SE/30 Video Circuit Problems -Horizontal and Vertical Lines

[davidg5678]

My recapped SE/30 (analog board, logic board, and PSU) has begun to exhibit a strange problem. When I flip the power switch on, one of four things happens:

1. Fan Spins, No video output
   
2. Fan Spins, Extremely Garbled Video output (see video #1)
   
3. Fan Spins, Thin vertical line briefly flashes on the screen, no video output (I was unable to recreate this)
   
4. Fan Spins, Thin horizontal line briefly flashes on the screen, no video output (see video #2)
   

After checking the components on the motherboard, analog board, and PSU, everything seems to be intact, and I did not see or smell any burning parts.

I am unsure what to test next or what might be wrong with the machine as this does not resemble any single issue I have read about. I am happy to provide more pictures of the circuits. Please let me know if you have any ideas about how to fix this. Thank you!

View attachment SE30_HorizontalLine.MOV
View attachment SE30_GarbledVideo.MOV

 

[Johnnya101]

Just a guess, bad solder joint? Try smacking the side of the case while on and see if it changes anything.

Edit: Watched the garbled video. Looks like an issue I had with my SE/30 and didnt you have this before as well? SE30_Neal is having a similar issue too. Thats a bad PSU (Or potentially AB, but Id say more PSU). Swap it and see if it goes away. You can see the video size shrinking and jittering. 

Of course, could be something else, but Id start there. You may also want to measure the voltages from the floppy port and report back what they are. Im betting they wont be anywhere near correct.

 

[davidg5678]

I just tried switching my SE/30 Logic Board with one from my Macintosh SE, and I was able to boot up the computer without any problems at all. The display looked fine and stood up to a smack on the side of the case, and the PSU had solid and normal voltages. This probably means that the problem lies in the video circuitry of the SE/30.