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Need some advice on fixing my OB-X

Need some advice on fixing my OB-X

2013-05-25 by Rod Abernethy

Thanks for letting me join the group, I'm a vintage synth fan from way back.   My beloved OB-X has started acting up lately and I'm going to be doing repairs on it for the first time since I bought it 15 years ago.

The symptoms are that I turn it on and some button lights come on and the buttons respond, some don't.  All patches are gone, some patch slots make sounds that are very sick sounding, others are empty.  The Autotune selector on the front panel lights on and off, but I see no LEDs lighting up showing that Autotune is doing it's tuning sequence on the sound cards.   I've replaced the 3V Lithium battery, but nothing changed.

I've already found some great reference stuff on other sites and now realize that I'm probably in for a wild ride to fix things.  But I would greatly appreciate any help from anyone who has experience with OB-X repair.

Thanks!
Rod

Re: [vintagesynthrepair] Need some advice on fixing my OB-X

2013-05-25 by Roger J

Re-solder the voice cards mother board, every connection.  That will solve 2/3 of the issues.

Inspect around bad battery for damage do to any leakage.

And as I recall, one of the two bridge rectifier gets too hot and should be up-rated, sure someone else will pipe up on that(or was that the OBXa).


Love the sound of a OBX, so if you give up on it, let me know!

R
Show quoted textHide quoted text
>________________________________
> From: Rod Abernethy <rod@rednoteaudio.com>
>To: vintagesynthrepair@yahoogroups.com 
>Sent: Saturday, May 25, 2013 9:19 AM
>Subject: [vintagesynthrepair] Need some advice on fixing my OB-X
> 
>
>
>  
>Thanks for letting me join the group, I'm a vintage synth fan from way back.   My beloved OB-X has started acting up lately and I'm going to be doing repairs on it for the first time since I bought it 15 years ago.
>
>The symptoms are that I turn it on and some button lights come on and the buttons respond, some don't.  All patches are gone, some patch slots make sounds that are very sick sounding, others are empty.  The Autotune selector on the front panel lights on and off, but I see no LEDs lighting up showing that Autotune is doing it's tuning sequence on the sound cards.   I've replaced the 3V Lithium battery, but nothing changed.
>
>I've already found some great reference stuff on other sites and now realize that I'm probably in for a wild ride to fix things.  But I would greatly appreciate any help from anyone who has experience with OB-X repair.
>
>Thanks!
>Rod
>
>
> 
>
>

Re: [vintagesynthrepair] Need some advice on fixing my OB-X

2013-05-26 by 65 Lotus

Here's something I ran across from Wes Taggart of Analogics. Worth a try...
=======================================================
Memory is a significant issue with the OB series of instruments (well any instrument with memory) in that it will do some pretty crazy things if the memory is bad or scrambled. Sometimes loading the memory is not enough. If problems still persist after loading the memory and replacing the battery, you may have to follow the procedure below:

Set unit to manual mode
pick patch A1
Turn every pot a couple times
Turn on and off every switch a couple of times.
This includes all the page 2 stuff also.
After the above, set a simple patch that you can easily identify. One oscillator, wide open filter, gate like envelope.
After you have the patch, write it to memory location A1.
Verify the patch is there by switching to another patch and then returning to A1.
Once verified, write this patch to every memory location. A real pain for those with 120 programs.
Load your program tape.

Scrambled memory creates issues because many times the value held in memory is outside the memory address range. So where the expected value is 0-255 and the actual value is -1,304,495. CPUs do not do well with this type of issue. Rotating the knobs allows the instrument to create a value within the expected value.

Wes Taggart
Analogics

RE: [vintagesynthrepair] Need some advice on fixing my OB-X

2013-05-29 by Lorne Hammond

Measure your voltages at the power supply.  If correct, leave well enough
alone for now.  If not recap just that area, check, if still not good do the
regulators.  You can always measure right at the regulators but that wont
catch bad caps.

 

Some synths will fail in the first 48 hours if caps have dried out or failed
anywahere in the system (failing to ground) or there are poor/cold solder
joints or minor cracks at connectors or edge of failing components like
regulators or transistors.  I would leave it on for 12-24 hours at a stretch
for a few days.  I'd say 12 in case of fire while your asleep.  If it still
behaves well then be happy.  Over recapping can lead to other problems if
your not a pro at it.  You could crack solder joints at the connectors that
were sound before, etc. 

