firesmile_01 Posted February 16, 2018 Share Posted February 16, 2018 (edited) Robert, Over Christmas, I finally took time to assemble John Carlsen's DAC with the converter, along with the case for it that I bought from COREi64 on the lemon forum. Problem is, I am getting some terrible interference on the Acer Monitor I had laying around. Waves going through the picture (most visible with certain colors on the monitor). I wanted to get in touch with John, but no go. Even the website seems to be down so I'm sorta pooched until I can get in touch with him. Do you know if he's still about? Oh, and I managed to purchase a serial cable through Amazon. Is there any way it can be the cable creating interference ? Any help in contacting John is appreciated ... and any help is invaluable. Curt Newfoundland, Canada Great Hierophant wrote: > Fair enough, here is essentially the circuit Carlsen used... Some history is necessary here. The original video DAC was created by Richard42g in 2008 or so. He talked about it on the defunct www.commodore128.org forum. I bought one of those, and after hand-building 30 of those, Richard stopped production and granted permission for anyone else to continue building them. Richard42g published the schematics and the list of parts on the forum. In 2011-2012, after much discussion, John Carlsen was convinced to build an improved version of Richard's design. In the meantime, Alex J (whose blog you have referenced) transferred Richard's schematic and part's list to the Erik Klein's Vintage Computer Forum (which was good, because when commodore128.org went down, all the information on Richard's design disappeared at that site). Alex J. built and sold more of Richard's video DAC without any modifications to the design. Then Alex stopped production on those copies. John Carlsen analyzed the Richard's video DAC and found out that the two or three of the colors displayed were off, the intensities being wrong but most glaringly, brown was not displayed correctly. John contacted Richard and discussed the original's problems. In 2013-2014 John worked on his own prototypes of the video DAC. With the use of a 1084 monitor to measure the colors displayed, John tweaked the values of resistors on the original list of parts. He was able to get true colors. See http://blog.retro-link.com/2014/01/c128-vga-adapter-latest-prototype.html The two prototypes were shown at the FCUG and SCCAN meetings and at the Commodore Vegas Expo v10 2014, where the attendees, most notably hardware developer Jim Drew, made comments on the design. In 2015 at the May (or was it the July) SCCAN meeting, John was able to meet Richard face-to-face and show the first production model. John was very proud of his design which used surface-mounted parts and was smaller than Richard's original. Richard had a big smile on his face and was very enthusiastic about what his original had become. At the Commodore Vegas Expo v11 2015, John released his production model, building a few to sell at CommVEx. Since the show, he has ramped up production of his video DAC, selling the units through his website and on Amazon.com Great Hiierophant wrote: > it's too late for him to patent it now. Nor does he want to patent anything. John has freely admitted that Richard's design has been the basis of the new video DAC. Back from today's FCUG meeting, Robert Bernardo Fresno Commodore User Group http://www.dickestel.com/fcug.htm Southern California Commodore & Amiga Network http://www.sccaners.org July 30-31 Commodore Vegas Expo v12 - http://www.portcommodore.com/commvex Edited February 16, 2018 by firesmile_01 Quote Link to comment Share on other sites More sharing options...
RobertB Posted February 16, 2018 Author Share Posted February 16, 2018 Curt wrote: > Over Christmas, I finally took time to assemble John Carlsen's DAC with the converter... You assembled the Video DAC instead of buying it pre-built by John Carlsen? > I wanted to get in touch with John, but no go. Even the website seems to be down... The website has been down in the past but has always managed to come back. > ...I managed to purchase a serial cable through Amazon. Is there any way it can be the cable creating > interference ? Serial cable? Do you mean a VGA cable between the Gonbes and your VGA monitor? Truly, Robert Bernardo Fresno Commodore User Group http://www.dickestel.com/fcug.htm Southern California Commodore & Amiga Network http://www.portcommodore.com/sccan Quote Link to comment Share on other sites More sharing options...
