EEVblog 1394 - Onkyo Receiver Repair - Part 1

hi it's repair time and we've got another bit of audio visual kit uh instead of i think we had a yamaha before i think probably had a couple of yamaha's anyway this is an uh an onkyo apparently you know quite a decent uh reputable brand it's the tx sr607 for those playing along at home and well you might be able to see the little standby led there it's on and well that's supposed to be on and it just relays a click in it it's gone out of standby some relays click internally but there's nothing on the display at all it's one of those vacuum fluorescent uh jobbies but i can't see anything and then you press the power button again and the little tiny itty bitty standby lead comes on there so i don't know if we got a display fire given that uh it does seem to come out of standby or i could i could physically this is not feeler vision but i could physically feel the transformer inside big ass transformer vibrate so you can feel the magnetizing current so those relays will only come on they're driven by like secondary side circuitry so obviously some part of the secondary power supply works to actually be able to drive those relays those like soft start relays and things like that so because you don't want the speakers to go thump like have a big whopping dc thump or something when uh you switch it on so usually they have like uh relays that defump the speakers when you switch on and stuff like that so that all so it all seems kind of normal like three four seconds click then there's not yet then there's another click so that sounds pretty normal but units like this they have many different uh supply rails in them so it could be anything like that it might just be as simple as the display power supply or something but anyway let's crack it open take a look here we are i think this thing can do with a bit of a uh it's i'll take it out into the stairwell and uh give it a good once over but um yeah very nicely uh designed and laid out inside and by the way i checked you can actually get this full service manual with schematics for this thing and it is beautiful beautiful so there's our massive transformer down there high current power supply um it's a absolute beast magnetic shielding around there yep there we go it's soldered there so yeah that's beautiful magnetic shielded a couple of fuses down there we'll check those i can see some relays down there and everything there's a board here which that just looks like a connection board going off to yeah some ribbon cables which bugger off down to the boards and stuff like that so anyway is that how they connect all the power via those ribbon cables maybe anyway um yeah as i said there's going to be many different types of power supplies and the main pcb down the bottom that's all uh single-sided shall we not that double-sided rubbish and uh it looks like these boards in here these will be uh driver transistor boards for the main um mosfets which all could be bjts uh for the main heatsink down here so because it looks like this board up the top here that's just like uh input uh switching and stuff like that so to get the main is the main power supply down on the could be down on the main board so to get all that out we're gonna have to take everything out but anyway um yeah just like the the cable ties and everything in here the cable in it's all very neat and tidy i like it there's a requisite backside for those playing along at home it's got all the you know newfangled hdmi inputs and stuff like that so it's reasonably modern um anyway our standby a soft standby switch is actually on this board here which then goes over curiously to the display board so there's got to be power to the display board and going over here and as i said that is a like a lot soft logic switch which then eventually you know powers relays um down on the main board down here like we've seen before and maybe there's another no that's an input board uh yeah down on the main board and stuff like that so there's got to be like you know digital supply getting to the board here to the processor this is probably just the display processor itself the main processor is probably down on the main board here so it's got to be getting digital power to all that and then you know and coming back from this board so there's a lot of stuff which has to work in order for that soft power button to work so that's rather interesting so yeah we could maybe be looking at just a like display fault perhaps maybe i could like feed in an audio signal and see if something comes out well there's nice attention to detail look at that they've gone to the effort to design two pcbs just to hold the temperature sensor to measure the heat sink there one little board just to hold the screw and then which uh presumably strapped down to the like the metal part which then is uh thermally coupled into the uh to92 plastic temperature sensor there so yeah but they've gone to quite a bit of effort just for that oh there's the power in the back there and it's labeled collector base emitter none of that gate rubbish actually right off the bat some of those solder joints on that uh transformer pc interface pcb there that would try as a dead dingo's dongle so i think it's worth just taking before we do anything just taking one minute just to resolder those that didn't help the display but it made me feel better now i've got it hooked up just to one speaker here and if i turn it on i don't know what channel i'm on but if i turn the volume right up i can hear your typical static at full volume on your speaker so it's definitely working it's doing something i think if i put a source into that i think we might actually hear something so i suspect it might be a display failure yep works a treat it's got a thousand hours battery life beautiful so i guess let that be a lesson to you uh if you can check as much functionality as possible because well you know look get nothing on display you might think okay the power supplies fail but then you realize oh it's doing the standby thing and i can hear relays clicking you have a quick look inside and you can see