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Faint line moving down Macintosh SE display?
- Thread starter hw2h
- Start date
That sounds like 60Hz interference with the CRT display. There are two prime causes of it, in general.
First, magnetic interference from a nearby transformer, electric motor or other machine. Does the line get more pronounced or less noticeable if you move the Mac around or rotate it? If so, the interference is coming from outside the Mac and the only solution is to move or reorientation the computer or whatever's creating the interference.
The other likely possibility is failing capacitors in the Mac's power supply, which may itself be part of the analog board (I don't know the SE well enough to say) . As the capacitors age, they both lose capacity and gain internal resistance, so they don't do such an effective job of smoothing out the incoming 60Hz AC power. The Mac's power supply is doing its best to give a stable output, but there comes a point when small 60Hz variations find their way into the output, which can affect the monitor in the way you describe. Replacing the capacitors isn't expensive if you're handy with a soldering iron and understand what safety precautions to take.
Those of us who live in countries where the power is 50Hz would see a disturbance on the screen flickering up and down 10 times a second rather than the slow-moving bar you're seeing. The movement of the bar on the screen depends on the difference between the local power frequency and the Mac's fixed 60Hz vertical scan.
Chris
First, magnetic interference from a nearby transformer, electric motor or other machine. Does the line get more pronounced or less noticeable if you move the Mac around or rotate it? If so, the interference is coming from outside the Mac and the only solution is to move or reorientation the computer or whatever's creating the interference.
The other likely possibility is failing capacitors in the Mac's power supply, which may itself be part of the analog board (I don't know the SE well enough to say) . As the capacitors age, they both lose capacity and gain internal resistance, so they don't do such an effective job of smoothing out the incoming 60Hz AC power. The Mac's power supply is doing its best to give a stable output, but there comes a point when small 60Hz variations find their way into the output, which can affect the monitor in the way you describe. Replacing the capacitors isn't expensive if you're handy with a soldering iron and understand what safety precautions to take.
Those of us who live in countries where the power is 50Hz would see a disturbance on the screen flickering up and down 10 times a second rather than the slow-moving bar you're seeing. The movement of the bar on the screen depends on the difference between the local power frequency and the Mac's fixed 60Hz vertical scan.
Chris
pics/video???
Probably wont be able to get a picture or video of that problem , since cameras don't capture CRT screens very well at alllll
I had this problem on one of my SE a Very FAINT line traveling up or down but I have to look very close to the screen to see it.
Switching around analog boards, power supplys, and CRT's, and after a full recap of analog boards and power supply, it was still there it was only present on one Samsung brand crt no matter what analog board or power supply i tried. However I did not check the board that connects to the back of the tube.
I didn't do much troubleshooting cause it wasn't a problem and I hate taking things apart and putting back together too much.
It is possible that it just picking up some interference from the hard drive lets say, I did notice the line More with an original 20mb drive vs the newer quantum fireball.
I had this problem on one of my SE a Very FAINT line traveling up or down but I have to look very close to the screen to see it.
Switching around analog boards, power supplys, and CRT's, and after a full recap of analog boards and power supply, it was still there it was only present on one Samsung brand crt no matter what analog board or power supply i tried. However I did not check the board that connects to the back of the tube.
I didn't do much troubleshooting cause it wasn't a problem and I hate taking things apart and putting back together too much.
It is possible that it just picking up some interference from the hard drive lets say, I did notice the line More with an original 20mb drive vs the newer quantum fireball.
Only CMOS cameras dont capture CRT screens well as the scan speed of the sensor cant be adjusted. A true CCD camera with variable shutter speed = Different Story.
That sounds like Magnetic interference from an outside source as far as I can tell, like CMJones01 stated.
When I was teaching Comp Lit to K-12 students, the labs literally had machines next to each other and the magnetic interference from one machine always affected the 2 or 3 next to it, displaying a faint line.
Got a PC/Mac, CRT Monitor, Radio and anything with a electro-magnet in it near your SE? Even a cellphone (with their strong magnets inside it), refrigerator and/or large AC unit can cause this. Try moving the SE around until the line fades away.
When I was teaching Comp Lit to K-12 students, the labs literally had machines next to each other and the magnetic interference from one machine always affected the 2 or 3 next to it, displaying a faint line.
Got a PC/Mac, CRT Monitor, Radio and anything with a electro-magnet in it near your SE? Even a cellphone (with their strong magnets inside it), refrigerator and/or large AC unit can cause this. Try moving the SE around until the line fades away.
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