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Apple Lisa 2 (A6S0200) - Is this Fixable

Lutiana

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Ahh, got it. Yeah as near as I can tell that is not corrosion, it's part of the silk screen that came off when they pulled/cut that bodge wire. More scratches and gouges than corrosion. The silk screen on this board is also pretty thick, which is lucky for me. And now that I look at it with that in mind, I totally see why you'd think it's corrosion. From what I have read, it sounds like the Lisa 2/10 actually did not come with a battery, so leakage and corrosion are not as much of a concern with this model, which again, is great news for me!
 

VERAULT

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Yeah the 2/10 did not have a battery. Mine was pristine and perfect when I bought it. But there are older board revisions and even Lisa 1 systems which got upgraded and still have a battery so I dont know if you can make the claim ALL LISA 2 systems have no batteries.
Not that anyone made a claim. I was speaking in generalities.

No that you mention scratching to the solder mask it makes sense.
 
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stepleton

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I don't think anyone in this thread has made a claim like that, since it would be wrong.

No revision of the Lisa 2/10 I/O board had a battery, at least none that was available for sale so far as I know. There is a six-pin header on the left that looks like it might be a nice place to plug a battery in, plus a component-free space where a battery could go, but the reverse-engineered schematics don't suggest the correct connections even for this usage (see J1 here). One pin is wired to +5V standby and the rest are connected to nothing, or so the schematic claims. You would at least need a ground line for a battery connection. I have not tried to verify the schematic on my own 2/10, however.

I/O boards for the Lisa 1 and Lisa 2/5 (whether those Lisa 2s were upgraded Lisa 1s or not) did have batteries, which is everyone's loss.

It is open for debate whether the Lisa 1/Lisa 2/5 I/O board is an older revision of the 2/10 I/O board, but that debate would be a pretty boring one. Despite their numerous commonalities, Apple chose a different part number for the 2/10 I/O board where Lisa 1 and 2/5 I/O boards all had the same part number distinguished by different single-letter revision suffixes and furthermore the two types of board are not interchangeable without some rework in another part of the Lisa if it's a 2/5 you're dealing with and in addition to this please note that... 🛌😴💤
 

Lutiana

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Ok, I think I have decided I will try to locate the missing ICs and ROMs first, if I can do that, the rest should be ok. So I am now working on getting my hands on a COP replacement, from there I'll look into the others (the 8530, 6552s, the Woz Machine chip and the floppy rom).

I have ordered:
2732 ROM
MOS 6504 CPU
6522
6522
8530

Mostly from Ebay (hopefully what I get will work). I also ordered new sockets for all of them from Jameco. But I cannot for the life of me find an IWM. Is there a trick to Google on this one?

Also, the schematics @stepleton links *might* not match my board (though it's more likely I don't know what I am looking for). I just spent like an hour looking for RP1 and RP2, they just don't seem to exist, though are referenced on the schematic. RP3 and RP4 I can find though. I am also having trouble locating C10 on the schematics, or C37. Both would seem to be "Capacitors" however they definitely are not, they look far more like glass diodes, was it a thing to replace caps with diodes in some designs? C10 is broken, so I will need to work out what it is in order to replace it, C37 looks to be intact.
 
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NeXT

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I am also having trouble locating C10 on the schematics, or C37. Both would seem to be "Capacitors" however they definitely are not, they look far more like glass diodes, was it a thing to replace caps with diodes in some designs
It's as weird as it is, but those are what we now call SMD decoupling capacitors but packaged in little glass beads with legs.

Double check but I believe you can steal the IWM out of a Macintosh Plus/512k.
 

stepleton

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I am also having trouble locating C10 on the schematics, or C37
C10 is on https://lisaem.sunder.net/LisaSchem/Lisa210SysIO5.gif above the label that says "SPEAKER AMP".

C37 is top centre in https://lisaem.sunder.net/LisaSchem/Lisa210SysIO2.gif, above and to the right of the COP421.

As others have mentioned, these capacitors are little SMD caps inside of an axial through-hole housing. I've always been curious about these --- how many boards were using SMD capacitors at the time? Did some factory make millions of them and then have to package them in through-hole packages so that they were useful for electronics manufacturers? :)

I just spent like an hour looking for RP1 and RP2, they just don't seem to exist, though are referenced on the schematic.
There's a chance that these are on the Lisa motherboard itself. The Lisa motherboard seems like doesn't really have a diagram in the later sets of Lisa schematics: instead it's more like its topology is implied by the schematics for the cards that plug into it (e.g. the diagram for J1 here: https://lisaem.sunder.net/LisaSchem/Lisa210SysIO1.gif).
 

Lutiana

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I managed to work out the resistor network parts. RP1 and 2 are actually 16 pin dip packages, and are there. RP3 and 4 are the single in line type, with RP4 being a regular 10K 8pin network. RP3 is also a single row of 8 pins, but each pin doubles the resistance of the last, so 10k, 20k, 40k, 80k, 160k and 320k. How on earth do I find one of these? I look for resistor networks, and the only ones I can find are ones with a single value on all the pins.

