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

[Brian Sturk]

Hi Tim,

I tried everything you suggested, still the same.  What's very 
interesting (and might help figuring this out?) is that it happens after 
a cold start but stops if I do a warm reset.  This was with a game 
cartridge.

~telengard

> I have seen similar symptoms with loose memory chip contacts, and gime 

> contacts.  Even though the machine is new, 25 years new! ha ha ha  I 

> would re seat all of the socked chips, and to an eraser job on the 

> motherboard rom-pak contacts.

>

> Tim

>

> Brian Sturk wrote:

>> 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

>>

>

>

> -- 

> Coco mailing list

> Coco at maltedmedia.com

> http://five.pairlist.net/mailman/listinfo/coco



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