Everything worked great with no issues however I replaced all the regulators (7805, 7812, etc.) and diodes. I never did bother to try to determine exactly which component was faulty, intead I just changed them all and checked the filter caps were good. When one of those voltage regulators begins to cause problems, the rest are soon to follow...

--- In oberheim@yahoogroups.com , "t851262gonzalopiotti" <el_barzata@...> wrote:
>
> Hi, I'd like to know if the 7805 replacement did work since the change.
> Mines matrix is having the same issue
>
> Thanks
>
> --- In oberheim@yahoogroups.com , "wesleyknick" <wesknick@> wrote:
> >
> > Yes, for now I just replaced the two 7805 and the single 7812 and threw the power supply board back in to see what it would do and now the display comes up normal at power-on. I had to order a 7912 regulator and have some 7905s hidden somewhere I have to locate but for the most part at least replacing the 7805s and 7812 seems to have fixed the problem. I haven't had a chance to measure the actual output with the new 7812 and 7805 regulators yet. I haven't seen -18v nor -3v on the ground pins. When I get a chance I'll look and see if I can see the same thing.
> >
> > --- In oberheim@yahoogroups.com , carl hourigan <sloppy.hq@> wrote:
> > >
> > > let me know if replacing the caps and regulators works. one thing i noticed is that the ground pins on the negative voltage regulators "-12v and -5v" were putting off -18v and -3v, is that normal does yours do this
> > >
> > > On Aug 2, 2012, at 8:24 PM, wesleyknick wrote:
> > >
> > > > For anybody interested in this particular issue, that of strange characters showing up in the display at power-on and those same characters changing as keys are pressed (almost like a typewriter), I've determined the power supply to be the problem. I had initially suspected the power supply when I began looking into the issue however after checking all the output voltages I had found them all to be within limits and looked elsewhere. Looking elsewhere I had also suspected the RAM which included my swapping out U6, U7, and U8 and still had the same problem. Again suspecting the power supply and trying an alternate approach, I removed the power supply board from my other fully functional Matrix 6 and installed it into the problematic Matrix 6 and all issues were cleared. I then proceeded to upload the original factory presets with no issues. I'm not entirely sure what component is bad on the power supply, possibly the +5 or +12 voltage regulators but either way I've finally narrowed down what's causing the issue.
> > > >
> > > > The bottom line, if you display starts displaying strange characters and gibberish, it's safe to say your power supply is showing inital symptons of failure. I'm going to strip the bad power supply board and check all the caps with an ESR tester and probably just go ahead and replace all the regulators with new and it should clear the problem.
> > > >
> > > > Hope this helps anybody else with the same issue...
> > > >
> > > >
> > > > --- In oberheim@yahoogroups.com , "wesleyknick" <wesknick@> wrote:
> > > > >
> > > > > It does play with output though after loading the factory patches they don't sound correct when compared to my fully functional Matrix 6 in addition to the garbled display.
> > > > >
> > > > > I went ahead and swapped the processor boards in the two synths, something not without some risk of damaging the good processor board. Nevertheless, installing the good processor board in the originally faulty Matrix 6 resulted in a fully functional keyboard with a slightly hissy output. Installing the suspected faulty processor board in the fully functional Matrix 6 resulted in power on problems whereby the display wouldn't light up, strange output on several of the factory patches, and a few of the keys in various places on the keyboard were non-functional. With regard to the power on problems, I'd have to cycle the on-off switch two or three times to get the display to light up. With the bad processor board in the 'good' Matrix 6 synth however, I didn't get a garbled display full of characters, only the display wouldn't usually light up on the first attempt at power on. When the display did light up in was readable. I went ahead and reloaded the original factory patches with the bad processor board however they still didn't sound correct...
> > > > >
> > > > > --- In oberheim@yahoogroups.com , carl hourigan <sloppy.hq@> wrote:
> > > > > >
> > > > > > I had the same problem for at least a year or so with my matrix 6. when it came to me half of the patches were normal the other half were the weird characters thing. the dude i got it from said he thought it was "some dead voice chips" i told him he was an idiot and to stick to playing guitars, then i bought it... (im dumb too i guess). one thing, mine sometimes would just be dead for a month then one day it would decide to power up and have crazy ass characters allover, or it would just power up fine to factory presets. after continuous tinkering for a year or so i have got it to power up every time into a hard reset/calibration mode, im not sure why it just jumps to calibration. In other words i cant save any patches i make unless i involve my librarian. Also i have no idea what i did to get it this far, because at this point ive tried every little possible thing to get it working right, voltages, battery, traces, wires, reseating, cleaning and psycho therapy...
> > > > > > anyway its interesting to hear im not alone, hope you guys figure this out, i would love to get mine working perfectly.
> > > > > >
> > > > > >
> > > > > > > Does it play OK, and you can still adjust parameters etc, only the display is problematic
> > > > > > >
> > > > > > > From: wesleyknick <wesknick@>
> > > > > > > To: oberheim@yahoogroups.com
> > > > > > > Sent: Wednesday, 18 July 2012, 22:06
> > > > > > > Subject: [oberheim] Re: Oberheim Matrix 6, Dead
> > > > > > >
> > > > > > >
> > > > > > > I just joined the group yesterday. If you can point me to the previous discussion I'd appreciate it. The problem is it sometimes powers on without a display, other times it's limited to 7 or so characters and other times the whole diplay fills up with random characters than change when I press the keys. It seems too erratic to be a self-test mode.
> > > > > > >
> > > > > > > --- In oberheim@yahoogroups.com , Peter Mörck <peter@> wrote:
> > > > > > > >
> > > > > > > > This sounds familiar...
> > > > > > > > Isn't this part of the display CPU self-test mode functionality, or
> > > > > > > > something like that
> > > > > > > > Wasn't something like this discussed on this list about a month ago or so
> > > > > > > >
> > > > > > > > BR,
> > > > > > > > Peter
> > > > > > > >
> > > > > > > > ----- Original Message -----
> > > > > > > > From: wesleyknick
> > > > > > > > To: oberheim@yahoogroups.com
> > > > > > > > Sent: Wednesday, July 18, 2012 10:47 PM
> > > > > > > > Subject: [oberheim] Re: Oberheim Matrix 6, Dead
> > > > > > > >
> > > > > > > >
> > > > > > > > Most of the time it just powers on with a string of characters in the
> > > > > > > > display and pressing the keys simply enters new characters in the display as
> > > > > > > > though I'm typing them in.
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