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Oberheim OB-8 - diagnostics Keyboard Synthesizers
Old 7th August 2014
  #31
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I'm going to try a full reset, and then I will probably need to recalibrate my envelopes.

I've never done anything like this before.

I've read through the service manual, and get what it's saying, but I'm not sure where I'm supposed to use my multi-meter to check the calibrations. Are the boards labeled inside?

Figured I should learn how to do all of the calibrations since I'm going to be keeping this synth for a long time, and I want to learn to work on it and keep it in good shape.
Old 7th August 2014
  #32
Yes, the boards are labeled, but some labels may be blocked from view by a component. Download the 600dpi voice board schematics from the Magnus OB-8 page. It has the labels for every component on the voice board. You can also download the CPU board schematics, but the DAC connections are clearly marked on the board.
Old 7th August 2014
  #33
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Quote:
Originally Posted by BM0 View Post
Yes, the boards are labeled, but some labels may be blocked from view by a component. Download the 600dpi voice board schematics from the Magnus OB-8 page. It has the labels for every component on the voice board. You can also download the CPU board schematics, but the DAC connections are clearly marked on the board.
Great, thanks.

I've read that these are among the easiest synths to run diagnostic settings one. Looking forward to really learning about how this thing works.
Old 8th August 2014
  #34
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XBS111 here!

I seem to remember my OB8 got confused one time and had that out of tune problem. i swear i did the hard reset ( hold a bunch of buttons and one more with your nose ) and it went away. the cassette / wav dump that i have ( not from my machine ) does not destroy the calibration! also, mine is OS B5 and has FACTORY MIDI on the side panel.

I use it with a DSX which is a lot of fun. The sequencer data recorded in the DSX IS TRANSMITTED to the MIDI out.

!!!!

also the 8 CV/Gate outs is rad.

XO!
Old 8th August 2014
  #35
Quote:
Originally Posted by NewAllianceEast! View Post
XBS111 here!
I use it with a DSX which is a lot of fun. The sequencer data recorded in the DSX IS TRANSMITTED to the MIDI out.

!!!!

also the 8 CV/Gate outs is rad.
The DSX is a highly underrated sequencer in my opinion, probably because you have to have an OBX, OBXa, or OB-8 keyboard to use one. My first two albums were all done on a DSX, a lot of Steve Roach's early albums were also done using a DSX sequencer. From what I understand their was some midi software developed but not completed for DSX which is too bad.

Sorry for the tangent! heh Great information here, I'll be resurrecting an OB-8 myself soon and will be using all the info gathered here.
Old 8th August 2014
  #36
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Recorded this little bit last night.

Old 9th August 2014
  #37
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Quote:
Originally Posted by D_Davis View Post
Recorded this little bit last night.

That's a seriously sweet sounding synth! My bender and mods section are starting to fail one by one - volume mod dead, rate pull pot stuck on rate, dead bend lever, arp going nuts.

I'm thinking it must be something on the processor board going sour. Hopefully a page 2 reset will magically fix it all, as soon as I get a dictator to send an army for holding the buttons heh

update: page 2 reset and wiping the RAM fixed most of this!

Last edited by Silverren; 13th August 2014 at 12:59 AM.. Reason: info
Old 9th August 2014
  #38
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Bummer, I was dying to hear some sounds.







HW

Last edited by Herr Weiss; 10th August 2014 at 01:18 AM.. Reason: bigger screenshot
Old 10th August 2014
  #39
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Quote:
Originally Posted by Herr Weiss View Post
Bummer, I was dying to hear some sounds.


HW
This should work.

Old 10th August 2014
  #40
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Thanks D_Davis!!

I forgot to mention that my provider slows down a bit once a month. I don't have the fanciest plan.

By next week things we'll be back to normal and then I'll get to listen to your machine. I do love the Oberheim sound, my favorite.

Congrats for having an excellent taste and good luck!!



Herr Weiss
Old 10th August 2014
  #41
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Ah, got it. Thanks!
Old 10th August 2014
  #42
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Ah, got it. Thanks!
Old 10th August 2014
  #43
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So out of the blue I called Larry Church, an old Oberheim and Moog tech, tonight. He called me back and told me that he thinks the problem is with some corrupted data in the RAM. Told me to pop out the ram and push the pins through some tin foil, thus shorting the RAM and completely resetting it. He thinks this should fix the problem. Going to try that tomorrow.

