[Coco] video composite on korean coco 26-3134A
Zippster
zippster278 at gmail.com
Fri Oct 3 15:29:58 EDT 2014
Check for a clock signal and address/data line activity at the cpu.
-Ed
On Oct 3, 2014, at 2:16 PM, didier derny <didier at aida.org> wrote:
> I'll probably order a pcb
>
> My main problem, is that I have absolutely no idea if the coco 2 is working
> at all
> I tested inside the modulator but I've not seen any signal looking like a
> video signal
> (no synchro seen)
>
> Is there any other way to know if it is dead or alive ?
>
> --
> didier
>
>
> -----Message d'origine-----
> De : Coco [mailto:coco-bounces at maltedmedia.com] De la part de Zippster
> Envoyé : vendredi 3 octobre 2014 19:21
> À : CoCoList for Color Computer Enthusiasts
> Objet : Re: [Coco] video composite on korean coco 26-3134A
>
> Mike,
>
> I made this board to replace the RF modulator box that was in my Korean
> CoCo2.
> I removed the modulator, and soldered pin headers in where the inputs to the
> modulator are. Y, øA, øB, CHB, CLK, Sound, and +5v are all in these
> headers.
> The area underneath the modulator is pretty much all ground plane, allowing
> me to drill mounting holes for the board, and use standoffs to attach it.
>
> Corresponding female headers on the board then just plug into the
> motherboard (except for
> 1 ground wire that needs to be attached). Then I made a cutout in the back
> of the CoCo case, basically expanding where the RF connector was. It makes
> for a pretty neat installation.
> (I’ll put some more pics up later).
>
> I’m not sure if all Korean CoCo2 main boards have the same layout in the
> modulator area, but I think we may have the same model, so it should fit.
>
> I know other CC2’s have differing layouts for the modulator area, but it’s
> easy enough to lay out a board to fit those (with measurements).
>
> I had also thought of the idea of a board plugging into the MC6847 socket,
> and moving it to onto the board, which is a good one. I’m planing on this
> approach for a Component Video board I’m working on. It would be pretty
> easy to socket non-socketed 6847’s if you’re willing to sacrifice the chip
> (utsource has them, I think I paid $5ea for five).
>
> - Ed
>
>
>
> On Oct 3, 2014, at 11:17 AM, mike at borncoco.com wrote:
>
>> Ed, I ordered some of your boards from OSHpark. Nice layout! I'll have to
> open up a Korean CoCo 2 this weekend to see how you made the connections to
> the motherboard. Any info on what you must remove? If you already discussed
> this here, just say so and I'll look in the archives later. As you said, it
> would not be difficult to use clip leads to make the connections for any
> CoCo2. I am still interested in creating a version that can be plugged into
> the 6847 socket. I know the other puzzle is that some models of the CoCo 2
> have the RF modulator box mounted in different ways - some at 90 degrees to
> the motherboard.
>>
>> Great work on the board and I appreciate the time and effort you put into
> this and sharing it with all of us! I look forward to assembling the boards
> when they arrive.
>>
>> Cheers,
>> -Mike
>>
>> -----Original Message-----
>> From: "Zippster" <zippster278 at gmail.com>
>> Sent: Friday, October 3, 2014 11:53am
>> To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
>> Subject: Re: [Coco] video composite on korean coco 26-3134A
>>
>> There was when it was sent, not sure what’s stripping them out.
>>
>> I’ll list them this way…
>>
>> https://sites.google.com/site/thezippsterzone/home/coco2-projects
>>
>> https://oshpark.com/shared_projects/lHtMJ67Z
>>
>> -Ed
>>
>>
>> On Oct 3, 2014, at 10:48 AM, Al Hartman <alhartman6 at optonline.net> wrote:
>>
>>> There's no link in that message...
>>>
>>> -[ Al ]-
>>>
>>> -----Original Message----- From: Zippster
>>> Sent: Friday, October 03, 2014 10:34 AM
>>> To: CoCoList for Color Computer Enthusiasts
>>> Subject: Re: [Coco] video composite on korean coco 26-3134A
>>>
>>> Hey guys,
>>>
>>> You may have missed my earlier post. I did a version of this circuit in
> Eagle.
>>> Sound output is included.
>>>
>>> The files are in the zip on this page. CoCo2 Projects (Tandy Color
>>> Computer 2) - The Zippster Zone
>>>
>>> I put it up as a shared project on OSHPark. OSH Park ~ Coco2
>>> Composite Out (Type 01) Rev 03
>>>
>>> I laid the board out to replace the RF modulator in my Korean
>>> CoCo2’s, but as long as you get the signals to it, you could mount it
> anywhere.
>>>
>>> -Ed
>>>
>>>
>>> On Oct 3, 2014, at 7:20 AM, Michael Rowen <mike at borncoco.com> wrote:
>>>
>>>> John is indeed correct. I have built the simple circuit that includes a
> 1372 that connects to the signal from the 6847. It works well on every
> monitor I've used with a CoCo 2. The circuit is in the data sheet for the
> 6847. I have not had the time to create a PCB with Eagle. Some CoCos have
> the 6847 socketed, so it would be easy to make a board that plugs into that
> 40 pin socket, with the 6847 plugging into the board. CoCo 2s with a
> soldered 6847, would require 7-8 clip leads, but can be done. I have bread
> boarded this on a CoCo 2. This was the same method used by the Colorware
> adapter. I scored one of these at last year's CoCo fest. Its circuit uses
> more caps, but the principle is the same. I have not found any significant
> quality differences using the reference circuit. Clean and sharp. Any Eagle
> experts with some time on their hands to create the PCB files?? :) It will
> probably be Christmas time before I get the chunk of time to tackle this.
