Apple Lisa 2/5

[max1227]

Hi everyone,

I've been working on repairing an Apple Lisa 2/5 with limited success so far. I'm not really sure where to start as the Lisa seems to be acting very strange, for example, if the back cover and front bezel are off, the Lisa will still switch on even though the safety switches are not being pressed. The soft switch doesn't work and the Lisa will turn on as soon as power is applied. It doesn't beep or make the typical 'clicks' from the speaker, like when the self-test is initiated. 

What I think works:

The CRT works well but only shows the raster (I will attach a picture soon for you to see)

The power supply seems good

I think both memory boards work

The Lisa Lite controller

The floppy drive

What I think doesn't work:

The CPU board - when the memory boards are removed the CRT doesn't show the vertical white bars that the Lisa 'Do it yourself' guide says it should

The I/O board - Cannot say for sure but it has suffered corrosion from the leaky batteries. When It is inserted into the machine alone, the unit does power up and the screen shows nothing (not even the raster). If it isn't inserted the unit fails to switch on, so it is recognising it. 

Any suggestions would be greatly appreciated. 

Regards,

Max 

 

[fri0701]

Hi Max,

I've experienced the same problem you're describing. I believe it means that your I/O board is not functioning correctly - although the system may recognize it, it's not dealing with the soft switch / interlocks correctly. The next step I'd suggest is making sure that all the gold fingers on the I/O connector (both male and female) are clean, and that the corrosion from the batteries hasn't completely broken any visible traces. Do you have a multimeter that can test continuity?

-fri0701

 

[max1227]

Hi fri0701,

Thank you very much for your response.

The gold contacts are very clean as they were cleaned very well by the previous owner, this is the same for the edge connector. I do have a multimeter so can test components. The corrosion does seem to have done some damage to some of the tracers, but I'm sure that some tests will determine if they are working properly or not. 

If you could let me know what I should test that would be greatly appreciated.

Regards,

Max 

Edit - Not sure if my multimeter can test continuity, I will check and let you know.

 

[rsolberg]

If your meter doesn't have a dedicated "beep" or "continuity" function, you can use the resistance (ohms) mode to determine continuity.

 

[BadGoldEagle]

Is there such thing as a Lisa schematic on the net? I can't seem to find it. That would be really useful to test continuity.

Nearly all 2/5 have problems with the I/O board. Damn batteries! Sometimes it looks clean enough and it's not. 

You said the previous owner cleaned it, so you should check traces with a torch first. Maybe it was badly damaged by the acid in the batteries...

(I don't own a Lisa but I'm well documented and I'm still looking for one to restore. I'm saving up for one right now.)

 

[rsolberg]

Do note that in North American English, "Torch" almost always refers to an incendiary device, not a hand held light source a.k.a. flashlight. I'm mostly commenting in fun, but I do know of someone unfamiliar with the UK/International meaning of torch and who had a deficiency of common sense that led to a rather nasty outcome for his boat.

 

[BadGoldEagle]

Yeah you're right man! You don't want to torch a Lisa. She wouldn't like it :disapprove:

 

[max1227]

Hi all,

Turns out my Multimeter doesn't have a continuity feature but it can act as an ohm meter (It is very old). I have inspected the tracers and there are a few dodgy ones but very few. Where should I start on the I/O board?

Haha, no I knew what you meant when you said torch. 

Regards,

Max  

 

[max1227]

Just a quick update for you all. I have made some progress and can now deduce that the problem is the I/O board. I exchanged a working CPU board with the same ROMS from my second Lisa and it still didn't work. I have also done some continuity testing on the I/O board and cannot find any tracers that are damaged enough to prevent a complete circuit, however I can find some that have an unusually high resistance. This is probably caused by the corrosion. 

I purchased some isopropyl alcohol and contact cleaner and cleaned the board and edge connectors as well as the gold plated contacts. This had no effect whatsoever on the operation of the unit. 

I also believe that the soft power switch is electrically/mechanically broken as when I substituted the card cage from my second Lisa into the 2/5, it made a constant ticking noise which I believe suggests that the +5V isn't within range so the electromagnetic switch triggers preventing it from starting up? I believe the interlock switches have been bypassed as when I used the power supply from my other Lisa that switch did need to be pressed in order for it to start up, which wasn't the case with the original power supply.

I don't really know what to do next. Any ideas?  

 

[CelGen]

Well for starters starters the schematics (save for the backplane in the card cage) are all available here.

The schematics for the 1.8A power supply is available here and here.

Typically I find when the batteries leak the CPU board never fails but the region around the batteries on the I/O board and the area directly on the backplane corrode up pretty bad. If you are finding traces with high resistances they are bad and need to be patched. Usually you should be reading between 0.01 and 1 ohm. You should never be reading a high resistance between two points on a trace with no components in between.

I seem to also recall that part of the power management was handled by the COP421 nearby. It's not a replacable part because it has apple code burned into the internal mask ROM so when the battery leaks you need to make sure the chip is okay and the socket has not corroded up.