The only other passive part I am not sure about is R41. I cannot find it on the schematics anywhere, so I am not sure what value it should be, but I suspect that it may not need to be there, as the few pictures I can find of the board do not show it being populated. Oddly, on my board it has obviously been cut off the board (the holes have solder, with leg remnants in them), so maybe it was a factor fix for something?

For those interested, here is the sheet I made with the entire list of parts of the board, from the schematics and verified with the board I have in front of me (though the schematics do not list the right chips in some places for some reason). Google sheet link

So this leaves me with working out how to get an IWM and a COPS41. I have lead on the COPS, but I have absolutely no idea where to find an IWM. Is there a part number someone can give me to search for? Is the IWM just an EPROM with code on it, or is it more like one of those chips you program once and you're done (PGA type thing)?
 

Lutiana

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Like the guy said above, in an old Mac Plus, or maybe an old SE. It's the floppy disk controller chip.

Yeah, I get that, but how exactly do I find such a beast? Searching for those models IWM also comes up with nothing (outside of articles on the IWM itself).
 

Lutiana

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Can someone with an Apple Lisa take a look at the board and tell me what the part number for RP3 is? It's between U9B and U10B. I cannot find what that part would be called, and I cannot find anything that looks anything like what the schematic calls for (each pin is twice the resistance of the last, starting at 10K).

1664771835990.png
 
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stepleton

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Can someone with an Apple Lisa take a look at the board and tell me what the part number for RP3 is? It's between U9B and U10B. I cannot find what that part would be called, and I cannot find anything that looks anything like what the schematic calls for (each pin is twice the resistance of the last, starting at 10K).

View attachment 1246894
You might consider making this thing yourself from individual resistors. Plant them in the board like cornstalks and then solder a single wire across the top of them that dives down into pin 1. A Google image search for "homemade resistor network" will show you what I mean.

But you could also save this project for later. This resistor network is a digital-to-analogue converter that converts a binary number stored in U9B into an analogue voltage for the amplifier U10. While it's nice to set the brightness of the display in software, you could temporarily connect pin 1 to +5V standby through a 10K resistor, and then I think your screen contrast setting would be fixed permanently at half brightness. It would be janky and it depends on how much of RP3 pin 1 is left sticking out of the board, but you might be able to accomplish this temporarily with crocodile leads: clip the +5V Standby end of C19 to a 10K resistor and then clip the other end of the 10K resistor to RP3 pin 1. For safety's sake, maybe you'd want to use a variable resistor that can go higher than 10K; then you can dial the contrast you want the old-fashioned way.

See PDF page 228 of https://lisa.sunder.net/LisaHardwareManual1983.pdf for more details on this circuit. Note that they call it a "summing network", which may also aid your Googling. I couldn't find anything comparable on Digi-Key, but I didn't look for very long.

It's not convenient for me to look for any identifying markings right this second, but if anyone else is closer to their Lisa than me, RP3 can be found on all Lisa I/O boards, not just in Lisa 2/10s.
 
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Lutiana

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It's a custom block of NMOS logic
So more like a PAL or GAL then?

You might consider making this thing yourself from individual resistors. Plant them in the board like cornstalks and then solder a single wire across the top of them that dives down into pin 1. A Google image search for "homemade resistor network" will show you what I mean.

I was thinking about doing that, but if someone could give me a part number that would help. I realize it's probably not a vital part now, I mostly just want to be able to add it to my pending Jameco order so as to save on shipping later (it's hard to order a low cost part from them without having to pay 10x or 100x the cost of the part in just shipping).
 

stepleton

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So more like a PAL or GAL then?
I don't think so --- a PAL or GAL or PLA or ULA or what have you would be a lot of generic logic that you wire together in an application-specific way, and my suspicion is that the IWM was designed for its job from the transistor level up.

if someone could give me a part number that would help
I'll ask certain... associates online that I know if they have ideas for sourcing a replacement :)
 

stepleton

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I'll ask certain... associates online that I know if they have ideas for sourcing a replacement
I've consulted wise and determined persons at a particular place not far from here.

It emerges that those who have made some effort to find a replacement device for exactly this requirement have failed. You will probably need to make your own.

As for the IWM, their advice is to find someone who forgot to take the battery out of their Macintosh SE. With great hesitation, might I suggest asking for help at 68kmla.org?
 

Eudimorphodon

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In addition to all Macintoshes before the 1.44mb-upgraded SE some late Apple II disk controller cards have IWMs, as do Apple IIc and IIgs motherboards. It’s not as if they’re really “rare”, you just, yeah, have to pull them from a corpse because there’s very little chance you’ll find a new old stock one.

An IWM would probably fit pretty easily on even a small CPLD but not on a GAL. A couple GALs and a PROM… maybe?
 
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