Casio CQ-1 Diagnosis and Repair
I usually, have a lot of projects, up in the air waiting for parts getting, stumped, and trying to think of something in the background while I work on something else so, when, I make videos about something, and then say, I'm going to do a follow-up and take forever to do that it's not because I don't want to do that video it's, just something it's gonna take me time to get back to but. Today we're. Gonna get back to this the. Casio, cq1. Released. In 1976. The Casio cq1, is a four, function, calculator clock. Calendar. And stopwatch. And. It has an eight digit vacuum, fluorescent display, no. I think this is a very, pretty calculator, which isn't too surprising because that's something Casio, was quite good at in the 70s, now unfortunately, I haven't been able to show this calculator running yet and that's because well. It. Does. Not work, I was. Sent this in by a viewer who was hoping. That I would be able to get it running and that's, what I'm going to try and do today now, the, first, time I showed this in the mail video that I opened it on I, didn't. Have, the, correct, batteries. For. The backup, so I wasn't, a hundred percent sure that. It would actually work without those. But, turns. Out that wasn't, the problem so there, is something actually wrong with this which, does. Seem to be common I've seen several, other instances. Of this calculator, not functioning, as well so, I think there's something that just goes wrong, with these now. When I got this in the mail video I'd tried to open it and troubleshoot it initially. To see if I could figure out anything was wrong and, unfortunately. I couldn't easily, find, anything, in particular that, was suspect other than this, diode now I didn't, cover what I did here in the, mail video but let me briefly explain it, this diode was originally, on the other side and it's. Right underneath the display and I'll show you when I take it out but the, diode.
Here Was shorted, so I was thinking perhaps it. Had been blown and was shorted across but, it turns out it's not the, two, sides of this diode are actually connected to the speaker. Which is shorted. Because that's how a speaker works so I have. Tried to work on this already but that was as far as I got and that didn't change anything all. Right and as I get it open and look in here we can see that right. Down in here there's, kind of a missing point. And that's where that diode was it's yeah. That was a total pain to remove. There, so that's why I didn't bother doing it on camera but, yeah, now we can see in here so it's it's. Time to start trying to diagnose. This thing okay. So the first thing I want to test here is whether or not power from the battery is even getting into this thing so I'm, gonna go ahead and install, that now, and then. I'm going to use my, multimeter, here to. Check whether or not the voltage is getting into, the calculator, so. Let's just, test, here, and here. Yep. I get 1.3, and, now I want to make sure that I'm actually getting that on ground, so I wonder where ground is on. Here, it's. Not that one it's. Not that one. Hmm. About, that that's big. And wide. Nope. Nope. Hmm. Gotta. Have it coming in from somewhere, so where. Does. It go. Hmm. Interesting. Let me track, down where that side, goes to on the, circuit board so it's actually connected to the other. Board that's mostly, used, for holding, the buttons and in reading the data off of those and connects. The actual. No it doesn't connect to the display the display is actually on here and that's what this, rows for the, display, is just it's really hung in there in a very awkward way so anyway, let me figure out where that finally, attaches to here, okay. It just goes from here. To here, and. If. I switch over to voltage we can see that I do get, a reading, from. The battery come. On you. Were just working there. We go, 1.2. Volts I do get the reading, from the battery but it's it's, kind of spotty so that that this, side still a bit dirty if I move it down there yeah it gets to a cleaner, area, but. That, connection that's pretty bad maybe I should just try cleaning, that and see what happens yeah. That is not good looking let's. Uh give that a bit of a scrub. It's. Looking better. Yeah. It's really dirty this is just gonna take some effort all. Right there we go now I've got that battery terminal looking a lot better I almost. Think it's brass because it looks like it was tarnished. I ended up taking a wire brush to it and just scraping, it with that and that did a lot more than scrubbing. With a toothbrush and CLR did so yeah. I don't know what's going on there brass would be a very weird choice but, maybe. I don't know let's. See if that helped at all. Unfortunately. That's not any better. One. Difference is now I, don't. Hear the speaker, when I rotate the battery so I think, power is, getting through to the rest of the board normally. Now so we, can start to try and track down where the issue is on here. Okay. So I've been digging around for a bit in here and I've got a, pretty, good lead on what the problem is so first, of all I want to show you that I have my really, noisy, old power supply connected here and it's, connected, to here which.
