 Greetings random electronics friends. Today I got a box in the mail and it was from eBay. So this is a Radio Shack TRS-80 Model 100. It's kind of like a basically a portable computer with a large LCD display. So I got it for $80. There are two of them and there was also a book. So the listing says one definitely turns on and functions with batteries. One is unconfirmed. Both are being sold for parts and repair as is. Comes with the handy reference guide to get started. Things to do with your TRS-80 Model 100 computer. Comes with two battery powered computers powered by four AA batteries not included. Electrical power possible with pro something or other. One of these units definitely turns on and powers up properly but further testing does not be done. One of the units does not appear to. So here they are. Let's take a look at them. And indeed, things to do with your Model 100 computer. Dilithium Press. Wow. When was this book? 1983. Interesting. Other high level languages. Pascal. There's a set. Well you can program this in assembly language. Your Model 100 computer is not ready to be programmed in assembly language. Oh, when you turn it on. You need an assembler. At present there are no assembler programs for the Model 100 but several should be available by the time you read this chapter. Well, that would be nice. I would like to program in assembly language. So yeah, they basically, oh look there are notes in here. Printer should be tractor and friction load. Parallel plus serial. Be sure the cassette tape is in the recorder and has been advanced past the lead in maybe a bit further. So that's interesting. Alright, well anyway, that's a book. Interesting, I have some fabric samples. I have a whole bunch of fabric samples. That wasn't in the listing but okay. Does anybody have any suggestions about what I should do with these fabric samples? Because I sure don't know. But that's fun. Okay, so here we go. Two computers. So let's take a look at these. So, wow, it's very, very yellowed. And if this is the original color, that's really yellowed. Wow. So there are two possibilities. I could do the usual retro-briding on this. I did see that somebody else basically used spray paint matching the color. And they say that it turned out pretty good. It looks like there are some scratches on here. I wonder if this is just easily replaceable. It's just plexi. That's kind of a keyboard that really neat. Wow, that's kind of sticky keyboard. Okay, so we've got, this is the battery cover. Okay, I did get batteries. That's interesting. So here it says memory power. And I read that there is actually an internal battery in here, which is not great. Because, of course, internal batteries always leak. That's interesting. It says super rom or something. I don't know what that's all about. But that's kind of cool that you could put a chip in it. So yeah, one of the definitely important things to do is if this does turn on, make sure that the internal battery is out of there. How do I turn this on? Is there a switch? There is a switch. There's an off switch. Let's turn. Ooh, it actually turned on. Well, okay. Apparently this one works. How do I move down? I don't know if the camera is picking this up, picking up the LCD. But yeah, in any case, this is actually working. Select, can I just type in basic? Apparently so. 10, 10. The one is a bit sticky. 10, print, quote. Hello. With 1L, 20, go to 10, enter, run. Apparently it just scrolled off the screen and maybe it's printing something. Well, anyway, okay, so this one seems to work. I kind of wanted one that didn't actually work. So that must be this one. Let's see. So the battery compartment, ooh boy, that's crusty. That could use a clean. And one of the battery contacts, I don't know if you can see this. Let me see if I can get the light in there. Yeah, so this battery contact right here is all crusted up and that is very possibly just why this doesn't work. So I'm going to, let's see. Rob tries to fix a thing. Well, I'm just going to clean these contacts and just see if that actually does anything. That's unfortunate. There used to be something here. What was there? Oh, the FCC sticker. All right, so let's take the batteries out of this one since I was so kindly provided with known working batteries. And let me go get my fiber stick and clean these. Okay, so there is that. And this is this fiberglass stick that I, so this is a fiberglass scratch brush. Got the idea from my mate Vince. He seems to like using these and they seem to work pretty well. The only thing is that they're pretty nasty because they give you little bits of fiberglass, which is pretty nasty. So what I'm just going to do is just sort of rub the top of this just to see if I could get past any initial corrosion, especially this one, which may just be a lost cause. I don't know if that might do something. It could do. And I'll just get this one. This one looks pretty good. Let's take a look at these. So these also look fairly decent, aside from the corrosion and chemical stuff crystals that are stuck in the battery compartment. So yeah, really the only one that I would be worried about is this one right here because that was pretty crusty. So all right, maybe I should do a quick continuity test because it goes from here to here to here to here, here, here, here, here. Well, no, I'll