firesmile_01 Posted February 16, 2018 Share Posted February 16, 2018 (edited) <snip> You assembled the Video DAC instead of buying it pre-built by John Carlsen? LOL ... Noooo, Sorry Robert, I lost ya in "translation." I don't have the mad skills I'd need. I bought the DAC from John, and the Gonbes-8200 from Amazon, and the Case from COREi64 on the Lemon forum. But I assembled the three components over Christmas and I managed to use an old Acer Monitor I had on hand. <snip> The website has been down in the past but has always managed to come back. Can't reach it at this point. But I'll keep trying. A fellow user saw my post and gave me an e-mail address for him, so hopefully that might get me out of the weeds. <snip> Serial cable? Do you mean a VGA cable between the Gonbes and your VGA monitor? Oh no, the Male to Female 9-pin cable that connects into the Video DAC board from the C128DCR. See Robert, I have - what I think is - a 10 foot 9-pin Female to Male straight through Serial cable I bought from Amazon going from the back of my 128DCR to the DAC, which then feeds up into the Gonbes Unit in the same case. I'm then using the VGA cable that I have, to get the VGA signal from the Gonbes 8200 unit to my Acer Monitor's VGA input. But there are noticeable diagonal wave-y lines running/moving down through the video output ... and I can't figure out where it's coming from. It's not TERRIBLE, but when I load Pocket Writer 2 into the 128 (in 80 column-mode), the wavy lines are bad (especially when I select medium grey as the text background.) I wondered if the 9-pin Serial cable from Amazon, running from the 128DCR to the DAC unit was the problem, or something bigger. To make things worse, I notice that the original cable that connects the 1084 monitor that I have to the C128DCR's video output is Male to Male. So, no hope of using the original Commodore Monitor cable with the DAC that needs a female. I need help. Edited February 16, 2018 by firesmile_01 Quote Link to comment Share on other sites More sharing options...
RobertB Posted February 16, 2018 Author Share Posted February 16, 2018 Curt wrote: > Oh no, the Male to Female 9-pin cable that connects into the Video DAC board from the C128DCR. See Robert, I have - what I think is - a 10 foot 9-pin Female to Male straight through Serial cable I bought from Amazon going from > the back of my 128DCR to the DAC, which then feeds up into the Gonbes Unit in the same case. Oh, I see. I would blame that video cable, because for the best signal quality, you should directly attach the Video DAC to the RGB output of the C128. Truly, Robert Bernardo Fresno Commodore User Group http://www.dickestel.com/fcug.htm Southern California Commodore & Amiga Network http;//www.portcommodore.com/sccan Quote Link to comment Share on other sites More sharing options...
firesmile_01 Posted February 16, 2018 Share Posted February 16, 2018 Dang, that's bad news... especially as I put so much $$$ into the case. I wonder if I can source some short cable that might be less prone to interference. CD Curt wrote: > Oh no, the Male to Female 9-pin cable that connects into the Video DAC board from the C128DCR. See Robert, I have - what I think is - a 10 foot 9-pin Female to Male straight through Serial cable I bought from Amazon going from > the back of my 128DCR to the DAC, which then feeds up into the Gonbes Unit in the same case. Oh, I see. I would blame that video cable, because for the best signal quality, you should directly attach the Video DAC to the RGB output of the C128. Truly, Robert Bernardo Fresno Commodore User Group http://www.dickestel.com/fcug.htm Southern California Commodore & Amiga Network http;//www.portcommodore.com/sccan Quote Link to comment Share on other sites More sharing options...
RobertB Posted February 22, 2018 Author Share Posted February 22, 2018 I just checked. The website is back up -- http://bit-c128.com/ Truly, Robert Bernardo Fresno Commodore User Group http://www.dickestel.com/fcug.htm Southern California Commodore & Amiga Network http://www.portcommodore.com/sccan Quote Link to comment Share on other sites More sharing options...
RobertB Posted February 24, 2018 Author Share Posted February 24, 2018 Curt wrote: > Do you know if he's still about? I saw John last night at The Commodore Story movie premiere at the Computer History Museum in Mountain View, California. He said that he was having health issues late last year but is better now. Truly, Robert Bernardo Fresno Commodore User Group http://www.dickestel.com/fcug.htm Southern California Commodore & Amiga Network http://www.portcommodore.com/sccan Quote Link to comment Share on other sites More sharing options...
motrucker Posted March 7, 2018 Share Posted March 7, 2018 I knew better than buying the Gonbes Unit when I did it. So,in the end it made a nice target for my .44 black powder pistol. I got a couple of almost new 1080 monitors, and one 2002, so I'm set. I'll stick with vintage stuff for now. Quote Link to comment Share on other sites More sharing options...
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