Repairing This Old 1980's Zenith Box T.V. So We Can Watch Wrasslin'

Ladies and gentlemen, welcome back to Amateur Repair Time. A few weeks ago, I did a video where I needed to show some VHS tapes, and we ended up watching those on a little TV that I had laying around, but this was the TV that I was going to uh watch them on. Uh, but whenever I got this thing out of the closet, I've had this for quite a while. Whenever I turned it on, it didn't work anymore. It would just click. it made like a kind of a little bit of a squealing noise and then would turn back on. So, if you don't watch our other channel, um I have a history of working on arcade games and pinball machines. That's kind of what I do for a living. And um in the arcade games, of course, you have to work on the monitors a lot. So, the the early arcade game or the arcade games we work on, most of them have Electro Home G07 monitors in them, which were 19inch uh monitors that came out in the late '7s, early 80s. Uh, and then a lot of Wells Gardener stuff like um the Wells Garner K4600, the K4900, the K7000. Um, and so those I'm pretty familiar with. I've worked with a ton of them, hundreds of them. Um, but on those it's kind of you don't even completely have to understand the circuits because you're working on the same model over and over again. So, a cap kit fixes a lot of stuff and then each one of them have their own little peculiarities or uh you go through it and you can get the thing going again if you know about them or you've worked on them. Well, this is a different beast. This is a Zenith color TV. This is a Zenith color TV television. And so it's a little different than the arcade monitors because it has a tuner. The um the the arcade monitors are just stripped down television monitors. Basically have a a simpler circuit because they just take a RGB uh video input and sync video input and they don't do audio um with the exception of the the stuff that Nintendo uses the Sano stuff. So, this is a little more complex, but it's still in the wheelhouse of what I've messed with before. So, I think this one's from like the mid 80s or late 80s. Um, and it's got the cool wood grain cabinet when we did that video with the the VHS tapes or the VCR. I u that little gray TV that we had. We've had that around the house for a long time, too. But it's uh this is more my speed. Um I was born in 78. So, when I was a kid, this was more of what you saw. you saw still saw the wood grain and the plastic and this was kind of like an 80s thing. That gray one is more like a late '9s thing. So, yeah, I've had those too, of course, but um I don't really have any nostalgia to those. This I have some nostalgia for. This kind of reminds me of playing um my Nintendo when whenever we first got our Nintendo, I think we got an 87, Christmas of 87, we played it on something like this. I remember it sitting on the the table playing it. So, out of the two, if I'm going to keep a CRT around, and actually I've got another one, too. But this is the out of the the more small portable ones. This is a 19. I think that little gray one's a 13. Um, I don't really need that gray one, but I'd like to have this one working and have this one running. So, I figured we'd see if we can repair it. I think I know what's wrong with it, but you know how that goes. So, I'm going to break a rule of uh common sense and turn the thing on not working knowing that it's not working. Um, and just so you can see what it does. I'm only going to do it for a second, but the problem is I've already done it. So, any damage that's done has probably already been done, right? I think the the there's a uh IC in the power supply that screwed up. So, I'm just going to show you what it's doing and then we'll um we'll go from there. I've actually already taken it apart. I've got the back off of it and stuff. So, I'm going to tinker with it, get it back together enough that I can power it up and so you can hear what it's doing and we'll go from there. So, that's what we got. And so, normally I wouldn't do that knowing that the thing's messed up. You don't really want to keep plugging it in, especially with the fault that I think it has. So, it I think the power supply is screwed up. There is a a IC in the power supply that creates the voltages and things. And um that's that squeal you're hearing. Usually when you get a squeal like that, something like that's going on. Well, I need a TV. I need a CRT if we're going to watch any of those videos. This one's pretty dirty, though. Probably needs a cap kit. Is it after midnight? No, it's only 11:30. [Music] So, I have recapped a lot of it, replaced a lot of the capacitors, thinking maybe the capacitors were bad. I