Xpantastic!

Hi to all members...
I'm Sergio Koval, from Barcelona, Spain.
A friend of mine gaves me his Oberheim Xpander that has a very big problem on its Power Supply, and I can't be able to find any info about it. It is the second version of the Xpander, manufactured in Japan, and the Power Supply is completely different from the service manual's one. 
I have released my own schematic of it, taken from the PCB I have, but there are some missing components (mainly resistors and capacitors) and I don't have any idea about their values.
If any user of that version of Xpander could take a detailed photo of its Power Supply board, it would be very useful to me. I could get the values from that image. 
I have been told that version of Xpander was sold in Japan and Australia. My friend's one came from Australia. 
Any help or suggestion will be very welcome.
Thanks in advance
Sergio

Hi,

maybe this can help you:
http://xpander.geek.nz/my-xpander-psu.html
http://xpander.geek.nz/my-xpander.html

regards,
/greg.

--- In xpantastic@yahoogroups.com, "kovalmoog67" <synthoma@...> wrote:

>
> Hi to all members...
> I'm Sergio Koval, from Barcelona, Spain.
> A friend of mine gaves me his Oberheim Xpander that has a very big problem on its Power Supply, and I can't be able to find any info about it. It is the second version of the Xpander, manufactured in Japan, and the Power Supply is completely different from the service manual's one. 
> I have released my own schematic of it, taken from the PCB I have, but there are some missing components (mainly resistors and capacitors) and I don't have any idea about their values.
> If any user of that version of Xpander could take a detailed photo of its Power Supply board, it would be very useful to me. I could get the values from that image. 
> I have been told that version of Xpander was sold in Japan and Australia. My friend's one came from Australia. 
> Any help or suggestion will be very welcome.
> Thanks in advance
> Sergio
>

Hi Sergio and Greg,

That xpander.geek.nz site is mine; unfortunately it hasn't turned into
the rhodeschroma.com-like site I wanted it to be, but I'm happy to add
new information to it so that Google can find it easily.

Sergio, if you would like to send me your schematic I'll add it to the
site. I'm pretty sure my Xpander's PSU is American, so the capacitor
values might not be much use to you.

I would think that these days it should be pretty straightforward to
just replace the whole PSU with a new one, don't you think? I don't
think there are any really weird voltages in there.

Anyway, all the best with sorting it out.

Cheers,

John :^P
--
John Pallister
john@johnp.net
john@...

On Tue, Jun 30, 2009 at 6:52 PM, baumont987<geebeex@...> wrote:
>
>
> Hi,
>
> maybe this can help you:
> http://xpander.geek.nz/my-xpander-psu.html
> http://xpander.geek.nz/my-xpander.html
>
> regards,
> /greg.
>
> --- In xpantastic@yahoogroups.com, "kovalmoog67" <synthoma@...> wrote:
>>
>> Hi to all members...
>> I'm Sergio Koval, from Barcelona, Spain.
>> A friend of mine gaves me his Oberheim Xpander that has a very big problem
>> on its Power Supply, and I can't be able to find any info about it. It is
>> the second version of the Xpander, manufactured in Japan, and the Power
>> Supply is completely different from the service manual's one.
>> I have released my own schematic of it, taken from the PCB I have, but
>> there are some missing components (mainly resistors and capacitors) and I
>> don't have any idea about their values.
>> If any user of that version of Xpander could take a detailed photo of its
>> Power Supply board, it would be very useful to me. I could get the values
>> from that image.
>> I have been told that version of Xpander was sold in Japan and Australia.
>> My friend's one came from Australia.
>> Any help or suggestion will be very welcome.
>> Thanks in advance
>> Sergio
>>
>
>

I had posted some time ago on here about uneven resonances on my xpander-bizarrely, it corrected itself when I re-mounted the unit on my stand and the resonances are perfectly in tune.  

