[Coco] video composite on korean coco 26-3134A

Zippster zippster278 at gmail.com
Fri Oct 3 18:16:34 EDT 2014 

You could rig up a quick and dirty piece of coax cable from the RF
port to the antenna in jack on a tv and tune it to channel 3 or 4 (whatever the
switch is on).  The picture may not even be that bad.

Or the relay.


-Ed


On Oct 3, 2014, at 4:30 PM, Chris <coronet1969 at gmail.com> wrote:

> type CLOAD and listen for the relay.
> 
> On Fri, Oct 3, 2014 at 3:29 PM, Zippster <zippster278 at gmail.com> wrote:
> 
>> 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
>>>>>>>> 
>>>>>>>> 
>>>>>>>> 
>>>>>>>> 
>>>>>>>> 
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>>>>>>>> 27-09-2014
>>>>>>>> 
>>>>>>>> 
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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.
>>>>>>> 
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