Xpantastic!

So you swapped the connectors between the 2 voices boards. We are agree that it was the connectors at the upper right corner, right ? I ask because I don't understand how the swap displaced the problem since there is no tuning specific wires on the connectors. This is a classic CPU bus.

Kris

Envoyé de mon iPad

Le 9 juil. 2012 à 18:19, Terje Winther <terje.winther@...> a écrit :

> Very interesting update:
> 
> The Matrix-12 is just two Xpander voice board on top of each other, right? So it should be OK to shift which one of the cards who is on top?
> Since I was always getting tuning errors on voice 7-12 while voice 1-6 was always right, I thought I could swap position of the voice cards to see what happens.
> And guess what: it is still voice 7-12 that gets the error - AFTER the swap. The card that was getting all the errors now works perfectly in tune.
> 
> So my conclusion is this:
> - Both the voice cards now work as they should.
> - There is something wrong on the processor board (or in the connection between the cards: I can check the multicable).
> 
> Since I am mostly an analog synth repair guy, I am getting towards my limits if I am about to debug the digital electronics. In my experience though, it is often some logic chips and/or some physical connection (on or off board) that fails. I really hope there is nothing wrong with the processor itself.
> It would be nice to get this M-12 completely fixed, as it looks good, and it is now so close, so close to being perfect.
> 
> Terje
> 
> 
> 
> 
> 
> Den 6. juli. 2012 kl. 20.42 skrev Karl Schmeer:
> 
>>  
>> 
>> Hi Terje,
>> 
>> Wow Two M12's :-)
>> 
>> The version of the M12 service manual I have " Bought from Factory long ago" is 
>> pretty thin on details. 
>> 
>> It's just schematics and a few engineering change orders.
>> If you have not done so check out the Xpander Service manual. It's in the files 
>> section of this group.
>> The calibration procedures for the trimmers you speak of  are in there, as well 
>> as a detailed 
>> 
>> description of what really goes on during the auto tuning routine.
>> 
>> You probably already checked these things but just to be sure:
>> Do the 2.2uF caps that were replaced have a 50VDC rating? If not they will not 
>> pass the audio signal correctly. 
>> 
>> Actually "the entire board failing tune "points to a more systemic failure. 
>> Both the VCO and VCF are tuned the same way with the exception that the VCF's 
>> resonance
>>  is set to oscillate.  A specific voltage is applied to the individual VCO or 
>> VCF
>> and the output  frequency is monitored by the CPU to allow tuning.
>> 
>> I would start at the DAC circuit ( page 19 xpander service)  There is a trimmer 
>> in that circuit for 
>> 
>> DAC offset calibration. ( The procedure is at the end of the Xpander service 
>> manual page 34.
>> Maybe thats all that is wrong :-) 
>> 
>> If not :
>> There is also a procedure for checking the board reference voltage ( page 34) If 
>> this voltage is off spec it could 
>> cause errors. 
>> Try swaping  DAC's between the "known good board" and your failed one. Or any 
>> other parts in the DAC circuit.
>> 
>> There is a circuit on page 31 (Lower right hand corner in Xpander service)  
>> Which is used in the auto tuning routine. It is built around an LM311 voltage 
>> comparator 
>> 
>> which ties to the output of  each voice. 
>> Something may be amiss here.
>> 
>> Report back after these checks and I will think about it some more.
>> 
>> Best Luck
>> 
>> Karl
>>  
>> 
>> ________________________________
>> From: Terje Winther <terje.winther@...>
>> To: xpantastic@yahoogroups.com
>> Sent: Fri, July 6, 2012 12:30:38 PM
>> Subject: [xpantastic] only one board active
>> 
>>   
>> Hi all,
>> Thanks a lot for all the help I have been given on this list. I have 
>> changed parts in the power supply, some CEM chips, all those el.caps 
>> who blocked tuning and sound, swapped some 74 series logic chips (so 
>> now all encoders works), and got new switches and rubber feet, and 
>> even a new key. And of course cleaned it up since all boards were out 
>> anyway.
>> The Matrix-12 is almost all right now - it is just one peculiar error 
>> left:
>> It seems that only one of the voice cards gets the proper commands.
>> Voice 7 - 12 fails tuning of VCOs and VCFs, but all other tuning 
>> passes and there is sound from all 12 voices (if I turn them on) and 
>> the voices are almost in tune, and VCFs seems to work like they should.
>> I also have another Matrix-12 in for service (yes, two M-12s in front 
>> of me - pretty sight!), and it too reportedly have an issue with only 
>> one of the voice cards working properly.
>> I have double-checked the connectors (the paralell connector and the 
>> two 3-4 pin connectors) and they all seems to be fine.
>> Any tips on what to do if one of the voice cards don´t responds?
>> 
>> On another question: While having all the boards out, I noticed that 
>> there are very few manual trimmers on the M-12, but there are some, 
>> and I can´t seem to find any info on how to calibrate them. I have the 
>> service manual, and I find the trimmers there, so I can pretty much 
>> guess what to do, but it would be nice to know for sure.
>> 
>> Terje Winther
>> terje.winther@...
>> http://www.wintherstormer.no/
>> 
> 
> Terje Winther
> terje.winther@...
> http://www.wintherstormer.no/
> 
> 
> 
> 
>