VOGONS


Reply 20 of 27, by darry

User metadata
Rank l33t
Rank
l33t

According to the Roland RA-50 manual, appendix 6, there is an internal battery.
I suggest everybody consider removing/replacing theirs before it leaks (hopefully the hardware still works without it).
http://cdn.roland.com/assets/media/pdf/RA-50_OM.pdf

Reply 21 of 27, by Salient

User metadata
Rank Member
Rank
Member
Cloudschatze wrote on 2020-06-20, 01:06:

So, this isn't gospel or anything, but:

Modification successfully implemented! 😀

Attachments

MIDI comparison website: << Wavetable.nl >>
(Always) looking for: Any Wavetable daughterboard, MIDI Module (GM/GS/XG)

Reply 22 of 27, by Salient

User metadata
Rank Member
Rank
Member

I might try to install a true CM-32L ROM set in there to see if that enables the extra sound effects. I guess it wouldn't be harmfull.

MIDI comparison website: << Wavetable.nl >>
(Always) looking for: Any Wavetable daughterboard, MIDI Module (GM/GS/XG)

Reply 24 of 27, by Cloudschatze

User metadata
Rank Oldbie
Rank
Oldbie

Well, so having now seen the service notes for the RA-50, I can at least say that there is no mention of a MIDI passthrough behavior, or similar, that would preclude the need for either SoftMPU or the hardware modification. This is hardly surprising.

Also, the resistor that I thought was in-series is just a pull-up, so it really isn't necessary to grab the MIDI signal where I'd initially suggested. Instead, pin 6 of either opto-isolator (IC44, 42) can be used. From a convention/consistency standpoint, it probably makes more sense to grab it off of the MIDI (SEQ) input, rather than the MIDI (KBD) input, besides.

Finally, and anecdotally speaking, I'm impressed with the output quality of the RA-50. I haven't done any actual, objective comparison tests between it and a second-gen MT-32 or CM-32L/64, but it certainly strikes me as being rather nice (punchier?). I can only speculate as to what the difference(s) might be, but I do note that the RA-50 uses Rohm op-amps, rather than the commonly-used New Japan Radio or Mitsubishi variety, and has a suffixed reverb chip besides (15239863-01, vs. 15239863).

Reply 25 of 27, by SmokeMonster

User metadata
Rank Newbie
Rank
Newbie

This is an awesome mod, thank you for documenting it. You can simplify it by using a SPDT switch and using CPU (IC28 / pin 1) as common:

unknown2.jpg
Filename
unknown2.jpg
File size
1.53 MiB
Views
292 views
File license
Public domain

I took MIDI from SEQ IN (IC44 / pin 6) as suggested by Cloudschatze:

IMG_20200816_152600.jpg
Filename
IMG_20200816_152600.jpg
File size
1.92 MiB
Views
292 views
File license
Public domain
IMG_20200816_160011.jpg
Filename
IMG_20200816_160011.jpg
File size
1.3 MiB
Views
292 views
File license
Public domain
IMG_20200816_160522.jpg
Filename
IMG_20200816_160522.jpg
File size
1.32 MiB
Views
292 views
File license
Public domain
IMG_20200816_150614.jpg
Filename
IMG_20200816_150614.jpg
File size
1.65 MiB
Views
261 views
File license
Public domain

I used a DPDT switch because that's what I had on hand. Using one row of a DPDT is the same as using a SPDT switch
CPU (purple) is common

Thanks to Keropi for the help with this

Reply 26 of 27, by Vanessaira

User metadata
Rank Newbie
Rank
Newbie

This is really cool. I am glad there is an interesting hardware option to allow people to get an alternate CM-32L.

An Analog Girl in a Digital World