Highly Liquid Forum facebook twitter google plus rss feed
  #1  
Old 05-16-2013, 07:00 PM
John's Avatar
John John is offline
Moderator
 
Join Date: Jan 2009
Posts: 3,007
Default Oberheim OB-Xa MIDI Retrofit

C. writes:

Quote:
I have an OB-Xa im going to use your UMR2 on and want to make sure i wire this right..

Im including the schematic of the OB_Xa that clearly shows the matrix.. (page 50)
my question is the control lines to the UMR2 go closer to the keyboard lines or more towards the CPU..

The data lines already have pullups so i am assuming that the UMR2 go hear and should have the POL setting set for pullups???? and the select lines going to the chip U12 on keyboard side..

Could you advise me on where to wire the UMR2 in..
I'm attaching a PDF of the page that contains the keyboard schematic.

Important:

Since the OB-Xa has an "active low" matrix configuration, connect the UMR2 polarity jumper like this:



In the attached PDF schematic:

- U21 pins 0-7 are the matrix select signals. Connect these pins to UMR2 "select in" terminals 1-8.

- pins SWD0-SWD7 are the matrix data lines. Connect these pins to UMR2 "data in/out" terminals 1-8.

Let me know how it turns out.
Attached Images
File Type: pdf OB-Xa.pdf (118.7 KB, 304 views)
Reply With Quote
  #2  
Old 05-16-2013, 09:47 PM
Chaztek Chaztek is offline
Junior Member
 
Join Date: Sep 2012
Posts: 4
Default OBXA MIDI retrofit

Thanks John this is great help...

I will be making this install in the next few days and week hopefully i can report back how it goes.. and give any tips to our community...
Most of what needs to be done is mounting and construction..

So far your instruction page is helpful but sometimes we need to clarify on these vintage synth's and be carful not to damage them..
Always better to double check and get expert opinion..
And i have been doing electronics for 25 years plus.. i even design them myself. But your product line is so inexpensive and well made that why reinvent the wheel...


Best
Regards

Chaz
Reply With Quote
  #3  
Old 05-16-2013, 09:51 PM
John's Avatar
John John is offline
Moderator
 
Join Date: Jan 2009
Posts: 3,007
Default

Hi Chaz,

Thank you for the kind words. Welcome to the forum.

I'm looking forward to hearing about your results with the OB-Xa.
Reply With Quote
  #4  
Old 07-09-2013, 11:40 PM
Chaztek Chaztek is offline
Junior Member
 
Join Date: Sep 2012
Posts: 4
Default Running into problem?

So...I have the unit all hooked up as instructed above and double checks all wiring..The OBX keyboard still works and all functions work on the unit.

Im using it as a MIDI Input so i left the mode switch open
I Power up holding the PRG button and see the green blinking light and can get it to PRG mode and it goes from green to red when you press a key on the master keyboard but after that all it does is stay red no matter what key you press on the master keyboard...no change in red light at all. even wile holding the key for an extra long time.....

Im stumped here.....What next?

OK update...what i did was hold the program switch..led is red .release the led goes green hit a key the led goes red close program switch and when the lights go out re power unit and its working.SORTA. this part about it learning the keyboard does not seem to be functioning and im getting mistrigering..ill be checking my wiring to make sure its right and include a picture soon..

Update2
Ah now i realize its not mistriggering but triggering auto tune mode.. the keyboard and switch matrix on the front panel is integrated.. i must have something wrong..OR the diodes on the keyboard need to be incorporated some how..im going to do a test to see if this is true.

setup instructions
3.3.1 Setup Procedure
1. Power off the UMR2.
2. Press (close) and hold the PRGM switch.
3. Power on the UMR2. The red ACT LED will light.
4. Release (open) the PRGM switch. The green STBY LED will blink continuously.
5. Send a single MIDI note to the UMR2. This note specifies the MIDI channel setting for the
UMR2. It also specifies the note number that corresponds to the lowest note on the keyboard. To
confirm receipt of the note, the red ACT LED will light for several seconds.
6. Wait for the red ACT LED to clear. The green STBY LED will blink continuously.
7. Briefly press and release each key on the host keyboard. Start with the leftmost key and continue
in order until the rightmost key is pressed. After each keypress, wait for the red ACT LED to
blink before continuing with the next key.
8. Press (close) the PRGM switch. The red ACT LED will light while the UMR2 stores the results
of the setup procedure. When both LEDs are clear, power off the UMR2 and open or disconnect
the PRGM switch.

