Back to Basics Service - Pioneer SX 3600 Part 1

hi everybody and welcome i just want to do this quick little intro uh i was going to do this video on this little pioneer receiver but i thought i'd have a little bit of fun this time and try to use the least amount of equipment to work on this as if you know we were just starting out just getting into the hobby and just wanting to use the bare minimal things that you have to buy and so that's kind of where where the direction of this video went or in the beginning that i was just going to do a regular repair video or test video whatever for this little receiver but the more i looked at it the more i thought hey let's let's change it up a little bit on this video so that's what i did i i'm going to put this video out to you who are thinking about getting into the hobby of audio electronics like this or vintage electronics or those of you who are new to electronics just got into it and kind of want to expand your knowledge a little bit and get some confidence that you don't need to spend a ton of money on a bunch of fancy equipment just to have fun at the bench working on a receiver you'll be surprised how much you can do with very little so that's what we're going to do in this video and if it sounds interesting to you stay tuned that's what we're doing next take care pioneer model sx 3600 and this is one of the what do they call them fluoroscan versions or something that has the blue fluorescent displays so they're very nice looking and this is kind of a little bit later model this is kind of the last of the silver faced series so after these ones were done you started you had some of the d series and then it kind of went to the to the 1980s you know blackface ones that you could really see that some of them kind of went down a little bit in their build quality as far as comparing them to this type of thing but this is a real sleeper i don't think people give this one a whole lot of credit and it's actually a hidden gem it's only rated at 30 watts per channel but it's got very low distortion it has discrete components in it instead of the integrated circuits and things like that it's very serviceable it has all of the main features in the design that you would see in a lot higher end model of receiver and it should perform extremely well for what it is not to mention it's actually a very attractive looking receiver when it's all fixed up so all of those things kind of make this one a good starter receiver for anybody who a wants to get into restoring and repairing this type of gear and b this is a good starter receiver for someone who wants to start getting into uh hi-fi audio and doesn't want to put a lot of money into it and doesn't want to get into the real big components yet so this is a really good unit now i've done the sx 450s and the you know and a bunch of other of smaller receivers from other models but this one here seems to be uh really a sweet spot because those older ones command a very high price and i these 3600s don't seem to command the same kind of price as maybe like an sx 450 or 550 or a uh 480 or any of those ones that are 580 those tend to be more expensive than these but this one's really got some good stuff going on so anyway i have not plugged it in it came in as you see it the cords all still coiled up looking at the back there's nothing special it does have am stereo out so we'll learn about what that is here later it has you know typical antenna inputs and it does have a ferrite rod antenna inside of it phono input auxiliary two tape decks and two sets of speakers and a couple outlets and that's it very simple and it's all you really need now of course you know me when it's completely unknown like this i'm not just going to plug it in we're going to check it out and make sure everything's okay it really didn't say much about if it's working or i don't remember i bought this a long time ago and it's been sitting on the shelf so i really don't know the condition of it i don't know if it has you know a problem but we're going to just kind of look on the inside and see what we have to work with first now another thing i like about this is the unique way that these are put together and the way that the cases are built on them a little bit different than the ones you're used to seeing where like this is all kind of one piece going around here you're going to see this is a little different and i think it's kind of cool so you take those two screws out and the side comes off and you can see this is actually plywood instead of particle board which i really like that so if we want to i have some really nice veneer out in the shop i could take this shelf paper stuff off of here and i could veneer this if i wanted to now of course it would have to match the top because the top is metal but needless to say this could easily be fixed up and made very nice now you got to take the other side off the same manner as i bang the camera and feel free to skip ahead if you don't like this part some people like this stuff some are in a big hurry for instant gratification so you do what you feel you want to do and then once you get that off there's two screws in the back here that we take out pretty much all of these this generation they have cases similar to this so this is nothing really unique here and get this apart and then we just kind of pick up and pull out and it has these little clips on the front and that's what holds it together so pretty simple well one thing i can tell you is it definitely is dirty look at the dust on this thing yeah um but the good news is this is just just just appears to be dust and probably can be just cleaned off now since this is a really simple receiver we're going to talk about very basic things in this video we're not going to get too complicated