that the relay that the soft logic button and the relays and everything is controlled by all the digital stuff and all that must be working there's a lot of stuff that has to work in order just to um have this button actually turn this led off and on and switch uh some of the relays and stuff like that so yeah as it turns out there's a good chance that everything else i see i'm not going to say everything but like i i choose the ox input and it works i know audio works so it's definitely worth double checking that before you chase a red and down a bloody rabbit hole um trying to like debug the power supply and stuff like that looks like there's probably nothing wrong with it so uh yeah i'm gonna look straight at the uh display board now so i'd have three screws on the bottom here and i remove the knob but and looks like this front fascia is going to lift out not without a fight but i think it's going to come out there's probably some hooks on the top note just had to get my thumbs under the bottom and tada there you go that's actually aluminium uh front uh case on that that's really nice brushed aluminium and there you go we can get in there there's any there any screws oh yeah there's a couple of deep screws in here that should lift off because the board is screwed into the front and it doesn't make sense if i was designing this i would not design it so that you had to get all of this guts out including the bottom board before you could even access the screws that hold on that front panel board it just makes absolutely no sense at all you want this to be like a finished assembly with the board in place everything else and then you can assemble that and test that on its own test station in the production line and things like that so yeah that's is there another sneaky screw in there it's actually another three sneaky buggers on the bottom now does that there we go now we're talking uh disconnect the hdmi show you this there's just one little annoying ground lead right there get him off that's just reference in the hdmi switching board which is down there the html no the hdmi receiver board and then it transmits um back through but oh there we go we've got the ribbon cable on the front over in that corner and that's about it nice they put tape there holding that in place nice touch so it doesn't get pinched when you put the metal case on top always remember when you're designing stuff to tie your cables down and things like that there you go there's the entire front panel assembly you can now work on that well there's really not a lot going on here is there i mean that looks like a single-sided jobby got one quad flat pack there this is all wave solder by the way thank you very much are the solder feed in there when the big solder wave comes over it that's to ensure that uh you don't get any like uh klingons and stuff like that on your joints well nothing worse than a bunch of klingons klingons off the starboard boughs i have to pull a number off that but yeah it's probably a custom jobby um it wouldn't surprise me at all and there's a little bit of action happening down here uh some discreet trainees and a little uh eight pin so there but no that's just uh like the audio imports that they were actually working that was working fine so that's probably like a you know jrc audio amp or something like that so really um there's no power supply stuff on this at all i'll flip it i'll get the board out and flip it over but um we could have a uh vacuum fluorescent uh failure so in that case i mean or if that's that chip we're probably not gonna get another one i think we might be screwed i'll show you the full schematic at the end of this so stick around for that but anyway because it is pretty fantastic anyway um here's our vacuum fluorescent uh driver it's the m66005 and yes it's obsolete um but you know you might be able to still get it somewhere and that just dries out vacuum fluorescent tube here and there's not much else surrounding that um so yeah there's not too much to go wrong now interestingly down here this is where our standby switch is on the front and the standby switch if well the sorry the standby led actually if you follow the money it's not controlled via that uh vacuum fluorescent chip it just goes straight back to the connector board over to here back to the main processor but curiously the reason i mentioned the chip is because this uh zone led and this uh pure audio led it looks like they're actually they do actually follow the money up here and these actually go into well it looks like some digital i o of the vacuum fluorescent driver chip so there you know you can send some data into the vacuum fluorescent driver and drive a couple of digital i o pins which they're conveniently using there to uh to drive those leds on the front but that's got nothing to do with what we're doing here the standby switch that's not controlled by that that's actually going all the way back as well so if you've got a fire on your vacuum fluorescent uh display here it's either the chip itself or one of the you know like handful of uh surrounding circuitry um by the way i think this that is your receiver and there's a little arrow coming in that's your ir that's your remote control ir receiver so it makes sense to have it on the display board because it's got little front panel pokery out bits that can see outside but anyway what we're interested in is the connector over here obviously like there's no blow holes in the chip there's nothing physical that we can actually see we've got various rails here we've got plus 3.3 we've got plus 5 display that's interesting plus 5 just for the plus 5 display you want to be measuring that and plus minus 15 volts as well but the plus minus 15 volts that looks like that just buggers off down to this um set it's got a setup mic you know when you're set up because it's one of these new fingers surround sound uh things if you get a calibration microphone you can um set it up you put it in the middle of the room and it auto calibrates itself they've got a dedicated uh mic preamp for that so that's interesting but anyway yeah i'd be