[Coco] [HW] Coco 3 video output corrupt when using cart port

[Brian Sturk]

Robert Gault wrote:
> Brian Sturk wrote:
>> Hi there,
>>
>> I have a very good condition Coco 3 (bought sealed new, used a few 
>> times) and I just recently started using the cart port/bus.  I've 
>> used cartridge games and the SVD virtual disk drive device and when 
>> using them the video output gets very garbly.  Any ideas on what it 
>> might be?  At first I thought it was the SVD but it happens with the 
>> games also.
>>
>> Hopefully a kind coco hw guru will have some ideas.   :) I'm going to 
>> go poke around looking for schematics and a way to search the mailing 
>> list archives.
>>
>> thanks,
>> ~telengard
>>
>
> Which video output do you mean? There are three video outputs on a 
> Coco3, RF (red RCA jack), Video (white RCA jack), and RGB (9-pin on 
> the bottom of the case.
>
> For any of these, the quality of the cable (poor shielding) might be a 
> problem. If using the RF jack, make sure the slide switch (CH) is 
> selecting an unused channel in your area. For the composite or RGB, I 
> can't think of any reason why a cartridge should interfere with the 
> video signal.
>
> -- 
> Coco mailing list
> Coco at maltedmedia.com
> http://five.pairlist.net/mailman/listinfo/coco
Hi there,

Sorry for not being more specific.  I'm using the composite video out to 
a 1702 monitor.  I'll try a better cable, good idea.  The interference 
only seems to happen when the cart port is being used and after.  If I 
just boot up the coco w/ something plugged in it stays fine.  And it 
seems like something bad coming out of the coco.
Interference from a magnetic field has a certain look and this seems 
more like something else.  On a black screen I can see hints of orange 
and blue.  It's almost like random repainting of the screen *and* the 
magnetic field effect.  Definitely weird.

thanks for the help, I'll report back,
~telengard

-- 
.------------------------------------------------,------.
| Brian Sturk - http://home.comcast.net/~bsturk / C/C++ | .>   )\,^a__
|-------------------------. bsturk%comcast.net | Python |(  _ _)/ /-."~
| http://www.telengard.com `--------------------`-------| `( )_ )/
| Telengard Technologies Inc - Win32/UNIX programming   |_<_s_<_s
`-------------------------------------------------------'