we're just going to talk about what some of these things are what they do and some of the things that you want to focus on and things you want to avoid so the first thing i will tell you is the way this thing's broke up this section over here is the tuner section and you can see your tuning gang for your am and fm here's your ferrite rod antenna i was telling you about c and that's pretty unique because the older ones if you recall had the antenna on the back and it was kind of on a fold out and actually that's a little better because it's away from the metal case and everything but often they got broken off and everything this one won't now if you look down in here in the fm section you can see these little let's see if i can get a little pointer out here you see these little coils how they're bent see how that one's kind of bent out like that and you notice this one over here the same way it's bent out a little bit don't try to go ocd and straighten those out those are actually that's actually part of your alignment if you move the distance of those coils you're actually going to throw the frequency off of that of that alignment so believe it or not those have to be in that position and a lot of receivers that you see there'll be some wax or some hot glue or something uh put over top of there to prevent them from moving these ones are not so again if you move them you've just put your tuner out of alignment and if you don't have the type of test equipment that's required to work with fm you may not be able to get it back into alignment and again i'm assuming that those of you who will be working on this may not have all of the test equipment that you need for all the different things we will get into that later on but we're not you know that will be optional because i can tell you right up front the alignment doesn't go out in these unless something goes wrong you will never have to mess around with the alignment typically i say that typically because once in a while you run into it so what i do when i'm checking these things out is i always just kinda look for things that may possibly be uh a cause for something to fail if i plug it in and power it up now the biggest part we want to be concerned with over here is this side of the receiver which is your power supply so you have your power transformer right here you have these four big diodes we can brush them off we can see them a little better i'll vacuum this out real quick before we get started too much but there's your four diodes that form your bridge rectifier here are your filter capacitors and these are the the kind of the main filter capacitors for the you know for them for the supply for the outputs so these are the big ones and they're actually really good quality nichikon capacitors and most likely they're going to be in good condition and not need replaced but these are the kinds of things you want to check in this vintage of gear from the 70s and 80s when you look well let's get you here in a good position where you can see if you zoom in really carefully here you can see around this capacitor this stuff right here see it if i brush it off a little bit you might be able to see that's glue that is not the capacitor leaking a lot of people mistake that and think that this is uh the electrolyte leaking out of the capacitor but actually that's part of the manufacturing process when they put these caps in here before they wave solder the board they'll go ahead and they will put a little dab of this glue around here and that holds the capacitor down remember these are heavy and that keeps them tight to the board before they solder them with the you know with the wave unit and then that also keeps them from wiggling loose and cracking the solder joints on the bottom because they're pretty small so that's a good thing but it's also a bad thing because the formula that they used for a lot of the different glues where they glue these components to the boards in time they become corrosive and they can damage the contacts they can damage the board they can even damage the the case of the capacitor they can even become conductive and cause shorts so what ends up happening is sometimes you end up having to clean those and you can tell the corrosive stuff because it'll change color this is kind of like a caramel color the way it looks and it's pliable like if you take a probe like this little stick and you kind of poke at it it feels it gives a little bit kind of like wax or kind of like you know kind of rubbery whereas when it gets real hard and crusty it'll turn a dark brown not like a caramel color it won't be transparent anymore and it can even turn kind of a green color as it mixes with some of the metals of the leads and stuff and starts to corrode things so those are one of those are some of the things you want to look out for on these now if this were getting bad like that you the only way to get rid of it is you can soften it up with some alcohol uh you know some rubbing alcohol or maybe a little bit of naphtha but be very careful because it could damage the screen printing on the board and then you just kind of have to pick it away with a screwdriver or a metal object but this one's not bad enough to do that so i'm not going to worry about it on this one now another place i like to look before i plug something in is i like to look at the the main diodes here these are designed to carry the heavy current because this this drives the the power rails for your outputs for the output section of the amp and they they can actually overheat sometimes and you'll see that like the insulating tubing on here the spaghetti tubing will get discolored or the the diodes will kind of discolor themselves they can crack if they short out or something like that we're just looking for