[Coco] GBS-8200 RGB to VGA

[Kandur]

Barry, sounds like a good idea to use current limiting resistors.
I was aware of the possibility that an IC may be damaged.
Took a chance and nothing bad happened since 2014/09/20 .
This Coco is on about 10 hours daily.

Kandur

Friday, September 4, 2015, 7:06:16 AM, you wrote:
> That solution may "work" but I strongly suggest adding at least 100 ohm
> resistors to pins 8 and 9 before tying them together, otherwise when pin 8 is
> high and pin 9 is low or pin 9 is high and pin 8 is low you are creating a
> short circuit across the hsync and vsync outputs of the CoCo 3. I checked the
> CoCo 3 schematic and there is no protection on those outputs, they are tied
> directly to the output of an inverter chip so if those outputs are shorted out
> you could eventually burn out that chip. At least they are not wired directly to the GIME chip.

> coco-request at maltedmedia.com

>> Date: Thu, 3 Sep 2015 21:29:50 -0500
>> From: George Ramsower <georgera at gvtc.com>
>> coco at maltedmedia.com
>> Subject: Re: [Coco] GBS-8200 RGB to VGA
>> Message-ID: <55E9021E.6030600 at gvtc.com>
>> Content-Type: text/plain; charset=utf-8; format=flowed






>> found the typed instructions in the third image.


>> George R.

>> On 9/3/2015 7:42 PM, Kandur wrote:
>>> I have mine working fine in OS-9, with 80 character display,
>>> without using any additional chips. Take a look at it,

>>> http://qdv.pw/coco/?p=317

>>> Kandur

>>> Wednesday, September 2, 2015, 11:46:33 PM, you wrote:
>>>> I have had problems feeding that sync signal to anything except a CM8, even
>>>> after fixing the polarity and boosting the signal. For some reason the sync on
>>>> the NTSC video works better. Anyway, try the 7402 and let me know if it works for this.
>>>> coco-request at maltedmedia.com
>>>>> Date: Wed, 2 Sep 2015 21:53:54 -0500
>>>>> From: George Ramsower <georgera at gvtc.com>
>>>>> coco at maltedmedia.com
>>>>> Subject: Re: [Coco] GBS-8200 RGB to VGA
>>>>> Message-ID: <55E7B642.2070102 at gvtc.com>
>>>>> Content-Type: text/plain; charset=windows-1252; format=flowed


>>>>> about it.

>>>>> 7402 is all that is needed.
>>>>> George R.