Xpantastic!

I have one of the DAC chips if you need one.
Doug 
synthparts.com

--- In xpantastic@yahoogroups.com, Karl Schmeer <shire03@...> wrote:
>
> Hi Terje,
> 
> It is a long shot, but try reflowing the solder on the socket of the DAC.
> Ya might get lucky. 
> Best
> 
> Karl
> 
> ________________________________
> From: Terje Winther <terje.winther@...>
> To: xpantastic@yahoogroups.com
> Sent: Thu, July 12, 2012 10:59:39 AM
> Subject: Re: [xpantastic] only one board active
> 
> Â  
> Hi all,
> Thank you very much for all the feedback and the hints of what to do.
> After a day´s break from the Matrix-12, I once again got into it with 
> renewed energy.
> I *might* have found the error, but I am not sure. To recapture:
> 
> Today a took both voice cards and swapped positions of the "board ID" 
> tag (strap). Earlier there was always voice 7 - 12 who failed, and 
> after the swap, voice 1-6 failed.
> So there is no doubt now: There is an error on the voice card.
> 
> I swapped the straps back to the original positions, and inserted the 
> cards and tried a few other options:
> - I tried new 4051 ICs at UX06 and UX07 on one of the voices. No change.
> - I tried new TL084 at UX08 at one of the voices. No change.
> - U108 (LM311) have been swapped. No change.
> - I have swapped all critical ICs U812 to U815 with the working voice 
> card. No change.
> - I have swapped the processor U907 and the timer IC U921 with the 
> working voice card. No change.
> Voice card two (the upper card) fails on all 6 voices as regard to 
> VCOs, VCFs and VCAs. It comes close, but not perfect (off by as much 
> as 0,5 - 3 notes).
> 
> On the other hand, this is what is working:
> - There is sound from all 12 voices (if I override the automatic 
> tuning and turn all voices manually on)
> - All 12 voices responds to keyboard, levers and such
> - All 12 voices change sound according to the stored programs, and 
> changes done on the front panel
> - All voices pass tuning of PW (Pulse Width) and RES (filter resonance)
> 
> So I started backtracking to other ICs, and I might have found the 
> error:
> U811, the 3140 DAC chip. If I swap this between the voice card with 
> tuning error and the working voice card, the tuning error follow the 
> chip. Kind of strange, since all other activities also goes through 
> that chip, and all other activities work as they should. Moving ICs 
> before and after U811 changes nothing, but moving the 3140 DAC makes 
> the tuning error move as well.
> 
> So I am tempted to borrow a 3140 chip from the other Matrix-12 to see 
> if I can have this Matrix-12 completely working. If so, then I have to 
> start sourcing a replacement - which seems to be quite difficult.
> Any hints appreciated.
> 
> Thanks for the feedback on the heat of the ICs. They get somewhat hot, 
> but I can touch them without getting burned, so it is probably OK. The 
> power supply regulators also get somewhat hot, but the hearsinks seems 
> to be able to handle it.
> 
> Terje Winther
> terje.winther@...
> http://www.wintherstormer.no/
>