little telltale signs of something that failed we don't we don't want anything like that of course you plug something in and one of these diodes is shorted you run the risk of damaging your transformer unless one of the fuses gives way first so i always check that sort of thing out now you can measure these with your meter or you can just visually inspect them we're going to show you a way to power it up carefully so we won't worry about that right now another place i will look at is the output section because quite often the biggest failure point of these receivers is the output section the power amplifier itself and if you look these are special transistors here they're called batwing transistors and what they are is they're very similar to a modern transistor package called the to220 except instead of having a screw terminal at the top they have a wider heat spreader flange on them and they have two screws to hold them in to help dissipate the heat to the heat sink more quickly and more efficiently so that's what you're seeing right here these transistors are very difficult to find in this package now so you would have to modify the heat sink and possibly replace the transistors with a different type if they were bad now you can't always tell a blown transistor when they short out they don't always burn up or crack or whatever but you can at least look for signs of that the other thing is when something shorts out these emitter resistors which is what these ceramic things are they will quite often and you can kind of see them down in there they will quite often discolor they'll get like a brownish discoloration to them because they overheat and then they'll they'll actually pop open there's actually two resistors in each one of these one that goes to this transistor and one to this one so this is your right channel this is your left channel so if you drew a line right down here you basically have two mono amplifiers inside there that are running on a common power supply now here's another reason why i like these and as i bang the camera with the amplifier here we go if we look down in here i don't know if you can see them on this receiver or not i'm almost positive this receiver uses them let me see if i can find one oh yeah it's there so let me zoom you in here tightening the camera mount down and if we zoom in a little bit do you see that transistor right there right here that's actually two transistors in one package and this is your differential input pair and we'll look at that on the schematic here in a little bit but these are really high quality transistors because there's two transistors that are thermally coupled together inside and they're very closely matched to one another and they share a common lead so for instance the the bases and the uh like the emitters will be the same but the collectors will be tied together or you know the bases and emitters will be individual and the collectors will be tied together so there's only five even though a transistor has three elements base emitter and collector these will only have five wires because one of the elements is tied together internally these are great little transistors and these are good performers the other thing we have to watch and i don't know if this amp has them or not there are a few problem problematic transistors out there and one of the most common ones used by this generation is called the 2s a726 and i don't know that's a 1735 [Music] it's this one that's a nope so this one might be okay but be aware there are a few transistors in these some of these models that were problematic and they had high failure rates they would actually go bad with age because the leads would tarnish on them and the tarnish would creep up inside the transistor and cause it to fail anyway other than being really cruddy this doesn't look too bad and i think we we would be safe to power this up at least under a current limiting supply so we'll talk about that next i'm going to brush this off a little bit and vacuum it and clean it off and then we'll try to power it up okay very simple i have i've been asked this question many many times how do you clean these boards that are all dirty like this well this one's not going to need too much you know it doesn't it's not going to be too drastic to clean it unlike some of them that have like crud that you have to scrub off with alcohol this is just dust so i actually can just use a soft brush and this is an artist's brush that i purchased at a well this one's a family craft store my wife does a lot of crafts and i go with her to the stores because you can get things like this very inexpensively and a lot of these are very good tools for what we do for working on this kinds of stuff and we're just going to brush this up and then i'm going to run my vacuum cleaner kind of above it to suck up the dust now the only thing you got to be careful of is anything any components that are loose of course there shouldn't be in this but anywhere there are loose components they could end up in there real quick if you don't watch so just be careful with this the other thing you have to watch with a vacuum cleaner is when things go through this plastic tube it can actually give you static charge and that static charge if unless it's an anti-static vacuum cleaner can actually cause little sparks and can damage components that's why it's important never to touch anything with this while you're vacuuming because that's a real uh that's a real risk that you can have the other thing you can do is put this onto the exhaust portion of your vacuum cleaner and blow the dust out but of course it's going to blow it all over your desk your you know your desk or your bench and you're going to be breathing it and it's gross so it's up to you how you want to do it i have