Mac SE30 not seing the FDD

pinto_guy

Well-known member
After so many years, I decided to go through a pile (dozen) of SE-30 logic boards that I had bought on CL. I meticulously recap them one by one, and some of them work, but others don't. This particular one gives me the following symptoms:

1) Booth chime is OK. Video is good
2) When no FDD or HDD is connected, I eventually get the Mac with the X icon, and not the usual Mac with the question mark
3) The reset button just turns off and on the video, but does not reboot
4) When I plug in an FDD, the SE30 does not "see it"
5) When I plug in an HDD, it starts booting on it, but eventually crashes with various error codes (depending on the HDD I use)

The LB is surprisingly clean, and there are no obvious issues with missing traces etc.. Do you guys have any clue on the issue ?

Thanks in advance.
 

alectrona6400

Well-known member
SWIM chip might be shot... sadly these commonly fail on SE/30s for whatever reason. speaking of chips, the cap leakage/corrosion may still be present underneath them, and couldve caused some traces to break.

also, on a less related note, if you are okay with it i would be interested in whatever se30 board you have that is not working, i need donor parts for mine...
 

pinto_guy

Well-known member
Thanks. Yes, the SWIM chip came to mind, but I'd hate to replace it if it's not the culprit. Would that explain all the symptoms I see ? I fail to see how it would affect the reset and HDD issues.

PS: I'll keep you in mind when my SE30 dust settles
 

djc6

Well-known member
When you plug in a drive, are you using the external or internal connector? What are voltages rails like when you test at the J12 connector?

Also curious in purchasing an SE/30 logic board, especially one requiring repair :) I just fixed my first one that had no video (ended up replacing chip UG8).
 

pinto_guy

Well-known member
It does not matter whether I connect the FDD and HDD with the internal vs external connectors. I get the same effect.

I spent the morning following the VSNS and RESET signals on the LB. I did not realize that the reset switch changes the VSNS from 5V to ~3.9V, with brings RESET from HI to LO. And the VSNS to RESET translation is done on one of the two Sony sound chips, the one on UB10. I also checked continuity of the RESET line to the SWIM and SCSI chips, but have not yet succeeded in tracing it to the 68k processor.

Another symptom seen today: if an HDD is connected, a power off/on resets the logic, and a new chime/boot sequence happens. But if an HDD is connected, an off/one cycle does nothing but refresh the frozen screen with the X in Mac icon.

So that's all so far for today. Thanks again to all. I'm making progress, but I'm not there yet.
 

pinto_guy

Well-known member
Update: the SWIM hypothesis is getting some traction. Thinking that by some kind of miracle there was a bad solder joint on the SWIM chip, I went ahead and hot-aired the perimeter of the chip. While it was still warm, I tried to boot, and this time, I could not get the chime/boot, and the screen showed the typical horizontal lines. The chime reappeared after a few minutes, when the chip had cooled. I also noted that this chip is slightly warm to the touch, when it should be near room T.

So I'll most likely have to do a swap. I have never done a replacement of a chip this size before. Can anyone point to a good tutorial on how best do this ?

Thanks!
 

pinto_guy

Well-known member
Sorry to bump this, but I could really benefit from a good advice. I read that hot-air de-soldering an SMD chip can fry that chip, with temperatures up to 400C. So removing the defective SWIM is not the problem. Re-soldering a donor SWIM is not a problem either. But how can you de-solder the new SWIM from a donor board without damaging it ? There are tons of youtube how-to's on recapping SE30 boards, but I could not find one on replacing ICs.

Thanks in advance
 

djc6

Well-known member
There are tons of youtube how-to's on recapping SE30 boards, but I could not find one on replacing ICs.

Adrian's Digital Basement recently had a video series on an SE/30 where he fried several PLCC chips while recapping. The leaking electrolyte from old caps removed solder mask from a trace under a capacitor, and when he replaced some data line got shorted to 12V and fried a bunch of chips. Here is link right to one of the videos where he removes and replaces one of the PLCC chips:

 

pinto_guy

Well-known member
@LaPorta: thanks. This also makes a lot of sense as the inner ground plane is a major heat sink that forces more heat into the chip and away from the pins. Some suggest to stick a heat sink on top of the SMD chip to lower the temperature. Looks a bit cumbersome to do, but it makes sense too.

@djc6: Thanks. Adrian's DB is a great resource. He uses solder paste to solder the good chip back on. Is this was you guys recommend ?
 

djc6

Well-known member
Thanks ! Has anyone tried a low temperature solder alloy like QuikChip ?

I used it for the first time recently to remove an SOIC package chip on my SE/30 - I wrote about my experience here:


The main thing is to use VERY LITTLE since its a challenge to clean up. Also, the docs I link to above say to set iron to "500 to 600Deg. Fahrenheit" - you need to old solder to melt too, the combination of the both will stay molten long enough for you to remove the chip. I used a screwdriver with some blue tack on the end to lift the chip with free hand.

[Thanks. Adrian's DB is a great resource. He uses solder paste to solder the good chip back on. Is this was you guys recommend ?

I've never tried, but solder paste seems the easiest route versus such fine soldering with an iron.
 

pinto_guy

Well-known member
Thanks everyone. I think that's all the info I needed. Will take the bull by the horn and hopefully acquire this new PCB rework skill :). I will report back
 
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