Rock Ola Jukebox 496 Amplifier Repair - It's Easier Than You Think

ladies and gentlemen this is Joe's classic video games back with another cool rockola jukebox repair video for you today this is a rockola 496 that's trying to find a record here let's see if it'll play it we've been working on this bad boy and we've got some problems with the amplifier so we figured we would do a video repairing the amp amplifier so if you've got similar problems in your jukebox hopefully this will help you um I've worked on a lot of these probably 50 of them or so maybe a little more and you run into the same problems on the amps usually so we'll check them out but uh I've got it turned down right now because the copyright protection on YouTube is so strict they're not going to want to let me play you a song but I'll turn it up a little bit so you can hear what our problem is okay [Music] we have weak volume here we have no volume here we have very weak volume here and no volume here so we got some serious issues so I suspect that the reason we have no volume here is because the left channel is out the reason that we have volume there but not there is because they have reversed the wires I think right here on the the audio uh connections on the speaker terminals um so I think this amplifier has a dead Left Channel and a weak right channel is what's going on um I'm going to try to test that a little bit well I think I'm just going to pull the amp out and we'll start taking it apart and look at it uh I'll show you what's inside of one of them and uh what usually needs to be replaced and we'll test what we can in there and then we'll put it back together and see uh what kind of results we get but I'm pretty sure on the bottom the wires are reversed there's a little this little bad boy these uh terminals here are so that you can hook up extra speakers to your jukebox so let's say you're putting in a bar Frankie's bar and Frankie uh has speakers in the ceiling and then he's also got some big woofers Down Under the bar whatever you know you hook them into these Terminals and you move these terminals are the bottom speakers so the two bottom ones if they're all that's running you can basically give them full power right now I'm going to look at the back of it here and try not to get Electro killed let me show you the back see these four uh gold kind of spade connectors here that are doubled up see how there's four of them two here on the top and then two on the bottom well this top one is like the Left Channel and the bottom one's the right channel see this first one says ground see how it's doubled on the back what that is is the black and green wire is the ground for that speaker okay and then this white wire here is the audio for that speaker or the positive for that speaker and then the two over here are connected down on the bottom on the right it's going to hang up here in a second um so they they have those kind of hardwired in the back to this 8 ohm connection okay someone has wired the base speakers at the bottom to the 2 ohm connection but I think whenever they did it they probably reversed the wires that's why we got the left one working um whenever the left Channel's dead on the top so that's what we're looking at so you can move these and change the power basically that's going into the speakers and you then you can also add external speakers so you can have 10 different speakers playing as long as you're smart about it all of this is covered in the manual though so I'm not going to get that into it uh because I never hook up external speakers so let me remove the amp and let's check it out so here is the amp they're all pretty similar but you will have a different model number on lots of them so this is a 55015 d a here's the big heat sink uh for the transistors that sticks out of the back of the who this sticks out of the back of the uh machine I've taken the two screws loose here of course um which is how that happened there is a nut on each one um but yours will look similar to this probably it'll have a little bit different but you've got Bas and treble uh switches over here how to adjust the background music level guess you put a screwdriver through there if the light is on it means the speakers are overloaded Overlord speaker Overlord I may be wrong maybe there is an Overlord setting but usually that says overload I might be wrong about that uh caution C service manual for adjustments and connections there is a scratch filter on these that you turn on and off AVC that you can turn on or test which it looks like is not easy to change so they I don't think that's broke I think they just made it where they didn't want to turn it on and off to that much uh you can set it on stereo or mono I don't know if there's an issue where sometimes uh if the one of the channels on the um on the cartridge if the wires broke or the cartridge is messed up or something and you're only getting the left input I don't know if you set this to Mono if that would make the speakers uh both transmit the Left Channel it probably would so that might be a good thing to do D set it to Mono if you're missing a whole side like we are uh mic kit and background music input it's all pretty self-explanatory basically uh they in some places you would have background music playing until somebody used the Jukebox and then they would walk up and then the Jukebox would override the background music and start playing whatever song they selected compact disc input the rockola 496 was the first rockola that allowed you to play to select uh CDs so it was an add one basic basically to this uh 10 amp lag okay big fuses speaker terminal strip that's where the wires come out to go to that little thing we were looking at in the front where the Transformer is down there and power input is literally like it says it's the power coming in from the uh power supply okay so with those screws off or the bolts off who if I don't break this whole thing got some wires hanging me up here somewhere well I don't want it to just hang on the wires oh here