never personally had any problems with the static on these but it can happen because sometimes you touch this and you get a little spark to your hand it's you know it's like static electricity i've always been very careful and i've never had a problem you probably could wrap a piece of wire around there and ground it i don't know just be careful that's all i'm telling you giving you a warning all right here comes the noise [Music] [Music] you can see with just a quick little bit of work you can see the difference already so this is going to clean up very easily on this and again that's really all there is to it that's how i take care of this kind of stuff now sometimes again if it's if somebody's been in here with the deoxit and they've soaked the board you know from spraying controls and switches and things it'll soak down onto the board you'll get this oily film on there and it'll mix with that dust you can't brush that off you have to reconstitute it with some alcohol or something to break it down and you have to kind of wipe it off that way it's a lot more work but it can be done all right i'm going to finish this up off camera so you don't have to listen to that noisy vacuum okay and after just a little bit of work you can see it looks much better now for me working around dirt and dust like that while you could it won't hurt it and you could plug it in and test it out i always like having a little bit cleaner environment to work on uh just to make it easier to see things i don't have crud all over my fingers every time i touch something things like that now a couple other little notes this brush here some brushes can actually build up static themselves and when you work with things like mosfets or certain types of integrated circuits things like that they can be susceptible to that static from the brush they do make brushes like this and this is an anti-static brush and these are special plastic bristles or carbon bristles whatever and they're designed not to have static buildup on them just like you can get anti-static hose for your vacuum cleaner which that's what we use at work on some of the sensitive equipment especially like with ct and things like that but anyway just so you know those things are out there be aware of it most of this stuff if you're just working on old stereos like this most of it is pretty bulletproof from that you don't really have to worry about it and it's you know it's i know people will warn you about it but it's really not a big deal another little worm of word of caution is when cleaning around the tuner section i already warned you about not moving those coils down here you also don't want to bend these little plates here on the tuning capacitor because if you bend them and then they make contact with one another they'll short out and your tuner won't work anymore so be very careful around that be very careful around the tuning dial string this tuning dial string is pretty tough but if you mess with it you can break the little stems off of the pulleys you can break the cable itself which would be horrible because now you have to restring this and if you notice it goes all the way across the front it comes out on this other side and then it comes around here wraps around the counterweight and then goes back down here and that would be a pain in the butt to re-string if you had to so be careful so before we get started on all of this i get a million questions about dim bulb testers and what they are and you can see this is kind of the one that i have that's implemented into my bench and it has multiple bulbs and things like that that you can use but it doesn't need to be that complicated and a lot of people ask you know can you show me a schematic how does it work and of course there's a million videos talking about it we're going to make an extremely simple one that's effective and that will work that you can do for very little or no money at all okay so let's look let's take a look at it okay in order to make one of these you really only need three items you need a light bulb and 60 watt and 100 watt are the two most common ones you need a light bulb socket this is a nice plastic inexpensive one that i purchased at a local hardware store very cheap and just a normal extension cord it could be an old one or a new one whatever just an extension cord all right so like i said a picture is worth a thousand words a lot of people ask well how do these work and how are they wired well essentially what we're going to do is we are going to break one of these wires notice there are two wires here okay one of them has little ridges on it and one of them does not now this is of course i'm over here in the united states other parts of the world have different wiring and different rules but a lot of this is can be adapted to that to what what you have on the us plugs like this most of the modern ones now will have one wide prong and one narrow prong now that wide prong is always going to be wired to the neutral and this is always going to be the hot of your mains and the other thing to notice is the wide prong is always going to be connected to the wire with the with the ridges on it and the smooth surfaced wire will always be connected to the narrow prong so we want to break the hotline although it doesn't really matter believe it or not because of the way the ac current works but we're going to break the hot line okay so we're gonna we're gonna actually break the smooth piece of wire now in order to do that we go about halfway down okay kind of like this and you can just take a knife a utility knife a hobby knife whatever you can get in there with we're just going to split this wire open right here once you get it started you can kind of pull it apart like this all right just like that then we're going to get