The soft power button I seem to recall is a momentary switch with a lamp. The easiest way to test it is do a continuity check. As for the interlocks I seem to recall the front and back switches are linked in series (they both have to be closed for the safety loop to operate) so if you can take the back off the lisa and it doesn't turn off (the switch is located inside the power supply) chances are soemone's defeated it from inside the power supply.

 

[max1227]

Thanks for the schematics. 

Yes, some are reading between 40 and 80 ohms with one being 200! I just don't have the knowledge on how to patch up the traces so I'm going to have to look for someone with more knowledge than me to do that.

As for the soft switch the COP421 is fine so Im sure it is damaged some other way. I think someone has bypassed the interlocks for convenience (no idea why)

 

[CelGen]

When I repaired the traces on mine it was a simple case of "find the nearest component solder joint on one side of the break and run a wire from there to the nearest component on the other side of the break. The schematics are extremely helpful here. I used wire wrap which is probably not all that easy for you to find so solid core telephone or network cable will work.The PCB is only two layers so you don't have to worry about traces you can't see.

Also I forget if it was Q1 or Q8 and 9 but one of those transistors were also part of the power circuit. They're located directly above the battery pack so check them for weak or broken legs. One of mine had lost a leg flush with the component package and I ended up replacing it.

 

[BadGoldEagle]

Good Job CelGen BTW on your repair job. That 2/5 I/O board was seriously damaged! Damn batteries!

Thank god the 2/10 never had this issue.

 

[max1227]

Hi everyone,

Thank you for all your responses and info. In the meantime, I have had the Lisa looked at by a specialist who has come to the conclusion that it is going to take a lot of work to repair as the motherboard is badly corroded. I don't think that there is any more that I can do with my limited knowledge about electronics and limited testing equipment, hence I am wondering if there is anyone else in the UK that feels that they could repair this computer? 

Kind regards,

Max 

 

[max1227]

Yesterday I made some progress with the Lisa and it now powers up and passes all the hardware self-tests. Unfortunately, the Lisa is still having some issues. The power button still doesn't work and neither does the keyboard, but oddly enough the keyboard works in another Lisa. Since the power button and keyboard connector are in the same module, maybe that module has failed?? I'm sure if it was the 6522 keyboard controller I would have received error 53 on startup. Sometimes I do get error 52 which relates to the COP chip which is responsible for the soft power feature. Most of the time I don't get this error and it passes fine, hence I'm thinking that the keyboard and power module is the problem. The second issue is that the floppy drive shows all sorts of error's when reading disks that are perfectly readable. MacWorks, for instance, has trouble reading any if not all tracks of the disks. Sometimes It will read track 1 and sometimes it won't. I think the head is having trouble accurately positioning itself along the read-write area. Any ideas? 

Finally, the ProFile won't boot even though it boots on another Lisa. This Lisa has suffered corrosion damage around the parallel port, I do have a parallel card so maybe that is the answer to this problem. 

 

[CelGen]

I found on my 2/5 that the corrosion around a bank of resistors added behind the parallel port caused any Profile attached to it to not be seen. I ended up removing the resistors and patching the cuts and it started working again. Have you tried swapping the 6522's around and seeing if perhaps one of your two have failed silently?

How is the Lisa powering up? Is it doing so immediately when power is applied?.

 

[max1227]

The ProFile is seen as it begins to boot but it then fails and lists an error (I can't remeber which one though, I think it was error 38). The ProFile boots perfectly on another Lisa so I dont understand what is going wrong. The memory boards have been tested and work fine in both Lisa's. This is the same with the CPU board. Therefore the issue must be the motherboard or the I/O board. I suspect that the COP421 chip is to blame. That is a good idea to swap the 6522's around. I havent touched the board in a while but that is certainly something I will try. 

Yes, it powers up as soon as you apply power to it. The soft power button on the front does nothing. 

 

[max1227]

Hello everyone, 

A quick update to this old post... I have now managed to get this Lisa to boot. Although there are still problems...

So I lubricated the floppy disk head assembly and then immediately it started reading some disks. This drive is highly selective when it comes to which floppy disks it reads. It will only read original software. If I make a copy of an original disk on another 400K drive then that works but if it's written by an 800K drive or newer then I get a read error. This is fine as I managed to repair the LOS files on the ProFile and now it boots. 

The power button is still an issue and the Lisa never starts up properly the first time. It always gives error 52 with a tick + cross through the I/O board. If I then switch it off and turn it on again it will always boot (no error). Any ideas? 

I was going to try and run Lisa test on it to see if it showed any errors. But I always get a read error when booting this disk. Is Lisa test 2/3 (can't remember which one, although I have the newest version) compatible with early Lisa's? 

Kind regards,

Max

 

[falen5]

Great work on getting it where it is now Max.These things can take months to figure out. Im still at power on light and nothing else. Waiting on a rom programmer to see if i have dead roms, another 2 or 3 weeks for that to arrive.  Always worth it though when the machine finally fires up