Hi, it's repair time. Let's take a look at this Sony Boom Box. It's a CFD V10 for those playing along at home. Old-school cassette and this newfangled art compact disc player and it's one of these are classic and Sony little sort of like desk boombox models.

Can you really call it a Boom box? It's not, It is, technically, but it's not like a tease. Boom Box: Anyway, this is late 90s vintage and this one belonged to my mom. It's been sitting around for a long time, speaking in various moves and whatnot. the poor antennas being broken, all the electrons are going to fall out anyway, as is common with these things, dual mains and bad and that looks like a D instead of those Mongrels C cells.

And the great thing about our Sony gear like this is that you can get the service manuals forum and they're fantastic. And yes, I can get the service manual for this particular Australian model and we'll take a look at that later, so stick around for that. but it's reflex body. I've got main driver plus a tweeter up there.

that's probably just one of those piezo type ones. Anyway, let's plug this in and see what's wrong with it. Hopefully it's still buggered. Oh yeah, there we go.

There we go. It's buzzing and that is independent. Oh yeah, yeah, there we go. I Thought I was gonna say that was independent of the volume control button.

Has it come good Because before it where damnit Murphy gets me every time I Swear it was. The fault with this thing has always been that it had this huge hammer in it. Regardless of any mode, it's probably come good if I work a CD in that it's probably gonna work now. Ah, coming guts up.

Do I even have a CD to put in it here in the lab I Don't think so. The first thing you would do is actually try this on jewel on battery power as well to see if it's anything to do with the mains. Our power supply powered from the bench power supply I Like this: how they use the board down there for the final contact. You can see just a couple of jumper links on there for the positive terminal.

Put some hot snot in there for good measure. now. I was wondering actually how they switch between the DC source in the AC they could just like diode or it. It's a bit like often they'll have like a DC AC switch on it.

Looked in here and I saw this. look at this I Reckon that is a little micro switch that automatically disconnects the batteries when you plug in. the AC power cord isn't that neat I Love it. Well done, all right.

Let's pair it up on DC So I'll switch the output of the power supply. well it's drawing knife all you can see that up there and you might be wondering where's the power switch on this thing? Well it's actually the tape CD radio off there it is he put in tight so let's whack it on. Well Well it turns out that radio reception sucks on the other side of my new lab here. I put it near the window over here.

Bob's your uncle? this is on the mains input working. Okay, hmm. Anyway, it's still I reckon it still has a problem. kind of come good.

but yeah anyway. let's take apart. We're gonna need a bigger boat. unfortunately.

that's the longest one. I've got reaches in here, doesn't reach in there dole. Unfortunately, this is a flooded yeah I'm short by that much, wouldn't you know it? Bloody And the screws aren't those combo flathead Phillips Eva Ah, and as usual, in Sony gear, it's got the little screw marker beauty. Well, I'm back and if it's worth doing, it's worth overdoing.

So here we go. It's some plastic in there. the heads too big. Unbelievable.

Eventually got it though. There we go. Liam Asked for fifty millimeters for those playing along at home. Uh-huh.

There's one pesky screw right up in there, which you can't obviously get in like that at just the angles don't work so you've got to put that down and get through the back there. Jeez, that's a bit rude. There we go like it just popped off all on its own. There it is.

Oh look at that nice length on those two. Open it up. That's lovely. Like you know they've thought about service in this thing.

It's really quite neat. Ah, it's a little slide ease. Nita's I Really like how the tuning cog thing works here. You can see this.

this yellow looks like a cable toy type thing. that's just the identifier on the front, that's just the marker on the the front window. But then they've just got this cog wheel which then goes up against here so you don't have to run or your little like little string things over to the front panel. Nice.

Check it out. They faked the tweeter. There is no tweeter. There's a little like it looks like there's a little tweeter in there.

Looks like it's a two-way Joby But it's not. It's just a some molded plastic that's terrible. Muriel Look at it. Anyway, there's a Sony full range driver there.

2.8 ohms, 4 watts for those playing along at home. The reason it has to be such a low value: 2.0 Nomes: Very common because this thing is battery-powered It's only like 9 volts maximum. You know it's going to operate that when the batteries drain, so you still want to get a decent amount of power out of the speaker's without having to generate the voltage doubler or something like that to generate a higher voltage supply rail. So yeah, they go for the low value jobs in those particular cases.