Runs Down to here, and, that does, trace. Around the board to a few places, but. One interesting thing is that the ground, input, from the battery isn't, actually. Connected, to any, of, the, chips or the really, important components, so, what's. Going on here is that this, inverter. Circuit is actually acting, as a. Voltage regulator, that, powers everything else so the, ground from battery isn't directly connected to the important stuff like the negative, rails on the capacitor, not, connected, to battery ground, so, the. Ground, doesn't, directly, get through here now. One of the problems I was having is, that I can't actually get a voltage reference to anything and when, I do turn something on or when, I do turn it on I should say the, voltage starts, to slowly drift one way towards, ground so, something. Isn't quite right which, means that it's probably, in, the, voltage regulator, circuit and, I'm. Pretty sure I, found, the, problem, it's, actually, very, identifiable. We. Can see this bent-over capacitor, on the voltage regulator circuit here and if. We pry. That up. Mmm. Yeah, that. Transistor. Doesn't, really look too good, there. So. Yeah. I'm pretty sure, something. Went wrong with that thing at some point, and we're. Not getting a proper voltage generation, now so. It looks like I could probably replace, this, part and have this thing back up and running which great. I'm you, know I really want to do that the, only problem I have is getting, my hand a replacement. For that now, I like, to usually do these videos and as short of time as possible and well. I could try and possibly. Order that one online it doesn't look, like it's a part that's continuing, to be made I could trace them an equivalent yada, yada but. I do have, this. On hand and s. 8550. Now, these are both 20, volt 700. Milliamp transistors. PNP. So. This. Should, be a pretty, equivalent drop-in. Replacement. There's. Just one problem you can see here, this has the, pinout listed emitter collector base. Well. This, is emitter. Base, collector. So. I'm gonna have to switch these, two pins. Over, here to, be able to get this one to fit in there and. It gets even more fun because, this. Separate, board here. There's. No way to get to the bottom of the components, on here I'll have to remove this, whole, thing.
To Be able to get this out so. Yay. Whoo. All right it's, finally. Man that was not. Easy it's almost like they didn't think anyone was ever gonna bother trying to repair one of these, now. Little. Little no here don't be surprised if one day the blue is d-mat disappears, you see how cloudy. And terrible. The image looks right where the transistor is well watch this. BAM. All. I did was put black, under it and it looks better. Yeah. The blue. ESD mat kind of reflects a lot of light up into the camera and causes, issues, I can make, it a little better too I can block a little more light yeah. So the. Yeah. Who would guess that a bright reflective, surface, isn't the best thing to film off of now, that it's loose we can really see that it's definitely toast, at Legg is all crusty. And black and it looks like there's a crack here that runs up along the case of the package so. Yeah, thing. It. Had a catastrophic failure. Hopefully. I am going to be able to replace it without, too. Much, difficulty, but, we'll. Have to see how that goes. Okay. There we go one dead. Transistor. It's uh. Yeah. Let's, see how this goes trying, to replace it I'm really you know hoping. This. Would definitely be the fun. Way to get the wrong pin out of transistor, to fit in there not. The best way though but, the fun way. This. Is the much more boring practical. Way to do it though and I, should. Probably just go ahead and leave it like that. All. Right all that's left to do is just to put that back, in there it's gonna be pretty boring you basically, already see me do that so let's just go ahead and skip to the next part, all. Right I pretty much put it all back together because I remember when I did the mail, video someone. Told me you needed these batteries, in here for it to turn on and there's, no way to really conveniently, hold those in there so. Let's. See what happens. Okay. That's. Really. Disappointing. Hmm. You. Know it seemed more disappointing, ah, there. Was something. Was. That oh. We. Have something, oh. I. Think the battery terminals are still kind of dirty maybe the coin-cell ones are. That. Looks. To be. Functioning. Maybe. Time. I. Don't. Know how. To. Use this okay, comp. Maybe, that's the computer one. Plus. Two, equals. We. Just calculated, on a cq1. Okay. So clearly, this. Thing's at least partially, functional now all right. Set.
