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Does anyone have a spare Lisa motherboard?

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patrick:
Beeep-Beeep means memory failure. So now you'll have to check the traces between CPU and memory board.

rayarachelian:
Well, the 68000 is good, so likely most of the CPU board is good, though we don't know if the MMU is good, or the RAM. As Dr. Patrick said, looks like it couldn't read the RAM ( https://lisafaq.sunder.net/single.html#lisafaq-hw-rom_beeps ), so as he said, check the connections to RAM boards, or the pins from the CPU board that go to RAM, maybe swap the RAM boards around as well.

You could try inserting just one memory board in one slot, then turn the Lisa off and move it to the other slot to see if anything changes.

I'm pretty sure it's not trying to boot at this point. The BIOS takes a very long time to test RAM and other hardware before it tries to boot, and even then it usually puts up a menu asking where to boot from (unless the PRAM has a setting that says boot from ProFile/Widget and that hard drive is on and accessible.)

On power on the MMU is in Special I/O space with the boot ROM mapped at address zero and also high memory. It will then do a checksum of the ROM, and beep if it's wrong. Once it finds some RAM, it will go out of SIO space and into MMU context zero, the display will turn on and it will start testing RAM and video memory will be at high RAM.

If there's a fault in page zero RAM where the exception vectors are stored, I think it will fail to show any video and will beep low. In your case you're getting lo,lo tones, so it can't see any RAM.

In terms of the floppy activity, it's more likely that the 6504 CPU which controls the IWM and floppy drive noticed there's a floppy there and initialized the drive which may have spun the motor or moved the heads a bit. But it's certainly not trying to boot yet.

I do see an X/Cops replacement board on vintagemicros for about $100, if it turns out bad, but so far we know it's good enough to power on the Lisa and have the main CPU start and fail the self test. So as long as all the pins and the connection to the mux chip it has are still good, it's likely working. You won't know until you have video if the keyboard and mouse are working. (And if the keyboard isn't working, most likely the foam caps are dead not the COPS on the I/O board.) Most likely any issue around COPS421 functionality is more likely caused by bad traces than by that chip itself going bad. Reflowing solder on its pins will help stop the corrosion too.

I'd replace all the large capacitors in the power supply, even if they're working, chances are they're over 20 years old, more like 35 if they're the originals so many would have failed, or are about to. This won't necessarily fix the CRT issue, but its still worth doing as you're going to have to do it at some point anyway.
However, if the 33V power supply output isn't working due to some caps not working, fixing the power supply will help you get video. This won't happen until it can access RAM, but I think it will still provide power to the CRT and the tube will warm up and glow, and pushing the brightness high should produce a white screen with some horizontal retrace reflection stripes, and since you haven't said you saw those, likely the PS has some issues.

I do see this as well incase you need it: https://www.ebay.com/itm/AMP-60-120-Card-Edge-Connector-Fits-Apple-Lisa-Motherboard/141821714914 - this connector should fit both the I/O and CPU boards.

AlexTheCat123:
I am only using one RAM board at the moment because the edge connector on the second one seems to have some corrosion damage, but I will try to fix the connector on the second board and try it out to see if anything changes. I have already checked the traces between the RAM and CPU boards, so I don't think that I have any problems there. As for the CRT, the power supply is putting out the 33V signal as it is supposed to, but the CRT is doing absolutely nothing. Not only is there no video, but there is not even a glow at the back of the CRT and these is no high-pitched whine from the flyback transformer. I also looked at the schematics for the power supply and determined that the video board is supposed to be sending 300V and -100V into the supply, which are supposed to run to the brightness and focus potentiometers on the back, but there is no voltage on either of these lines. This makes me think that something is wrong with the video board itself.

rayarachelian:

--- Quote from: AlexTheCat123 on November 17, 2019, 06:30:31 am ---I am only using one RAM board at the moment because the edge connector on the second one seems to have some corrosion damage, but I will try to fix the connector on the second board and try it out to see if anything changes. I have already checked the traces between the RAM and CPU boards, so I don't think that I have any problems there. As for the CRT, the power supply is putting out the 33V signal as it is supposed to, but the CRT is doing absolutely nothing. Not only is there no video, but there is not even a glow at the back of the CRT and these is no high-pitched whine from the flyback transformer. I also looked at the schematics for the power supply and determined that the video board is supposed to be sending 300V and -100V into the supply, which are supposed to run to the brightness and focus potentiometers on the back, but there is no voltage on either of these lines. This makes me think that something is wrong with the video board itself.

--- End quote ---

Ok, incase you don't have it, here's the video board schematic: https://lisaem.sunder.net/cgi-bin/bookview2.cgi?zoom=0?page=24?book=6?Go=Go

One thing that's common is that heat can cause the solder joints on these boards to crack. (or perhaps the corrosion has spread there too) I'd pull it out (careful of capacitors, CRT, etc.) and reflow the solder there, maybe replace some caps.

AlexTheCat123:
Thanks for the schematic! I just removed the video board (which was quite difficult because some of those connectors were really tight) and there do appear to be about 20 questionable looking solder joints on it. I will reflow the whole board and see what happens.

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