our wire cutters and we are going to snip that smooth wire which represents the hot line okay so we're going to snip it in half and you can see we have two wires now i'm going to strip them off just like that and we're going to wire them right into the bulb so if you look at the picture now right you have the two prongs with the two wires so you got line in neutral or live and neutral or hot and neutral however you want to word it and they travel down these two wires and then this wire we're breaking open and we're putting this light bulb in series with the hot line now what does that do well when we plug our device under test into this outlet here the current is going to flow through these two prongs out to the device but notice it has to go through the bulb now before it gets to your device under test so you've interrupted the circuit by this bulb that's going to do a couple of things first of all it's going to limit the current that can get out to that to that device under test right it's also going to protect you against a short because that limited current the bulb will take up all of the current if it has to because remember this bulb's designed to run directly on the mains line so i could put it right across this line here and it would it would be perfectly happy it will light up full brightness but it will be perfectly happy so what that's going to do is it's going to allow some of the current to pass out to you pass through to the device under test but not all of the current so if something is shorted like those two those four diodes i showed you over here right here if those are shorted all that's going to happen is this bulb is going to take up the excess current and it's just going to light up and it's going to prevent the circuit from being damaged if you didn't have this in there well and something was shorted then that shorted circuit has to dissipate all that energy and of course that's quite a lot of energy you know at 120 volts at up to 15 or even 20 amps and in other parts of the world it can be 230 240 volts and 13 amps or so so that's a lot of power a lot of energy so we want to limit it now if you don't have the means you can just strip these down and wrap them around there and tighten them i'm going to put a couple little terminals on there to make it a little neater okay i've just gone and gotten a couple of little fork terminals and i may have stripped this wire back too far we may have to clip a little off because you really don't want this sticking out too far there we go yeah that should be okay and we're just going to crimp this on there we'll put this one on crimp it and you don't want that wire sticking through there too far because you don't want the the actual wire impeding with the screw and then all we're going to do is put this on here and tighten it up if i can find my screwdriver here we go okay and if you notice this has those little teeth on the end so literally if we wanted to move this around to this side and tighten it down we could do that as well and that'll kind of keep it from pulling out that locks it in a little better maybe we should do that there you can even feel it kind of click in there okay all right and there's your dim bulb tester see that wasn't so hard was it people talk a whole lot about these things but really that's all they are now people make fancy ones because you can actually put a switch across here and when the switch closes it will short these out to allow full power to the device and if you notice that's what i have over here so if you look on my bench see where it says direct and limit okay so if i flip it this way i'm shorting out the bulbs and we're allowing the full power to get out to the device and if i click on limit it opens up all these bulbs now if you notice on mine you have multiple bulbs and that's just a little bit of convenience for me and that's the same as if you would take two more of these sockets and wire them in parallel so two of them here and two of them here and they're all wired together like this and then all i did was i would put if you took this wire out and put a switch between here and here if i switch it on it switches the bulb in if i switch it out the bulb goes away right so i would put a switch on each one here and then i would put a master bypass switch from here to here right so it would bypass all of them or i can switch in as many bulbs as i want of course the more bulbs i put in parallel the more current it will pass so if i put two 100 watt bulbs in parallel it will allow 200 watts to pass now of course i could also unscrew this and put a 200 watt bulb in there right it would be no different and there are you can get bulbs up to three to five hundred watts that will fit this type of base and you can get very small bulbs clear down to like 10 or 15 watts if you want to for instance if you're testing out a small radio or something that's very low power you could do that so you don't need that fancy setup that i have over there all you need is what you see right here if you know it's just convenient to have something like that on your bench that you can switch in and out very quickly now to power a device like this up we're going to take the device and here's the connect the plug for it we're going to plug it in just like so and then we're going to take this end and we're going to make sure the power on the stereo is off and we're going to plug this in over here there we go now when i turn this on what's what should happen is remember we looked at these big capacitors that were over here those big you know eight thousand microfarad capacitors when a capacitor first charges up it draws a very large amount of current there's it's called in rush current and for that brief amount of time this amplifier is going to draw a heavy amount