unfortunately I don't have a schematic for it. You can see my new beautiful green caps in there. There's stuff all over the place I've recapped. Um, but still the problem persists. So, I'm going to pull the board out so we can get to that little part and uh I'll show you what I think the culprit is. So, I'm going to show you the top of the board and I'm going to show you the bottom of the board. That right there is an IC chip. It's like a power regulator. Okay. And there's a capacitor here, a capacitor here, and I have replaced those. I've looked around at the other things like check the resistance here and stuff just to see if the cap shorted. Uh, and again, I don't have a schematic, so I'm not completely sure what the circuit is like. Is that bulged up? No, it's not. It's just a reflection. Looks weird because it's new. So, I was about to say, did it burn up? Turn it on. Let me No, it's just an illusion or are it? Okay, let me flip it over and I'll show you the circuit on the bottom a little bit. So, there's the bottom. Again, I don't have a schematic. This is the transformer. Uh, where does the power come in? Power comes in here. Fuses and things, you know, it's doing its thing. Um, and then like I said, this is the this is the transformer. Well, if you look right here, these five pins right here, that is a voltage regulator chip. the Sanos that I've worked on. Oh, not the Sanos, the uh Wells Garner K7000s that I've worked on, often you have problems with the power regulation like the the this chip can be a problem. Uh so looking online I found luckily that radio TV phonon nut had did a couple videos where he talks about these Zenith8s sets and he mentioned that this trans that this power uh transistor goes bad in them a lot and also the capacitors that that work in that circuit go bad a lot For the 10th time, I don't have a schematic. I don't I mean, I hate to keep saying that, but without that, I'm kind of flying blind. And I can't find anything like it. There's a whole bunch of sites online that are, you know, you got to sign up, you got to give them $20, and then they claim they'll give you the schematic. I'm, you know, my mama didn't raise no fools. I'd rather just figure it out myself than pay $20 for a schematic that may or may not exist on that site. And this isn't really my wheelhouse. Yeah, I work on arcade monitors, but this is really, you know, a completely different thing. So, I don't have a ton of experience with the with the TVs. But I do have a lot of experience knowing that radio TV phone knows what the hell he's talking about. So, if he says that that that transistor goes bad a lot, I don't mind pulling the thing out and comparing it to a new one and seeing if I can tell anything. So, that's what we're going to do. Um, and um, we'll go from there. So, yeah. So, I'm going to get the soldering iron and I'm going to desolder those five pins and then try to slide that thing out. I think it's one of the ones that just has a clip holding it in place or something. I can't quite tell. Yeah. So, that little silver clip there, that will just pop out of that heat sink and then we should be able to get it out. So, wish me luck. That's next. Okay, so here is the original part 223-28. That apparently is a Zenith part number, which is actually a Sano STR53041. Or is it Sano SK? I think it's Sano, isn't it? Let me think. Yeah, that's Sano. Um, so these are supposedly tested working Sano and this would have been I guess Zenith's part number for the same thing. I wonder if you can tell by that little See if it's got the little Sano die. Yeah. Yes. Okay. Um so the theory that we're working on working behind is that something shorted a cap somewhere shorted on the secondary. So that you know the prime the primary would be the the B+ going into it and then the or I guess not that wouldn't be the B+ I guess the the line voltage going into it the 120 and then the there's secondary voltages coming out of it. Um on a on a K7000 I think there's only one voltage that comes out of it though. I don't know whatever. One of the pens isn't hooked up as well. So, like uh I think it's this fifth one down here doesn't actually connect to anything. It mounts in the board. Um but it doesn't actually have a trace attached to it, which is the same on the K7000s. Okay. So, what I'm going to do Oh, so the the working theory is that a cap shorted and shorted this out. And then now I have replaced the caps. So, there's no longer a short, but this is screwed up now. Um, it may have been, you know, this cap right in front of it or this one here. Uh, so that's the theory that we're working on. So, I'm going to test this by just checking resistance from leg to leg and comparing