Macintosh Color Classic 640x480 Video

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rvp
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Joined: Dec 31 2007
Posts: 6

Hello guys, I recently did a video upgrade soldier to my Macintosh Color Classic. It seemed to go very well except for one thing. My monitor is now goes from big on bottom and top and narrow in the middle (hourglass like). I am not sure if I am describing it correctly.

The system 7.5.3 says that it is in the 640x480 at 67 Hz, which is what is suppose to be. I tried to adjust this problem, however, the PB will not move enough to fix it. Has anyone over the years done this upgrade to the Macintosh Color Classic. Let me know if you had this problem or if you were able to fix it. I tried every little pin hole on the back to adjust, but nothing has made a big difference.

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cc-fanatic's picture
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Joined: Dec 19 2003
Posts: 10
Hi, not sure what you mean

Hi,

not sure what you mean with PB. To adjust geometry and color there are a row of pots in the rear of the a/b (analog board). You have to open the case. The range of the pots should be sufficient for the adjustment.

Did you perform the senseline hack or the voltage hack?

I placed a mirror in front of the CC when I adjusted the pots from behind.

Good luck!

eeun's picture
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Joined: Dec 19 2003
Posts: 1891
When you tried to adjust your

When you tried to adjust your monitor, were you attempting to make the middle stretch to meet the upper and bottom width, or shrinking the top and bottom? One of the consequences of the voltage mods can be a decrease in the viewable screen area. The capacitor addition to CL26 on the analog board -may- help: 1000V (1 kV), 1-4 nF for preference.

You did the "hi-res" mod, running at 67 Hz.

There's also Chris Lawson's VGA mod, which runs at 60 Hz. You might find it to be more compatible with your aging video circuitry. Both mods are similar enough that you won't have difficulty swapping from one to the other.

VGA mod: Link

...and here's a link that will show you what each of the adjustment pots on the back of the board do.

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rvp
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Joined: Dec 31 2007
Posts: 6
Apple Monitor Information

Hello, I am very glad that you had that information, because the computer screen on the machine was excellent, but then after I did the upgrade (as you said) it puts a strain on the hardware especially since it is such an old machine. I am going to try the suggestion you provided in the link to fix the hourglass problem, because the only thing that has to happen is that the screen needs to come out horizontally so that it is not hourglass shape. I will keep you posted on the status of how it goes. Thank you very much.

-RVP

rvp
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Joined: Dec 31 2007
Posts: 6
Apple Monitor Information

Hello, I am very glad that you had that information, because the computer screen on the machine was excellent, but then after I did the upgrade (as you said) it puts a strain on the hardware especially since it is such an old machine. I am going to try the suggestion you provided in the link to fix the hourglass problem, because the only thing that has to happen is that the screen needs to come out horizontally so that it is not hourglass shape. I will keep you posted on the status of how it goes. Thank you very much.

-RVP

tmtomh's picture
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Joined: Dec 20 2003
Posts: 568
Re: Macintosh Color Classic 640x480 Video

rvp wrote:

Hello guys, I recently did a video upgrade soldier to my Macintosh Color Classic. It seemed to go very well except for one thing. My monitor is now goes from big on bottom and top and narrow in the middle (hourglass like). I am not sure if I am describing it correctly.

As eeun says, your problem most likely cannot be solved. Converting to the 60Hz "VGA" mod (instead of your current 67Hz "High-Res" mod) might help a bit, but it might not. Ditto for the CL26 trick - sometimes it helps, other times it doesn't.

Nine times out of 10, a 640x480 mod on a Color Classic will result in the display area being a bit narrower than with the original 512x384 resolution - it's just a limit of the hardware. Most of the time, though, the display width is acceptable, even if it's not quite as wide as one would ideally want.

Good luck - let us know if you make any progress!

Best,
Matt

rvp
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Joined: Dec 31 2007
Posts: 6
Color Classic Display

Thanks for the reply, I will keep you posted. The display at the time is actually quite bad as it is very hourglass shaped and it is very unique viewing the software that way, but I will give these things a try and try to get it as close as I can. I will keep you posted.

-RVP

rvp
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Joined: Dec 31 2007
Posts: 6
Problem finding the additional part - help!

Hello guys, I tried using google to find the capacitor that would help to correct the problem with the screen, however, I am not really sure what I am suppose to be doing. I am good at following the direction (like to mod the Color Classic), but I do not really know a lot about the capacitors.

If anybody could provide me a link to locate the capacitors need to get this little machine fixed up again. that would help me out a lot.

Keep me posted, thank everyone.

-RVP