Hello, and welcome back to the 8-Bit Guy!
So, I’ve been wanting to do a documentary on the Laser 128 and XT Compact computers
for quite some time.
But, I’ve had some trouble getting my hands on the machines.
Now, the Laser 128 is not that hard to get a hold of.
And I did manage to pick one of those up not too long ago.
These are, I don’t want to say they’re common, but they’re um, you can get them.
There’s usually at least 2 or 3 on eBay at any given time.
Now, if you’re not familiar with these computers, don’t feel bad, they’re um, they’re
not a really well known computer today but they have a really fascinating history, which
I want to talk about in the documentary.
But, before I can do the documentary, I’ve got to get these machines working.
Now, this one actually works.
And, like I said, the Laser 128 is not too hard to find.
This one is actually, believe it or not, Apple II compatible.
Yeah, it’s actually a clone of the Apple IIc, supposedly.
And it runs Apple II software.
The one that’s hard to find is the Laser XT.
This is an MS-DOS computer.
And while it looks extremely similar to the Laser 128, the XT is entirely different on
the inside.
I’ve been looking for one of these for almost 2 years.
And there just simply have not been any to even bid on.
And these two showed up on eBay not too long ago.
And they were from two different sellers, both of them wanted about $80 a piece for
these.
Both of them said they are untested, as-is, and both are missing keys.
And, neither one had power supplies.
And they do use a proprietary power supply.
So, the goal for this episode is to see if I can take these two laser XT computers and
make at least one fully functional and properly restored computer out of it.
And, that means I’m also going to have to build a power supply.
So, let’s get started.
So, first let’s have a little overview of these units.
Both of them are pretty dirty and need some restoration work, but nothing that I can’t
handle.
Notice that this one is missing these three keys.
Now, the good news is, while this one is also missing a key, it isn’t the same key as
the other one.
So I should be able to make one complete keyboard.
Now, the first problem I want to deal with is this power port.
It’s a really unusual port in that it is a 7 pin DIN connector but what makes it unusual
is that it is male jack on the back of a computer.
Interestingly enough, I do have the power supply to the Laser 128.
And it actually has the exact same connector.
So take a look at this.
It’s quite unusual.
I knew I’d have to find one of these and trust me, it was not easy to find.
And you can see how it plugs in here.
Interestingly enough, it says right on the back that it is DC 15 volts.
So, it’s the same plug, and same manufacturer.
So you might think you could just use the same power supply on the XT unit.
And it does actually fit just fine.
However, when I plugged this power supply into the XT, there was a big spark right here
at the connector and then the power supply started to hum really loudly.
So, I knew something wasn’t right and I unplugged that right away.
Interestingly enough, this power supply actually has the pinout listed right here on the power
supply.
So, one of the things I checked was to see which of the two pins on here were providing
the 17 Volts of power that this power supply provides.
And, I discovered that those two pins on the XT are both ground.
So, yeah, it was just a straight short circuit.
Fortunately, it probably didn’t hurt anything in the machine.
The XT has no indication of what sort of power it requires either on the port itself, or
on the bottom.
Information on this computer is very hard to come by.
I did see a user forum where somebody posted the pinout from the manual.
The trouble is, there was no graphic so I wasn’t sure if Pin 1 was over here and counted
this direction, or was it the other way around?
So I used my multi-meter in continuity mode and started looking for ground pins.
I figured the shield on these ports should also be ground.
I managed to prove that these 3 pins here were ground, which seemed to correspond to
the pinout that I found online.
So I could fill in the rest of the blanks like this.
The connector I ordered finally arrived by mail.
And it does appear to be a good fit.
However, when examining the number markings on the connector, I became concerned because
I could see they weren’t how I expected them to be.
In fact, the pins are labeled like this.
However, if this were true of the computer as well, that would mean the grounds would
have to be on these pins.
But that doesn’t agree with the research I’ve already done with my meter.
So I think for the time being, I’m going to ignore this.
So I’ll just need to find something I can solder to this that has the correct voltages!
Finding a power supply for this would actually be easy if it weren’t for the fact that
it requires negative 12 volts.
So, that being the case, the only thing I had around the house that would do this is
an old AT style power supply from a desktop computer.
I decided to hack up this old Commodore power supply brick.
This one is dead, as I’ve marked that it has no power on the 9V AC lines, but it should
have at least 4 conductors in this wire, probably rated for similar amount of amps.
So I’ll just cut it off and make use of this wire.
However, I decided it would be best if I took the computer apart.
I figured I would probably be able to verify some of those voltages by continuity testing
with something familiar like the floppy drive.