> I'm a newbie with Eaglecad. I'll try to post a video this weekend.
>>>>
>>>> Cheers,
>>>> Mike Rowen
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> "John W. Linville" <linville at tuxdriver.com> wrote:
>>>>
>>>>> NTSC CoCo2's use a modulator that does _not_ take a composite video
>>>>> input.
>>>>>
>>>>> The 6847 outputs signals called Y, phiA, and phiB. These are
>>>>> (very) roughly analogous to the YIQ signals that form a composite video
> signal.
>>>>> A Motorola 1372 chip is used to combine those signals into
>>>>> something useful. The 1372 chip can produce either a baseband
>>>>> composite video signal or (by use of an RF tank circuit) a
> TV-compatible radio signal.
>>>>>
>>>>> On the Coco1, the 1372 only produced a composite video signal that
>>>>> was then fed (along with the audio signal) to an off the shelf RF
>>>>> modulator. On the CoCo2, the 1372 chip is only included as part of
>>>>> the RF modulator itself. The Y, phiA, and phiB signals go straight
>>>>> to the modulator where the RF-equipped 1372 turns them into a TV
> signal.
>>>>>
>>>>> I'm not sure if there is a pristine composite video signal
>>>>> available anywhere inside the RF modulator on a CoCo2. I was never
>>>>> able to find one, FWIW. You probably need to pull the modulator
>>>>> and build a new 1372-based circuit to replace it.
>>>>>
>>>>> Good luck!
>>>>>
>>>>> John
>>>>>
>>>>> P.S. It sounds like the PAL CoCo2 might be designed more like the
>>>>> CoCo1 in this regard. Of course, that only helps you if you are
>>>>> using a PAL CoCo2... :-)
>>>>>
>>>>> On Thu, Oct 02, 2014 at 09:56:31PM +0200, didier derny wrote:
>>>>>> Hi,
>>>>>>
>>>>>> I tried but no success...
>>>>>>
>>>>>> I don’t have any image on tv (connected to the antenna) No idea if
>>>>>> the coco 2 is broken or if my tv is unable to process the signal
>>>>>>
>>>>>> With the oscilloscope I've not been a able to find a composite
>>>>>> signal Inside the modulator...
>>>>>>
>>>>>> Any idea ?
>>>>>>
>>>>>> Thanks
>>>>>>
>>>>>>
>>>>>> --
>>>>>> didier
>>>>>>
>>>>>> -----Message d'origine-----
>>>>>> De : Coco [mailto:coco-bounces at maltedmedia.com] De la part de
>>>>>> Simon Jonassen Envoyé : samedi 27 septembre 2014 16:26 À :
>>>>>> 'CoCoList for Color Computer Enthusiasts'
>>>>>> Objet : Re: [Coco] video composite on korean coco 26-3134A
>>>>>>
>>>>>> Hey....
>>>>>>
>>>>>> I did mine by tapping into the feeds that go directly to the rf
>>>>>> modulator....
>>>>>>
>>>>>> A couple of shielded wires soldered on to the pins and 2 rca jacks
>>>>>> on the rear of the case (audio/video)
>>>>>>
>>>>>> Works fine... No extra components needed (PAL machine)...
>>>>>>
>>>>>> /Simon :-)
>>>>>>
>>>>>>
>>>>>> -----Oprindelig meddelelse-----
>>>>>> Fra: Coco [mailto:coco-bounces at maltedmedia.com] På vegne af didier
>>>>>> derny
>>>>>> Sendt: 27. september 2014 13:23
>>>>>> Til: 'CoCoList for Color Computer Enthusiasts'
>>>>>> Emne: [Coco] video composite on korean coco 26-3134A
>>>>>>
>>>>>> Hi
>>>>>>
>>>>>> Is there an easy way to get a video composite signal on this machine ?
>>>>>>
>>>>>> I guess a video composite signal or something approaching should
>>>>>> be found Somewhere near the modulator or inside the modulator ?
>>>>>>
>>>>>>
>>>>>> Thanks
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Coco mailing list
>>>>>> Coco at maltedmedia.com
>>>>>> https://pairlist5.pair.net/mailman/listinfo/coco
>>>>>> -----
>>>>>> Ingen virus fundet i denne meddelelse.
>>>>>> Kontrolleret af AVG - www.avg.com
>>>>>> Version: 2012.0.2247 / Virusdatabase: 4031/7782 - Udgivelsesdato:
>>>>>> 27-09-2014
>>>>>>
>>>>>>
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>>>>>>
>>>>>>
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>>>>>>
>>>>>
>>>>> --
>>>>> John W. Linville Someday the world will need a hero, and you
>>>>> linville at tuxdriver.com might be all we have. Be ready.
>>>>>
>>>>> --
>>>>> Coco mailing list
>>>>> Coco at maltedmedia.com
>>>>> https://pairlist5.pair.net/mailman/listinfo/coco
>>>>
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