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Color Classic VGA Mod. the CORRECT way

Macdrone

Well-known member
isnt there black and white games at that resolution that mess up at 640x480 much as 040 macs could do 1024x768 but the game takes itself to 640x480 to play?

 

Trash80toHP_Mini

NIGHT STALKER
Never give up pixels!  : :)   However, if you want to teach the horse to sing, build an A/B switchable PCB with both configurations, jumper wire it to the MoBo's contact points, it's all analog after all.

 
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Bunsen

Admin-Witchfinder-General
I'm contemplating the viability of making the sense lines switchable in order to allow use of the stock CC board and lower resolution in a VGA modified CC.
Now, I have heard that a 575 AB can drive the CC monitor at 800x600, so one wonders if that would also be possible with these mods.

 

uniserver

Well-known member
that is sick…  bunsen …  do you remember the details of this,  was that using the same deflection coil?

 

Bunsen

Admin-Witchfinder-General
I don't remember much about it.  It was on Applefritter IIRC, and yes, I think there were no alterations to the CRT/yoke/etc assembly.

Topic pinned, btw :)

 
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Bunsen

Admin-Witchfinder-General
One thing I think I remember is that they left all the sense ID lines unconnected, and used the "Show all resolutions" setting in the Monitors control panel.

 
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Macdrone

Well-known member
Tech if you have a mouser or digikey list for this so I can order and go to town I just recieved a CC I want to do this to. If not Ill wait until i get a day off to look it all up.  Will have to be after STAR WARS tho.

 

techknight

Well-known member
No, I didnt do any cross-referencing to modern part numbers. I just grabbed the values and voltages of everything before shipping the board back out. 

The only thing that you have to get right is the two capacitors I listed at the top. They are the box style. Mylar film I believe. Everything else is garden variety. 

 
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Bunsen

Admin-Witchfinder-General
OK, finally found the details on the 575 analog board in a CC.
 

This analog board comes from Apple configured at 640x480 66Hz. The "Hi-Res" mod or "VGA Mod" are *not* required, and will probably kill your 575 board. However, the sense line coding issues are still the same ...

I set my monitor sense line to "VGA" which gives me several working resolution choices: 640x480x66Hz, 640x480x60Hz, 800x600x60Hz, and 800x600x56Hz. ... 800x600 is nice and usable, though the dot pitch is a little grainy.
.
Note that this mod requires physical modification to both the 575 AB and the CC inner framework to get the board to fit.  Given that, it's probably better to do the "correct" VGA mod on an original CC AB, unless you are absolutely determined to get to 800x600 on the original CRT, or don't care about sawing up the CCs internals (which is required for some motherboard mods anyway).

People who know more about this than me:  what are the chances you could get the same result using a "correctly" modified CC AB, with sense line ID set for VGA?  I seem to recall someone here who did a MiniITX CC did just that.

Other caveats and gotchas at the link:
 

Live: http://www.fenestrated.net/~macman/CC575/

Archive: http://web.archive.org/web/20141113164633/http://www.fenestrated.net/~macman/CC575/

 
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zwarder

New member
Great post I picked up an old color classic & was recapping the analog board & cannot however find RL70 resistor RL69 no problem.

Also RF11 is badly fried can someone supply the correct value.

Thanks

 

avadondragon

Well-known member
RF11 is 340Ohm

I've been staring at this board for quite a while now and can find RL70 either.

 
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avadondragon

Well-known member
While getting prepared to order parts and try out this new VGA mod I discovered the following discrepancies. I think I have a rev D board as it is labeled 820-0360-D in the bottom right corner. I'm not sure I should attempt this now since there could be more differences between my board and the DVT board that weren't noted.

RP61 – Already populated with 7.5 K resistor

J104 – Couldn't find - suspect it is populated and has an R-designator?

RL54 – Has 18Ohm resistor in place not 33Ohm

RP8 – Already 33K resistor

RP23 – Empty

RF14 – Populated with 243K resistor

RP6 – Populated with 5.6K resistor

 

mraroid

Well-known member
Any resolution to your problem avadondragon?  I am about to place a order with Mouser...

Also, what did we decide re the flyback transformer?  Is the one on a 575 more robust?   Anyone have a source for new flyback transformers for the CC or 575 board?

jack

 
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mraroid

Well-known member
techknight....
 
I am thinking of doing this mod to a CC analog board.  If I did this mod, I would probably roll in a logic board from a 575. 
 
If I did that, would I still need to do the sensing mod with RezEdit to the 575 logic board?  Or could I just slide the 575 logic board in after this analog board upgrade?
 
One last question...  My CC analog board work fine.  But DL21 and DL22 look dark and old.  I was thinking about replacing them.  However, I can not read the values on the diodes.  Do you know the values?
 
Thanks.
 
jack
 
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