it with this one and then just seeing if there's anything obviously different. I've been able to do that on the Sanos um on these um that are in the the Wells Garner monitors. And what you'll find is one of them will be shorted or two of them will be shorted. So, two of the legs will be shorted together if there's a problem. Well, I got good news and bad news. The good news is it's not burnt up. The bad news is it's not burnt up. That would have been the easy fix. So, H. Okay. So, this is testing exactly like these. And there's no short or anything. And there's a the center plate on these is connected to the center leg. And if you just measure pin to pin against each other and everything, all three of these act exactly the same. Um, it still could be that the thing just doesn't work under voltage. So, we'll put one of these in whenever we put it back in. But, I'm not so sure that that's our problem. So, I think what I'll do is I need to look up the schematics. We don't have the schematic of this, but we can get the schematic of this and see what the output what the secondary side is. Um, and just look at like, you know, a circuit diagram of how this is typically used. And it should help us test to see if there's a short, an obvious short on whatever the output of this is. You usually whenever you get the squealing sound like that, there's some kind of short going on. Aha, I did find the schematic. What do you think about that? All right, so this is the regulator over there on the left. Switch mode power supply IC 3431. That's what we're messing with. So it looks like that's fine or test fine. So the output is appears to be pin two there. And there are two electrolytic capac capacitors C432 and C434 that appear to cause issues. So that's I'm pretty sure I replaced both of those. cuz I think I did everything. But let me double, triple, quadruple check just to make sure cuz googling it looks like that's a common problem. And that's what Radio TV Phon Nut mentioned. I've been messing with this thing for a few months. So, or yeah, I think a few months. So, uh I can't remember for sure if I definitely swapped both of them. Let me go check. 432 and 434. And now for a special treat. We're going to test the tube. See if the tube has a short in it, which is what's frying the board. Hopefully not. I can't remember if on setup you can already see the shorts. 6.3 heater 60 volt G1 line voltage is at 115. That's got to be off. That's got to be off on ours here at the at the house. It's like 125. Okay. But I use this all the time. So you see your shorts down here. No shorts. All right. So let's set our cut offs. or not set our cut offs. Wonder if I'm using the wrong adapter. I don't think I am. Something's wrong somewhere. Wow. I must just have an incredibly weak tube or I have fried this thing without even knowing it. So, you're supposed to set your cut off to the first little hash after zero. Let's put it back to normal. See if it likes that better. It doesn't like anything. Something's wrong somewhere. What am I doing wrong? Let's put it to test. Yeah, it does not like something. It's saying I've got a little bit of green. Something's wrong somewhere. That's better. Bad connection on the uh tube socket. Well, no. Still not letting me adjust it. Did I bring home the wrong one? Did I bring home the one that's fried? Yeah, I'm screwed. I know I'm on setup. Never mind. Never mind. It's supposed We're We're at the same place we were. Basically, I got nothing on the cut offs. So, when I test, I get a little bit of life on the blue. Ah, yeah. I think the tubes just slap worn out. I'll see if I can clean it slightly. See what happens. All right. It actually worked out really well. So basically I was getting nothing on it. You saw I was I couldn't even really set the cut off on the blue. So um I mean I barely could. You saw I could get up to like hash two, right? Um and uh so I just put it on restore and rejuvenated all three channels and it's looking a heck of a lot better now. So, I went back to set the cut off and I am able to dial it in now like usual. I think the tube was just flat out I know for a fact that this TV sat around. It was one of those deals where it was in a bedroom and uh people would go to sleep with the TV on. And so I know for a fact that it was on um for years for hours each day. It's one of those sets that just got played hours and hours and hours and hours and hours. Right. Um so we've got our cut off. Now let's now let's test and see what we get. Now, that shaking isn't great. Okay, so the red looks like it's pretty strong. The green is a little bit weaker and the blue is pretty strong. So, I'm cool with all that. Okay, so you can also do this