Last edited by Chaztek; 07-10-2013 at 12:00 AM.
Reply With Quote
  #5  
Old 07-11-2013, 07:23 PM
Chaztek Chaztek is offline
Junior Member
 
Join Date: Sep 2012
Posts: 4
Default UGG i think i damaged the UMR2

Well from fiddling around i seemed to have dropped a small wire onto the UMR2 wile it was on and now i don't get any key responses from it with Midi going to it.. UGG..

So i can only advise being very carful. power down wile striping wire.
I know better but there ya go....

Ill have to send it back and buy another one. grrrr arg!
Reply With Quote
  #6  
Old 07-16-2013, 01:41 AM
Chaztek Chaztek is offline
Junior Member
 
Join Date: Sep 2012
Posts: 4
Default SUCCESS...and im a dumb ass

OK update

SOOOO...sins im a sorta guy that wont give up easy and figure most likely if it does not work its pilot error.. i tried again today and realized the reason i was NOT getting results is i kept trying to make it learn using the master keyboard instead of the "host" keyboard... DUH... Host being the keyboard the unit is installed in.
but the very first key press sets the midi channel and this must come from a master keyboard attached to the midi in port...

What i did was wire one line to pin 8 of U21 (instead of 9) and its actually ground and this cause the whole keyboard to restart and this caused the auto tune to go off again...so what was happening was i was triggering a short to happen during a key press.

SO it seems the unit is still good and working fine..the pic line of chips are known for being very robust..I like using them and code on them myself. and its a good choice for this unit...

So ill post pictures soon of my install so everyone can see this was actually quite easy to implement. (barring my mistakes)

I am supper pleased with this product and i hope my input will inspire people to use it despite my mess ups

Last edited by Chaztek; 07-16-2013 at 01:54 AM.
Reply With Quote
  #7  
Old 07-16-2013, 08:50 PM
John's Avatar
John John is offline
Moderator
 
Join Date: Jan 2009
Posts: 3,007
Default

Quote:
Originally Posted by Chaztek View Post
OK update

SOOOO...sins im a sorta guy that wont give up easy and figure most likely if it does not work its pilot error.. i tried again today and realized the reason i was NOT getting results is i kept trying to make it learn using the master keyboard instead of the "host" keyboard... DUH... Host being the keyboard the unit is installed in.
but the very first key press sets the midi channel and this must come from a master keyboard attached to the midi in port...

What i did was wire one line to pin 8 of U21 (instead of 9) and its actually ground and this cause the whole keyboard to restart and this caused the auto tune to go off again...so what was happening was i was triggering a short to happen during a key press.

SO it seems the unit is still good and working fine..the pic line of chips are known for being very robust..I like using them and code on them myself. and its a good choice for this unit...

So ill post pictures soon of my install so everyone can see this was actually quite easy to implement. (barring my mistakes)

I am supper pleased with this product and i hope my input will inspire people to use it despite my mess ups
Hi Chaz, that's great news! Thank you for the update.
Reply With Quote
  #8  
Old 09-21-2013, 02:06 PM
Mondovermona Mondovermona is offline
Junior Member
 
Join Date: Sep 2013
Posts: 5
Default UMR2 OB-Xa How I did it

The other day I retrofitted my OBie with no problems at all. Thank you for this wonderful little interface.

I decided to avoid soldering as much as possible. I used a standard IDC 16-pin connector and pressed it directly on the ribbon cable running from the lower control board to the keyboard's PCB.

A separate ribbon cable was connected to a mating IDC 16-pin connector on one side and was soldered individually to the UMR2 on the other. That's it.

The UMR2 was simply fixed to the left wood panel with short wood screws (be shure to use not too big or too long screwsif you do not want to predrill - else there is a risk the wood panel breaks)

GND and +5 Volts were picked up directly from the power board by direct soldering the wires directly to the PCB's fat tinned traces (e.g. near connector F or A)

Please have o look at my pictures and let your OBies rock with the UMR2!
Attached Images
      
Reply With Quote
  #9  
Old 09-28-2013, 03:31 PM
John's Avatar
John John is offline
Moderator
 
Join Date: Jan 2009
Posts: 3,007
Default

Hi Mondovermona,

Welcome to the forum, and thank you for posting the excellent photos of your installation! The install looks really nice. It's funny how tiny the UMR2 looks compared to those massive thru-hole boards
Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT. The time now is 10:31 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.