However, I was pleasantly surprised to see these 3 connections right on the board behind
the power input, and they are labelled with each voltage.
So I was able to verify with my multimeter that my original pinout is in fact correct.
So, time to do some soldering.
I’ll use my quad-hands for this, as two hands is never enough when soldering wires.
One unfortunate problem is that the wires are slightly too large to fit in the holes.
I suppose I could try trimming some of the threads away, but the easiest solution for
me was to just solder the wires to the sides of the terminals.
So I’ll just tin the leads on both sides like this.
Then I’ll join them together.
Time to plug this thing in.
I didn’t want to put the shroud on until I was sure it was working, so I just plugged
it in like this.
I’m going to connect my TV to the composite video.
I have an RGB monitor in the attic but don’t feel like getting it down at the moment.
OK, first test is to simply turn on the power supply and see if any magic smoke comes out.
So far, so good.
Next, I’ll turn on the computer.
Cross your fingers.
Well, that’s interesting.
Ahh.. and we have text!
It’s very hard to read since it is 80 columns on a TV, but that’s to be expected.
I thought I’d try inserting a DOS disk and see if it will boot.
Well, I noticed something wrong right away, the floppy drive won’t stay closed.
I figured I would just hold it closed and see if it would boot.
But nope.
It just keeps resetting to this screen that says press a key.
I press a key, and the cycle starts over again.
So needless to say this unit has some problems, but at least the logic board mostly works.
So, I figured it was time to put this one to the side, then evaluate the second unit.
OK, so let’s power this one on.
OK, this looks promising.
So, this one has a sharper image on the TV screen for some reason.
Not sure why.
Lets’s see what happens if I try the boot disk.
Fortunately, the drive does stay closed.
And I can hear it ticking away.
And sure enough, it does boot right up to DOS.
I think this one is going to be a winner.
Just for kicks, let’s try a game.
In case you didn’t know, this machine has CGA graphics.
One neat thing about California games is that it does actually support a 16-color composite
video mode.
I did a whole video on how CGA graphics work so if you haven’t seen that, you might want
to go watch it.
Anyway, it appears to be working!
All right, so now that I know the cable works, I want to finish it up with the shroud, however,
I ran into a problem that the cable was just a bit to thick and the friction ended up breaking
off the strain relief.
Oh well, I don’t have a second one or another 4 conductor cable for the moment so I’ll
just use what I’ve got here.
So I’ll just clamp this little piece down here on the cable and then just pull this
piece up here until it clicks.
And that should do it.
Let’s test it.
Great, it fits, and now it’s easy to pull it back out since I can grab the connector.
OK, so moving onto the restoration, one thing I’m going to need to do is take the keyboard
completely apart.
And one of the reasons is, if you look, the actual stalk is broken.
These keys weren’t pulled off, they were knocked off sideways.
So there’s no way to repair this, it will have to be replaced.
Fortunately, this keyboard looks very straight forward to disassemble.
Here’s the actual keyboard unit, and what’s interesting about it is that it is designed
very similar to a keyboard for a desktop unit and even has the little micro controller to
convert to an XT keyboard signal.
I’m sort of surprised they didn’t find a lower cost method to do this on an integrated
keyboard.
Anyway, let’s unscrew the contact board here.
And let’s have a look.
Interesting.
I’ve taken apart a lot of keyboards before, but I’ve never seen one done exactly like
this.
It’s not that it’s a bad design, it’s just unusual.
Anyway, so this here is the piece we need to salvage to repair the other keyboard.
And, of course we need the key as well.
While I had this unit open, I thought this would be a good opportunity to look at the
logic board.
I’ve unscrewed these RF shields, so let’s take a look underneath.
Interesting.
There are actually two daughter boards, this one looks like a RAM board, and I’m not
sure what the other one is.
I’m going to pop this one off because I want to see if this is just an expansion board,
or if it is the only memory in the entire machine.
I think this may be the entire 512K right here.
OK, now off with this larger daughter board.
Well, here’s the main logic board and to be honest I don’t recognize most of the
chips on this board.
In fact, I haven’t even found the CPU yet, but I suspect it is under this heat sink which
appears epoxied on so I won’t be removing it.
All right, so time to start working on the second unit.
This is the unit I actually want to restore.
I’m going to start by removing the keys.
The main reason I need to remove them all is because they are filthy.
While it is possible to clean them in place, I can always do a better job cleaning all
5 sides of each key if I remove them.
So, you can see these little stalks here that the keys attach to.
And you’ll notice this one is missing.