tracking adjustment. I don't know that I can do it while I'm holding a camera. So, basically, you hold the button down and you turn the knob until you're lined up with tracking. So that's on red and then the green is within that area and the blue is within that area. So that's actually good tracking too. Now you could zap the green just a little bit more. H I don't really like doing that though. I don't I don't like uh trying to perfect them because every time you zap it, you're taking a little life off the tube. you know, what like I said, I've done a ton of arcade games, but uh watching Shango do these old TVs, he never rejuvenates them because he basically says, "Look, if the tube is is worn out, you're done." That's kind of been my experience with the arcade games. If you zap them, it kind of wears off after a while, and it's not long. So, I don't know. I don't know. Um I think I'm going to just be happy with that. We had all of them down at nothing. And now we've got them up looking pretty good. So, I think I'm just going to live with that. All right, folks. I'm kneede in this thing. I've been working on this on and off for like a week. And um I don't really know how these switch power these switching power supplies work. So, what I did was I thought maybe I got some fake parts, you know, because you can't trust anything on eBay. So, I ordered some more that are confirmed pulls from Zenith uh television set. See this little dot? That means that like basically it's it has something to do with that's uh the actual part that Zenith was using if they weren't using their own numbered one. Anyway, these are confirmed pools from Zenith equipment, new old stock Zenith modules, right? So, I put one of those in. Same thing. Um, like I said, it's been a week, so I don't know if I showed you all this, but I've got 163 volts here. I've got negative 7 volts here. I don't have any output um where I'm supposed to. I have 163 volts here. I have zero volts here. What's going on? So, then I started thinking, well, maybe there's something over on the secondary side that's dragging it down. And it just cuz if you look at this, uh, this is just going to be on whenever it's plugged in. Or maybe this line here turns it on. I don't know. But if there was a problem with the the other side, if there was a short over here, it would do just what ours is doing. It would squeal because this is turning on and off, on and off, on and off, on and off really quick. That's the squeal that you're hearing, right? Um, so I started checking. Clocks are going off. It's clock time, folks. What? It struck kind of weird. Did you hear Do I get extra one in the middle there? Or maybe I was I think it was two clocks or something. I don't know. Anyway, so what I've done is I've checked every trace. I've checked every component with the exception of some of the small capacitors that you know those hardly ever go bad. Um I was getting to those next. And uh when I check here on this 15 volt, this diode check checks out fine. All of this is good. But if you check here, this diode tested shorted. Ah, what's going on here? So if I tested from this point, my 122 volts, which is going to be the B+, you know, also known as the most important voltage in the set. when I and by the way on TVs the B+ voltage that actually comes from radios they had the B voltage on radios that's where that originated because radios preceded televisions um so this B+ um I'm getting a measurement of 11 across the filter capacitor 11 ohms across the filter capacitor and this is tested basically shorted right but you know this is just a diode on a heat sink. That's not usually it. So, our old friend, the hot, the hot is dead shorted. Shorted all the heck, uh hopefully the flyback isn't as well. But when I remove the hot, it is in fact shorted. And here on the board, if I check uh the traces that the hot was in, they are no longer shorted. And my filter cap is no longer shorted. Typically something like a hot doesn't just die though. You know something usually blows it. So it could be capacitors or I you know I don't know hopefully it was capacitors and I swapped a good many of the capacitors. So hopefully we found whatever was doing it. It could be the flyback. I've heard that on this set the flyback is pretty pretty rowdy, pretty randy. Um, so I got to figure out what I can replace this hot with. If there's a different part number or um, you know, maybe this is something more standard that I've already got at the shop or if not, I'll order one. But that's our next step. All right, folks. So, I was able to buy some brand new hots on eBay 1141-01, which is the like the zenith number. And uh another so I put one in. We're going to