driver issues, I guess this has become
a more wide-spread issue.
On Linux, the generic USB Audio/MIDI driver is used just like the
audio-less SD-80, even when the USB Driver is set to Vendor on the
SD-90. As I’ve also noticed for the SD-80, the MIDI performance on Linux
is noticeably worse than on Windows with an official driver. However at
least it never produced unusable recordings.
Other random rants
I had much to say about SD-90’s built-in sound module and the
differences between it and the SD-80 in my second SD-80 post. Click here to read that
rant.
I got my SD-90 for 150 USD, and it arrived with all the original
paperwork and software discs, a bargain if I do say so myself.
The built-in audio effects of the SD-90 is not a feature I used very
often. In fact I think I might have used it exactly once in
production.
If you came here for a generic review of the SD-90, and have been
tremendously disappointed to find out it’s anything but: well, first of
all I’m surprised that you’re still here reading this. And why don’t
check out these other excellent posts?
That’s about it. Phew! That went on for much longer than I
thought!
Gallery
All photos in this gallery are taken by me. I offer my apologies in
advance for all the shaky and out of focus photos.
 “This is peak.”
|
 “XGL.”
|
 Connected to a
PowerBook G4 and disguised as XV-5080.
|
 Least buggy
MacOS X software.
|
 Accessories.
|
Disassembled in the first hour?!
|
 Early
specimen. Multiple unpopulated components visible.
|
 CPU.
|
 CPU RAM and
flash memory.
|
 USB
controller and audio interface.
|
 First XV
chip.
|
 Second XV
chip and one of the two sample ROM chips.
|
 Second
sample ROM chip and effect RAM chips.
|
 Power
supply section and MR3 DSP chip.
|
 Major
chips on the analog board.
|
 Power supply
section with new capacitors. Go ahead and roast my terrible solder
joints.
|
 Other swapped
capacitors. Red capacitors are 100% more powerful when they blow up.
|
 How I did the
recap. There’s no flux in sight …
|
 Service manual.
Mystical 1.00 firmware. Yes I was reading it on the road.
|
 Version
information.
|
Acknowledgements
Major thanks go to KRPalto47 for the PCB photos and morale support.
I’d also like to thank Eason20000 and others in the Touhou Instrument
Sources Research server for providing firmware version information of
their units.
Special thanks to archive.org’s Wayback Machine for preserving the
Internet’s history.
[1]: There aren’t a
whole lot of Roland products that share this feature set: SC-D70, SD-90,
SD-50 and SonicCell. That’s all that I can recall.
[2]: ZUN alluded to the
idea of finally stop using it altogether in a recent event, citing
difficulties installing the driver. Curse you, Microslop! But one thing
he said when they were on this topic is very true: it is not the
instrument he used that made his music distinctively “his”. Also here’s a link to the event
live stream with the timestamp, if you want to check out in detail
what they were talking about.
[3]: PCB: Printed Circuit Board, not Perfect Cherry
Blossom.
[4]: Until you noticed who uploaded it…
[5]: Well, it seems that Archive.org decided to take it down before
this post is even made public. Contact me if you want to see portions of
the manual I guess?
[6]: Well,
it’s been on the Japanese website, and it’s still there as I’m writing
this blog post. However I couldn’t find anything about this update on
their English website.
[7]: Except this vogons post,
which unfortunately doesn’t provide much insight either.
[8]: For example, some chips
take any voltages > 2V as a logical 1, while others take voltages
> 3.5V as a logical 1.
[9]: It can be argued that
since there are some amount of semiconductors between the XV chip and
the wave ROM chips in the newer design, these cheap transceiver chips
may serve as some form of protection for the ROM chips if things ever go
wrong, i.e. if the XV chips go crazy, instead of damaging the ROM chips,
the transceiver chips get damaged, protecting the ROM chips. But that’s
certainly not guaranteed to happen.
[10]: These are the names used for their signals
on the main board. On the analog board where these encoders actually sit
on they are actually referred to as EN2, EN3,
and EN4 for some reason.
[11]: Having support for page access basically means accessing
consecutive addresses can be faster.
[12]: Each mask ROM has a
“mask code” assigned by its manufacturer. You can think of this as an ID
for the master copy of the content stored in that chip. All mask ROM
chips from a given series bearing the same “mask code” should
theoretically have exactly the same data. Conversely, chips in the same
series but different data usually have different mask codes.
[13]: For example, evidence from their owner’s
manual and service manuals seem to suggest that these are designed in
Italy instead of Japan, by Roland Europe s.p.a. Internals of these
models also show an extremely different design philosophy, one that’s
almost too modular. This entity seems to be the one responsible for a
few lower-end / education-oriented / oddball products from that era,
like the EM-10/20, EM-2000, VA-76 and VA-7/5. I’ll stop there before
this post gets hijack into a post on Roland Europe.
[14]: Although this
doesn’t rule out the possibility that it’s only written to when a system
update is being installed.
[15]: Since the MU2000 loads / records samples into a
4 MiB wave RAM, permanent sample storage requires a SmartMedia card to
be installed.
[16]: Also keep in mind
that the MU2000 was released almost two years before the
SD-90!
[17]: I have no idea why SDO1,
SDO2, and SDI0 are skipped, but they seem to
be completely absent from any pin function markings that I’ve seen. A
similar situation exists in the XP series of chips, but they have one
fewer output port, and the ports are named differently too:
SDOA[0..5] and SDIA[0..5] for the “ESP bus”,
and then SDOB, SDOC, SDOD plus the input named
SDIB.
[18]: This mechanism existed since the original XP
chip. It’s sometimes referred to as the “ESP bus”, even in models that
doesn’t use the ESP4 chip. In addition to point-to-point communication,
it also supports a ring topology, e.g. in the Fantom-G: WX chip ->
first WSP chip -> second WSP chip -> back to WX chip.
[19]: Sometimes
between it and another type of DSP chip as well, e.g. the ESP4 chip in
Fantom-S, MC-909, and MV-8800.
[20]: The XV-5080
doesn’t seem to do anything meaningful with this input.
[21]: Fantom-S and MC-909 have menus that
display a real-time VU meter. If I’m going to make a blind guess, that
is probably what the signal is used for.
[22]: Goes into the AK4527B
DAC, but the output doesn’t go anywhere. This output is used in the
MC-909, which shares basically the same main board.
[23]: MV-8800 handles its
onboard analog audio through the ESP4 chip.
[24]: The indicated part
number is actually a Miniature High Density connector.
[25]: Because it’s a chip from a different series, a
different mask code does not necessarily indicate changed
content.
[26]: This was
unfortunately also experienced by
me.
[27]: equivalent series
resistance
]]>
