How to repair your Bally Pinball Machine Score Displays

ladies and gentlemen this is Joe's classic video games back with another cool arcade game video game pinball machine repair video for you this afternoon we're working on a pinball machine a Bally and we need to get five sets of displays working so I know a lot of people probably have displays and their machine that they picked up somewhere that are a little flaky so we figured we'd do a little video and show you what you can do about that so you get several things that can go wrong with the displays we figured we would kind of highlight some of the more common ones let me see what I've got several here that we're going to work through let me say okay this is a good one so first of all if you're Bally or stern pinball machine has a display in it that looks like this when it's turned off you're pretty much done now you can probably still use it but it won't look good so everywhere see those little black spots on the segments the glass is burned which means that the only way to fix that is to replace the glass it's kind of like how you get burned burned in on your CRT in a video an arcade game so basically the only way to fix that is to replace this entire glass piece you can see a solder the one with like what's that maybe 40 pins so if you've got displays that have that on it the only way to fix it just replace the glass the glass cost as much as a brand new display so it's pretty much trash you might want to hang on to it just to save save it for parts you can fix some of your other ones with it as you can see this one is a pretty bad off all of the six digit ones are the same and the seven digit ones are just slightly different they just have an extra digit obviously so they have this little decoder chip here that basically decodes the signal sent to tell it with the strobe which segments to light up and all the information so if you've got one where you've got these it isn't marked like this so it looks clean like this one alright and you're getting strange numbers like the numbers are wrong the first thing to do is to swap another display into that same connector like so say if this is player one and it's giving you a strange numbers on the display and you think there's a problem with the display take out player fours or something and swap it into player one of course do all this with the Volt with the power off because these things run like almost 200 volts through them which is worse than your wall right I guess it's DC so I guess it's not as bad as your wall but still don't play with it with the power off swap the display and see if it keeps doing it if it if the new display does it as well then you know the problem is in the machine if the display now looks right well then you know the display must have a problem okay so if you've confirmed that it's definitely the display that's the problem and not the machine that's the problem then you can go ahead and start trying to repair it so the first thing you want to do is look at your solder joints sometimes you'll get problems on the actual pins that go into the glass and then sometimes you'll get problems down here where the connector plugs in let me see if I can find one that's got bad solder on it or one that's never been greased honored oh I think I might have just done that okay so here's another one that I've got but if you notice it's pretty good see the ends are a little bit lighter than the other ones so that it's burnt a little bit because you know it usually says zero zero whenever the game first gets turned on so these two get lit up a little more often so they burn a little bit so this particular one if you look really closely on the bottom this is where the connector plugs in and it's never been restored so let's see if this'll let you get a pretty close look at the pins let me look at it with circumcircle what's more it okay yeah alright so looking all the way down here look at that second one I said you can barely see a little ring around the pin a little circle that's bad solder so basically that's either just barely hanging on or it's no longer actually touching the contact that it needs to touch so that the SiC the electrical signal from the gets through the pin down through the pin and onto the PCB board so since that's one of these chips one of these signals that goes to the decoder you could bet but that this one would have had some kind of crap going on on the screen so we're gonna restore all of that that's the first thing you want to check now a lot of times you'll get one and it'll be like this someone's already resolder dit so if it looks pretty decent you can probably just leave it alone if you keep getting problems you might want to look at it again but so that's the first thing you want to look at all right now if you get one where one of the digits is completely missing so if let's say this one's missing right whenever ladies work is when it first comes into the machine it runs through these resistors here R 1 R 3 R 5 r 7 r 9r 11 see those these resistors have a bad habit of burning up and whenever they burn up they go open where they're no longer connected and so the signal won't get through for the digits so if you've got a digit missing check these three resistors see if they're all similar and check these three resistors 100 K ohms you can tell whenever you check it with a multimeter but basically they should all be similar if you've got one that's way out of range like if it's 350 and the other ones are 100 then you know it's probably a problem so if you've got a missing digit check that first now if you have a digit that locks the one a little brighter than the