LisaList2

Quote from: berskyboy on November 04, 2026, 11:53:57 AMQuestion is it salvageable?

Yes.

QuoteI think I would need to put jumper wires

Yes.

Note that some traces are daisy-chained across the row of chips, so you need to make sure that those traces connect to the chips on both sides. eg. if the trace is broken, re-connecting to the chip on one side with a jumper may still leave the chip on the other side disconnected.

Since/if you have another working memory board, comparing continuity tests with it may be helpful.

QuoteI'm looking for the Lisa Memory Board Schematic

You can use those, or you can find originals on bitsavers, eg: https://bitsavers.org/pdf/apple/lisa/hardware/Lisa_Memory/050-4010-B_Mem.pdf

AFAIK, the bitsavers' Lisa Hardware directory has all of the Lisa schematics now. ( Thanks Al !)

You'll be able to get them through MacEffects as well!

Quote from: sigma7 on November 03, 2026, 10:36:54 PMOn your pic of the bottom, it looks like there is a broken trace beside pin 11, and it looks like the wide trace connected to pin 16 may not reach the pad any more.

On your pic of the top, the trace that runs through the gap between pins 7 and 8 looks suspect, there is a potential solder bridge from pin 10, and it looks like the wide trace connected to pin 16 may not reach the pad any more (might just be lighting).

hi Sigma7,

I decided to try again with another IC socket, but before I do that, I think I have issue with my lifted broken traces.  I see from the photo problem areas.  (Pins 9, 10,11)

https://www.dropbox.com/scl/fi/z660yxfq5twpkzsxud2t8/IMG_4233.jpeg?rlkey=ldghw6pws4zuj3zo0uaj7oz56&st=ag7pc1xx&dl=0

https://www.dropbox.com/scl/fi/5uyvbthtz8ecpktuo49kd/IMG_4234.jpeg?rlkey=ahddlbbqhci6yea3zrsj1loc7&st=eu8vc57z&dl=0

and that might be the issue previous to my. first attempt. 

Question is it salvageable?  I think I would need to put jumper wires 9, 10 and 11. ( they seem to be just connected to the adjacent chip) so D7 in this case so I could run those wires under the board.  Is there any other problem areas?

YouTube Video (Top of the board)
https://www.youtube.com/shorts/FUjApAEzW-w

YouTube Video (Bottom of the board)
https://www.youtube.com/shorts/YZtorRMpPoE

I'm looking for the  Lisa Memory Board Schematic,
are they these ones?

The Vintage Compu85 Mirror: You can access the direct circuit GIF images via the [Compu85 Lisa Schematics Index](https://compu85.homeip.net/stuff/Apple/lisa/Schematics/ "Apple Lisa "Memory Board Schematic" pdf"). On this server, look for the files specifically named ram512-1.gif, ram512-2.gif, and ram512-3.gif. These three files contain the complete multi-page logic layout for the 512K memory expansion board.

Quote from: AlexTheCat123 on November 03, 2026, 02:09:05 PM

Quote from: wottle on November 03, 2026, 07:28:36 AMSorry, I actually thought you were done with your standalone version.  I certainly wasn't planning on trying to jump in front of you with a custom version.  No rush on finishing - for some reason I thought I had seen the standalone version already published on GitHub.

It's pretty much fully tested and working at this point; I just need to get everything together and write the readme to release it. The reason it's taking so long is because I had to add Disk II, Disk ///, SmartPort hard and floppy disk, and Hard Disk 20 emulation on top of what it already had, along with some other cool features, and those took quite a while to implement and debug since I'm doing it by hand without AI! The version that's on GitHub right now is still just the base LisaFPGA-integrated version that only emulates Sony 400K/800K and Twiggy.

I think you may have already answered this somewhere else... Other than building my own, where will they be available?

From the notch/dot at one end of the package, viewing from the top, the pins count counter-clockwise (reverse of what you show in your video). On the bottom side, they count clockwise.

On some boards (including this one), pin 1 of each chip has a square pad and the rest have round or oval pads.

On your pic of the bottom, it looks like there is a broken trace beside pin 11, and it looks like the wide trace connected to pin 16 may not reach the pad any more.

On your pic of the top, the trace that runs through the gap between pins 7 and 8 looks suspect, there is a potential solder bridge from pin 10, and it looks like the wide trace connected to pin 16 may not reach the pad any more (might just be lighting).

On an earlier pic of the newly installed chip, the solder on the bottom of the board looked ok, but from the top of the board, the holes did not contain solder, indicating there was not enough heat for the solder to wick through the board. Some of the solder joints in the PSU repair pics also look like there might not be enough heat applied for the solder to flow properly; reviewing a DIP soldering tutorial might be helpful (or I might be misinterpreting the pictures... it is hard for me to discern what shape a shiny 3d surface is in a 2d picture).

Due to the difficulty of desoldering on these heavy copper 4-layer boards, you want to minimize the amount of re-work, as the damage to traces and pads and delamination will accumulate. This is one of the reasons for using a socket (when there is room to do so). In this case there is also the concern that maybe the problem is not isolated to that one part, maybe the replacements are bad or mis-marked, etc. so being able to change the part easily is valuable. Sockets can cause intermittent problems, so you want to use a high quality one.

In addition to checking for continuity from a pin of the new ram chip to the same pin on another chip, it can also be helpful to check that adjacent pins at the replaced chip are not shorted together due to an unseen solder bridge.

Using the Lisa Memory Board Schematic, you can determine where all of the pins of the replacement chip are supposed to be connected (not just to the adjacent memory chip, but elsewhere on the board) and so you can verify them all.

Quote from: wottle on November 03, 2026, 07:28:36 AMSorry, I actually thought you were done with your standalone version.  I certainly wasn't planning on trying to jump in front of you with a custom version.  No rush on finishing - for some reason I thought I had seen the standalone version already published on GitHub.

It's pretty much fully tested and working at this point; I just need to get everything together and write the readme to release it. The reason it's taking so long is because I had to add Disk II, Disk ///, SmartPort hard and floppy disk, and Hard Disk 20 emulation on top of what it already had, along with some other cool features, and those took quite a while to implement and debug since I'm doing it by hand without AI! The version that's on GitHub right now is still just the base LisaFPGA-integrated version that only emulates Sony 400K/800K and Twiggy.

I probably would if you can help it. The vast majority of people only have 1MB of RAM, and only a tiny fraction are lucky enough to have an XLerator.

UPDATE:  I did put in a IC Socket and checked the continuity and they reach all the way down to the bottom of the board.

Pins 1,2, 4,5,6,7,8,9,10,11,12,13,14 all beep to the corresponding chip.  Leaving 3, 15,16 that don't but I think that's by design. 

I put the problem RAM board in and it gave the following error (1 512K RAM in slot 1)

00000186  0000 0000 FF00 FF00 0000 0000 0000 0000

then I tried with two RAM modules and it gave a checked screen.  Took out the known good RAM leaving the problem RAM still checked screen.  With the know good RAM in slot 1, it boots fine.  So still and issue with the problem RAM.  I wish there was a better way to test the troubled RAM board.  (or maybe I need a replacement?)

I am lucky that I have an AST card and an XLerator so I likely have more ram than most.

Should I make MacWorks apps assuming most people will only have 1meg of RAM or ?

Not at all. All for making these new apps easier for others to get onto their Lisas.