of current and because of that this bulb is going to light up very brightly as that heavy current is trying to flow into those capacitors and the transformer and all those things and then as the caps start to charge up you'll see the bulb dim back down that's why it's called a dim bulb tester if everything's correct once this thing once the caps charge up in this radio when we first turn it on this bulb should run very dim now the smaller the bulb the brighter it'll run because this thing does have a certain amount of idle current that it's going to run at so i have a 100 watt bulb in here right now a lot of times i'll even use a 60 watt bulb it just depends on the device that i'm trying to power up and sometimes a big device may need more than that because it won't even be able to power up all right let's turn it on let's see what it does and there you go did you see that the bulb flashed on for a second and then it dimmed down very slowly and you can see the bulb is essentially off there's no it's not glowing at all now and there is current flowing through there believe it or not if we take our meter and we measure the voltage right there should be if there's current flowing across that bulb which is acts like a resistor it should have a voltage drop correct so if we go to ac volts and we try not to move everything there should be a voltage drop across there and there is and you can see it's only about 6.8 volts and the reason it's only six volts is because the the idle current is so small right now that this filament is hardly dissipating any current at all now as we increase the power to the amp like we turned the volume up and it starts dumping a load into the speakers you'll see this light begin to get brighter because there will be more current flow which will be a higher voltage drop across the filament we'll look at that later though but you can see right now it looks as if the amplifier is powering up and that's a good thing because on these fluoroscan units a lot of times these uh some of these things will burn out those little fluoro displays or whatever those fluorescent displays so i don't know if you could see all that but so i think we can now do our next test okay i've moved the bulb off to the side it's still in the circuit the amp is still powered up and we have the speaker a selected right now i have the volume all the way down and we're going to select auxiliary so there's no sound because there's no signal being applied and we're going to turn this around until we can see our speaker terminals and what we are going to do is we are going to check our a speakers so here's right and left speaker a and we're going to look for a thing called dc offset dc offset is a bad thing if the amplifier is working properly you shouldn't see any voltage at these speaker terminals with no signal it should only be in the tiny little amount of millivolts range so we're going to put it on dc millivolts okay so we're looking at dc volts on this meter there's a millivolt range so we can actually look at it i don't know if we can prop this up with something there we go and i'm going to go between the two speaker leads there we go 25 millivolts i was actually reading between the positive of speaker a and the positive of speaker b so here's here's the negative terminal and here's the positive terminal of speaker a and we have about 25 millivolts and that's to be expected you're going to see that on these types of amplifiers they don't have an adjustment for it some of the bigger amps actually have a pot that you can adjust to make it as close to zero as possible 24 millivolts is 24 000 of 1 volt so that's nothing and most likely when you put your speaker load on there that'll even drop a little bit more if i go from here to the other speaker you can see it's a negative voltage see that so yeah it's a positive voltage here and it's a negative voltage here and that's normal and we'll talk about why it can be positive or negative even if we're holding the negative probe on the negative speaker terminal so one channel's got a negative offset the other channel actually has a negative offset my bad they both have negative offsets on them so it could also be positive if you hold the probes the right way dummy so those are what i would call acceptable anything under 100 millivolts in this kind of stuff and this type of equipment is acceptable although once you start getting at that 100 millivolt range or a little above a very very low volume levels technically you could have some uh audible or noticeable distortion now some people will hear it some people won't but i'm just telling you that up front i like to see it as close to zero as possible and with these lower end amps these lower power ones if it's somewhere around 50 millivolts or less or even under 100 millivolts you probably won't hear it and it certainly will not hurt your speakers at all if one of these big transistors over here were shorted one of these would be very high voltage it would probably be somewhere in the line of 30 volts or so and if you put that 30 volts on to your speaker you will cause damage now some higher end amplifiers have a circuit called a protect circuit that monitors these outputs just like my meter did and anytime that voltage gets over about 500 millivolts or so it brings a relay out that disconnects the speaker terminals from the speakers and it does that to protect your speakers now these lower end units do not have speaker protect circuits the only speaker protect you have if you look down in here is these little fuses here there's one here see it see the fuse and there's a fuse for the other channel here if by chance there is a bad uh shorted transistor that speaker that fuse will blow because the speaker will draw heavy current and hopefully the speaker