 

Lorne in Canada
Show quoted textHide quoted text
From: vintagesynthrepair@yahoogroups.com
[mailto:vintagesynthrepair@yahoogroups.com] On Behalf Of Rod Abernethy
Sent: Wednesday, May 29, 2013 6:38 AM
To: vintagesynthrepair@yahoogroups.com
Subject: Re: [vintagesynthrepair] Need some advice on fixing my OB-X

 

  

Well, the gods smiled down on me this morning.

 

I was looking through my Encore Midi Kit manual that I installed about 12
years ago and it dawned on me that I hadn't reloaded the original 32 patches
from the Encore card.  I reloaded the patches and it works!  I have the
simultaneous feeling of being a supreme idiot along with the joy of my OB-X
working again:)

 

Is there any upgrading I should do to my OB-X to help preserve the
electronics.for example re-capping, replacing pots, connectors, etc?

 

Thanks for all the help,

Rod

 

 

On May 29, 2013, at 9:19 AM, Rod Abernethy <rod@...> wrote:





  

Wes, I gave this a try but no cigar:(

 

Here's something that I've noticed with all the switches.   

 

All switches light on and off except:

 

Hold

Reset

Modulation/LFO/Rate/SINE

Modulation/LFO/Rate/S/H

Oscillators/Frequency 1/Waveform/SAW

Oscillators//Frequency 2/Waveform/SAW

Filter/Osc 2/Full

Filter/Noise/Half

 

All Programmer buttons turn on and off

 

Does anyone see a pattern in this?  Could it be a power supply problem  or
CPU problem?

 

Thanks!

Rod

 

 

 

On May 26, 2013, at 2:17 PM, 65 Lotus <Lotus@...> wrote:





  

 

Here's something I ran across from Wes Taggart of Analogics.  Worth a try...

 

=======================================================

 

Memory is a significant issue with the OB series of instruments (well any
instrument with memory) in that it will do some pretty crazy things if the
memory is bad or scrambled. Sometimes loading the memory is not enough. If
problems still persist after loading the memory and replacing the battery,
you may have to follow the procedure below:

Set unit to manual mode
pick patch A1
Turn every pot a couple times
Turn on and off every switch a couple of times.
This includes all the page 2 stuff also.
After the above, set a simple patch that you can easily identify. One
oscillator, wide open filter, gate like envelope.
After you have the patch, write it to memory location A1. 
Verify the patch is there by switching to another patch and then returning
to A1.
Once verified, write this patch to every memory location. A real pain for
those with 120 programs.
Load your program tape.

Scrambled memory creates issues because many times the value held in memory
is outside the memory address range. So where the expected value is 0-255
and the actual value is -1,304,495. CPUs do not do well with this type of
issue. Rotating the knobs allows the instrument to create a value within the
expected value.

Wes Taggart
Analogics

Re: [vintagesynthrepair] Need some advice on fixing my OB-X

2013-05-29 by Rod Abernethy

Thanks Wes, I'll give this a shot and post the results.

-Rod



On May 26, 2013, at 2:17 PM, 65 Lotus <Lotus@...> wrote:


Here's something I ran across from Wes Taggart of Analogics. Worth a try...
=======================================================
Memory is a significant issue with the OB series of instruments (well any instrument with memory) in that it will do some pretty crazy things if the memory is bad or scrambled. Sometimes loading the memory is not enough. If problems still persist after loading the memory and replacing the battery, you may have to follow the procedure below:

Set unit to manual mode
pick patch A1
Turn every pot a couple times
Turn on and off every switch a couple of times.
This includes all the page 2 stuff also.
After the above, set a simple patch that you can easily identify. One oscillator, wide open filter, gate like envelope.
After you have the patch, write it to memory location A1.
Verify the patch is there by switching to another patch and then returning to A1.
Once verified, write this patch to every memory location. A real pain for those with 120 programs.
Load your program tape.

Scrambled memory creates issues because many times the value held in memory is outside the memory address range. So where the expected value is 0-255 and the actual value is -1,304,495. CPUs do not do well with this type of issue. Rotating the knobs allows the instrument to create a value within the expected value.