Mr. Church lives in Oregon not too far from me. I might be hooking up with him for day to go through my OB8 and learn all about it so I can keep this thing running as long as possible.
Old 10th August 2014
  #44
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Quote:
Originally Posted by D_Davis View Post
So out of the blue I called Larry Church, an old Oberheim and Moog tech, tonight. He called me back and told me that he thinks the problem is with some corrupted data in the RAM. Told me to pop out the ram and push the pins through some tin foil, thus shorting the RAM and completely resetting it. He thinks this should fix the problem. Going to try that tomorrow.

Mr. Church lives in Oregon not too far from me. I might be hooking up with him for day to go through my OB8 and learn all about it so I can keep this thing running as long as possible.

Good news all around!!


HW
Old 10th August 2014
  #45
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F*ck yeah!

Fixed the Oberheim.

That was one of the scariest things I've ever done. I saw $3k being flushed down the toilet.
Old 10th August 2014
  #46
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Amen brother, amen!!
Old 10th August 2014
  #47
Cool. I would never figured that one out.
Old 10th August 2014
  #48
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Quote:
Originally Posted by BM0 View Post
Cool. I would never figured that one out.
I'm thinking that the new back up system you linked to earlier would prevent this from ever happening.

Definitely going to be checking that out.
Old 11th August 2014
  #49
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BTW, Larry said that the foil trick can also work with dead voices.

He said that the computer control system on these things is a little too complex for its own good, and sometimes causes the chips on the boards to go a little crazy, and then they can get reset.

So, I guess the less is, if you can determine which chip is giving you problems, might as well remove it, punch the pegs through some foil, and reset it.
Old 12th August 2014
  #50
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Quote:
Originally Posted by D_Davis View Post
BTW, Larry said that the foil trick can also work with dead voices.

He said that the computer control system on these things is a little too complex for its own good, and sometimes causes the chips on the boards to go a little crazy, and then they can get reset.

So, I guess the less is, if you can determine which chip is giving you problems, might as well remove it, punch the pegs through some foil, and reset it.
Thank you so much for posting this - I stuck all 3 of my RAM chips through foil, and after putting them back in, my OB-8's volume mod works again! This probably saved me big $$$ from a tech, once again a million thanks!
Old 13th August 2014
  #51
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Sure thing!

I have a feeling this little trick can solve a lot of problems.

Imagine the time you'd have to pay for a tech to find what's wrong!
Old 17th November 2014
  #52
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My OB8 totally freaked out last night.

I have the MIDI IO run through my Novation controller, used to control stuff on Ableton. I started up Ableton, and something happened where the controller freaked out, and it must have sent some kind of signal to the OB8. The OB8 completely froze up, and when I restarted it, all my patches were gone! Every patch was nothing but chaotic noise and random elements. So weird. Lost like 24 amazing patches I had been working on for an album.

Oh well.
Old 17th November 2014
  #53
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Quote:
Originally Posted by D_Davis View Post
My OB8 totally freaked out last night.
Sorry to hear that, that sucks.

I back up my patches religiously every time I make a new patch on my OB-8.

I know there's some way to do a patch dump but I can't figure it out.

I do it the old fashioned way - I just run a cable from the tape out into my converter/DAW and record a track of the tape output. If I need to reload it, I just run the output from my converter into the tape input and reload the patches.

Works fine.

I know it's archaic but it works and I come from that era anyway so it makes me feel nostalgic anyway using the tape outputs to back up hardware. I used to have to do that all the time except now the DAW is a lot more reliable then the old cassette tapes used to be.

Good luck,
Frank
Old 18th November 2014
  #54
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Yeah - I should have done an audio dump to my DAW. I even thought about it the night before!

Oh well. Creating patches is so much fun on the OB8 that I don't really mind, although I have a handful that were just lovely, and will be hard to recreate.
Old 18th November 2014
  #55
That had that happen to me. I had a backup though. You can send a Sysex dump request to backup all the patches rather than using tape.
Old 4th March 2018
  #56
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Reviving an old thread to ask a remedy for my OB-8.

My OB-8 works perfectly in Manual mode, however if any of the stored sounds selected no sound coming out of any of the outputs, well in some patches some quirky sounds. I need to note that leds on the panel changes, as different sounds recalled. If manual mode is selected back, OB-8 returns to the controls seen on the panel.

