Please help - I think I just blew my SCSI chip on my SE/30

slaquers

New Tinkerer
Nov 24, 2021
5
2
3
Hmm well I was messing about with my self assembled RaSCSI board, and realized it was not assembled correctly when I went to format the image Apple HD Setup crashed and then it wouldn't recognize images at all, I hooked up a known good drive and get nothing. I am quite upset at myself, I do have a spare Classic board with a 53C80 chip on it but have never soldered or unsoldered a chip like that before. I do have a hot air station, what else would I need - and is there anyway I can test the 53C80 on the SE/30 board?
 

slaquers

New Tinkerer
Nov 24, 2021
5
2
3
Also the chip was warm to the touch when every other chip was not as warm or warm at all, even the CPU :/
 

slaquers

New Tinkerer
Nov 24, 2021
5
2
3
I have removed a 53C80 chip from my Classic board, it is an AMD chip, not NCR - was easy enough to get off. Going to order some flux and a copper braid and see if I can get it done.
 

demik

Tinkerer
Oct 11, 2021
42
36
18
If it helps, Zilog is still producing 53C80 chips for less than 10 bucks. Sometimes you break theses old chips just by heating them.
Avaible here and other locations. @trag also has a nice NoS part number IIRC

Good luck on the transplant
 

appleg33k85

New Tinkerer
Nov 13, 2021
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12
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Have you done any more testing like connecting the good drive up to the classic board just to make sure nothing happened to it? Swapping around cables? I thought for sure I had a bad scsi chip until i found out that my scsi cable was bad. might be a couple things worth doing / checking out.
 

slaquers

New Tinkerer
Nov 24, 2021
5
2
3
Have you done any more testing like connecting the good drive up to the classic board just to make sure nothing happened to it? Swapping around cables? I thought for sure I had a bad scsi chip until i found out that my scsi cable was bad. might be a couple things worth doing / checking out.
I have not, but I intend to - and I will update when I can, not going to attempt to transplant the SCSI chip until I have eliminated all other issues - it is very possible the drive or cable failed at that moment, and I will test when I can (another known drive is in storage, along with most my Mac stuff, just the SE/30 lives here at home lol) but I do intend to check these issues before I create more. lol Would be really cool if it was just a bad cable or drive, but I have a pretty good feeling that I probably shorted out something, somehow lol.
 

YMK

Active Tinkerer
Nov 8, 2021
358
285
63
Check fuse F3 and diode D3. These feed TRMPWR which should have ~4.5V on it.
 
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slaquers

New Tinkerer
Nov 24, 2021
5
2
3
Check fuse F3 and diode D3. These feed TRMPWR which should have ~4.5V on it.
Thank you my good sir, I shall do so. I believe I was staring at D3 earlier wondering about it. Lol. Perhaps someone could guide me in the direction of the SE/30 schematics, if available?
 

svenvendetta

Tinkerer
Nov 3, 2021
35
54
18
Boston, MA
One thing I've noticed with the RasSCSI is that when you connect the 25 pin connecter to your Mac there is definitely voltage that is sent through the SCSI bus which I assume is normal. I noticed that my SCSI2SD LED blinks whenever I've connected it.
 

rikerjoe

Tinkerer
Oct 31, 2021
146
220
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Here are the redrawn SE/30 schematics.
 

Attachments

  • Macintosh SE_30 Schematic Redraw of 050-0253-01 MAR-31-2021.pdf
    1.6 MB · Views: 138

Branchus

Tinker Different Public Relations Liaison 2023
Staff member
Founder
Sep 2, 2021
220
476
63
Some SE/30s have self-healing fuses, others don't. If the board has the flat, metal, rectangular type of fuses, they are self-healing, so if that's the case, it's probably not the fuse.