just plug it in. Why not? Oh yeah, plug it in. I could always plug it in to something, external power, see if it works, but I'm not happy with how that sat in there, especially since it was backwards. Why are these backwards? Why did I put them in backwards? This one goes like this. This one goes like this. This one goes like this. All right. And this one goes like this. All right, well, let's just see if it powers up at all. Oh, I hear something. Oh, wow, that's not great. Yeah, there's something rattling around in there. And the Y key seems to be stuck. Well, okay. Yeah, well, again, the Y key is stuck. You can see that there's a streak down here. Maybe that's because the LCD connector is not working properly. The contrast seems to be off. See if I can pull that Y out. Okay. Yeah, seems to be working or not. Pressing I and I'm getting a 5. S works. W works. T works. Oh, that must be num lock, I guess. Yeah, there was a num lock here. And unfortunately that's stuck too. All right, so this one obviously needs a little bit of work. The keyboard is stuck. The LCD display appears to be part of it. Maybe one contact is not working. But aside from that, this also seems to be working well. So this one is the one that needs help. So let's see if we can help it, especially with the thing rattling around in here. All right, so let's just turn this off. Okay, so the one that doesn't work, so again the listing says one of the units does not appear to. I should probably look at the printout. One is unconfirmed. So maybe that was just because of the corrosion, because it definitely works. Yeah, this could also use some cleaning. There's some tape on here, which I can... I don't want to use the razor blade right away. I will probably use some, what is it called, goop off or goof off or oof off or something like that, which sort of loosens the adhesive. Let's see what was in here. Did I look at what was in here? I don't think I did, because this seems to be a little bit stuck. Let's see what's inside. Nothing. Okay, so apparently there is some sort of extra chip that you can put in here, which I did not know about, but everybody else who is familiar with this does know about it. Okay, let's use one of these fabric samples to... There we go, I've got a use for this. All right, let's go ahead and open this thing up. There appear to be four screws here. It's nice that they didn't hide them here. Two of the rubber feet are missing, but that's only to be expected. Gonna come out. Not without a fight. Let's see. Okay, maybe I should just get a spudger to open this up. I'm kind of assuming that maybe there's a tab. Let me see. Were there any screws over here? I don't think so. No. So there's no screws here, no screws here. So let me go get a spudger. Here is my spudger, and see if we can feel around in here. There we go. Okay, so that's one side, and it just promptly closed again. Let's do that again. All right, there's one tab. Should be another tab here. And there would be one more tab here. All right, there we go. Let's see what we've got. Okay, interesting. It opens up like a book. Okay, what was rattling around? A screw. There was a screw in here that was rattling around. That's not great. This is the famous reverse chip placement that pick and place machines would not want to do. So, yeah, upside down chips here. Right set up chips here. So, well, that saves some space. I'm not sure why that was done. Let me zoom out because I'm looking at this and I don't really see anything in particular that would require that unless they just did that because it was convenient for routing. I bet they just did that because it was for routing. Here is the battery that really should be taken out because they do tend to just leak. So, I'm probably going to just remove that. There are a lot of, let's see, there are a lot of things in here. There are a lot of things. That's interesting. A little rubber thing on a post. So, the keyboard definitely needs work because we've got some stuck keys here. The Y key is stuck. The num lock is not doing anything. The caps lock just got stuck. This is all stuck. So, I really just want to clean this. So, maybe that should be the first thing to do. I can probably take this out entirely and there are just two connectors, it looks like. So, let's see. Well, that's interesting. This is all loose. I wonder if somebody has already had a go at this. This must be where that other screw came from. It's kind of rusty. And, yeah, I think that is where the other screw came from. Here. And, wow, yeah, okay. So, it is a little rusty and a bit corroded. And the reason for that is that the battery compartment is right above it, which means hopefully, I don't see any corrosion in this area, which is good. So, yeah, so I don't think this is a damaged board. I think it will work just fine. Once I figure out the LCD problem and once I clean the keyboard out, the spacer here for the keyboard, and here is the keyboard itself, appears to be a metal bracket of some kind. That goes on to the keyboard over there. And this just comes right out. Let me unplug these. These are a bit tight. I don't see any particular locking mechanism. So, I'm just going to assume that you just pull these out. That's really tight in there, but it comes out. So, there's that. Okay, it is