What may be the problem ? and anyone has an idea how to fix it ? It is gonna drive me crazy. I already tried;

- reset (pressing 1-8 programs and split simultaneously) with memory protect off
- I took out 3 memories U18-19-20 according to the schematics, and pushed them through copper foil, then put them back in the same order.
- I firmly pushed the ribbon connectors to their place.

But problem persists. Can anyone please help me on this ?
Old 5th March 2018
  #57
Quote:
Originally Posted by omer99 View Post
Reviving an old thread to ask a remedy for my OB-8.

My OB-8 works perfectly in Manual mode, however if any of the stored sounds selected no sound coming out of any of the outputs, well in some patches some quirky sounds. I need to note that leds on the panel changes, as different sounds recalled. If manual mode is selected back, OB-8 returns to the controls seen on the panel.

What may be the problem ? and anyone has an idea how to fix it ? It is gonna drive me crazy. I already tried;

- reset (pressing 1-8 programs and split simultaneously) with memory protect off
- I took out 3 memories U18-19-20 according to the schematics, and pushed them through copper foil, then put them back in the same order.
- I firmly pushed the ribbon connectors to their place.

But problem persists. Can anyone please help me on this ?
The weird sound is typical when the memory has been corrupted or wiped. The few times that happen to me, I just restored my programs from a MIDI SysEx backup and it is all good. If you don’t have a backup, you should be able to find the factory cassette tape online in wav file format.

Did you check the voltage on the battery? The battery is probably supplying a capacitor, so you may want to look for that as well.
Old 6th March 2018
  #58
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Quote:
The weird sound is typical when the memory has been corrupted or wiped. The few times that happen to me, I just restored my programs from a MIDI SysEx backup and it is all good. If you don’t have a backup, you should be able to find the factory cassette tape online in wav file format.

Did you check the voltage on the battery? The battery is probably supplying a capacitor, so you may want to look for that as well
I checked the voltage, I get around 3V. It is a new battery.

I dont have MIDI, so I found the wav file from some other thread here, yet the procedure did not work. I did not even hear the lead sound . I enabled the cassette, then memory protect off, connected headphone out of computer to "TO OUTPUT" jack of OB8. However, the lead sound did not come out of OB8 mono or left right outputs. I checked the audio cable which is working, I checked the Play button's legs with multimeter which has proper voltages when pressed and released.

It is gonna drive me crazy.

What might be the cause ? Any ideas ?
Old 7th March 2018
  #59
Quote:
Originally Posted by omer99 View Post
I checked the voltage, I get around 3V. It is a new battery.

I dont have MIDI, so I found the wav file from some other thread here, yet the procedure did not work. I did not even hear the lead sound . I enabled the cassette, then memory protect off, connected headphone out of computer to "TO OUTPUT" jack of OB8. However, the lead sound did not come out of OB8 mono or left right outputs. I checked the audio cable which is working, I checked the Play button's legs with multimeter which has proper voltages when pressed and released.

It is gonna drive me crazy.

What might be the cause ? Any ideas ?
I’ve never actually used the cassette interface. I believe I’ve read that you may need to play around with the volume level of the computer output when using these types of interfaces. The manual specifies that you should set it as high as possible before distortion occurs. Keep at it, you’ll probably get it to load eventually.

EDIT: Once you get the programs restored, maybe consider getting the Encore MIDI kit for the OB-8. I have one installed. MIDI SysEx backup is much more convenient to work with. No fiddling around with the cassette interface. Very easy to backup all your programs and just as easy to restore. You may need to be patient with Encore as people have been reporting that response is pretty slow. It’s one guy operation and apparently he isn’t always watching the site for orders.

Last edited by BM0; 7th March 2018 at 12:38 AM..
Old 10th August 2018
  #60
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Thanks for the comment BM0.

I checked all the digital ICs one by one in proper boards and they all seem to work properly. then I recalibrated oberheim (everything's calibrated without any problems) but I put envelope offsets to 0.000 since my OB-8 is rev. A4.

But still I could not get sounds from memory or cannot hear any sound from the wav file when I record from computer into OB8. The PLAY light never becomes when dumping into OB8, however, OB8 successfully dumps into the computer which buzzing noise coming out of OB8 (not the lead sound).

I want to buy new memory chips and this magnetic RAM. Anybody has experience on this ?

Magnetic RAM upgrade by Electrongate

any other advices are really appreciated.
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