we go I got one looped there it didn't like that okay there we are all right this wire was looped around that transistor trying to kill me okay so here this board here is basically it's got all of the little adjustments and stuff on it and then you've got these two driver boards this is typically where your problems are you can take these are the same so you can take one and swap it to the other side if you're testing to see you're trying to find out where you're where you're losing your channel you know if like the left one's missing this thing's probably dead or whichever one's left right um but it could be as well the transistors on the heat syn so if you've got bad transistors and you swap the boards you're going to mess up both boards so what we're going to do is we're going to check the fuses first okay I'm not going to power up any of this now the proper way to do it is to put it under load to power it up uh to test each component as you go through I'm not skilled enough to do that so the way I usually do it is I test the things that I can like I look for transistors that are shorted and then I pretty much um uh shot gun replace the capacitors in it cuz typically radio of this vintage or stere um amplifier of this vintage you're going to have a lot of bad caps um so that's what we're going to be looking to do okay so let me do this I'll check the fuses and everything give it a look over see if I see anything that doesn't look right and then uh we'll pull out one of those driver boards and start looking at it and see what we can test on it here's the right driver board we're just guessing that this is the right channel I don't I don't know um so you've got some little pots here that are to adjust the bias with there's a setup in the manual if by the way if you don't have a manual for your jukebox you're missing out at first I didn't want to buy one because they're always expensive they're 30 40 bucks usually if you don't have it sometimes you can download them off the internet depending on the model this 496 I cannot find a manual for or the schematics it doesn't exist apparently it's unobtanium but um a lot of times for yours whichever one you're working on you can download the manual or buy a manual even if you have to buy one $30 $40 it's worth it's Wai in Gold because it tells you how to do things like adjust the bias uh and it tells you the part numbers and stuff so like what is that transistor supposed to be you know and so there's probably 30 or 40 adjustments in it that you can make depending on what you've got going on you might have the records not setting down right or what whatever you know that uh will it will tell you in the manual uh how to adjust and uh just the schematics and stuff showing how everything everything connects how the the amplifier connects and all that it's just it's worth its weight and gold if you can find one but this is what we've got we don't have the schematics so let's say an npn an npn transistor and a PNP a P&P transistor I wonder if they say that because it's not that important what the actual trans uh uh transistor is as long as it's npn or P or PNP mj1 15 150 and there's more to it I couldn't read it so if you get a transistor that's shorted a lot of them are going to blow the fuse right I check the fuses none of them are blown these four now why do they have four fuses I'm guessing I don't know for sure but I'm guessing it's these four transistors right or maybe it's two for the transistors I don't know but none of them are blown so these chassis mounted transistors are probably fine I did check these three already and the small one and they're not shorted so it seems like they're fine who knows under a under a load though and they might be leaky uh but I'm more concerned with this little board here so you've got couple transistors here couple little baby ones there little pre- drivers or something a few here I see a diode or two there and then a bunch of capacitors youve also got this thing what is this MD 8003 I have no clue what that is there's the Motorola logo though and you see the 87 date code so uh it's a late 80s box so looking on the back one of those transistors is or two of them have obviously been replaced at some point probably back in its days of earning that money let's see if there's any cold solder joints we this B huge connector connects to it sometimes on arcade games and pinball machines especially we get cold solder joints here and it's always on the end usually those look pretty good I don't know probably worth reflowing but I think they all look pretty decent okay so that doesn't look like an issue but again I think this might be the working board um the Box caps I ually I don't have any trouble with so yeah I think I'm just going to recap it so let's see here I've got one two three four huh four little capacitors um I leave the Ceramics of course and I'm going to test these transistors just with the the diode check just just make sure there's nothing that's obviously shorted um and then we'll put it back in another thing I like to do whenever I mess with these two some people don't like this but this these are the bias adjustments right I like to just turn them and turn them back just kind of just in case they're stuck on a spot that's it's not happy with right so uh I'll check these like I said with a multimeter replace the caps and then we'll move on to the other one I think the other one might might be messed up or something I want to show you something on these bias pots too so this is the one I just recapped this is the one I haven't if you look the bias parts are set pretty much identical on them so it's probably like a factory thing um now two of the Caps I have changed the value of because I had to um I don't know if that mess up our vas voltage or not though but we have here all of you audio files are going to hate this but look I am not an audio file clearly I am not an audio expert so this is a 150 micro farad my camera is acting up 150 microf farad uh 16 Vol and I don't have 150s so I put a 220 okay