test it. Another thing that I noticed that's kind of interesting is this board, the neck board was once part of this board. So they were producing them on one um on one chassis and then I guess populating it and then cutting it loose um to make the neck board. I just think it's kind of neat. Just interesting seeing how they were doing production. All right. So, we're going to fire it up and that will test our flyback for us. It could be the flyback's bad. But typically, when I have a problem like that on the arcade game, at least um whenever you remove the the hot, the board will still seem shorted and there's the short is gone. It's only on the original chip. With that said though, usually something makes those fail. So, I've replaced the caps or most of the caps. So, hopefully it was just a cap or it had a bad night or something and it doesn't just fry again as soon as we get it up and running. If it does, we'll have to suspect this flyback. Um, I've heard though, like I said though, that these flybacks are pretty reliable. Okay, so let me slide it back in the tube and keep your fingers crossed. All right, folks. So, the hot is right there on the side. I'm going to plug it in. And remember, the TV's not turned on. We were getting that squealing because of the hot being shorted. That's the theory at least. >> That sounded better. Let's watch it for a second. >> It's not squealing. Doesn't seem to have caught on fire. But again, we don't have the, you know, the nothing's turned on, but it's not squealing. What do you think? Are we out of the woods? Will she fire up? >> Will she fire up? I don't know, man. I'm a little worried. Come on, baby. Come on, baby. Act right now, baby. Come on now, baby. Hey, she's back. I love it. I always like this TV. It's just a cool freaking TV. Um, now it may blow the hot again or it may have a problem that we didn't fix. That was what originally blew the hot. But it is working right now, but you know what? We're going to do a twofer on this video. I've got another piece of equipment that I want to test with this TV. So, let me turn it back off and carefully put the back back on it. And then I I have a a piece of equipment that I want to use this TV to test real quick. Okay. So, I don't have the right cables, but it's going to be all right, folks. Don't worry about it. So, this is an NTSC video tester thing. I bought this at an auction a while back for like $8, but I just noticed the fuse is missing out of it and I don't have the right power cord. So, I have jumpered over the fuse and have tied one lead to one side of a stripped power cord and then the other side I didn't have another good test lead. So, I've got this little tiny one on the other pin for the power. Right. And um it's actually plugged in right now. So you were worried about nothing. So So that's the power. But then the other problem is it has a little output cable here, but the output cable has test leads on the back and I need to get it in the so the and I don't have the So I just kind of used some clips to get it on the cable and I put a cable in it. Look, folks, don't worry about it. You're not even here. You can't possibly get hurt. >> So, of course, we'll just flip her on real quick. >> The lights on. I've never used one of these. BNK precision. >> Dino scan >> raster convergence. This is so cool. standard patterns. Hell yeah, man. I hope this thing works. >> Oh, I hope it works. So, I hooked it up to the composite video. >> I would think that would work. >> What do you think? Um, >> and then there's a sound. >> Okay. All right. So, hopefully it don't fry nothing. Ooh, I think it's working. I don't know what channel it would be on. You know, >> I kind of see it. How do I change the channel? Okay, let's do raster on convergence dots. Okay, you can only do one. Okay, raster on. Let's see if I can find the channel. >> You would think it'd be on like channel three or something. >> Yeah, I think I've got it. Just you I kind of see it whenever we go between channels. See, like it's kind of there. So, I'm sure I got something messed up. Oh, there's a I can do a minimum and a max. [Music] NTSC standard patterns, staircase, low, high, bars, IWQ, chroma, full burst, top burst. I don't know. Crosshatch. I wonder if I have it on the wrong output. There's an output on the back as well. If I change the sync, it changes. It could be I've got a dodgy connection with my little connectors, too. How do I change the channel that it comes in on? Maybe it won't work with this tuner or something. >> I do have it on crosshatch. channel 68. So, it looks like we're too high now. She's trying. I wonder if I I wonder if I've got something misadjusted here. This actually says