Very common with you know, little portable ones like this. and a 12-volt car stereos too. So it's real easy just to take that entire front panel assembly out. That's neat.

So this is like a little that's a little LCD there that just displays the track number and a few buttons. and that's about all she wrote. So I Find interesting about the inside of here. all the dust that's accumulated over the years.

But look, they got a foam piece there which is sort of blocking that bit. There's no matching foam piece there. There's no foam over this side, yet. there's some foam strategically struck down as stuck down on this side here.

Just find that rather curious. Anyway, there's our set. our date coat. yeah, what does that say? So acoustically, that just seems like a symmetrical.

well. that's right. you know, maybe because they've got the transformer over this side here. but I Don't know if anyone's got any clue why they would strategically place one bit of foam there, one one there and not match it on the other side.

Please let us know. Anyway, they haven't done like a proper acoustic cavity in there, but you know this would have been designed somewhat. What's interesting is this down the bottom here. this sticky bit that goes on the back of battery compartment.

That's that bit there. I I Don't understand that at all. what on earth that is doing there? So if you have a look at the battery terminals here. Positive from that.

PCB We saw before the negative that's going over to this primary side mains board. so that little micro switch is way down in there that's integrated into the mains input terminal. It's really interesting. This is just the main power out, so it's just a single tap.

And of course, the PCB single sided. Another expensive double-sided rubbish. Oh I See a little resistor I Spy a little resistor in parallel across a diode there. here's all our wave soldered surface mount.

As is typical with Sony construction. SMUD Wire down here. It's got this. It's got some hot snot there and that's just jumping all the way over there.

That's a ground that's as good as a star ground point as you'll ever see. Look at that. and they're tapping that off so they aren't actually bulges. That's just a way.

That's just. they've done that for layout reasons. so they've got that. going over to the headphone jack.

goes from the star grounding point. Look at all. They count the number of branches off there. That's really quite nice.

And then they jumper that all the way over to here. This is the Am antenna rod. so this is all part of the Am/fm section, presumably so yet they just couldn't get a decent ground on the layout from there over to there, they just needed a separate one. So let's run a wire.

no workers and you know, extra extra production steps. Somebody's got to assemble all that, but that would have been cheaper. Then go into a double sided die. PCB Layout: Check out that one down there.

It's a little diode nicely stuck down with silastic. Look at that on top of that little s Oh fine pitch s a package there. Neat. So the first thing we're going to do is just like visual inspection.

Of course you would suspect because it's failed, there's big harm in it. and then it sort of came good. but trust me this is I powered it this up a few times over the years that I've had it lying around hoping to get around to fixing it and it's done that horrible harm every time. Except when you go to shoot the video of course some hot snot on the lid there.

look at that. Anyway, here's the big single inline set package. power amp chip. we can have a look at what one that is, but yeah, they've got had to bend it over like this.

another one, another big cap right up there. right next to the heatsink. that's not good layout. what are you doing Sony and all this tape.

Look it. Really. Start: That's all just powdery stuff. It really starts to disintegrate here and you might be able to sit.

You know the board comes out of there pretty easily. although that ribbon cable at the back I just I pulled that out as part of bringing the board back, so that might be annoying to get back in. Anyway, there's our CD mechanism and you'll notice that his rubber baby buggy bumper compliant. So just for any vibration, our tape drive for you tape aficionados.

So there's the PCB And really I can't see any any bulges in those caps. doesn't on the surface, doesn't look to be a problem no pun intended. But yeah, putting them directly under the heatsink like that? that's a bit. silly.

buggers, love the jumper that goes right over there like that. Terrific. See the star grounding in there and the star power as well. That's terrific and you can see the solder feeding on the chips as well.

This is when they put it through the wave solder, they put these little less solder traps and they would that will last stop the pins actually getting shorter when it passes through the way of soldering machine over in that direction or in that direction because they mount. They deliberately mount these chips at 45-degree angles like this to actually prevent shorts between the pins because you'll notice that there is no solder mask. now that solder mask rubish between pins. So there's nothing really to prevent shorts in there apart from the physical orientation because if you have it, if you have your chip square like that, then all the pins on one side again being a sharp shadow, a solder wave shadow as it passes through the Machine and you're more likely to get shorts and little traps on the backside of your if you chip.

