OBERHEIM SYNTH

latest update:
 
after hitting 'tune' many many times and hitting tuning 
while the machine was at various different presets, i noticed that:
when the machine was autotuning and it was in a preset 
that was very complex with lots of modulations and vco modulation as well, 
then voice 5 failed in the vco tuning as well, (and, at one time, vco 1 
failed!). 
when the machine was autotuning, while it was in a simpler 
sound preset (some brass or synthlead...), then the voice 5 only failed in PWM 
and maybe Res... but it passed vco tuning....!! 
so maybe its a problem in another board of the machine 
(like the CPU) and not in the voice 5 board ?
 
maybe this indicates that i should re-sit the chips in the 
main CPU /memory board as well?? do you think i shoudl take the time and re-sit 
all the chips in the CPU board? would it make sense?
 
thanks for all your help everyone!
 
best regards,
Bakis.


________________________________
 From: Tobbe Bergman <tobbebergman@...>
To: oberheim@yahoogroups.com 
Sent: Friday, January 27, 2012 4:45 PM
Subject: Re: [oberheim] Re: [oldberheim] Re: Xpander problem, any help? [1 Attachment]
 

  
[Attachment(s) from Tobbe Bergman included below]
Hi Bakis

It's obviously not anything wrong with any chip. ( Now that's a relief ! )

My guess would be a capacitor on the voice 5 that has dried out just like it did on my Xpander.

As you can see in the attached image I have replaced one cap on voice 6. 
There are several ( orange circles )

I haven't heard of any hard reset for the Xpander and it will certainly not cure it if any cap is gone bad, also the service manual only mention the software reset !

It's time for the old solder iron, or just to be safe hand it over to your tech-friend

Good luck

Cheers / Tobbe




2012/1/27 Bakis Sirros <synth_freak_2000@...>

 
>  
>latest update:
>
>
>swapped ALL of the chips of voice 5 with the chips of voice 6 and still the same problem appears on voice 5. 
>
>so ALL the chips in the voice 5 section are ok for sure.
>
>
>do you think a 'HARD Reset' may fix the problem? how do i do this?
>
>
>thanks,
>Bakis.
>
>
>
>
>________________________________
> From: Bakis Sirros <synth_freak_2000@yahoo.com>
>To: "oldberheim@yahoogroups.com" <oldberheim@yahoogroups.com> 
>Sent: Saturday, January 21, 2012 8:48 PM
>Subject: Re: [oldberheim] Re: Xpander problem, any help?
> 
>
>yes, thanks for the suggestions.
>
>
>but this is work for my tech, as i am not good with the soldering iron and to remove the old capacitors and put new ones, for me would be a difficult task....
>
>
>thanks again,
>Bakis.
>
>
>
>
>
>________________________________
> From: takeit2m <takeit2m@...>
>To: oldberheim@yahoogroups.com 
>Sent: Saturday, January 21, 2012 7:38 PM
>Subject: [oldberheim] Re: Xpander problem, any help?
> 
>
>  
>Check my post a few days ago about recapping a DMX
>I didn't add but the DMX (or was it DX... no matter really)
>has a bunch of small sub-boards for the voices. when I was looking at the schematics I noticed that each of the sub boards had several smoothing capacitors for the voltage supply.   I don't know about the expander, but I'd bet 10,000 dollars;)  its a similar setup. 
>
>I've repaired and built a lot of vintage electronic gear and when it's getting noisy or acting buggy I re-cap it.  This clears up the problem 90% of the time.  It's less risky taking a soldering iron to it then waiting for the capacitors to fail completely and possibly kill those cem chips.
>
>
>--- In oldberheim@yahoogroups.com, Bakis Sirros <synth_freak_2000@...> wrote:
>>
>> 
>> 
>> ok, swapped both CEM3374 and CEM3372 of voice 5 with another working voice 
>> chips and still the fault appears on voice 5. so, both the CEM chips are Not the problem...
>> 
>> any other ideas?
>>  
>> Bakis 
>> 
>> 
>> ________________________________
>
>  From: Bakis Sirros <synth_freak_2000@...>
>
>> To: Oberheim group <oberheim@yahoogroups.com>; Oldberheim group <oldberheim@yahoogroups.com> 
>> Sent: Saturday, January 21, 2012 12:01 PM
>> Subject: Xpander problem, any help?
>> 
>> 
>> hi list,
>>  
>> so, i found a bought a USA model 
>> Xpander.
>>  
>> works and sounds great...  ...apart from voice 5, 
>> which, after its shipping to me, does not pass the auto tune test.
>>  
>> sometimes the 'PW' ('pulse width', not 'parallel 
>> worlds'... ok, silly joke...) section of it fails, sometimes the Res section 
>> fails, sometimes all the section of voice 5 fail (except the vca section of 
>> voice 5 that never fails). 
>>  
>> clearly seems there is something wrong with voice 
>> 5.   :D
>>  
>> even if i activate the problematic voice, after its 
>> been automaticaly shut off by the Xpander OS, it sounds a bit different from the 
>> others in filter tone and tuning (of course, as it cannot be tuned,) and very very low in volume. 
>> another weird thing i noticed: when i direct voice 
>> 5 in its 'direct' output 5, then, from this output, i can hear all of the 
>> xpander voices (together with voice 5) but very low in volume. 
>> all the other direct outputs work as they should, 
>> for all the other voices.
>>  
>> i performed software reset, re-sitted all ribbon 
>> cables and all of the chips in the voice 5 section of the xpander voiceboard 
>> without success,
>> i also performed all the tests for the xpander 
>> (memory, vmemory, etc...) and all are ok, afaik. 
>> plus i resitted chip U106 which is responsible for 
>> the panning output section of voice 5 (after studying the service 
>> manual).
>>  
>> is there anything specific i should check? 
>> everything seems connected.... i cannot resit ALL the chips in all boards 
>> obviously... but maybe i should resit a specific chip from another section of 
>> the xpander boards....? any ideas / help?
>>  
>> i really do not want to break anything inside the 
>> Xpander (i do not want to use a soldering iron, after all, everything seems in 
>> place), but i can remove and easily re-sit a specific chip or two, if needed of 
>> course....
>>  
>> btw, after re-sitting the CEM 3374 Dual vco, of 
>> voice 5, the vco tuning of voice 5 almost always fails... it did not do that 
>> before. 
>> but i am very very certain i removed and resitted 
>> the chip without making any damage to it or its socket. 
>> (i have replaced chips in other analogue modules 
>> before without any problems...)
>>  
>> btw, the seller is very honest and he insisted that 
>> the machine worked fine (all 6 vooices) before shipping, and i believe 
>> him...
>>  
>> thanks in advance for your help!
>>  
>> best regards,
>> Bakis.
>>  
>> Bakis Sirros 
>> 
>> www. parallel - worlds - music. com 
>> 
>> www. facebook. com/ pages/Parallel-Worlds/192093934136476
>> www. myspace. com/ parallelworldsmusic
>> www. myspace. com/ interconnectedmusic
>> www. myspace. com/ memorygeist
>> www. DiN. org. uk
>> www. musicamaximamagnetica. com
>> www. vu-us. com
>>
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