So, I’ll eventually have to take it apart and replace it with this one.
OK, all of the keys are removed, and there’s a very thin outline of dirt showing where
the boundaries of the keys were.
Anyway, I’ll clean that up later.
Anyway, I’ve decided to just clean the keys with windex and a paper towel.
There are many ways to do this, including using running water in the sink, but I’ve
found this method is just about as fast and I don’t have to wait as long for the keys
to dry.
One thing I noticed is that a few of the keys are slightly darker than the rest, almost
like they have yellowed some.
It wasn’t as obvious when the keys were dirty.
It seems to be only the white keys, so I’m separating out the gray keys.
I’m going to try the heat method again.
This will be my first time using it on an actual restoration project.
I’m going to keep the water at around 140 degrees this time.
I’ll add a generous amount of hydrogen peroxide.
And then I’ll dump the keys in just like I’m cooking some pasta.
And I’ll let that cook for about an hour.
So back to the computer, I’m going to start cleaning the case.
And even though I’m going to take it apart, sometimes when scrubbing is required it is
easier to do that while it is still put together.
Unfortunately, Windex didn’t have a lot of effect on this machine, and there’s a
fine layer of black gunk coating almost the entire machine, hopefully you can see it in
the closeups.
So I’m going to try baking soda and water, which I’ve had great luck with.
I’ll try scrubbing just one little area so we can compare how well it worked.
I know it’s a little hard to see on camera, but there is a pretty noticeable contrast
in person.
The right side here looks much cleaner and brighter.
Well, time to do the rest of the computer.
OK, I’ve cleaned the entire right half of the computer at this point, so hopefully you
can at least tell that the left side is still dirty.
Anyway, time to do the rest.
Now that I’m done with that, time to take it apart.
After working on that last one, I realized you are supposed to pop the rear plastic off
first before the rest of it comes apart.
There are little hidden tabs here, so I have to be careful not to break them.
They just require a slight bit of encouragement with a screwdriver, but not enough to dent
the plastic.
OK, now the top will come off!
Just like before, I’ll need to remove the keyboard.
But unlike before, this speaker will need to come off.
That’s because I’m going to take this plastic outside and rinse it off.
Not only will this remove the baking soda, but it will clean out those vents that were
full of crud.
It has been an hour, so time to drain out the keys.
And I’ll put them in here for now.
Before I put them back on, I want to clean this part of the keyboard.
It should be pretty easy.
Now to take this keyboard apart so I can replace that one plastic part.
And this is the one piece here we need to replace.
And I’ll be replacing it with this one.
OK, so the top piece is all reassembled and it is looking good!
Before I put this back together, I decided I should do some maintenance on the floppy
drive, even though it is working.
I don’t even need to remove the drive from the computer.
I just need to get access to the rails.
I can’t remove this board without a lot of extra effort, but as long as I can reach
the rails, that’s all that matters.
I just need to put a small amount of fresh lithium grease on both of them, then move
the head back and forth a few times.
I’ll also put some on the other sides here.
The heads probably need cleaning too.
This is pretty simple, a cotton swab dipped in alcohol will easily do the trick.
And the last thing I want to do is re-lubricate the closing mechanism.
In this case, I’m going to remove the old grease first.
Then I’ll add some new grease back.
And I suppose I should test it, and everything seems fine.Time to reassemble the computer.
When I went to attach the rear panel I noticed this wire was broken off from the switch on
the back.
I was just about to reach for the soldering iron, but then I realized I had a parts computer,
so I just took the panel from it.
That panel has a few broken tabs, so I’ll just unscrew the switches and swap them.
And now time for the fun part, re-attaching all of the keys.
And here’s the finished computer.
It looks a thousand times better, and it has all of its keys.
For my final test, I thought I’d grab the RGB monitor so I can test both the composite
output as well as the RGB output.
I’ll run them both at the same time.
Let’s power it on!
OK, so far so good.
I think I’ll try a game.
Looks like they are using the ugly CGA palette here on the RGB side.
The composite side looks a little better.
I think most of the early games looked better on composite.
However, for comparing text, that’s another story entirely.
There’s little question that the RGB monitor is king in this area.
All right, so that about wraps it up for the restoration of the Laser compact XT.
Now, I realize that this power supply solution that I’ve come up with is not particularly
elegant.
But, it does work, at least temporarily until I can find a better solution or better yet,
hopefully some day I’ll find the original power supply for it.
But, in the meantime, I should be able to start getting to work on the documentary on
the Laser 128 and XT, so stick around for that, and well, thank’s for watching!