and oh no it's an 85 degree from the factory oh what were they thinking oh that's so horrible they only put the cheap cap in it from the factory I have seen it all now why would they do that I'm trying to see if the other ones are I don't know what the other ones are I don't know this don't look like a high quality cap to me so like I said we shotgun replac them there just a few anyway uh and that's kind of because we mainly deal with arcade monitors and we work on the same like um it's just a it's just a kind of different setup than how most people do radio repair but we're working working on a lot of arcade monitors and on a on a monitor if you have bad electrolytic capacitors or ones that are just off value a little bit you're going to get all kinds of geometric problems on the screen so you're going to get stuff folding over you're going to get a curl the top of the screen you're just going to get you know a picture that's not as big um so in a arcade monitor you kind of have to replace all the electrolytic capacitors every time so even though shotgunning them isn't the greatest thing to do because you're not really finding the problem and correcting it you kind of in an arcade monitor you get away with it because that's that usually fixes most of the stuff you just need to replace all the Caps right and there's other stuff too like the flybacks often need replaced and you know on Arcade monitors we can troubleshoot them pretty well because we see the same monitors over and over again and then keep in mind too that an arcade monitor is on so what I'm saying is if the cap is a little off you will see it on the the screen which is kind of unacceptable on a monitor right so you kind of have to replace all of them and we see the same models over and over again and they're left on all day long for years and years and years and years so it's just a thing on these the jukeboxes it's a similar thing they're left on constantly they play non-stop right now on home radios a lot of people do like radio repair and they're much more knowledgeable than I am about repairing them so they can go find the one little part that's messed up and replace it instead of shotgunning it but they're also dealing with something that's not on all the time you know so I wish I had the skill to go through and and find the exact spot where something's not quite right but I'm not there yet so I've had good luck though on a jukebox amplifier with shotgunning the electrolytics so that's why we're doing what we're doing all right so uh another thing I'm going to do just for testing purposes is I'm going to put the one that took out of here back in here I'm going to swap them all right I've checked the transistors and they they test identical so they're they're not you I'm just testing them with a diode check but I'm not getting one that's uh a big problem and I'm also not blowing any fuses so we don't have a short situation that or it doesn't seem that way and then what we'll do is whenever we power it back up if we still have the same problem on the same channel well we'll know that it has nothing to do with these if we still have the same problem but now the channel is switched we'll know that it's with one of these right so it's just a little looking ahead a little bit so uh I didn't find anything bad on here whenever I tested it I tested all the transistors again with the diode test no problems so I'll check this one and uh then we'll move on to Big Papa here all right so here is the board that I was assuming was for the left side now my multimeter is over here it's on diode check you can't see it but you can hit hear it this transistor shorted now it could just be something else on the board is shorted so we're going to pull it out check it out of the board now keep in mind on the other one these two had been replaced huh huh seems like we found something let me try on this one up here that's in circuit ain't that some crap all right look what we have here what are they calling this little bad boy the amplifier PC assembly okay okay so the AVC is made like that they just have it so you have to put a screwdriver in there to turn that on and off okay so uh yeah this is where it gets a little dicey my idea of just shotgunning the Caps might not work on this there's like a 100 caps um okay so the input from the uh uh cartridge comes in here and then immediately runs over to some of these these we've probably got everything kind of divided into twos I would imagine are those just 555 timers that says RC everything's upside down to me right now 4555 is that what it says 4550 let's put way too much light on the situation 4558 yeah those aren't 4558 uh I don't see anything obvious your volume control connected here here's some more RC 45 58s up here um H and then you've got some potentiometers here these are the kind that kind of get dead spots in them but so it's you know base trouble base trouble or something like that which I would assume these are connected to there's also a whole bunch of modifications on the back that are probably Factory uh let's see what are these connected to so it says right B might be balance and L and then an extra one there's a test Point all right yes I'm going to poke around a little bit see if I find anything that's obviously messed up and if not we're going to try it back in and see if our uh see if our little swapping the two channels trick has uh yielded any results but I'm going to uh test like the few transistors and stuff that are on here but you know it's not likely to do anything because like this one there's only one and we're missing a channel you know it could even be something with the um with the cartridge still you know we don't know but I don't see anything obvious you know there's nothing burnt up or obviously shorted or bad solder or anything everything looks pretty good so we're going to have a flaky cap somewhere doing it or one of these four preamps or whatever they are has a the bed on us or it could be a a wouldn't be one of these but it could be a uh it could well I