Apple IIc RGB Color Enhancer by Video 7 - reverse engineering?

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Some weeks ago there was an Apple IIc RGB Color Enhancer by Video 7 listed on eBay. Unfortunately I was tight on cash and couldn't bid on it. I want to get one to connect a Macintosh 12" RGB Display to my //c.
These adapters are very rare and hard to get, plus expensive if you find one. I'm thinking maybe somebody knows how to reverse engineer the Video 7 to make one out of an RF modulator?
Any ideas?

Regards

javster

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speedyG's picture
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Joined: Nov 16 2011
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Re: Apple IIc RGB Color Enhancer by Video 7 - reverse ...

Hello Javstar,

first of all before discussing the process of reengineering a device it´s upmost important to have such a unit.....
without unit it´s rediculous to discuss about the task....
the basic of reengineeringare plenty of pictures or the circuitplan....
unless you don´t have a circuitplan and no unit, there is no chance to walk back by pictures to a PCB and a circuitplan...

just for example take a look of the long process we have taken here by reengineering the
Mountain Computer Expansion Box..... and when i have completed the running tasks
there will be first the reengineeering of the Apple //e diagnostic card......+
that card is at least present for analysis....

but of course, if you want to start such task ( without needed material ) ... happy working....

sincerely speedyG

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Re: Apple IIc RGB Color Enhancer by Video 7 - reverse ...

Quote:

I want to get one to connect a Macintosh 12" RGB Display to my //c.

Wrong monitor... you'd need a CGA type monitor.

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Re: Apple IIc RGB Color Enhancer by Video 7 - reverse ...

Well, thanks SpeedyG. Seems like I will have to rephrase my request: Is there a way to make an Apple //c to RGB adapter? maybe following the known Video port schematics?

Sfahey: what do you mean CGA? The adapter specifically outputs RGB, according to the information. Here is a link to the ebay item:
http://www.ebay.com/itm/221253849708?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

Cheers
Javster

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Re: Apple IIc RGB Color Enhancer by Video 7 - reverse ...

Hello javstar,

at the moment i´m pretty hard up with other tasks...
but to make it short: in former days several companies made adapters ....
output of Apple IIc is ( depending to country where the computer was sold ) PAL or NTSC signal....
the other video output at the IIc was rather poor....
input of Mac 12" RGB is as far as i remember analog RGB ( just to mention - not the same like TTL RGB ! )
and there have been several IC´s availiable to convert the one kind of signal to the other kind of signal....
NTSC to RGB or PAL to RGB ....
requires some search in datasheets or circuitplans of former old RGB cards....
search for example old Apple II RGB card from Apple or from IBS or other third party manufacturers....

maybe i can search in a couple of days, unless someone else wants to carry out that task.....

sincerely speedyG

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In early days I had a lot of money but no time - now I have no money but a lot of time....
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Re: Apple IIc RGB Color Enhancer by Video 7 - reverse ...

Quote:

Sfahey: what do you mean CGA? The adapter specifically outputs RGB, according to the information.

It outputs digital RGB, and almost all Apple branded monitors are analog RGB (with the exception of the rare, expensive M100 which can be switched to go either digital or analog).

Some info:

http://apple2.org.za/gswv/a2zine/faqs/Csa2MONITOR.html#024

You want *THIS* RGB adapter:

http://www.ebay.com/itm/VERY-RARE-Apple-IIc-RGB-Interface-by-Video-7-/380705555730

It does output analog but you still can't use a Macintosh (Apple-branded) monitor with it because every Mac monitor I know of doesn't support a low enough horizontal scan frequency (30kHz vs. 15 kHz). You could use a IIGS RGB monitor, or another brand with a 15kHz horizontal - Sony multisync, some Magnavox monitors, Commodore 1084 series...

It's also worth mentioning that the //c video expansion port wasn't really designed with a color RGB adapter in mind, so the Video 7 adapters don't output all the colors correctly.

The ultimate option is to find a Guimauve 2000... someone should track Gregory down and get some more made. I have a couple of them and they work great.

http://a2central.com/1977/guimauve-2000-vga-adapter-for-apple-c-now-available/

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Re: Apple IIc RGB Color Enhancer by Video 7 - reverse ...

Hello javstar,

short research comes up with following result:
IC from Philips TDA8390 was used for converting PAL signal to RGB output ....

datasheet may be viewed at:

http://pdf.datasheetcatalog.com/datasheet/philips/TDA8390.pdf

sincerely speedyG

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Re: Apple IIc RGB Color Enhancer by Video 7 - reverse ...

As what sfahey mentioned, the Video 7 Color Enhancer IIc outputs TTL RGB (can be connected to a CGA monitor), while the Video 7 RGB Interface Adapter outputs analog RGB (15 kHz).

Still on Henry's download site are pictures of the internal PCB of each (sadly without schematics):
http://www.downloads.reactivemicro.com/Public/Apple%20II%20Items/Hardware/Video_7_Color_Enhancer-IIc_RGB/
http://www.downloads.reactivemicro.com/Public/Apple%20II%20Items/Hardware/Video_7_RGB_Interface_Adapter-IIc/

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Re: Apple IIc RGB Color Enhancer by Video 7 - reverse ...

Wow, seems like it will make better sense to get one of those devices. Thanks guys for enlighten me on the different types of RGB, and the links to all options.
Regards

javster

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Re: Apple IIc RGB Color Enhancer by Video 7 - reverse ...

Just if anybody cares, I found the page for the "Guimauve 2000":

http://silicium.org/site/index.php/edition/hardware

I request information, hope they answer and we can have a way to get the adapter.
Cheers
Javster

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Re: Apple IIc RGB Color Enhancer by Video 7 - reverse ...

Well, here's the semi awful translation of the site: http://www.microsofttranslator.com/bv.aspx?from=fr&to=en&a=http://silicium.org/site/index.php/edition/hardware

Which basically states "unfortunately it's out of print."