However, I noticed when cranking up the FM last night that despite my best efforts to untune and then retune, I could not get the FM consistent across the voices.  They are not wildly different, but different enough to make chromatic playing difficult.  

There is no consistency between which voices are more in tune with each other either, so I can't immediately say it's chip related.

So I guess my question is-should I expect the voices to be identical when full FM (on filter) is used?  I seem to recall this being possible when I first got my unit, but I don't actually use FM that often.

Hello Matt,
When using the FM on an Xpander / M12 you should expect the tuning to
remain consistant between each of the voices. However because of the
very slight drift of the analog VCO's you may find the tone will change
as you play in different ranges of the keyboard.  In other words,
If you play the same note repetedly ( with an arppigiator for example)
the tuning should be consistant as you rotate through the voices, but
playing notes at different ranges of the keyboard the tone will change.
B.T.W. The (DAC) control element used for the FM is very precise
compared to the (VCA) control elements used in other parts of the synth.

There are many things that could cause this, but a bad solder connection
or slight oxidation/corrosion between an IC pin and the IC socket, seems
most likly, because you report moving the synth changes it's
performance.

- Karl

--- In xpantastic@yahoogroups.com, "mattvrazo" <vrazomatt@...> wrote:
>
> I had posted some time ago on here about uneven resonances on my
xpander-bizarrely, it corrected itself when I re-mounted the unit on my
stand and the resonances are perfectly in tune.
>
> However, I noticed when cranking up the FM last night that despite my
best efforts to untune and then retune, I could not get the FM
consistent across the voices. They are not wildly different, but
different enough to make chromatic playing difficult.
>
> There is no consistency between which voices are more in tune with
each other either, so I can't immediately say it's chip related.
>
> So I guess my question is-should I expect the voices to be identical
when full FM (on filter) is used? I seem to recall this being possible
when I first got my unit, but I don't actually use FM that often.
>

Thanks Karl,

The voices are consistently slightly out of tune on one key, so I am wondering if it's a chip thing-when no FM is employed but the rez is all the way up, you can hear the SLIGHTEST vartiation, but I only notice those particular voices because using FM accentuates the irregularities more so.  

The movement factor would certainly indicate something might be loose (though rotating it further forward doesn't rectify anything unfortunately!)


--- In xpantastic@yahoogroups.com, "shire03@..." <shire03@...> wrote:

>
> 
> Hello Matt,
> When using the FM on an Xpander / M12 you should expect the tuning to
> remain consistant between each of the voices. However because of the
> very slight drift of the analog VCO's you may find the tone will change
> as you play in different ranges of the keyboard.  In other words,
> If you play the same note repetedly ( with an arppigiator for example)
> the tuning should be consistant as you rotate through the voices, but
> playing notes at different ranges of the keyboard the tone will change.
> B.T.W. The (DAC) control element used for the FM is very precise
> compared to the (VCA) control elements used in other parts of the synth.
> 
> There are many things that could cause this, but a bad solder connection
> or slight oxidation/corrosion between an IC pin and the IC socket, seems
> most likly, because you report moving the synth changes it's
> performance.
> 
> - Karl
> 
> --- In xpantastic@yahoogroups.com, "mattvrazo" <vrazomatt@> wrote:
> >
> > I had posted some time ago on here about uneven resonances on my
> xpander-bizarrely, it corrected itself when I re-mounted the unit on my
> stand and the resonances are perfectly in tune.
> >
> > However, I noticed when cranking up the FM last night that despite my
> best efforts to untune and then retune, I could not get the FM
> consistent across the voices. They are not wildly different, but
> different enough to make chromatic playing difficult.
> >
> > There is no consistency between which voices are more in tune with
> each other either, so I can't immediately say it's chip related.
> >
> > So I guess my question is-should I expect the voices to be identical
> when full FM (on filter) is used? I seem to recall this being possible
> when I first got my unit, but I don't actually use FM that often.
> >
>