polarized, which I always check when I take a connector off, because if you take it off and it's not polarized, what's this? Is this a bug? Mouse dropping? Because if you take off a connector that's not polarized, then you don't know which way it goes back. This is a little dangerous. I don't really want to lean up against or force against those capacitors there. This is coming out now. These are just very tight connectors. Okay, there we go. Done. Done and done. So, we've got what appears to be a fabric on top of the, below the keycaps. I guess I could just pull the keycaps off. Is that possible? Yeah, they're still stuck. Let me see if I can pull one of these keycaps off. Maybe the caps lock button. Yeah. Okay, so the keycaps just come right off, and then the felt comes off of that. Oh yeah, okay. So, it seems as though the problem with these keys is actually inside the key. So, what I may end up doing is what I've done before is basically take all the keys out, take all the keycaps off, and unsolder all of these keys from the printed circuit board. Then, you can actually get inside each key and clean it. And that seems to work really well for these keys. Alright, so that's something that I'm going to have to do. Let's take a look at the LCD. See if there's anything funky going on with that. So, we've got a ribbon connector here, which does have tabs on it. So, I want to actually know that those aren't tabs. That's just the ribbon connector itself. Alright, is this polarized? No, it is not. However, will it just go on one way? Well, it's not going to twist like this. So, it's going to be straight like this. So, that's fine. And we've got an LED connector over here. So, let me remove that. So, we've got red on the left side, red on the right side here. Let's remove it from this board. Let's not. Let's remove it from this board. Something a little more firm. These connectors really are quite resilient to being pulled out. Okay, and this one is polarized. Great. So, what I will probably end up doing with this side is removing the PCB and just giving it a nice clean with IPA. None of the pins seem damaged. The reset button seems to work okay. These switches, well, I haven't tried. This is the power switch. This other one is answer and originate. I guess that must be for a modem. And then we've got this connector, whatever that is. Printer port, serial port RS232C. That's a serial port. But it's 25 pins. Okay. Here's the volume control. There's some dust in there. And there is also the on-off switch. And oh, what is this? Deer and ACP. I don't know what that is. So anyway, I would definitely take this out, clean the corrosion off of the battery. Okay, we've got this LCD. So let's see if we can figure out what's wrong with the LCD. Let's take it out first. And yeah, so the problem was on this side. And notably, that screw was missing. So I'm wondering if there is an elastomeric strip connecting to the LCD. So we've got the piezo. Let's remove that with the piezo connector. Like every other connector, it's extremely strong. And the piezo comes off. There we go, finally. Okay, so. Okay, this is the front. I don't know if there is a polarizer. If this is a polarizer or not, it may not be. It'd be nice to make a new one of these. Let's see. It looks like... Yeah, okay, so the bottom is just one piece of plexi. But then it looks like there is another piece of plexi that's glued on top. Better off leaving it alone. And it appears that there is some sort of... Yeah, there's obviously some printing over here, so I don't really want to mess with that. Okay, so that's this. So let's see. Oh, this LED is looking a little bit sad. It should be straight. There we go. I don't see anything obvious. I do see an elastomeric connector over here. Elastomeric connectors are used on LCDs that don't have pins on them. They're just glass with pads printed on them. And the elastomeric strip is basically just a rubber strip with basically conductors running through it like this at a very fine pitch. So essentially you just slap it down and you get wires that go down like this. So that's nice because it means that you can just take your LCD and put it down and just line it up with the pins. And it doesn't matter where the strip actually is as long as the strip is a fine enough pitch. So we've got one, two, three, four, five, six, seven, eight, nine, ten. Ten of these display units. Presumably that is to drive one-tenth of the screen. So if one of these chips were bad, I would assume that part of the screen would also go bad. So let's see. It was like this. And like this. Okay. So we had a bad streak over here. Now why is that? It could just... See that really says to me that there could be some bad connection in there and all that needs to be done is to have it cleaned up a little bit. In order to do that, I would need to twist these out of the way and then pull the shell off and then the LCD would just come right off. But I just want to see if there's any other sign of damage. I don't really see anything over here. The other possibility, no, I don't think it would be this ribbon cable because again it was just affecting a part of the screen and I think that this is just for communication to these chips. So again, if there was something wrong with this ribbon cable then I would assume that a