That's why all three of these jobbies are all at 45 degree angles. Oh, something's happening. This is switched off. There's a winding sound.

1.2 3 amps. Sounds like something's gonna go. Yep, it's not good. All right.

Switch the pair off and that heatsink is surprisingly warm for the few seconds I had that on. It's turned on. Again, it's drawing 10 watts. That's one sick puppy.

Yeah, one of the good things about this design is that you can actually take it out like this. And really, all we've got is our DC input here. We don't even have to hook up the front panel. That's just the LCD and some CD control switches at the top.

This is for the disk detection that the lid is closed. This just hooks up to the CD mechanism and then all these just hook up to the cassette up the top so we shouldn't really have to do anything. We just plug the speakers in here and Bob's your uncle. So it's really quite nice when you can work on it just out in the open like that.

You can flip the board over and you can probe stuff and uh. but anyway, it's drawing 10 watts just on idle like this. So yeah, something's up. Ok I've just switched it back on again and it's not doing that.

So it's now drawing point for 40 milliamps. Oh, there it goes. Yep, it's doing it. Yep.

1.2 amps All right. Out of curiosity. let's see what's getting warm here. Once again, it's drawing the 40 milliamps.

Gotta wait for it to do something stupid. It's not gonna fail on me now. Hot tiny hot spot over there that's interesting. What is that? one specific hot spot there that is the base of a cap? that puppy down in there shouldn't be using my metal paper? should I? Yep.

I just had to go up to a nap something behind. Yeah, that's the power amp. And of course that makes complete sense because I the heatsink is getting warm and beards dissipating. 10 watts.

Where are you going to dissipate 10 watts? If you dissipate 10 watts in a cap, it's just going to explode. So maybe we've got to run away some sort of oscillation on our power amplifier chip down there. But it doesn't mean there's anything wrong with that power amplifier chip. It could just be like the power supply.

Like this hot spot over here. I'm going to check that cap there and see what the business is. Yes, I haven't even measured voltages yet. Thou shalt test voltages.

But anyway, and at this point, we'll have a look at the awesome service manual for it. I Love Sony Service manuals. They're absolutely brilliant and it's published by the Quality Engineering Department and good on your Quality Engineering Department. printed in Japan 1998 There we go Anyway, it starts down with all the specs and then disassembly how to disassemble it.

Of course, there is no troubleshooting art procedure in here, so you're on your own in that respects. But the fact that you've got this, it's just that. look at the disassembly set front cabinet LCD Board software I see and let Ludlow how to like deconstruct it like that's just. it's just absolutely brilliant.

Well done and old-school tape speed adjustment Staff mechanical adjustment Sides: the video Just the VCO I founded CD section. Here's the main boy. It's just absolutely fantastic. No reference waveform I Pat and look at that.

that's that's just EF Balance adjustment Ah, Focus tracking gain adjustment on the CD focus bias generator art that's you know it's fantastic. This is block diagram so there's the there's the AC in thing with the switch. that's the switch that's connected under president of a dotted box around that like that to show that it's physically connected. little micro switch that I showed you on the back this disconnected lis that's a switches between mains or AC input there and we're going to regulate ahead and which we will suspect and then here.

this looks like yet this is the function switch here so as you can see like the bottom position is like off but it does actually consume some power in the off position. I think I Don't think it's entirely off So this regulator is a seven volt regulator here so I just love these overlays. They're absolutely brilliant. There's our rectify our board over there.

that's our secondary right? so it comes in here. Here's our power connector input. Okay, and here's our regulator and I can tell you that that can this suspect capacitor I believe is this one that one they got a little bit warm? Ski is C Nine, Five six here forty seven Mike 10 volts. So they've just got an A single transistor regulator there.

That would be the first thing I'd be checking just to make sure they are check voltages says our five volt regulator. Okay, so that's doing it for the lead digital logic stuff. So yeah, like single - single transistor, they don't need anything more than that. That's they're saving money on that compared to when like an Lm7805 voltage regulator for example, is going to be a couple of cents cheaper to implement that.

and I always find these things a bit hard to follow. Like you know when you have to put the the switch in different positions and stuff like that like in multiple places across. You know, the schematic often in different parts of the schematic like oscilloscopes are classic for this and things like that just trying to keep things like get the signal flow go in anyway. that's that's a nice schematic.