will blow or i mean the fuse will blow before the speaker does does that make sense but theoretically even with that fuse you could damage or blow a speaker especially like a tweeter or something if that fuse doesn't go away fast enough so while this is some form of protection it's not as good as a protect circuit and if you go back to my uh sx525 video i believe it was i actually added a a stand-alone speaker protect board with with offset measurement to one of these to a similar low end receiver to this and you can do that so go back and check that video out if you want to know more about that but since the offset is good and we have offset to begin with another thing if that was just completely zero volts flat on zero and it wasn't fluctuating around then it could be that something's open maybe that fuse is blown one of the emitter resistors is blown open something like that now the reason i'm taking all this time to explain all this so carefully is because you folks who are new to this this is this should be your standard procedure when you're first checking out a new receiver you know put it on the dim bulb bring it up make sure the bulb dims back down while it's still connected to that check your speaker terminals for dc offset now some types of amplifiers these lower end ones will also have what's called capacitive coupling to the speaker terminals that means they put a capacitor between the transistors and the speaker terminals to remove that offset because they're a different design okay and i get into that too when we talk about the classes of amplifiers i did a video on that as well you can read through that those even when the transistors are shorted we'll never put dc out to the speaker terminals unless that capacitor shorts out technically but getting off track with that so measure for offset make sure the bulb dims down see if the face plate and everything lights up and it looks to me like this thing is ready to test out now another thing we could do is we can do things like we could put the tuner on and if i turn this turn this up with the muting off you can see how the power meters are deflecting with no signal so the amplifier at least the preamp circuit or you know most of the amplifier is working we don't know how well but we know that it is working now don't ever try this on a vacuum tube amplifier vacuum tube amplifiers are different if you're bringing them up it's a different procedure you have to have a load a proper load connected to the speaker terminals or you could damage the output tubes and you know that's another whole video we're talking solid state amplifiers from this era right now all right i think we can hook speakers up and listen to it okay we have some speakers connected and we have an audio source connected and i have not listened to it yet i haven't even turned the amp back on and what we're going to do is we're going to look at this and let's put something behind here that's a little bit darker to show the contrast of the bulb filament there we go and let's see here you should be able to see the filament somewhat yeah that should be enough you should be able to see it okay we're going to turn it on i have the volume turned all the way down and i don't have music yet give me a second okay let's turn the receiver on and did you hear there was a little bit of a thump and the reason there was a thump was because well let's let's do it again i'll hold the the microphone next to the speaker we'll do this once again okay here we go did you hear that a lot of people get nervous by that on these types of amplifiers remember there is no protect circuit so there is no relay that comes in after a set amount of time do you ever notice on the bigger amplifiers when you turn them on there's always a little delay of several seconds and then you hear click those are the relay contacts clicking shut and the reason there's a delay is so you don't hear that thump going into your speakers now since this one is a lower end model and doesn't have a speaker protect circuit or a relay circuit you get that little thump it does not hurt the speakers so don't worry about it now you can see we're measuring across the bulb right now and there's no light lighting up the bulb if i turn the music on and i don't know if this is going to work or not okay um i've not listened to this yet so i have no clue if it's if this receiver works at all i think it will but notice when i turn the volume up you're going to see this voltage increase because as the amp draws more current to feed the speakers this filament is going to have to dissipate more energy and because it does you'll actually see it light up so let me start up a song this is youtube safe i'm picking a random one let's see this one is and i've never listened to this before it's called snake on the beach by nico staff n-i-c-o-s-t-a okay here we go [Music] notice as i turn the volume up that light flashes more and do you notice whenever you hear a bass passage the bass draws extra current and the the light bulb actually lights up brighter and notice what the meter is doing okay here we go [Music] by the way this thing sounds fantastic i don't think we're gonna have to do anything to it [Music] now what's gonna happen is the higher powered amplifiers or these smaller light bulbs will light up brightly more quickly and when that happens you're going to starve the amplifier for power and you're going to start hearing distortion now on a receiver that has a speaker protect circuit that speaker protect circuit is going to detect when that thing saturates and it's going to detect that distortion when it sees that distortion it's gonna open the relay contacts and disconnect the speaker and that's perfectly normal once again that's a normal reaction to having the dim bulb in the