IBM PCjr Repair and Restoration


Hello, and welcome back to The 8-Bit Guy. So, in this episode, what I’m going to be
doing is a complete restoration of this IBM PC jr. Now, this was recently donated to me by Sean
Hafeez, and it’s actually not in bad shape, but it actually does have a problem with the
monitor and the keyboard. So, let’s see what we can do to fix it up! Looking at this system, cosmetically it is
in pretty good shape and just needs some minor cleaning. But the keyboard is noticeably yellowed compared
to the computer. It also has some nasty gunk between the keys,
which shouldn’t be too hard to clean, but it is also missing the little silver badge. The monitor is a different story. As seen here in the original unboxing video,
the monitor doesn’t work, even though it was working before Sean shipped it. Since the PCjr has a proprietary video connector,
there was no easy way to test this monitor on another system, so I plugged in a composite
monitor to the PCjr to verify the computer was working. After that, I took the monitor partially apart
to look for anything loose, but couldn’t find anything. Eventually, I discovered that if I whacked
the side of the monitor, it would come on for a short time, but the picture was unstable. So we’ll come back to the monitor later. For the moment, let’s have a look at the
keyboard. This thing has a lot of black scuffs on it,
some that don’t show up well on camera. So, I’m going to use one of my tried and
true methods, where I just put some baking soda on a paper towel and then wet it with
water until it becomes kind of a mushy paste. This works extremely effectively on this keyboard. Here’s one on the side that wouldn’t come
off easily with windex or alcohol. And it just wipes away in seconds with baking
soda. Once I’m happy with the exterior, I decided
I should open it up, for a number of reasons. For one, it will make it easier to clean the
keys, but also I want to retrobrite this thing. While removing the screws on the bottom, I
also noticed that it has these little rubber feet here, and one there, but it is missing
this one. So I will have to find or fabricate a replacement. Despite removing all of the screws, I couldn’t
get the keyboard open. Feeling around on this label, it felt like
maybe there was a hidden screw under there. And sure enough, there it is. After removing that, it opened up easily,
and oops.. I forgot to take the batteries out of this
thing. Ok, here’s the circuit board, and here’s
the little rubber contact mat, which appears to also double as a spring for each key. This thing is pretty filthy and will need
to be cleaned up as well! I wasn’t sure how the keys came out at first. Looks like the space bar comes out easily
enough, as does the enter key. It appears the keys just pop off with some
force like this. So, I thought maybe I should get out my key
puller and use that. And while that does work, it occurred to me
that it might be easier just to push them out from the other side. And that works fine too. The easiest way to clean this mat was just
a good spray with the hose. Then I gave the keyboard a good spray as well. And here they are. They aren’t fully dried off yet, but you
should already be able to tell a big improvement there. Although, it’s interesting how it has this
discoloration now. And plastic seems much improved as well. OK, so this is a little bit of a mystery before
I start the retrobrite. If you look at the actual PC junior’s case
color and compared to say, this space bar, the color matches perfectly already. I see no reason to attempt to treat these
keys at all. But, when you compare to the keyboard case
itself, the keyboard is noticeably more yellow than the computer. I think it may be less visible on camera,
but there is clearly a difference in person. But here’s where things get interesting. The inside of the keyboard is essentially
the same color as the outside. This typically indicates that this may be
the original color of the keyboard because UV light damage willl usually just affect
the outside. So, I am not 100% sure if what I’m about
to do will change it any. But I do know I want to take some alcohol
and remove the residual adhesive from this little badge area here, because I plan to
fabricate a new badge. And it looks like alcohol did the job for
that. Now, all of the keys on this thing are dirty,
but 4 or 5 of them have this really sticky gunk on them like this. I tried using windex, and later alcohol and
neither one made a dent. However, I found that I could use my fingernail
to carefully scrape the gunk off. After that, alcohol removed what residue was
left. And this is the finished key. So, now just to do the rest of the keyboard. Since the keyboard is fairly small, and to
avoid any streaking, I decided to use the submersion method on it. I filled up a small bucket of water, just
deep enough for the keyboard. And one concern I had was that the back of
the keyboard had a lot of air pockets and I wasn’t sure if it would sink or not. Fortunately, it did. I’ll be using the clear salon developer
liquid. And then I’ll let this sit out in the sun
for a few hours. And while that’s going, I thought I’d
turn attention to the monitor problem. OK, so, for the CRT part of this problem,
I thought I would enlist some help. So, I know my way around a CRT a little bit,
I’ve done videos on CRTs before, but I am by no means an expert, and so I thought I
would ask DJ here, who lives in town, he also runs a YouTube channel doing all kinds of
old retro computer junk too, so I’ll put a link down in the description. Anyway, he knows a little more about CRTs
than I do so he’s going to help me out with this. Hey y’all, I’m DJ and I’m not an expert