Wes Taggart
Analogics


Re: [vintagesynthrepair] Need some advice on fixing my OB-X

2013-05-29 by Rod Abernethy

Wes, I gave this a try but no cigar:(

Here's something that I've noticed with all the switches.

All switches light on and off except:

Hold
Reset
Modulation/LFO/Rate/SINE
Modulation/LFO/Rate/S/H
Oscillators/Frequency 1/Waveform/SAW
Oscillators//Frequency 2/Waveform/SAW
Filter/Osc 2/Full
Filter/Noise/Half

All Programmer buttons turn on and off

Does anyone see a pattern in this? Could it be a power supply problem or CPU problem?

Thanks!
Rod



On May 26, 2013, at 2:17 PM, 65 Lotus <Lotus@...>; wrote:


Here's something I ran across from Wes Taggart of Analogics. Worth a try...
=======================================================
Memory is a significant issue with the OB series of instruments (well any instrument with memory) in that it will do some pretty crazy things if the memory is bad or scrambled. Sometimes loading the memory is not enough. If problems still persist after loading the memory and replacing the battery, you may have to follow the procedure below:

Set unit to manual mode
pick patch A1
Turn every pot a couple times
Turn on and off every switch a couple of times.
This includes all the page 2 stuff also.
After the above, set a simple patch that you can easily identify. One oscillator, wide open filter, gate like envelope.
After you have the patch, write it to memory location A1.
Verify the patch is there by switching to another patch and then returning to A1.
Once verified, write this patch to every memory location. A real pain for those with 120 programs.
Load your program tape.

Scrambled memory creates issues because many times the value held in memory is outside the memory address range. So where the expected value is 0-255 and the actual value is -1,304,495. CPUs do not do well with this type of issue. Rotating the knobs allows the instrument to create a value within the expected value.

Wes Taggart
Analogics


Re: [vintagesynthrepair] Need some advice on fixing my OB-X

2013-05-29 by Rod Abernethy

Well, the gods smiled down on me this morning…

I was looking through my Encore Midi Kit manual that I installed about 12 years ago and it dawned on me that I hadn't reloaded the original 32 patches from the Encore card. ;I reloaded the patches and it works! I have the simultaneous feeling of being a supreme idiot along with the joy of my OB-X working again:)

Is there any upgrading I should do to my OB-X to help preserve the electronics…for example re-capping, replacing pots, connectors, etc?

Thanks for all the help,
Rod


On May 29, 2013, at 9:19 AM, Rod Abernethy <rod@...> wrote:

Wes, I gave this a try but no cigar:(


Here's something that I've noticed with all the switches.

All switches light on and off except:

Hold
Reset
Modulation/LFO/Rate/SINE
Modulation/LFO/Rate/S/H
Oscillators/Frequency 1/Waveform/SAW
Oscillators//Frequency 2/Waveform/SAW
Filter/Osc 2/Full
Filter/Noise/Half

All Programmer buttons turn on and off

Does anyone see a pattern in this? Could it be a power supply problem or CPU problem?

Thanks!
Rod



On May 26, 2013, at 2:17 PM, 65 Lotus <Lotus@....com> wrote:


Here's something I ran across from Wes Taggart of Analogics. Worth a try...
=======================================================
Memory is a significant issue with the OB series of instruments (well any instrument with memory) in that it will do some pretty crazy things if the memory is bad or scrambled. Sometimes loading the memory is not enough. If problems still persist after loading the memory and replacing the battery, you may have to follow the procedure below:

Set unit to manual mode
pick patch A1
Turn every pot a couple times
Turn on and off every switch a couple of times.
This includes all the page 2 stuff also.
After the above, set a simple patch that you can easily identify. One oscillator, wide open filter, gate like envelope.
After you have the patch, write it to memory location A1.
Verify the patch is there by switching to another patch and then returning to A1.
Once verified, write this patch to every memory location. A real pain for those with 120 programs.
Load your program tape.

Scrambled memory creates issues because many times the value held in memory is outside the memory address range. So where the expected value is 0-255 and the actual value is -1,304,495. CPUs do not do well with this type of issue. Rotating the knobs allows the instrument to create a value within the expected value.

Wes Taggart
Analogics




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