RF. Maybe it'll like my RF better. Channel three. That's that. Bam. Boy, it really works when you read the uh instructions, doesn't it? Okay. Uh this is pretty cool. God, so cool. That is so cool. Okay, so N is white. Maybe that should be red. Green. Okay. Green. Red. Oo, that don't look good. Blue. Yeah, my my red. It's looking pretty rough. But is it the Is it that or is it the tube? Green looks good. Blue looks really good. Yeah, red doesn't look very good, but I don't think this has individual color. Oh, you know what? It might have a a hue tint. That's what it's got. Let's tint it, shall we? Green. Yeah, red's not looking that great. um picture black level, color level, and sharpness. So just color level shouldn't make it be more red, you know. Oh no. Well, I take that back. All right. And then we also have picture. So there's picture and then we have black level. Okay, we'll do that. There's picture >> and this is sharpness actually which we're not going to be able to tell. Okay, so that's red. Green's much better. Blue is much better. If I turn on red and blue, you don't even see the red come in because it's so uh it's so out of adjustment. You know, I could, you know, we tested the tube and the tube was fine. Hm. Wonder if it's just an adjustment on the neckboard. Well, hell, I'm going to have to take the damn back off again. All right. So, uh, yeah, the the red knob was actually turned down a little bit um maybe it was stronger or maybe it was weaker um before we zapped it and that's just how it was adjusted the last time. So, now I found this uh color bars screen and I think you can use it to set the tint, but I don't really know how it's how it's supposed to be. So, we've got white, yellow, blue, green, red, red, blue. So, if I turn the tint now, we've got white, yellow, kind of baby blue, green, purple, blue, purple, red, and blue. So, blue and red make purple. Green and blue make yellow. And then this is kind of like a gray. So, I don't know. That's probably right. Isn't it? Let's see if I keep going. See, now it's too green. >> Yeah. So, that's all green. And if I go the other way, it's all red. So, it must be that you're supposed to be somewhere in the middle. I'll bet these are supposed to help you do it. So, if I go all the way that way, we got blue here, but not there. Then, if I go all the way this way, we've got blue here, but not there. And this stays white. So maybe you match the two bottom ones about like that, which looks about right. And so this is um color level and you can make it burn out. >> This is sharpness. blurry. >> I don't know how sharp we want it. Um, >> that's picture. And then this one is black level. So, another thing too is if you look, see the green? So, it's a little too green, but tint won't really fix that. Um, you could argue that the green should be turned down a little bit on arcade games. That's kind of how we do it. We'll turn it up the the the background up a little bit and then you can see what color there's a little bit too much of. I guess there's a little bit too red. I mean, a little bit too green, which would also be not quite enough red, but we're probably pretty close. So, um, looks pretty good. All right. So, that's the bars, the staircase, green. H, that's the same thing we saw in the background. Center cross looks white. Dot hatch looks white. Crosshatch looks white. The dots look white. Okay. And raster. There's our red. Little washed out. There's our green. a little washed out. There's our blue. Pretty There's the bars. Black and white and chroma. It does look a little green, so maybe I'll try to adjust the green down a little bit. Okay, folks. So, I looked online at some pictures of the color bars, and that's pretty much dead on the money. Um, in the pictures online, I was reading something about that if you turn off all the colors except for blue. Like, all four of these will be blue or something like that. Um, and on the pictures online, that one seems slightly more purple than this one, which is kind of how this looks. I don't know. It looks good to me. I bet it's close enough, right? Um, now the convergence being off a little bit. I'm not going to mess with that. On the arcade games, we mess with that a little bit and it's uh it's not a good thing. And I don't know about the bar at the end. This isn't centered if you look. So, I don't know if that's a problem with the TV or um I mean that might just be a horizontal position thing. So, I guess we just need to hook up some kind of signal to it and we can tell from there. I like this NTSC generator. I need to repair it, though. I need to get the fuse that goes in it, and I need to get the proper cord for it. But that's really all it needs.