whole tenth of the display just wouldn't work. The rest of the board looks pretty clean. So why don't we start with this. I'm just going to hook this back up to see if maybe the problem fixed itself. That doesn't mean that I should not clean it. I definitely should. So what I'm going to do is hook up the ribbon cable. Okay. So now I can just put that sort of over there like this. Hook up the keyboard. So now the keyboard is hooked up. And is there any external power connector? There's phone, cassette, printer, RS232. Yeah, there is. That's actually looking a little crusty as well. Look at that. Here, let me zoom in. Look at that. That's all crust. Yeah, wow. All right. That's going to need replacing. That's definitely going to need a replacement right there. So, okay. Well, we're going to go with the batteries for now since we know that works. So I'm going to carefully turn this. I don't want to damage the LCD. Let me zoom out. Let's go ahead and put the batteries in. Turn the unit on. Let's turn it upside down. Turn it right side up. And I don't want anything touching anything else. Okay. Let's turn it on. So, yeah. So we do have this streak here. Pressing down doesn't seem to do anything. This LED. Oh, I see. That LED says low battery. So that should not be lit, which is fine. But there's definitely something going on there. And pressing down doesn't seem to do anything. It almost seems like it's just one character. Right? Because the F is missing from here. And only the F. And it's seven pixels across. And I think these letters are all five by seven. So I wonder if there's something wrong with maybe a character generator. So maybe it's not receiving characters properly. I mean, what in here would do that? I don't know. So again, I'm pretty much suspecting this. So I'm going to take a chance. And I'm going to open this up. And I'm going to give it a nice clean. And then put it back and see if that does something. And the traces all look okay to me. So yeah, let's just do that and see what happens. Right. So in order to take the LCD off, I'm going to have to twist these bits of metal. And I hate twisting the metal because that always means that you're going to add fatigue to the metal. And fatiguing the metal means that you always have the possibility of breaking one of these tabs off. And then you're not going to get nice compression on that elastomeric strip, which kind of ruins everybody's day. So I'm going to use this, the Nejisaurus engineer. This is cool because it has usually pliers just have these lines running this way. This one has them running this way in the middle so that you could actually grip the head of a screw and turn it without too much trouble. So I think this is probably a good tool to use to turn these tabs. It seems to be working pretty well. I don't want to turn them very fast. And I also don't want to scrape the PCB because these vias are awfully close. Okay, that's all of them off. So I should just be able to push the top off to see what we've got going on underneath. I want to be a little gentle. I don't want to bend too much because this is a piece of glass in here. And replacing LCDs is pretty much impossible. Where's my splutcher right here? Looks like this could use a little help. So there's this. So it appears that it went on like this. And it is polarized because we've got two little slots cut out on either side so this can't go. It can only go one way. Now I lift this off and elastomeric strips are just sticky. So you can just peel it off. And then of course the important thing is that you have to know where the LCD itself goes. Because the LCD has lots of fine pads. So lining up the LCD when you put it back is pretty important. So yep. All right. Can you see that? Can you see the corrosion? That is the source of our problem. So there appears to be maybe a little bit of corrosion here as well. A tiny bit here. But yeah. That would definitely do it. If we look at the underside of the elastomeric strip. Yeah. See unfortunately it's sticky. You know you do have to make sure that it's clean when you put it back on. So okay. So I'm not going to remove the elastomeric strip from the LCD. There's no reason for me to do that. I think it's probably just fine. It probably sealed okay. The corrosion came from the other side. So let's just go ahead and give that a nice clean. First I will just use a little bit of the fiber to get just the top off. And then I'm just going to take some IPA and wipe that. So I've got my IPA container here. And I've got some Kim wipes. Just give it a nice clean. The corrosion is still there. I have to give it a little bit of fiber cleaning. I don't want to get too aggressive with the fiber cleaner. Because I don't know if the pads will come right off or not. If I do that. I heard that sometimes you can also use vinegar for this problem. Just to neutralize the corrosion that's in there already. It's still there. Let me give it a gentle scrape. Just a very gentle scrape on the top. Let's see if we can get anything off. It's being kind of stubborn. I'm going to look at it under the microscope to see what exactly it is. So it was a little bit of a sticky kind of residue. Scraping at it did help somewhat. So now it looks a little better. It's not perfect. There's still what appears to be a little bit of corrosion on