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| LC III RAM Limit Issues |
Posted by: sheppy1 on 2026-08-21 10:38:35
Hello 🙂
Having an issue with an LC III I have which I've swapped all the components over to a Reloaded Motherboard, fully recapped etc.
I'm having an odd issue though where I have a 32MB double sided RAM stick installed and the other week it saw the full RAM just fine (36MB total), but since then (I don't know what changed!), it's now only seeing 20MB total...So exactly half of the 32MB stick + the 4MB soldered RAM.
The RAM slot is also brand new and the RAM stick is in generally good condition. Anyone know why this might be? I've contact cleaned the slot, re-seated it, checked continuity from RAM slot to RAM pins, enabled 32 Bit mode etc. to no avail.
Thanks |
Posted by: Schmoburger on 2026-08-21 11:26:01
So whilst this is going to sound like flogging a dead horse, the first question that needs to be asked is, has the logic board been fully recapped? The sudden loss of half the module's capacity would seem to indicate that one bank has failed the startup memory test, which can be as a result of either physical failure of a chip on the module itself, causing the entire bank to be isolated, or that an electrical fault within the parts of the memory circuitry that handle addressing has caused the bank to fail the startup test and be isolated... that fault can be anything from a dirty, corroded or otherwise damaged contact on the module or the socket, to a broken circuit trace, to a short caused by leaked cap goo. A faulty memory controller might also cause a similar issue, however look at the more likely stuff first.
Have you got the opportunity to substitute in another known working RAM module into this machine, or place this machine's module into a known working machine to see if the module can be reasonably discounted as the source of the fault? |
Posted by: sheppy1 on 2026-08-21 13:34:19
Everything has been recapped including the PSU yeah. Sorry I should have said that!
Also just as I was tying this and after reading your list of things that could cause the issue, I decided to just drown the GLUE and CPU in IPA and scrub it and voila! Solved the issue!
I will add I also had the whole thing under a microscope but couldn’t see any bridges! So assume it was a tiny piece of solder just hiding away somewhere on a RAM data line pin! |
Posted by: Schmoburger on 2026-08-21 15:33:23
Awesome mate, glad you got it sorted! 😎 |
Posted by: Phipli on 2026-08-21 15:57:21
has the logic board been fully recapped components over to a Reloaded Motherboard, fully recapped etc. @Schmoburger - when they say "reloaded" the mean they've built a reproduction board. It is usually more likely that there is a dry solder joint or they've socketed something and don't have good contact because you usually use all new caps when you build up a new board.
Sounds like they've made progress though 🙂 |
Posted by: Schmoburger on 2026-08-21 16:10:21
@Schmoburger - when they say "reloaded" the mean they've built a reproduction board. It is usually more likely that there is a dry solder joint or they've socketed something and don't have good contact because you usually use all new caps when you build up a new board.
Sounds like they've made progress though 🙂 Im not sure if that info was there to begin with... if so i may have missed it. But yes, with that being the case, soldering issues are absolutely another possible source of grief to take into account. Luckily though whatever the issue was seems to have been sorted. 🙂 |
Posted by: max1zzz on 2026-08-25 10:57:10
Also just as I was tying this and after reading your list of things that could cause the issue, I decided to just drown the GLUE and CPU in IPA and scrub it and voila! Solved the issue! I can't tell you how much grief soldering issues on the Sonora ASIC gave me when I was designing & testing those boards, The very fine pin pitch makes those not fun to solder 😅
Glad you got it sorted! 🙂 |
Posted by: sheppy1 on 2026-08-28 00:25:18
I can't tell you how much grief soldering issues on the Sonora ASIC gave me when I was designing & testing those boards, The very fine pin pitch makes those not fun to solder 😅
Glad you got it sorted! 🙂 Yes, this!!! I think I spent more time dealing with floating pins on the GLUE chip than the rest of the components combined! Fortunately I did invest in a digital microscope which made finding said floating pins easier, but it didn't make them any easier to solder! 😄
Top job on the board BTW! Genuinely had zero issues with the board itself and it allowed me to arrive a badly battery bombed LC III which now works perfectly! I also paired it with a beautiful Apple 15" Multi Scan display too to complete the build. |
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