EEVblog #696 - Apple Lisa Retro Computer Teardown

[EEVblog]

Dave, could you at lease take picture of each board so we can see how bad it is.  You could with the right info just recreate a new board and any good IC off the old board and just replace the cheep part.  It take time is the only with this project.

It would take a lot of time, which is my most precious commodity.

[EEVblog]

When I was in my teens I had bought an original Compaq at a used computer store for $20.  I put an NEC V20 in it and added an 8MHz crystal.  Rather I cut the old crystal out, soldered in 2 wires that were about a foot long and soldered the 8MHz Crystal to the other end.

I did this with my Tandy 1000. But I had to build an add-on board that got the various clock phases right.
Circuit was published in EA or ETI somewhere at some point.

Ah, here it is:
http://youtu.be/av5NQ_3mW9A?t=5m45s

[Stonent]

When I was in my teens I had bought an original Compaq at a used computer store for $20.  I put an NEC V20 in it and added an 8MHz crystal.  Rather I cut the old crystal out, soldered in 2 wires that were about a foot long and soldered the 8MHz Crystal to the other end.

I did this with my Tandy 1000. But I had to build an add-on board that got the various clock phases right.
Circuit was published in EA or ETI somewhere at some point.

Ah, here it is:
http://youtu.be/av5NQ_3mW9A?t=5m45s

The V20 I had was one I bought several years earlier and installed it in my Tandy 1000HX which was already 8MHz but apparently the V20 was a little faster.  Initially I had bought a V30 (8086 clone) not knowing they weren't pin compatible but it didn't work.

Come to think of it, it wasn't a 8Mhz crystal in the Compaq, it was a 20. It originally had a 14.7 Mhz crystal that was /3 for the CPU and bus.  The 20MHz crystal was the next speed up I could find that wasn't going to overclock the processor.

[Rasz]

When I was in my teens I had bought an original Compaq at a used computer store for $20.  I put an NEC V20 in it and added an 8MHz crystal.  Rather I cut the old crystal out, soldered in 2 wires that were about a foot long and soldered the 8MHz Crystal to the other end.

Now that I understand things a bit more, I am surprised it ever worked like that.

afair original 8086/8088 required somewhat weird 1/3 duty cycle on its clock, this is why intel provided special 8284 clock generator
V20 was fine with 50% duty, but other parts of the system wouldnt work if all you did was a crystal swap,original XT used 14MHz crystal (divided by 3). turbo mod required 20MHz crystal, or 24MHz oscillator and rewiring 8284
im so old

edit:bah redundand post, everything is ins dave's video

[SeanB]

I think I still have some 8284 chips around, along with the processors.

[LabSpokane]

The memory board marked "Sanmina" was likely produced by Sanmina Corp. who is a custom manufacturer (quite a large presence in N. America) and is still alive and well.

http://www.sanmina.com

[lapm]

I was thinking these boards would make wonderful examples for fundamentals fridays: How to fix circuit boards when you have no choise but do it...

[SeanB]

The other board bears a striking resemblance to old HP boards with the colour, layout and matt finish. Must have been made by the same US board fabricator.

[LabSpokane]

The other board bears a striking resemblance to old HP boards with the colour, layout and matt finish. Must have been made by the same US board fabricator.

Very likely.  Sanmina is/was a CM for many.  They are HQ'd out of southern CA. 

[jaxbird]

I think we need a vote on how many people would like to see these boards fixes and the original Lisa booting up again:

I vote fix it. Doesn't have to be Dave doing the actual work. Could be a distributed effort.

 

[sparx]

Would definately be something I would watch, even if some techniques are useless now with massive 4+ layer boards and SMD whatnot.

[Rasz]

I think we need a vote on how many people would like to see these boards fixes and the original Lisa booting up again:

you just got outvoted by +40K people that click on a mailbag clip as long as there are tits in the thumbnail

[miguelvp]

I think we need a vote on how many people would like to see these boards fixes and the original Lisa booting up again:

you just got outvoted by +40K people that click on a mailbag clip as long as there are tits in the thumbnail

Maybe it's because of the knife... nope, you are right the other thumbnails with the knife on it didn't get that many views.

[Rasz]

I think we need a vote on how many people would like to see these boards fixes and the original Lisa booting up again:

you just got outvoted by +40K people that click on a mailbag clip as long as there are tits in the thumbnail

Maybe it's because of the knife... nope, you are right the other thumbnails with the knife on it didn't get that many views.

yep
https://www.youtube.com/results?search_query=mailbag+eevblog&search_sort=video_view_count

We are Daves lab rats, he is testing different thumbnails looking for secret YT sauce I fully expect Kinder Surprise thumbnail in the next one 

as for voting - democracy leads to idiocracy, aww my balls and pewpewDie, best just leave Dave to decide what he wants to cover

[jaxbird]

I think we need a vote on how many people would like to see these boards fixes and the original Lisa booting up again:

you just got outvoted by +40K people that click on a mailbag clip as long as there are tits in the thumbnail

Dude, everyone knows that showing tits doesn't count, no educated male have the strength to resist a pair of tits.

[timb]

I can't believe Dave hired a hot model just for one mailbag clip. YT must be paying well.


Sent from my Tablet

[ssharp]

I need to dig through my files. I received a certificate from Apple back in 1984 for being one of the original purchasers of the 1st Mac. Given to everyone that bought one in the first 90 days after release. $2495.00 us. Never will forget that a box of 10 400k single sided 3.5" disks cost $49.95. How times have changed.