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Mac SE/30 only sees 1024kb of ram regardless of the ram attached on either bank?
Posted by: naruse on 2024-10-30 19:23:59
hey everyone, so I am trying to get back my SE/30 back to working order after full recapping everything (logic and analog boards, and PSU) and today when I turned it on out of nowhere it only sees 1mb of ram?; is there any reason why this could happen?

I have tried everything, adding 4mb on bank A, 4mb and 4mb on Bank A and B and regardless it only sees 1mb or ram


FWIW TL071 died on me so I took it out and I now don't have sound on the speaker -- yet on the headphones it chimes correctly -- I can boot to System 6.0.8 and see it reported on the finder.

This has me quite puzzled on why this started to happen and I am not sure what to even check on as I havent seen this before (not that I am an expert on this, I am just starting)


also, bonus question to whoever knows -- Can the Mac SE/30 start without UB11? šŸ¤” (the sound chip connected to the reset signal but not the main PLCC sound chip (UE10))
Posted by: dv- on 2024-10-30 20:10:06
Thereā€™s a chip responsible for detecting ram simm size; it was called out in a recent repair video Adrianā€™s Digital Basement did on YouTube but I donā€™t remember which one it was. If you zip through his last video on the se/30 he was repairing itā€™s in the second half I think.
Posted by: Chopsticks on 2024-10-31 05:41:47
You can boot the se/30 without ub11, itā€™s been awhile since Ive done that myself but I believe you might need to manually trigger reset. Pin 5 of ub11 is the reset signal, itā€™s active low so grounding it momentarily should work

tl071 is an OP-amp used to boost the line level audio signal for the internal speaker so itā€™s audible. Itā€™s actually connected to pins on the headphone out jack that gets deactivated when you plug in a pair of headphones. Itā€™s common for the contacts inside that 3.5mm jack to get oxidised over the years preventing internal sound working. when you replace the op-amp if the internal speaker still doesnā€™t work trying some contact cleaner in the headphone jack.

while I havenā€™t seen Adrianā€™s latest se/30 repair videos I suspect @dv- is referring the the GLU chip and the SIZ0/SIZ1 pins used to detect ram sizes. Consult the schematics for the exact pins but they should connect back to the cpu somewhere. It should be direct connections as thereā€™s no buffers on the logic board.
Posted by: cheesestraws on 2024-10-31 05:57:14
Check that A10 (? if I've got my maths right) is going to the right places and isn't being pulled down or up by anything.
Posted by: naruse on 2024-10-31 07:05:02
ha! -- I havent checked the latest video of Adrian, I will follow up on that one next! thanks @dv- .

Also great to know that I could boot with UB11 because most of the time "it just boots" and sometimes it doesnt and I could boot it by manually triggering ping 5 to ground on UB11 as @Chopsticks mentinoned.

Itā€™s common for the contacts inside that 3.5mm jack to get oxidised over the years preventing internal sound working. when you replace the op-amp if the internal speaker still doesnā€™t work trying some contact cleaner in the headphone jack.

interesting, I will use then some Deoxit on it, thanks! šŸ™‚

Finally -- I will be delving into the schematics to look into SIZ0/SIZ1 to confirm they are going where they are supposed to go and will also look into A10 as @cheesestraws proposed.

Thanks Everyone for the leads! -- i will follow up with what I find
Posted by: naruse on 2024-11-03 15:19:07
Hey guys! I SOLVED IT! šŸŽ‰

Again thanks for all the feedback -- I ended up checking Adrian's video and as I was planning to check the signals -- oddly enough if SIZ0/SIZ1 signals would mismatch with the actual ram I believe the computer wouldn't work YET, that was the lead I was needing!.

Turns out while I was checking for the pin numbers in the GLUE chip a microscopic sized blob of solder was in between 2 legs, I removed it, started the machine back again and wohoo! 8mb automatically recognized by the system!

I would have never thought such a tiny blob could cause me so much trouble but at least I managed to figure out what was the issue -- Lesson learned and I will be checking with more detail from now on every time I solder / desolder stuff.

Many thanks to everyone for the suggestions and the leads! šŸ™‚
Posted by: JYewman on 2025-02-04 11:23:41
Hi guys, sorry to revive this thread but I'm experiencing exactly the same issue with my SE/30, I have 4 x 1mb sticks installed (as well as 4 x 256k) stick and my SE/30 only reports 2MB! I have checked the traces for SIZ0/SIZ1 and they are both fine, I've also reflowed the GLUE chip and I'm still getting the same issue. I have completely run out of ideas. "HELLPPP!!!".
Posted by: naruse on 2025-02-05 10:26:00
Hi guys, sorry to revive this thread but I'm experiencing exactly the same issue with my SE/30, I have 4 x 1mb sticks installed (as well as 4 x 256k) stick and my SE/30 only reports 2MB! I have checked the traces for SIZ0/SIZ1 and they are both fine, I've also reflowed the GLUE chip and I'm still getting the same issue. I have completely run out of ideas. "HELLPPP!!!".
I would check for microscopic traces of solder balls touching pins, that was my case. good luck !
Posted by: noe on 2025-02-07 11:30:54
I would check for microscopic traces of solder balls touching pins, that was my case. good luck !
Where did you find the solder balls exactly and how did you detect it? Knowing it would help, because I have the same problem and I have verified all lines with the multimeter and I have not found any problem.
Posted by: naruse on 2025-02-07 20:01:00
The micro ball was between two pins behind a SMD IC. Itā€™s not about the traces, the balls where stuck between two legs on the ICs
Posted by: JYewman on 2025-02-18 08:03:50
pins behind a SMD IC. Itā€™s not about the traces, the balls where stuck between two legs on the
Was it on the GLUE chip?
Posted by: naruse on 2025-02-19 18:52:44
Was it on the GLUE chip?
hard to recall šŸ™ but could be? -- it was one of the larger ones
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