don't think the if one of these was bad I don't think that it would completely block that channel it would just screw with the tone of [Music] it me like you just B okay so um one of the channels is woken up and it it's much louder now but we've still only got the one speaker so one of the channels is still dead and we got a problem down here on the bottom so I'm going to check to see uh if that's supposed to be on two ohm like it is that might be in the wrong spot let's look in I don't have the manual for this but let's look in a manual and see where that's supposed to be okay so we've got this little chart here uh in the manual for a CD 3000 which was a little newer than this but it uses the system 4 M CPU this is the system 3 which is very similar and it uses that same uh Power setup that or speaker setup that we're looking at down on the bottom and so it's it's basically a little cheat sheet to tell you how to hook stuff up to it it's hard to read but it says phonos speakers connected to left and right the 4 ohm Terminals and ground power per Channel 65 Watts if you were to connected to 2 ohm terminals in ground 32 watts the 1 ohm terminals in ground 15 watts bubble blah blah BL blah and what they're doing is they're dividing the wattage between where you're connecting the internal speakers and where you can connect the external speakers so 65 ohms so like in this instance you could have 98 n ohms 65 Watts you can have 98 Watts outside of the box and 32 inside the box if you connect to the two ohm terminals so that's where we're at right now I believe so it's not going to make the speakers work but they should probably be on the for since we don't have have any um external speakers hooked up and then uh it shows you here that if you have it on that uh you can't um hook any speakers to the 4 ohm terminals any 4 ohm speakers to the 4 ohm terminals for external right but you could hook one speaker to the 4 ohm terminal uh you could hook one 4 ohm speaker to the two ohm terminal blah blah blah blah blah right so it's like a little cheat sheet so it looks like we should be on the 4 ohm terminals okay so I I've got I think three speakers working but not this one little whing Jennings for our buddy n that watches um so here's what I did this is not permanent we're testing this is not the same one is that manual I was looking at but it kind of works the same so Red's right so where it says phono apparently is where they're supposed to be but it's 6 ohms in the manual it's saying 4 Ohms there's also an 8 ohms but I left it alone so with the red here and the white here you've got the one top right speaker working so this is the Left Channel I just since we you can connect external speakers I just connected it over onto two ohm and both of the left speakers are working okay now we can't leave it like that but that's what's going on so this left channel is dead or not hooked up right so there maybe maybe we got a bad wire connection somewhere uh and I think this speaker is probably bad or it might just be disconnected it's really hard to get down in there though there's no way to take it apart on this so so we've still got half of our um half of our amp not working working so next piece of the puzzle I am looking at the schematics for the the amplifier in a rockola 490 which should be very similar uh and this is where the cartridge plugs in the middle wire there is the ground and then you have the um I'm talking about J1 here the top connection and the bottom connection are the two different um sides of the cartridge left and right channel so you can see that the way the mono and stereo switch works is it is right there at the beginning which is actually good because it can help you test the cartridge so you know if you had a scenario where one wire was broke off the cartridge or something was messed up uh and let's say that the signal was just coming in on the Left Channel off of the cartridge well if you slid this up to Mono this switch it's going to short the left side with the right side that you don't have which would provide the right side so you know what I mean so if the wire was cut that line would be dead but if you put it on mono it wouldn't matter that the line's dead you're getting a signal on one side or the one channel or the other and it would join them both together right at the beginning so it's if it did that all the way at the end or something like that uh you wouldn't be able to use it to troubleshoot very well because U um well actually that would help us because we wouldn't have to fix one CH but this helps us determine that it is in fact not the cartridge because if I slide it on mono we still only have uh we still only have uh one channel working so that's not it and that has eliminated the tone arm so it's something actually on the amp all right I'm back inside of it now I found something though I have went back and watched the video maybe you can go back and tell I don't know depends on how much time you have I went back and watched the video because of what I found check this out so I was telling you that there's all these mods on here uh most of these wires are actually for this mute board over here mute relay board whatever that it uses to mute it uh whenever it cancels the record it mutes the amp right okay so that's what most of that is but there are a couple other mods like there is a resistor there and there's a little jumper wire there and this is probably stuff all done at the factory there's a little cut there they um they just did stuff like that sometimes the the silk screen wouldn't be quite right and so they just mod every one of the boards for thousands of machines it doesn't seem like they would do that but they did okay and then down here let me see if I can set it up here I'm going break the freaking thing if I keep finagling it is Finagle a word that we can use so we got this little number here okay this is where the not only does this connect to the mute board but the plug plugs in here that connects to the two driver boards okay so look at this little