other ones and that's what this one was doing I'll show you here in a second this one digit number four is clearly just locked on which is messing up all the other ones okay so you see how that one was locked on a little brighter basically when the signal comes in for each digit the strobe right it runs through these six transistors and these six transistors travel through the board again to these six transistors and these are linear so basically if that digits messed up it's that transistor if that they're just messed up it's that transistor if that digits messed up inside transistor that digits messed up it's that transistor if that digits messed up it's that transistor if that digits messed up it's that transistor so you can check these with a multimeter which we're going to do here in a second so if you've got a digit that's locked on you're almost always gonna have one of these six transistors and this it'll be the one in order that corresponds with it or one of these six transistors so like if this one's locked on it's either gonna be this transistor or this transistor right if you get one where the digits missing and the resistors fine then it gets it could also be one of these transistors so we'll check that here in a second and whenever you if you get one where there's a segment missing so you can see each eight has seven different segments so you got the top one that's one the middle and that's to the bottom one that's three and then four five six seven there's seven little segments that make up each digit if you get one where this where there's a segment missing on each one so say let's say the top line is missing on every one of them then what you need to do is look at all of your solder again on the glass itself and if you look on the back as a neat little trick you can actually figure out which pin does which segment and if you look you know you could sure you can see all of them it's not like this one every glass but on most of the glasses you can look at the back and figure out which pin is which and just kind of track it down and you may find that you've got a bad solder joint or something so you can check that but usually if you've got a segment missing it's one of these seven transistors here that drives the seven seven to the seven segments so if you've got a segment missing it's going to be one of these so what we'll do is we'll plug a few of these in see what's going on with them and then we'll come back here and try to fix it so we'll try that out all right we'll resolder this one real quick it's at a kind of strange angle but that's all for you like this we'll try it just so you can get a good idea we're just adding a little bit of solder basically just reflowing it now sometimes if you do this and you you notice that it just doesn't look good like it's it's not flowing good about time to replace that tip don't you think if you notice it's not flowing good sometimes you need to remove the old solder first but usually you can just add a little bit more and these these three here connected together so you don't have to do it on purpose but as you do it you'll notice that they kind of flow together that one's missing of course the reason that you have bad solder on these is because as you remove the connector it kind of flexes the it kind of flexes the pins and after doing that many times they crack alright let's see what that ended up looking like looks pretty good do y'all see anything that's connected so those three are there supposed to be so I think that's pretty good the solder doesn't look bad on the pins of the glass so I'm gonna leave it sometimes what what you a way to tell if you need that as if it Wiggles a little bit you can see that the way they did it is there's a screw through the bottom of the board into this little holder that holds the glass in place if that is cracked or if that screws missing then it'll you're getting a lot of wobble out of this and you'll see a lot of those break loose but we don't have that problem so on to the next problem all right so now that we've restored it remembers the fourth digit which is actually the hundreds digit so that's like the ones digit the tens digit the hundreds digit right so we've got it's either this transistor or it's this transistor because it's stuck on one if it was missing we'd look at the root idea of resistors so I've got my multimeter set on diode check and so on something like this it's real simple you just the trickiest part is I guess I can do it from the top hopefully you can see this so all you want to do is you're gonna put one pin on whatever's the base and the other panel whatever's the what is it the anode and the cathode with a collector in the admit er all right so this we're getting some weird stuff let's see here we should be getting between 4 & 6 let's see I'm not getting anything good all right so I'm doing I just jumped over to one of the other ones that we think is good and so see if I'm getting point six between this pin and this pin and then on the other one I'm getting point six so that's kind of what you would usually see so if we check this one all right there we go so we're getting a little better connection point six and then point six on the other one so this one is reading very similar to the one that's working so data that transistor is probably fine might be bad but it's probably fine right so let's jump back here to these ones that are a little the other set right push them all straight so we can get to him all right so we'll do this one that we think is good thing as I switched the leads around so now I've got the red one on the center leg and the black one on the one of the outside legs so