with monitors either but I’ve had a lot of experience with them over the years and
I’ve learned a lot from one of the modern experts in CRTs. And there’s only a few things that are probably
wrong with this thing given what its doing right now. And the one thing that I think we’re probably
looking at here is something to do with the flyback transformer. This monitor was working before it got shipped
here and upon arrival it was intermittent or non functional. And typically what this means is that the
flyback transformer, which is a big heavy part mounted on top of a PCB probably had
some rough handling of the entire monitor during the shipping. It’s a miracle these days that you can ship
a CRT and have it arrive in one piece. But, with that flyback transformer getting
jostled around it’s quite possible that it’s broken solder joints or possibly cracked
a trace on the PCB and so, what we really need to do is just kind of open it up and
see what we’re working with and see if we see anything that stands out. So, DJ got to work disassembling the monitor. Of course, I had already done this myself
but hadn’t gone any deeper than than just taking the cover off. So, let’s turn it on here and see what happens. Hey! We got high voltage! So, we already knew that that was intermittent. But, what I wanted to turn it on for was to
check and see if we could tell that the heater was glowing. And I do see the heater glowing. Just faintly. I actually had to turn the lights out in the
room and make it completely dark before the camera was able to really see the heater glowing. Well, that tells us that the heater is not
the problem. I just wanted to see if the heater was going
to come on, but we got high voltage this time, so something changed regarding the orientation
of the machine, or us banging around on it trying to get it disassembled. All right, so when we had it face down and
we were working on it, we noticed it was turning on every single time that we tried to turn
it on and had a picture every time. And then, we flipped it down to this orientation
and it stopped having any high voltage. If I turn it on at this point, it kind of
goes whit, but it doesn’t make any high voltage. But, if I flex the board, it comes on. And so I suspect we’ve got either a bad
solder joint or a broken trace. So, even though I don’t think this thing
is charged any high voltage, I want to make sure the tube is discharged before we mess
around with it too much more. So I will hook onto the DAG ground there. So this screwdriver is now grounded. And we just get it up under the cup. And there was no curpaps. So, it’s not charged. All safe. After discharging, DJ started to disconnect
all of the cables so that the boards could be removed and examined more closely. During manufacturing they had placed a big
blob of what looks like some kind of silicone like they use for windshield sealant. Anyway, we couldn’t get it loose so DJ just
sliced it off with his knife. Finally, we had all of the boards disconnected. OK, so we noticed this from the other side
as we were disassembling it and we suspected that there was a crack, but here is a big
ole crack that goes clear over to here. And it cuts, it possibly cuts through this
trace, definitely cuts through this trace cuts all the way across this solder joint,
then there’s this gap here, an air gap for this transistor, but on the other side of
it, it continues across here and cuts through this trace, and possibly this trace and maybe
into this one. So, we just need to investigate that and see
what we need to bridge out there. Since this crack might be hard to see for
some of you, I thought I’d get the magnifying glass out and let you see a bit more closeup
what we’re dealing with here. And I created this little diagram so you could
see exactly where the crack is and how much of the board it covers. As bad as this looks, it doesn’t actually
cross that many traces so, this could have been a lot worse. OK, so the first two that we’re going to
tackle are this one right here, which we can actually, if you get into it with the magnifying
glass you can see that there’s a crack right through the middle of that hole, but all we
need to do is reflow that joint to make it whole. This one here, though, we need to get in here
and scrape away some of the solder mask on either side of this crack, so that we can
make a bridge across the crack. I’m using a very high tech tool here, its
called my pocket knife. I just want to expose enough copper here that
we can do that bridge. Next, DJ added a little solder to the copper
he had exposed, then he bent a paperclip to an approximate size and soldered it right
across the crack. Then he just chopped off the extra paper clip,
and the joint is repaired. OK, so then I just want to make sure that
this joint that we just made has continuity so I’ll go here and the meter says yes. After that, we worked to re-assemble the monitor,
which took about 20 minutes. The whole time we were crossing our fingers
and hoping this fixed everything. We had to cut several zip ties, so we replaced
those with brand new zip ties. We also used some hot glue to fill in that
area we had to cut away before. Well, let’s see if we let the smoke out
or if it blows up or something like that. We’ve got it all put back together again. Hoping for the best. Hey, I hear high voltage. Look at that! I’m going to poke at it now. Still got high voltage. Alright! I’m calling that one fixed! OK, it’s been a few hours, so time to check
on the keyboard! I’ve got to admit I can’t see any difference,
but it’s hard to say until I rinse it off and take it inside to compare with the PCjr. So here it is after rinsing and comparing