I Love it. And yeah, like I don't think there's that. Like we don't have to worry it concern ourselves with all this digital logic down here like we're We're gonna come a gut say here. Ah, here's our power amp.

So yeah, that's just a basic goes in a reference. there's a 7 point 5 volt Zener Why do we get 6 point 9? Well, 7 point 5 - no point 6 volts drop typically base emitter drop. Thank you she is 6 point 9. We don't We're not chicken dinner.

it's a to SD 23 not any. 6 for those playing along at home and you can see that bad practice over here. They've put the dot there's always you know you put that through a couple of facsimile Zijn docket, vanish, direct battery input here, and that actually goes directly. Pals a chip known this protection rubbish and then that drops down here.

Very a protection resistor appoints two, four, seven ohm into the regulator here. That's kind of weird. they call that B plus six point nine volts and B plus nine volts I I'm not sure what the deal is anyway. I'm gonna go in and check that job.

er, there. Let's go there. We go. Six point eight.

What? Oh, there we go. It's doing the file I didn't even touch it, but that's remaining so it's not that rail. So yeah, it's drawn eleven Watts again. So anyway, this is where like you don't want to be probing in there like that.

You can accidentally short things out and you can really come a gutter. It's best to get like little easy hooks or some other probes that you can hook on. So I've got one just hooked onto the bottom and one just hooked in and then just pair it up and do it one by one. It's just safer.

Now, there's actually no need to suspect these two big 2,200 mic caps here because they're just the AC output coupling caps for the speaker. But of course, one of the problems we're suspecting a cap here is that there is no ripple. We're pairing this from a DC supply. So like, even if one of these caps, like a big main input bypass cap had gone, it's not an issue because we're seeing like, presumably some sort of oscillation of the parent module.

So you know the cap really has it, there's no effect whatsoever. Okay, I'm gonna probe 295 to down here. There we go. There's our five volt rail.

So now Six Point Nine volt rail and our five volt rail are both fine. Nothing to do with that. Alright, so what we're going to look at now is because it's most likely to be this power amplifier it's doing because it's getting really hot and it's most likely like not. The input is your volume front panel while volume pot and your tone control.

By the way, like it's it's almost certainly not a signal being actually injected into here, cuz that wouldn't cause it to do all this funny business. So look. but we've actually got our DC voltage levels here. so we've got four point three there.

Well, these are just bias DC bias levels. We've got our VCC coming in here, which is our nine volts, which is basically direct from our supply input. Four and a half volts on that pin. Seven, half volts on that pin, nine volts on this standby pin here, and half a volt on these as well.

They're just the tube line ins. That's just a bias level, so let's check those. Okay, this is our nine volt input. We expect that to be perfect and nine volts.

It's off at the moment and we turned it on and we're getting the noise again. It's oscillating, doing whatever, and it drops because of the voltage drop. So we'd expect that I turn it off and it's still going. Don't know if you can hear that, but it's still there Again, We're looking at pin Five, which is one of the filter pins.

It's just got a couple of caps on there. It could be one of those and once again, we're fine. and we switch that on. and it's drawing 11 watts during one point.

two amps. Five volts. it should be four and a half and our next pin should be 7.5 volts. We're getting four point two.

Aha now. So both of these forages here are off. They're not four point five, this one's gross. grossly low, so these could be like if one of these fails.

Maybe it's just it's not going to be stable anymore. But these are. these voltages are not being fed in because this is ground here. these are being generated internally.

I Can probably put up the block diagram internal of this thing. so these are generated inside. So we've come. a guts are right there.

So right off the bat, you'd want to be checking those two caps so it slows. - there see three, nine, one, three nine. -. they look okay.

but of course they could be dead as a dodo. now. Interestingly, those caps are down around here, basically under this hot snot. So yeah, that's what's usually pretty good.

but I don't know. I'm just gonna remove that - just see. it's like there's nowhere contamination or something on there that's causing it to come. A gutter Houston, we've found the problem.

I Should have given this a better visual inspection. Look at these joints. Look at that. Troy is a dead Dingos donger Wow These are of course the pins for the power amplifier.

Yeah, they've just dumped. They've just completely cracked thermal over the years heating up, cooling down. That didn't they had to explain. it comes up the top.

No, no, no, no it. Oh they've all come. he gots up. That's terrible.

