[sdiy] Roland MKS-80 Revision Differences

[cheater cheater]

Hi guys... I have two MKS80's here...

One has a broken cartridge slot - any idea how much this part could
cost and where I would get one?

TL;DR: they sound almost the same and the difference is probably going
to be easy to mod in or even trim in.

There are some sonic differences between them, wonder if you guys can
come up with where they come from. It might be due to fine-tuning: I
haven't calibrated the units (yet? - not sure if I want to tune the
Rev3, it sounds just right, but the Rev4 can definitely use some time
with me and a screwdriver)

One is Serial No. S00001, a Rev3, the other is an SN491214, a Rev4.

The sound differences might be a bit more than the zone of two units
of the same model/revision sounding different, but not that much
overall. The xmod is somewhat different (probably due to calibration
as the XMOD area seems very much the same electrically), and the
thing's output distorts in a different way.

They both sound vastly different from the Rev 5 I had a chance of
using via Richard in Cambridge, who sold me a couple Yamaha SY-2's
which both sound different from each other as well!

Let's start with the most obvious difference, the DAC:

one has IC10 coded:
Intersil
ITS80141
8311 A

and next to it IC11:

TL081CP
J333A

and IC12:

IR9022
544C
SHARP

The new one has a socket for IC10 into which a board was input:

It has got:

-two small toshiba DIP-10's (narrow body) labeled:

TC40H273P
8439H

(they have an 'old' Toshiba logo with a pretend-hand-written cursive fontface)

- A part with what seems to be the mitsubishi logo (could be wrong:
it's a triangle with what seems to be smalle triangles on its
vertices. it's very fuzzy)
It is labeled:
D/A CONVERTER
MD6205 2510

It's a weird die format that i've never seen before. It has a silicon
die in the middle, and it's on what I've seen referred to as a
'hybrid'. That hybrid is a white board and holds the pins. The silicon
die is a bit smaller than the hybrid and the difference is glued
together with what looks like gray silicone glue.

The add-on board also has 4 small caps and a small resistor. It has
wires going off to IC12:

IR9022
54XA (probably a different lot)
SHARP

red wire connects to top left pin, blue to bottom right pin, seen with
text facing the normal way.

IC11 is changed to:
TL081CP
J441A (different lot?)


Wonder if that's similar to the 'bit depth' upgrade the Jupiter8's
have seen (and maybe Jupiter 6's? Did they have one?)

--------------

Interesting to note that both have BA662 311 A's in the VCO 1 and 2
mixers for IC37A-D and IC38A-D respectively except the older unit has
a BA662 401 A for IC37B. It certainly is factory installed. All
BA662's are 331 A on the lower slave board.

The VCOs on the old one are all:
CEM3340
MOH 2466F-01
8328
(with a white dot)

The VCOs on the new one are two kinds:
CEM 3340
8431 2468G-01
(white dot)
upper board: IC32A, IC32C, IC34A, IC34C
lower board: IC34D

CEM 3340
8435 2466G-01
upper board: IC32B, IC32D, IC34B, IC34D
lower board: IC32A, IC32B, IC32C, IC32D, IC34A, IC34B, IC34C


The old one has the waveform selection chips:
(motorola logo) MC14052B
CP  J8416
for IC36A, IC36B, IC36C, IC36D

The new one has:
4K4 Y
HD14052BP
for what is now labeled as: IC36AB, IC53AB, IC36CD, IC56CD (they're
the same sockets as the old IC36)


(Most) el caps near the hinges are 35V 47 uF 105*C on the older one
and 50V 1 uF 85*C for the newer one.

Some more differences in the filter part as well:
The CEM3360's are a different rev, and so is the IR3109.

The IC46 JFET is changed from the old one's
082DT
JRC
3107

to a:
TL082CP
J441X

Anyone know what it does? Possibly the voice mixer's makeup stage. The
new one sounds somewhat cleaner - but then, less beefy - wonder if
that could be a related thing.. Wonder which of those is electrically
superior. Maybe the TL082 has a trimpot somewhere that will give it
more/less distortion...

Oddly enough, one end of a resistor in RESO CV AB in the old one
didn't make it through the hole, it's soldered to the next resistor's
leg.

The pcb layout is a bit different in the old one where the new one
(MKS80 rev4) has an empty spot for C143. It has got some wire patching
in that place and no silk screen.

The Rev3 slave board has some hotwiring on the underside, and even
some resistors added here and there. The Rev4 has the same resistors,
but there's no hotwiring. The wires are stuck onto the board with the
same gray silicone glue as in the DAC - seems the Roland Corporation
was very fond of gray glue ???

The rev4 really sounds like it needs some fine-trimming. For example
one of the voices seems to decay longer than the others..

On both of them, the stand-offs supporting the lower module board are
broken. On the older one, one of the lower stand-offs has broken off
where it screws into the part that is welded to the chassis. On the
newer one two of the things that the lower standoffs go into have
become unwelded from the chassis (the weld points broke off).

The Rev3 supposedly belonged to James Brown and the Soul Collective,
as a side-story. Was difficult to get it off the previous owner - had
to notify the police after he would keep hanging up on me for a week.
He'd sent it out the same day, but I'm still waiting for the receipt
so that I can file it on expenses (another case for Scotland Yard?).
When it warms up it smells of what seems to be vanilla cigars or club
smoke. Probably not club smoke. Did James Brown smoke vanilla cigars?
(I might be wrong - never been a smoker - but that's sort of what it
smells like). Wonder if someone can confirm or deny that little
factoid about it having belonged to Brown. Either way - not selling
this one - it sounds real good, no matter who used it before. It
sounds so good it's allowed to stink of cigars TBH.

They both use the same rack ears, but they're mounted with 3 screws on
the Rev3 and 4 screws on the Rev4. Wonder of they added a fifth screw
in the Rev5. Richard, what's your comment?
The Rev3 has six holes in the chassis actually - no idea why, they
don't line up with the rack ears.. maybe for mounting the rack ears
backwards, or something like that.

Cheers
D.