circuit because it's it doesn't know you have a current limiting device in there and it's going to think that something is shorting out so it's going to disconnect the speakers it'll wait that five or ten seconds and then when it sees that there's no shorts anymore it'll close the speakers again and then this will light up again real if you don't turn the volume back down it'll light up real bright again and the speaker protect relay will click open again and it'll just be this loop until you turn the volume back down on this amplifier that won't happen it'll just distort the sound now what would happen if something in fact shorted inside the amplifier okay well usually we know what would happen a fuse would blow the wires would blow apart you'd start a fire you would damage everything in the amp all kinds of bad things could happen right i'm going to do something i'm going to tell you never to try i'm doing this so you don't have to and you could under so you can understand the importance of using a dim bulb tester i'm going to take this screwdriver i'm going to short the ac mains right inside the amplifier it's like shorting out the prongs of the of your ac mains cord ready we're going to do it right now here we go what happened first of all the amplifier shut off because it's shorted but what happened to the bulb and look no damage to my screwdriver and the amp comes right back on the reason that that happened that way was because when the amplifier shorted out the current all the current was absorbed by the filament of this light bulb so the highest amount of power that could be flowing through the wires and through my screwdriver was whatever this bulb was rated for so in this case would be 100 watts so instead of the full power of your ac mains which is could be 1800 watts or 2000 watts or more you only have 100 watts of energy which is more than adequate wiring to handle that kind of current it's designed to handle it right that's the reason we use these i hope that makes sense i know this is a review for many of you but you have to understand there's a lot of people that watch these videos that are trying to learn this and trying to get into this hobby and this is going to be very important for them to understand and what happened to the to the voltage did you see that we'll do it again 120 volts that's your full power right and now once the amplifier powers back up it's a very small load so now all the voltages is present inside the receiver and only seven volts is being dropped across the resistance of this filament it's ohm's law good old mr ohm we love him he's never wrong okay so far we've only used two pieces of test equipment we've used our homemade dim bulb tester and we've used our digital multimeter you do not need one of these if you look one of these up online a fluke 187 if you can even find one anymore they're very expensive and the fluke 87 is also very expensive in fact all of the fluke meters tend to be expensive except for some of the there's a few of them that are made in china now like the i think like the 115 and there's a couple other models they're very good meters also but again more expensive you can buy a low end meter and it will do the same thing that this one does it's just this one's ruggedized it's designed to last a long time to be used out in the field but if you don't have the means to purchase one of these you don't need this i mean let me see if i can find another one here so here's an example of a little meter this is nice because it has a little clamp on it and it can measure both dc and ac current because this uses like a little hall effect sensor and so that's nice because you could actually put this in your dim bulb tester like so and it'll actually monitor the current flowing through the bulb and through the circuit and then you can on the back on the bottom of it you can connect your probes just like this and it works just like this meter it'll check ac and dc volts it'll check ohms it'll check diodes it'll check capacitors it has a little continuity tester and it even has a non-contact voltage tester which is really nice because if you want to see if something has power in it you can just let's see if i can get you close to a power cord somewhere over here you can take this and see and it checks for voltage i mean it sees if there's voltage in a wire without actually having to come in contact with it so these are nice and you know this this very unit is made by is uh marketed under different name brands unity is one of them but there's a lot of them you can find them on amazon ebay you know alibaba banggood you know you name it aliexpress all the different haunts out there and you can buy these and this one even reads true rms you can look up what that means give you some homework huh but uh yeah with something like this you can do a whole lot and you don't even need any other test equipment now if you want to get into aligning tuners and different things like that of course now we're talking signal generators and oscilloscopes and things like that but you don't need all that to start right here is what you need or that meter i just showed you or something similar it's not really important as long as it can read volts amps ohms you know all the basics now what i'm going to do for this video is we are not going to use anything more than those two pieces of test equipment for everything we're going to do in this video everything else is going to be done with our minds with our hands and with basic techniques and hand tools and things you

Channel: xraytonyb

Views: 17,720

Keywords: electronics, vintage electronics, stereo, receiver, amplifier, amp, pioneer, sx-3600, repair, service, restore, restoration

Id: yBo-Kl33mZU

Length: 61min 28sec (3688 seconds)

Published: Sat Oct 16 2021