The other day, an SE/30 with a Kensington mask was put up for sale on Yahoo Auctions. I had a photo with the caseback removed, so I knew it was clean inside. I bought it immediately.
2 days later it arrived. I turned on the power of the SE/30, but I could see the initial screen as shown in the listing photo along with the startup sound. However, since it does not recognize SCSI, I opened it to see what was going on...
Holy cow!!! The logic board was miserably replaced with TK radial lead electrolytic capacitors, and the SCSI chip was stripped and soldered incompletely. It is a shame for the Japanese people to do such half-hearted repairs. I decided to seriously fix this awfully SE/30...
Replace SCSI chip 53C80
I stole 53C80 SCSI chip from the spare logic board and replaced it. However, as a result... Oh no, SCSI was not recognized... When I removed the unsightly electrolytic capacitors, when I found the disconnection of the footprint, Wow! I fixed it with a jumper wire, but it's a common symptom to open the footprint by leaking 3 capacitors near the power and video10-pin Molex connector.
*The AM53C80 chip in the pic doesn't seem to be reliable, so I replaced it with the NCR53C80 chip.
Check pin energization
Suspect disconnection from the GLU chip to the 53C80 SCSI chip. This route is not visible as it passes through internal layers.
While looking at the schematic, I focused on four lines from 53C80 to GLU chip. When I checked the continuity, one line was OK, two had a resistance value of about 0.5 ohms(It must be zero ohm here), and one was completely disconnected.
As shown in the pic below, the disconnection is from the 18pin 53C80 to the 68pin GLU.
When I connected the broken wire, God came down! Hallelujah! I've been most impressed in the past few months.
In the SE/30, it can be said that the line from this GLU to the SCSI chip is easy to disconnect. I think it's probably due to the electrolyte. I can't say that I can fix it by blindly repairing it, so I will check each continuity with the schematic in one hand. Computer wiring is very thin, so oxidation may cause disconnection or thinning wires to become resistance. It is important to check ohms as well as continuity.
Perfect SE/30 logic board
The logic board was all recapped with the correct electrolytic capacitors and pristine. In addition, one lock of the memory socket was broken, so I also stole parts from the spare board and replaced it. I hate amateur work. The part needs to be thought through and what is good and the capacitors should be durable and placed correctly. A well-cured board looks like a genuine product and I feel proud of it.
Most of the SE/30s that are listed as is have not only destroyed the IC and footprint around the battery with the Maxell bomb, but also the internal layers have been destroyed by the leakage of the electrolytic capacitor, and there is no knowledge geeks cannot fix it. It cannot be repaired by simply replacing the capacitor or chip.
Below is an example of a good Australian Bruce Rayne's repair works. He is in the same BlueSCSI seller group as I am, but he has a very high level of repair skills. You can also enjoy other videos of his friendly nature.
Postscript:
The analog board swayed horizontally, so I recapped it, but I couldn't fix it. When I looked around, I found traces of solder touched on BU406, so when I removed it, the footprint was peeled off. Fixed this and done...