we're getting point six now on the other one same thing point six so that's one one that we think is good so if we move over to door one that we're suspect about 0.85 three that's not point six and then right here point eight six six that's not point six people so this one is giving us a different reading than the other one so see if we test this one on this side we think is good same thing 0.6 0.6 generally if you're doing a transistor you want it to be between point four and point six if it's a little high that's fine especially on one like this yeah I'll just check this one and it's almost identical to this one but this one's all screwed up I'm sorry I just checked this one and this one but this one's way different you know it's point eight it's not even close people so what's that tell you this transistor is probably bad so I'm gonna pull it out and we'll look at it and see if we can swap another one in all right so I pulled that sucker out of there with the soldering iron and the solder sucker and it is here's what it says on it okay it's a Motorola all right so it says well I meant I don't know that motorola it says f 585 - 3 3 8 3 5 right so that's like they're part numbers so they don't want you knowing what this is so basically what it is is an mps a 42 so if you've got an mps a 42 that's what you need to order for that these particular six since I've got so many displays that have burnt things I was just taking one off another display now if you've got new ones they're real cheap don't mind like a dime pop them in but we don't have it in right now so I'm just gonna put another used one in there but I'll test it to make sure it's right before I put it in so I'm gonna swap that now and then we'll put it back in a game and see if that fixed it for us okay so our fourth digit that was locked on her was too bright is now fine everything looks good right and so we've plugged in another one too and check out what this one's giving us if you look real close the top-left segment on each one is like kind of trying to light up right so we've kind of got like a segment problem right and it's on all of them so usually whenever you get gibberish on everything you're looking at a problem with the the chip so we're gonna we're gonna check that out now it could be that that top left segment transistor is shorted on or something and doing something weird but the way it looks to me like that would just always be on and then the other stuff would be doing what it's supposed to do so we'll check it out all right so if you notice the decoder chip actually has a hole blown right through the top of it I noticed this earlier on this one but I forgot that I had one like that and put it in the Machine anyway probably wouldn't have been smart to plug that in but hey we've already done it now but you see the hole in it BAM not good so that chip is kind of expensive I think it's five or six bucks but guess what we could take it off of one of the ones we have this glass is burning right so we'll pull that chip out and swap it you know I'm also gonna check these seven right because that top left one was doing something weird so it could have just been that this chip something shorted I'm sure things are shorted but it could have been that something and the chip was making to do that or it could be that the chips obviously screwed up and one of these transistors has screwed up some of the check both and go ahead and swap the chip alright folks so as you can see replace the chip right right back we put it in a socket let me show you I put it in a socket so that if there's another problem another reason I did that was because I was using a used chip so it might have not been any good at all for the other board there's really not an easy way to test them besides just putting it in a in a display but it works so we're good now the last one we've found another one that works but you can see that on the left see how that digits a little weak I don't know how much this shows up on video but that that digits a little weak just because it's burnt we found another good one here right and then we found this one which has a real interesting problem see that little dot there if you look real close that's a short inside the glass so that's yet another problem that you can't really fix it's inside the glass so you're done and unfortunately it looks fine everything else is fine on it it's just that one little dot but you know it'll probably get worse and worse but so that glass is basically no good so we're gonna find another one to swap in I didn't find any that had a bad resistor I wanted to show you that but if you get one where just one hold digits gone you've probably got one of those resistors bad and I looked it up there 100 100 K so there 100 K which is a hundred thousand right hundred thousand ohms so if there are 98 thousand ohms or there 104 thousand ohms you're fine you can leave it but if you test it and it's 350 thousand ohms and you know that's probably your problem that's why your digits not working but hopefully I'll show you how to fix a couple common problems that pop up with them I guess we only fixed a couple but we kind of ran through all of the other things that it could be and showed you how to get them back up and go in and showed you how to resolder the connectors so if you have any questions just comment below we didn't get any that were too crazy this time where we had to work through too much stuff but hopefully that'll help you if you've got one that's acting up and give us a thumbs up for taking the time to film it for you and walk through it a little bit leave your comments below and we'll see you on the next video