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stepleton

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  1. Since you also have a working board, you may be able to do some side-by-side comparisons between what the electronics do on both. Do you have equipment you can use to take measurements of signals on the board? An oscilloscope or a logic analyser would be especially helpful, but not everyone has these to hand.
  2. I'm not aware of it having this meaning, but it's possible that I haven't run into this sort of problem before. I hate to advise it, but study of the 247-page ProFile Level II Service Manual might shed some light on what's happening here. Page 142 and onward seem to describe what the ProFile firmware attempts to do during power-on, so if you can relate that narrative to what you're seeing, you might make some progress in your troubleshooting. This is a lot of work, but it probably beats reading the reverse-engineered firmware, which you could do instead I haven't rea
  3. I'm not sure that decapping the chip will tell us too much from a restoration perspective --- maybe if we examine a failed device, we can learn something that can help us mitigate those kinds of failures, perhaps some kind of hardware mod. But I expect it'd be hard to fill in missing data on the equivalent schematic based on what you see in a die photo. Even if it is possible to reconstruct this information, it may not be necessary to do that to fix a broken SE. The Mac 128k, 512k, and Plus generate the same vertical sweep using discrete components, so if the world runs out of TDA1
  4. SE and Classic analogue board (and Lisa video board) technicians will know the TDA 1170 chip as one reason your display can collapse into a narrow horizontal line (see for example page 165 of The Dead Mac Scrolls). It's a funny-looking device: meant to handle more voltage and current than your typical IC, it has these thick heat-dissipating wings coming out of the side of the DIP. I've often wondered whether these might be interesting to look at on the inside as well. There are various people out there who are skilled at decapping ICs and taking photos of the die inside, and I've b
  5. I was also thinking MMU. The Lisa boot ROM does test the MMU (see address $01B0 onward), but I'd have to study the hardware manual to understand how rigorous this test is. It's a shame that LisaTest won't boot for you --- that sure would help. That said, I think LisaTest is built on the Monitor (an early in-house Lisa development OS), and if I remember right from studying the Monitor source code, early versions at least don't make use of the MMU. (I could easily be wrong, and also it could be that the LisaTest GUI does involve setting up the MMU in some way --- maybe it
  6. I know you know your phosphors , but weirdly, my Lisa 1's CRT seems to have P4 phosphor (for those reading: no green after-glow) and my 2/10's CRT has the P7 type (yes after-glow). I don't know if either was a replacement tube at some point in the computers' lives, but it's funny that there's a difference. Still, I've never seen a Mac with P7 phosphor, so no matter what, if the OP sees yellow, then something's probably up!
  7. For a time, FloppyEmu wasn't compatible with 2/5 systems. This was fixed last May. Is your FloppyEmu's firmware up to date?
  8. Is it just a beep, or is it beeps of various kinds? Some of the Lisa's beeps are diagnostic
  9. Well, as if to teach me a funny lesson, my 1.8A DataPower PSU has just gone kaput --- it shuts itself off immediately after power-on. I have a rather noisy 1.2A PSU that I can use as a backup for now, but I'll want to get that 1.8A unit working again so that I can power my Widget drives. (I have an external PSU that I can use for Widgets, but that's mainly for maintenance work on the bench.)
  10. Oh interesting. You know, I don't think this is the first time I've seen a picture of that wiring harness with the "PROTOTYPE" label, although I forget the other circumstance. My dim recollection is that there was no other indication that the computer was an unusual machine. I've been off-and-on trying to reverse engineer the Applenet card for a long time (mostly off, thanks to other projects ), and the github linked is all the progress I've been able to make so far. The two big steps left to go are to understand what the GAL does (the equations are on bitsavers) and what the Z8 mi
  11. Nice photos! It may be worth pointing out that this is the (superior) 1.8A PSU as found in the Lisa 2/10. The Lisa 1 and 2/5 use the 1.2A PSU, a completely different unit with different components.
  12. That's good to know. I think that was the same limitation the FluxEngine faced.
  13. The disks look somewhat better than Pascal's did While there is localised discolouration, I'm not seeing the white crust that you find on really mouldy disks. It's possible then that what we're observing is media degradation of a different kind (oxidation, delamination, etc.), which may not be too uncommon either. I wouldn't assume in any case that the disks will be unreadable. My experience with BLU is that sometimes it recovers itself and reads beyond tracks with bad sectors, and sometimes it doesn't. My hypothesis is that failures to recover aren't really BLU's faul
  14. Hello! Yes, I am quite willing to give it a shot, although the process is not necessarily fast! And as the experience with Pascal demonstrates, results are not guaranteed. I tried my best to recover LisaList and was not successful over multiple rounds of cleaning and attempting to image, and so gave up there. There was too much mould to clean without removing the media from the disk envelope, and even then success would not have been assured. Ray's warning are also pertinent here --- I'm fairly confident in the ability of Royal Mail and other parcel shippers to deal with the virus
  15. Thanks @lisa2, I didn't know about these parts. It's nice that you could make this network out of discrete components in a pinch. Do you know what the risk would be if you were to "Muntz" these filters away? Are they for signal integrity, safety, or compliance, or some mixture of the three?
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