[Coco] need help repairing a coco 2

[Didier Derny]

Thanks for the information, I tought that the 6847 could not produce
a video signal without a correct configuration

I'll turn my breadboard composite into something final
and I'll socket the 6809

thanks

--
didier



On 16/10/2014 12:52, Luis Antoniosi (CoCoDemus) wrote:
> yes, the 6847 is already wired to produce text video, in fact you cannot
> turn it off.
>
> and yes, i had one 6809 with 2 pins blown.
>
> Luis Felipe Antoniosi
>
>
>
> On Thu, Oct 16, 2014 at 3:02 AM, Didier Derny <didier at aida.org> wrote:
>
>> the 6847 can produce the "beginning" of an image without being programmed ?
>>
>> the 6809 can be only partly blown ?
>>
>> thanks
>>
>> --
>> didier
>>
>>
>> On 16/10/2014 00:25, Retro Canada wrote:
>>
>>> its pretty easy through a mialigned cartridge to blow the 6809. you coul
>>> blow it entirely or some pins. this is the first thing to replace. the
>>> second is the ram chips. the you go for sam and pias.
>>>
>>> the 6847 is working fine
>>>
>>> On Oct 15, 2014, at 6:14 PM, "didier derny" <didier at aida.org> wrote:
>>>
>>> I have a coco 2 with no video on tv output.
>>>
>>>
>>>
>>> I built the composite interface on a breadboard
>>>
>>> Obviously I'm getting an image.
>>>
>>>
>>>
>>> But the machine is not correctly starting
>>>
>>>
>>>
>>> When I start or reset the machine I get
>>>
>>> The following patterns:
>>>
>>>
>>>
>>> 1/ Orange screen
>>>
>>>
>>>
>>> 2/ mix of green/orange lines not correctly synchronized
>>> http://netfilters.eu/p2.JPG
>>>
>>>
>>>
>>> 3/ black screen with random green square containing the letter 'P'
>>> http://netfilters.eu/p3.JPG
>>>
>>>
>>>
>>> 4/ mixed pattern, orange bands with green square containing the letter 'P'
>>> http://netfilters.eu/p1.JPG
>>>
>>>
>>>
>>> I removed all the component on socket and clean the pins.
>>>
>>>
>>>
>>> If I remove   ram or sams or  eprom I don't get any image
>>>
>>> So my "theory" is that the 6809 starts
>>>
>>>
>>>
>>> The coco 2 is a 16k Korean one with 2 small sockets beside the ram chips
>>>
>>>
>>>
>>> Any idea ? it's the first time I repair a coco
>>>
>>>
>>>
>>> Thanks
>>>
>>>
>>>
>>> --
>>>
>>> Didier
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>> --
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>>