jake18125
Well-known member
So I have a bit of a problem
I recently acquired an SE/30 that was showing symptoms of vertical failure - on boot up it only displayed a single horizontal line.
After reflowing the joints on the P1 connector, replacing the TDA1170 on the analog board without any improvement I finally put my SE logic board in the case to verify that it wasn't an analog board.
What do you know it wasn't, the analog board on the SE/30 worked perfectly.
After probing the logic board with a multimeter, I found that the video PAL IC responsible for generating Vsync (part number 341-0747-A) just wasn't outputting anything. The 60.25hz vertical sync signal was missing.
This led me to source a replacement video PAL, which unfortunately didn't change the output whatsoever. It still has a complete loss of vertical sync.
I have also checked every single connection in the area in accordance to the SE/30s schematics, and I am now at a complete loss. I am thinking it could be the 74xx
series ICs by the video PALs, but quite frankly I have no idea (unfortunately I don't have an oscilloscope).
Hopefully someone has encountered this before and can figure it out!
Also when a boot floppy is inserted it seems to boot from it (obviously I can't see whats going on but it does react to the keyboard commands to eject the floppy)
Finally I just want to stress that this is NOT an analog board issue. My SEs logic board works perfectly fine in the SE/30s case, and the SE/30 still has no vertical when it is in the SE case.
View attachment 73DE0BC8-6743-41B1-9065-488FA237AF45.heic
I recently acquired an SE/30 that was showing symptoms of vertical failure - on boot up it only displayed a single horizontal line.
After reflowing the joints on the P1 connector, replacing the TDA1170 on the analog board without any improvement I finally put my SE logic board in the case to verify that it wasn't an analog board.
What do you know it wasn't, the analog board on the SE/30 worked perfectly.
After probing the logic board with a multimeter, I found that the video PAL IC responsible for generating Vsync (part number 341-0747-A) just wasn't outputting anything. The 60.25hz vertical sync signal was missing.
This led me to source a replacement video PAL, which unfortunately didn't change the output whatsoever. It still has a complete loss of vertical sync.
I have also checked every single connection in the area in accordance to the SE/30s schematics, and I am now at a complete loss. I am thinking it could be the 74xx
series ICs by the video PALs, but quite frankly I have no idea (unfortunately I don't have an oscilloscope).
Hopefully someone has encountered this before and can figure it out!
Also when a boot floppy is inserted it seems to boot from it (obviously I can't see whats going on but it does react to the keyboard commands to eject the floppy)
Finally I just want to stress that this is NOT an analog board issue. My SEs logic board works perfectly fine in the SE/30s case, and the SE/30 still has no vertical when it is in the SE case.
View attachment 73DE0BC8-6743-41B1-9065-488FA237AF45.heic