Apple Monitor II Strange Picture effect

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Apple Monitor II Strange Picture effect

Hi,

I have a picture problem on my Apple Monitor II (A2M2010) at near the top of screen. (Please see the attachment) I try to repair it by changed all Electrolyte capacitors, but they were not help. I need the suggestion what the components should have defective.

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Looks like a V Sync issue.

Looks like a V Sync issue. The picture of the Apple screen looks typical of early motherboards that had bad vertical sync generation. But the greyscale is obviously coming from a generator that presumably is outputting a correct signal. Other possibility is the input capacitor on the video input of the monitor. Are you sure you changed that?

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That monitor looks like it is

That monitor looks like it is way out of adjustment as far as picture size goes.  Both horizontal and vertical.  In general Apple II video should have a black border around the displayable portion.  The cross hatch pattern goes off the screen at the edges, and it shoudn't.  Control may be better if the picture size is reduced to fit all in the displayable part of the CRT with a small border all the way around.  Also brightness and contrast probably need to be adjusted.  Brightness should be turned down so that lit pixels don't bloom out.  Contrast should be set so the background is dark.

 

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jeffmazur wrote:Looks like a
jeffmazur wrote:

Looks like a V Sync issue. The picture of the Apple screen looks typical of early motherboards that had bad vertical sync generation. But the greyscale is obviously coming from a generator that presumably is outputting a correct signal. Other possibility is the input capacitor on the video input of the monitor. Are you sure you changed that?

 

Yes, I'm sure that I changed all Electrolyte Capacitors. Next, I plan to change Milar Capacitors around IC301 TDA1170. If not help, I will change IC301 TDA1170. I plan to do these because I found Vertical hold issue if the Apple II is in graphic mode (use BASIC command "GR") then exit to text mode (use BASIC command "TEXT"), the vertical hold is fail to lock the screen (adjust the V-Hold knob not help). If I use the BASIC command "HOME" to clear the screen, the screen is back to normal.

 

 

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softwarejanitor wrote:That
softwarejanitor wrote:

That monitor looks like it is way out of adjustment as far as picture size goes.  Both horizontal and vertical.  In general Apple II video should have a black border around the displayable portion.  The cross hatch pattern goes off the screen at the edges, and it shoudn't.  Control may be better if the picture size is reduced to fit all in the displayable part of the CRT wit

 

The Apple II picture in attachment is in 80-Columns mode, not normal 40-Columns mode.

 

 

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Fenix+ wrote:softwarejanitor
Fenix+ wrote:
softwarejanitor wrote:

That monitor looks like it is way out of adjustment as far as picture size goes.  Both horizontal and vertical.  In general Apple II video should have a black border around the displayable portion.  The cross hatch pattern goes off the screen at the edges, and it shoudn't.  Control may be better if the picture size is reduce

 

 Wow! I made the assumption that the crosshatch and grayscale images were from a test pattern generator because they were overscanned. If all of these images are from the Apple, then I would agree that the first thing to do is adjust the H and V sizes.  If that doesn't help then I would suspect the Apple and not the monitor. What Rev motherboard is it?

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My Apple II mainboard is very

My Apple II mainboard is very old. It should be Rev. 0. The picture from pattern generator are overscanned because I use the pattern generator for PAL system (625 lines) to test with the monitor.

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Do you have this issue if you

Do you have this issue if you plug your monitor straight to the back of the Apple II and not though the 80-column card?

 

Btw, is your motherboard really a Rev.0 - you sounded like you are not sure. A small detail worth several grand last time I checked on eBay. :)

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Yes, I have the same problem

Yes, I have the same problem in 40-Columns mode, too.

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Problem is solved.

Finally I found the root cause of the problem which came from the sync signal problem from my Apple II Rec.0. I found many document to discuss about the same problem on other monitors. Then, I switch to Apple IIe, there is no problem anymore. Thank you for all comments.

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