it. But I think we can call that done. So, yeah. And it did seem to cover just about five pins. Actually not seven. So that would definitely be the source of the problem. All right. Let's go ahead and give the rest of the pads a nice clean. And then we'll see if we can bring this LCD back to life. I don't know if I'm supposed to be cleaning the elastomeric strip with IPA. But we'll see. I'll just give it a gentle going over. I just really want to get any of the dust that's stuck onto it off. Any dust or hairs or anything like that. Because that could really ruin your day. I can also look at this under the microscope. Okay, yeah. There were definitely bits of things stuck on here. And if you can look a little closely at this, it's really hard to see. But you can see that there's a strip running down the elastomeric strip like this way. That's the thin... Come on, focus on this. All right. How about we just do this? Okay, so that's the thin contact area. That'll contact this. So if there is like a little piece of dirt on that, then that kind of ruins your day. So how did this go on? Any clue? Any clue. I believe that there was a little bit of a defect on this side. You can see that over there. And that went on this way. I did notice in scraping this that there was a tiny bit of corrosion left stuck on the strip where the other corrosion was. So there appears to be a guide here and a guide here which presumably is where the strip should go. But it doesn't quite fit. So I'm a little bit at a loss to figure out where this is supposed to go. One possibility is simply to put it here and to move it over until it's done and then just call it a day. So let's see if we can do that. So I'm just going to line this up. So I've got it lined up like this. So now the question is how far back and forth do I have to move it? So let's go ahead and hook this thing up. I'll just attempt to hook it up. I need to put the batteries in it. Let's do that first. Batteries are in. So I'm just going to leave it like that and turn it on. It is on. So we can maybe move this a little bit back and forth. I'm not getting anything. I am getting something. It says select. Is it lined up? I think it might be lined up just like that. And you can see, hopefully, you can see the F in Microsoft. Now we are seeing a strip down the middle that isn't being lit up, but that's only because I'm not squeezing hard enough. So I think this is aligned. So the reason that I think it's aligned is that there's an S all the way over here and it's all the way to the left edge. It doesn't appear to be any more pixels in that direction. So I'm kind of hoping that that's it. Also, it appears that these two little lines over here are roughly centered. Place this here. And then see about attaching this back. Let's zoom out a bit. The idea is that I want to... Huh, I wonder if this is the thing that aligns the LCD. Could be. Because I do see that the edges pretty much correspond with these slots on the end. So maybe I didn't have anything to worry about. There it goes. Right in there. Let's just get rid of any crumblies. Okay, so. So now the key is that the strip is going to be compressed by the twisting of these tabs here. So what I have to do is basically press it down pretty firmly and then move the tab. So that's it. Now I don't know if that applies sufficient force because I don't know if in twisting these things whether they actually lift it up or not. I suppose that I could also compress each one of these tabs like this. I'm not sure I want to do that though, but I may have no choice if it doesn't work. So let's plug it in and see what we have. Let's plug it in the right way. Here we go. Plugging it in. Turning it on. Off. On. That sure didn't work. We're not getting much of anything. So I'm looking at the sides of the LCD to see if maybe it had to be moved over a little bit. Maybe it does. Ah, there we go. It works and I found the contrast control also. Okay, we've got a few lines that aren't showing up. So if I turn the contrast up a lot we can see that we've got some lines that are not properly connected. And if I squeeze these, if I squeeze this area it does seem to work okay, but it looks like this pixel down here is sort of bleeding into the other pixel. You can see this zero over here is a little thicker. It's basically duplicated pixels. Same thing with the E over here. So I think what's happening is some of these just aren't lined up quite correctly. There's some other doublings over here. So you can see that the Y is cut off down here. I think that is just on purpose because it just runs off the end of the display. The top of the Microsoft is on the top of the display which is correct. Although I kind of sort of see a pixel, a couple of pixels up there. A couple of pixels up here. See just above the zero? There's like that dot over there. Does that mean that we're missing an entire row? Well, okay, so what I can do is remove this again which unfortunately will cause metal fatigue and try to line it up properly again and this time try to be sure that it doesn't actually move. And actually comparing this to this working one I can see that the Y in bytes is actually complete. So in fact there is supposed to be an extra row and the whole thing is supposed to move up. So this is definitely misaligned. So I'm