mod they've done basically you've got left channel uh Left Channel right channel ground right so look at this little mod they've done they have cut the trace and soldered a resistor to it and jumped it to the part of the trace that they cut and then they've soldered a capacitor to that and then cut the trace again and jumped into the new the other part of the trace so they've made this little island in there to to connect the resistor and the cap to pretty wild of course it's broken loose a little bit right but it's still connected however this one they did the same thing except the resistors broken loose the resistor is not soldered to that and guess what that's the Left Channel so the signal is broken right there so I'm going to solder that back on I can't tell by looking at the video if it was like that when I took it apart but it is now that would kill the entire Left Channel which is what we're doing what we've got so I'm going to solder it back and see if I can clean it up and figure out how to keep that from shorting and put it all back and then test it one more time I looked at all the caps and everything I can't find anything wrong with them the the four little um these little chips here that I was calling preamps I don't know what they are opamps maybe um I I used a diode check and just tested the legs against each other you can any kind of any kind of IC that has like uh a uh a gate in it like a you know anything any kind of any kind of uh IC that has a transistor relationship inside it between the pins you can check with a multimeter to look for shorts or opens you can't tell if it's working right but you can check and see if there's anything obviously wrong and I can't find anything obviously wrong with those four they all uh measure identical to each other in circuit and uh we know two of them are working because the right um the right channel is working uh so hopefully that little resistor being broke loose was like that from the very beginning and that was all that was wrong with it cuz I can't find anything else wrong with [Music] [Music] it fixed it that freaking resistor must have been broke the whole time but I can't tell by the video I just can't quite tell wow so cool I can't play any music though YouTube they hate me okay uh so uh we need to put this speaker still isn't working though we need to get that out and see if maybe the plug came off maybe we'll get [Music] lucky sounds great all right so we pulled out the speaker bad news folks the speaker's blown if you check continuity between here you get high you don't get any resistance I mean you get a lot of resistance infinite resistance um and if you look the cone has completely detached from the whatever you call it I believe this can be fixed right you people tell me down below can this be fixed now if I if I don't don't have like this is open this is no longer connected but if you look it's still connected to the paper down there I figured that that would still be connected that you'd get your 8 ohms like the other one um and then it would just need the cone glued back on but apparently that is not the case so it could be that the cone's messed up and something else is messed up I don't know I don't know though you let me know what you think down below but you know what we did we put another one in it we had uh we have some brand new ones that we put in them if they need it so we put in another one everything's cool same size everything's cool um and uh all four speakers are now working wow so I'm going to see if I can find one of my uh Records that YouTube allows us to play and then I'll slide it in there and uh we'll finish up um but uh basically just looking at connections inside and replace the caps on the driver boards and it brought that one channel back but to be honest I don't know if the Caps did it or if it just was a bad connection or something but we got it up and running all right folks we've been cleaning it up a little bit this is the uh David rockola signature model which I think they all wear so it's not like it's valuable or anything it's no more valuable than just a nice clean cool rockola jukebox so cool so I'm going to play you a song that I believe will defeat YouTube's uh uh copyright system we'll see we'll see if it plays the wrong song or if it just disappears then you know that something happened okay so I'll I'll do my little spill and then I'll play the song and then if I had to cut it off I'll cut it off so uh we hope you enjoyed the video we replaced the speaker everything's cool everything's looking good uh if you're working on your amp don't be afraid to get in there and check it out that's what you're kind of looking at that's kind of how we go past them but really there wasn't much wrong with it that I could tell uh we're trying to learn more about them as we go along make sure to give us a thumbs up for taking the trouble to film it for you and you know how you can support our Channel go to Amazon uh if you're going to Amazon go to Amazon through one of our links Down Below on the video um down in the description of the video we have some links to Amazon for different countries it basically just uh gives us a tip for sending you to Amazon so if you decide that you're going to buy anything online don't ever type amazon.com use one of our links and then we get money so we appreciate everybody that's been doing that we like to be uh very upfront about that right uh and finally last but not least don't forget to check out my brother Donnie my brother has his own channel here on YouTube uh where we do arcade games jukeboxes pinball machines and uh my brother Donnie does Vehicles old buildings things like that we we're over there with him a lot having a good time so let let's see what I can do here play a little song to uh send you home hopefully YouTube will allow it now this is oldfashioned to to defeat the copyright strike but you can see that all four speakers are [Music] working [Music] [Music] la [Music] [Music] [Music] d [Music] back time to hit the [Applause] [Music] house