Xpantastic!

Hi Terje,

Great trouble shooting!  
Yes,  do reseat the chips and connectors on the Main processor board. 
This has been a mojor problem with these synths, but the sockets sure make
repairs easy.

BTW
I took photos of the M12 schematics and sent them to Chris this weekend. They 
are large files but very fine resolution.

I have to go back to work right now. 
Chris, could you please forward/send Terje copies if he needs them?

If anyone else needs them, Please drop me a email and I will send them to you. 
They are too big to put on the group files section.
Best Luck 

Karl


_______________________________
From: Terje Winther <terje.winther@...>
To: xpantastic@yahoogroups.com
Sent: Mon, July 9, 2012 11:19:24 AM
Subject: Re: [xpantastic] only one board active

  
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/