Mariel Well, I could have saved myself a little bit of time if I had just done a better visual inspection of those like I should have like yeah, no excuse I should have looked at the power transistor of course, but it fits the symptoms that we're seen. like it's like intermittent. Of course the joints like this, it'll be horribly intermittent it based on like it changes when you power the thing up I guess like thermally, it's different and who knows what issues you're gonna get caused by not just one, but potentially more than one. Or that might only be one that's actually the cause, but they all look horrible.

Classic failure mode. So let's go and resold. Or shall we just show you a bit those a bit better up close that's Gonski Look at them. Yep, don't even think about why it's you know how what mechanism is? Call in that issue.

Yeah, well, you got crack joints like that and you pair amplifier. it's gonna ruin your day. and there's the after shot. Look at that.

Beautiful I sucked out all of the solder and put on fresh stuff and that look sighs. Beautiful thing of beauty. Joy forever. All right.

So let's pile that back on. I'm pretty darn confident that's the issue. Yep, there we go. Yeah, it just faded out like I kind of remember it doing that.

There we go and it should fade out. I should turn it off because as the capacitors discharge and then it instantly cuts off because there's like a standby feature. See, it can't pick up anything it in here even I am they still transmitting I am. Anyway, pretty confident that that sucker is fixed.

Classic joint. A classy joint. Classic Fault in the joints of a power device in this case, the main, a power amplifier chip. but you'll get it on main amplifiers and stuff like that, you'll get it on individual power MOSFETs or Bjts that and every time you use them, they thermally cycle.

They actually heat up and you know not all heat gets out of the heatsink somewhat like the the pins heat up and you know they cool down, heat up, and cool down. You do that for 20 years and and the thing can fail. So yeah, and it depends upon the exact type of alloy solder that they used at the time. Different batches can cause problems, and earth, they change the type.

You know, there's all sorts of, you know, metallurgical stuff that goes into that as well, so that was a pretty easy fix in the end. I'm gonna put this sucker back together and I'm pretty sure it'll be winner. Winner chicken dinner. All I gotta do is find a CD to try it.

or maybe cassette I Think it needs a good cleaner, the head and all the drive in that sucker. If I ever use a cassette anymore, maybe a good mix tape? Yeah, and to get those cables back into there from the CD mechanism there, I've got to take the whole top part of that off. so there's your rubber baby buggy bumpers for you. Tape transport fushion ADO's sorry about the dust.

Hmm yeah. I know I'll clean it. Yeah, so the whole idea is that you take this top part off the whole city transport mechanism comes out. that is very, very nice.

and that's really minimalistic, isn't it? That's what you'd expect. Of course, you don't need anything more than that. And of course this ribbon cable. You can now get in there.

there's the thing down there, and also this cable here pops up. so there we go. You plug that into there and then you can plug that ribbon cable in. Yeah, Bob's your uncle, so you can actually really get a feel for how this is all assembled cheaply.

This would be assembled on one line, the tape transport mechanism on another line, the PCB on another line, and although you know the front panel, then that, just like it all just comes together bang and in like I don't know 30 seconds the whole thing's assembled. I'm really liking this thing. This is just the Ducks guts. Oh, one interesting little cost-saving measure.

I Noticed the screws on the back here that are actually visible there are black and the ones that actually go down into those deep dark holes. They're just up. You know, passivated with a gold passivated or whatever it is. These ones are probably a bit, you know, over half of Bees Dick.

more expensive than these ones. So yeah, yeah, they save cost on the internals because you can't see them. Beauty: What on earth is that song? I Don't know. Anyway I Have enough CD Here in the lab to fix this - well, to check the CD or a mix tape.

But anyway, that's a winner. Winner chicken dinner. And yeah, we could have fixed that without the schematic at all. I Mean that was house an easy visual fix.

No problems whatsoever. But good thing about this Sony gear is that you can actually get even for like a cheap-ass Oh well. I know how cheap this was at the time, but you know, probably some hundred dollars or whatever and you get the full service manual for then. This isn't from the 70s or the 80s when that thing was the go.

this is from almost the year 2000. Is it like 1998? So Wow you know, Fantastic. But anyway I hope you enjoyed that. It was a classic gunfire and if you didn't like it, please give it a big thumbs up.

And as always you can discuss down below. Catch you next time.