SE/30 Horizontal lines due to an oversight

[Elemenoh]

I recently recapped a SE/30. After cleaning, it booted to a gray screen with cursor and nothing else if a SCSI drive was attached. It booted okay if only a floppy was connected. As a matter of troubleshooting I removed the SCSI IC, cleaned underneath and put it back. Afterwards, it was then showing horizontal lines on the screen with no chime. I was going nuts looking for what was wrong, assuming something with the RAM. After tons of hunting I found D28 was short to +5v. I replaced a diode and kept hunting along that path until finally getting back to the SCSI IC where I found a bridge from pin 23 (D28) to 24 which happened to be +5v. D'oh!

It was a hard bridge to spot, but still I should have obviously just rechecked the SCSI IC more carefully before going on a wild goose chase.

Have any of you had similar moments? How did it change how you perform repairs?

 

[rikerjoe]

After my first handful of surface mounted chips didn't work after initial replacement, I developed the habit to brute-force check every pair of neighboring pins for those hard-to-spot bridges. When I get a continuity beep, I double-check the schematics in case the neighboring pins are actually connected via a trace. It takes time, but where I am in my repair learning (I'm still more of a novice than a proficient repairer) it has started leading to more successful repairs.