Horizontal lines on SE/30 Display

[mmaseda]

I’ve been working for a while trying to determine the cause of very faint horizontal lines that move from the bottom to the top of the CRT every few seconds. While I can see them perfectly with my eyes I’ve had a hard time documenting them in a photo or video. Here is my best attempt to capture them in a short video. I don’t have a good camera where I can fine adjust the shutter speed so this was just done on my iPhone. I can reproduce this on several SE/30 and SE computers and I have an idea what might be causing it but would rather not get into that at this time until I can get someone else to confirm they have also noticed this.

Manuel

 

[ArjenCNX]

Video ram comes to mind here, check the Vram chips and make sure there is no capacitor spillage around them, and that the Vias are OK, a few gentle taps on the board can sometimes expose bad connections.

 

[mmaseda]

Thanks but that isn’t the problem. I can recreate this problem on multiple computers each with a different logic board. At this point I’m just trying to see if anyone else has every noticed the problem before.

 

[ArjenCNX]

yeah, that solidly excludes that option indeed, just considering the way it works, it would be possible that there is a soldering issue on the motherboard somewhere along the video signal as in comes in, some percussion there may show you something, as could cooling things down with some canned air. other then that i'd have to have the unit in front of me to say much more useful things. Best of luck though!

 

[mmaseda]

Since nobody else seems to have the problem I just tell you what I found. Turns out to be an issue when using a Sony power supply. Don’t see the problem with Astec supplies. Have tried multiple Sony and Astec supplies on several different computers and the problem is always there with the Sony supply.

 

[Mark_W]

Not on a se30 but I got this problem on a color classic, alternating white and dark lines are constantly moving from top of the screen to the bottom. Check the video and if you look closely you can see them crossing the bottom edge of left window at the beginning and around 3-4s. Hard to capture it in the video but it's more apparent to naked eyes.

https://imgur.com/a/W6skH6X

Btw this is the color classic I posted earlier with a dead logic board power supply, which I repaired by hacking in a standalone 5v/12v power supply. It's sitting right next to the tube and I believe it's some interference caused by the switching frequency of PSU. Tried to wind the output wire on a ferrite ring for a few turns, it helps a bit but the scrolling lines are still there. Anyway I just ignore them for now, till I can come up with a better solution to isolate the PSU.