OBERHEIM SYNTH

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@...>
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@...m, 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 
> 
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