going to have to figure out how to get it properly aligned. Well, I suppose this means I should try again and this time I better get it right because otherwise I will fatigue these tabs too much, they'll break off and then they won't apply any pressure to the elastomeric strip anymore. Alright, so I've given the thing a good clean, gotten rid of all the little dirt specs and now I know how to align this properly. So I'm just going to place it very gently. Okay, so it does actually look like there are two missing pads on either side. Now it doesn't even seem to be toggling. Okay, so how do we remove this? It doesn't seem like there's any obvious point of entry. It's possible that the top could get levered off. Let's try it. Yeah, it doesn't look hopeful. Maybe what I could do is just consider this key a sacrificial key and just, you know, replace it. But for now, let's see if I could take the top off. How's my microphone doing? Still working? Yep. Okay, well I couldn't find anything really online about opening one of these up. So I'm just going to have to experiment and see, maybe sacrifice one of these just to see how it's taken apart. Alright, so what I did was I cracked open one of the sides. I guess I'll just, maybe I'll try pushing on this side. See it's not. It's not. Ah, okay. So maybe the key is that I just have to get enough leverage in here to open it up. So we've got a spring. We've got the key stem here. And the mechanism, let's see, we've got a plastic piece here with what appears to be a little wire through it and contact. And on this side we've got some copper metal, but I don't see what's supposed to provide the buckling action really. Oh, I see. There is actually some plastic formation here on this key stem, which may provide the buckling action. And possibly this also acts as a hinge. So let's just attempt to put it together again on the off chance that whatever was preventing it from working is gone. Not likely, but who knows. So I think what's supposed to happen is that when you press this key down, maybe this thing slides back and forth. We're supposed to slide back and forth. Well, it's certainly not doing it now. This is just supposed to go the other way. Beats me. It's a mystery. In theory this would get put back like this if the tabs weren't all broken. Well, it's almost working. It does kind of feel that it wants to lock, but it's not going to. So that's a loss. But hey, check this out. I got the LCD totally working. No blank lines. So I did that by just finding where the blank line was. That's where the signal should be and gently squeezing. So not too hard so that the glass would break. But the idea is that the strip really needs to press up against the pad on the printed circuit board and the pad on the LCD. So if there isn't enough pressure just in that one particular spot, you won't get a connection. So it actually looks like it works. So really all I need to do now, I've cleaned the keyboard. It feels okay. These aren't the greatest keys. But the problem is the toggle switches. So I really have to go on eBay to find parts, computers, because unfortunately, or maybe fortunately, the other three machines that I have all pretty much suffer from the same problem, which is that the LCD has a few lines that are missing that can probably be solved relatively easy like I've showed. And the keyboard needs to be cleaned. And that's really all that's wrong. So I'm basically just going to look on eBay for bargains just so that I can use them as parts computers. And I guess that's really about it. I don't really have much to do. I do have to replace this power plug. So again, that's something that I'll have to use a parts computer for. But aside from that, I'm pretty satisfied. This thing just turned off. I'm not sure why. I guess it turns off after a while. So yeah, that's about it. There's not much that I can do with this thing as it is right now. I can run basic. There's a text editor. There's a modem, which of course I don't have. There's an address book and a calendar application. And that's about it. And you can put your own applications here and presumably they go into RAM. And let me just turn this off. So you're probably thinking, well, if they go into RAM and you just turn the machine off, what happens to all those programs that you wrote? There's a switch on the back which says memory power and you could turn that on or off. And if it's on, I believe what happens is this battery here gets connected to memory so it retains its memory. I have no idea how good this is. I can certainly measure the voltage, if any, coming out of it. 4.6 volts. That's actually not that bad. So the RAM itself doesn't take a whole lot of current. So you can see that the voltage is actually not drooping even though it is maintaining voltage for the RAM contents. So that's actually pretty good. Unfortunately, I do see some leakage. So I am definitely going to have to remove this and either replace it or just leave it out as is sometimes suggested so that this doesn't happen again in another 40 years. So, yeah, I can just take that out. And I think that's about it. So there we go. Sort of fixing a TRS-80 model 100. Thanks for watching. And don't forget to subscribe if you want to see more interesting fix-it videos or electronic design videos. Thanks again. See ya.