it with the other half of the keyboard, I can’t actually see any color difference. So, I think this is the original color after
all. That being the case, it is time to put the
keys back in. Fortunately, I do have a picture I took of
the keyboard before I started, which will make it easier to re-assmble. Popping keys back into a freshly cleaned keyboard
is always extremely satisfying. It’s like you just bicycled up a really
tall hill and now you are coasting back down the other side. And here’s the freshly cleaned rubber mat. And the logic board. And the back piece. And here’s the finished keyboard. The color may not have changed, but it looks
a hundred times cleaner now! It looks almost brand new, except for one
problem, which is that missing badge. So I had an idea of how to solve this. Looking at the PCjr itself, I assumed the
badge probably matched this one. They are the same size. I think I can use my brother label maker to
print a replacement. I always keep several different colors in
stock for this sort of thing. I think I’ll use the black text on clear
background. So, I’ll pop this one into the label maker,
then I made a quick little design here. Since the labels aren’t wide enough, I made
it as two separate parts. And now to print it. Of course to make this look right, I want
to stick the labels onto this aluminum tape. So I first had to cut a square that fit perfectly
in the hole. And once I was sure it fit, then I peeled
the backing off the label like so, and I think you can see where I’m going with this. I just stuck this right to the aluminum. And here’s the finished badge. Granted, this is much thinner than the original
badge. But I think it will still stand up to scrutiny
in most cases. And there we have it. It’s obviously not perfect, but it was easy
to make and I would imagine the average person would never notice that it wasn’t the original. I went to the hardware store to find rubber
feet, but it’s hard to know which one will fit. As I’m always needing rubber feet in various
sizes and I’m just about out of them anyway, I just bought one of each package. I’ll likely use these at some point in the
coming years. This keyboard uses unusually small rubber
feet. I tried the smallest one I got and it was
still too large. What I’ll do is order some smaller ones
on eBay, but for the moment I can just cut these down to size and they should fit just
fine. And so yeah, there you go. Fits fine now. However, there’s still a problem in that
the new foot is slightly taller than the rest, especially this one on the opposite end. So what I’ll do is go ahead and pull that
one out too, and replace it with another of the same kind. And then I’ll turn it over and test it out. Yep, it is not wobbly anymore. As for the computer, it still needed to be
cleaned, but it was mostly just scuffs and dirt, so I just used my usual methods to clean
it up. Once I was done cleaning, I thought I’d
better go ahead and do some disk drive maintenance. I used some alcohol and cleaned the disk drive
heads. This one is double sided, so you have to clean
top and bottom. Then I used some lithium grease on all of
the moving parts, especially the rails. And now it’s time for a final test. The computer looks good. And it appears to be working properly as well. This restoration project has been a complete
success, unlike some of my earlier projects. All right guys, I hope you enjoyed this episode
on restoring the PC Junior. This is one of my more successful restoration
projects. And I always want to give a thanks out to
DJ for helping me with this monitor. There is something that I want to mention,
though. First of all, this video was not planned,
I just needed to get it done because I am planning on doing an entire documentary on
the PC Junior here relatively soon. So, I just needed to get it working. The other thing that I wanted to mention is
because I am using a CRT display in this video, I just thought this would be a good opportunity
to mention a problem that pops up from time to time. I always get comments down in my videos saying,
“Hey David, can’t you remove that terrible high pitched whine noise that I hear, it hurts
my ears.” Well, here’s the thing. Actually, I do. In fact, 95% of the time I get that whine
removed, but 5% of the time I don’t. And you’re hearing the 5% of the time that
I’ve missed it. The reason I missed it is because my 42 year
old ears simply can’t hear the sound, at all. Now, I know what the sound sounds like because
I remember hearing it when I was younger. So, what I have to do is I have to look for
any scene where I’m using a CRT and then I can actually dump a high pitched filter
in there in the editing process to hopefully reduce or remove that sound. But, here’s the thing. When I’m done with a video, I typically
watch it two or three times looking for spelling mistakes, or you know anything wrong with
like where something needs color correction or something like that and I can see those
things most of the time when I’m reviewing the video. But, I literally can’t hear the high pitched
whine so if I’ve missed it then I’ve just missed it. So, all I can do is apologize for that, hopefully
I got it all in this video, I tried. I went back like three times and verified
every clip that has a CRT in it. I put the filter on there. Sometimes the filter doesn’t always work
too. I’m not sure why, but I’ve been told sometimes
they can still hear it even when I know I’ve put the filter on there. So, I hope I got it all out, maybe I didn’t. Anyway, I’ll apologize for it in advance. And, I look forward to presenting the full
documentary on this computer. It’s a really fascinating piece of computer
history. Until then, stick around and thanks for watching!

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