Man. I don't, know how to do anything. On here now one. Two plus. Three equals no okay so time. Lap. I don't know. Would. Stopwatch, be how. Would I do that. St. I don't know what this is. Hmm, Oh edits. I'm clear, okay. Those. Don't do anything time. See. What time does. Time. Doesn't want to do anything okay. Well. There's, no guarantees at that blown, transistor, was the only, problem on. Here. Whoa whoa haha. So. What I do I pressed equals off. Equals. Okay. Getting. Closer. That. Looks like, minutes. Seconds. Milliseconds. If you know sub seconds. None. Of those are doing anything come on. Work. Equals. Okay, so. Clear. One. Of these has to do. Something. Period. So. Maybe these buttons. Aren't. Working right now I. Think. I need a manual really. Okay. So my first instincts, were right here, it's, the buttons so I can press time. Really, hard and. Then it will start the, stopwatch, all, this. Thing's really sweet. Now. I can also. Go. To set. And set. The time so if I want to set it to the, current date which is December. 27th. 2018. One, eight, one. Two. Two. Seven. And. It. Now has the date and now I can set the time the current time is, 9:40. A.m. nine. Four. Zero. BAM. And, then I believe it's plus. Time. Larry, oh now I, don't. Know. Quite. How you up there we go 9:40. On the 27th, I don't, know how I show. The date. But, sweet, okay. So. Compute. Time. How, do I see the date, or set an alarm maybe I got a press real hard to, set an alarm ah. Now. That's oh well. Hold on here holding. That no. I think. I need to get back into here and clean these out. It's. Oh so convenient. To get to all, those buttons in there and got it take. Out every single one of them screws. Actually. Got. Into, this. Calculator. This deep last time I just didn't show it all on video like I said. In the mail. Video well add the little thing. On-screen had a lot of false leads. On air the first time around, I'm. So, happy this thing's working this. Is nice yeah. That. Makes me really happy. Okay. How. Does this have. To have spent a while all right there we go oh they're just carbon. Pads. That's. Not good. Smell. Like a whole lot I can do about carbon pads not working. Huh. We have like some secret buttons down here. Actually. Hold on these are. Those. Are super, weird are these all connected. How. Does this work hold on these aren't these. Aren't interleaved. Like, your, usual carbon, pad buttons. They're. Just solid pads, and, they're, all connected, even. Huh. These. Look like just carbon. Grids. I have never, seen that before that's super, strange wow, I didn't notice that last time I was in here well obviously. Huh. Okay. That. Means there's gonna be something. Like connect. It down to, the bottom, here so weird, how how, does that work so. Okay. There's an open, pad they're hoping, pad there okay. All. Right, so, then, there should be. Some. Here there there and there alright so there's. Many, pads wow, this is crazy okay so. These. Are the, touch, points, that make, up like, one row or column and, then that's that whole thing, Jase, is. They. Really wanted to save i/o on this thing yeah. Except for these buttons, each one of those gets their own oh, man. Alright so who. Maybe. I should try. Pencil. Eraser on those a little bit those are the failure point those are rubbin constantly. We're. Good just try it and graphite, from a pencil on there yeah yeah. That's. That's. Different, I've never seen, matrix. 2 karbonpad, it's matrixed, in the carbon. Huh. No. Unfortunately this thing's a massive, pain to put back together because it has a little plastic tabs all over the case and that's, how it goes together and comes apart and I know eventually if I keep trying to open this thing and put it back together they're. Gonna break and then it won't go back together right it does have one, screw that holds it together but that's almost token, I don't even know why it's there that could be that. Holds, it way less than any of the tabs do so yeah. I'm just gonna go ahead and do all of the. Procedures. I can think of on here to try and resuscitate. This, all at once and then just, hope that that was enough because I don't want to keep trying to open this up and put it back together and, eventually.
Get It to work so let's just do it all right now. Number. Buttons felt, fine but I'm just gonna go ahead and, be. Sure about this whoops. Guess. There's no reason not to take, that off but huh. Okay. Let's. Try getting, a little. Carbon. On here, or graphite. Aid. In the conductivity. All. Right since these ones really kind of felt flying over all I'm not gonna do, these ones too much let's just stick with that and see how that goes all. Right I've got it all buttoned, up now after cleaning off the contacts. For that I can, set it to stopwatch, give, that a press not too hard and it. Works now. One thing I find confusing is, this says start/stop that says lap that, does not lap that starts, and stops it and it's, not that these are somehow shorted, in doing the same thing if, I turn it off set, it back to that I can hit lap and then, it does that which is different. But. Then it continues, going, on so I don't really know but hey. It's working too and I can go back over to calculate, or, compute, you. Know twelve times. Three equals, thirty-six, and it's, working just fine, so, this. Is clearly, a successful. Repair which, is just awesome, now. I will say there is still one further problem, I don't know how I got it to turn on but I got the alarm to turn on and the speaker, output is, extremely. Weak but. That could be my fault after I messed, with that diode, in there and I'm. I'll. Live without the alarm that's not a big deal it's. If. Anything that's just gonna be less annoying maybe it might have an alarm because often, the batteries, get low but yeah. For, now it's. Working and this was a very satisfying repair, it's been really driving me nuts eing this sit on my shelf in the background of stuff. And just not working, I'm sorry. It took me this long to get to it I'm just kind of having a problem getting to the male videos I usually do. My videos when I get something new. That's really, exciting and I get all this male stuff in at once it's really hard to pick what to do and then, while. I'm sitting there thinking I should, do this I should do that I usually get something else that's not male and then if I do that I'm not putting preference. Over one male item over another so I'm. Sorry I'm gonna try and get to do the male stuff, more, it's, just I also. Want to do other stuff that I'd get, in so like the next things definitely, not going to be a male video but pretty. Sure you guys will be ok with that well. I hope this was, enjoyable. And maybe, you guys learned something especially. About replacing, transistors, that, was kind, of fun all I did was bend the legs around but yeah, I hope you guys enjoyed that and I'll see you next time.