checking that plus 5 volt display and the plus 3.3 there because if you can't get that well you're buggered good thing is we can just swing out this display and probe it right up its clacker while it's powered on brilliant thank you very much to the pcb layout person who thoughtfully provided um the silkscreen overlay there for all the pin out so if you didn't have the schematic you could go in there check the rails beautiful lucky pin 13 is the 5 volts whoa 4.78 but make sure i had the right ground point this is digital ground the relays just clicked that's interesting hello relays are clicking something's going on i wasn't touching it and the relays were clicking on me okay let's try that again i know that point there is digital ground and that's five oh there we go yep so the point i was measuring uh trapped for young players buzz it out don't assume it's ground just for kicks we'll measure those other power rails plus minus 15. yeah they're good but that's got nothing to do with the vfd but it's always good to check power rails because it can be indicative of something else because other rails could be derived from higher rails so you never know but in this case not because you wouldn't derive a 3.3 volt or 5 volt digital rail from a 15 volt analog but you know yeah the principle's there 3.3 is 21. there you go our 3.3 volt rail is good so all our rails are good so ah yeah it's either the vacuum fluorescent display the vacuum fluorescent display chips or uh one of the surrounding components or something like that or it could be something exotic like i don't know a front like a a solder joint cracked or something like that or um something is you know it's probably worth like a quick one minute visual inspection on the chip and whatnot and the other parts but we're not done on our power supplies yet because vacuum fluorescent displays think of them like well they're vacuum tubes it's in the name they actually need a filament supply to work and they're usually the pins on the end of the display here so if you want to actually uh measure one they're usually either you know on one end like that or a cross like that so um yeah sure enough look there's two pins on this end shorter two pins on this end fl1 fl2 and if you follow the money they actually are not generated by the chip here um they actually go over to here on the connector and sure enough fl ac1 and ac2 pins one and three the filament ac supply there so we need to measure that so for this we use our special vfd mode on our multimeter no that stands for variable frequency drive not vacuum fluorescent display anyway we are getting diddly squat on that so aha there's our culprit we've found it we're getting nothing on the filament for the vacuum fluorescent display and well vacuum tubes and vacuum fluorescent displays don't work if you don't heat them up with the filament that's what it's there for their vacuum tubes so yeah no filament no electrons and it turns out that filament ac signal goes through uh quite a few boards as you saw you know it goes into that uh side uh board and then goes into the main amplifier board and anything but anyway the uh fl ac not sure if you can read that but anyway that basically goes from you know it just goes like through this board like this over here to another one and then another one and it eventually gets back to uh of course the filament tap on the main transformer here and that's the board i uh resolded at the start and you can see like there's a series resistor there's but uh yeah let's um let's start right at the source and measure our ac because i don't know something might have happened to the wind in there i'm sure the solder joints okay but you know never know it doesn't actually tell you what the filament voltage is but a classic uh valve filament voltage 5.6 volts five or six and 5.66 there you go so it's fine uh does it get through that resistor there oh 4.4 it drops on the other side of that resistor so we must have some drop yeah actually there's 1.2 volt drop across that um 8 ohm resistor there geez sure enough on that board it's actually rated as a half watt resistor so that makes sense you probably wouldn't use a half white you'd only use a quarter watt if there was like naf or current so using a half watt for a reason there it's obviously not open but i'll just verify that that's 8.2 nope it's half that but that is in circuit well it turns out that i was actually measuring the wrong pins there it uh wasn't those ones on the end it's actually this one over here and i'll spare you all the footage that i shot of um trying to track that down but anyway it was really annoying so it's actually here and here there we go 4.4 volts okay so we have a filament voltage um is it supposed to be that low i'm not entirely sure yeah so we've got ourselves our ac filament voltage there so that's okay so uh what's left driver chip even that all the magic smoke from the vacuum fluorescent displays escaped thou shall measure voltages and well we have one more to measure there's a plus a 3.9 volt rail in there which that transistory there is doing something but that is uh vcc one there for the uh main driver chip so if we're not getting 3.1 uh 3.9 volts on there where is that being derived from aha it's been derived from the uh ac supply here so there's something wrong in there we're not getting that 3.9 volts gotcha and it's that point in the video where i thought i was going insane but no it turns out murphy has bitten us on the ass look at this i was wondering why i was measuring uh like you know the voltages weren't off and then i started them were off and then i started to uh check grounds going to the chip and the grounds didn't match up and everything like over here on the schematic pins 19 and 20. right i was using those as a ground i was tracing that back as a ground reference and i was wondering why 19 and 20 weren't shorted look at the silk screen 19 and 20 over here are led standby and key into um it's 14 and 15. that actually ground the schematic does not match the pcb yet this is the schematic for this model number but maybe they've got a different rev board or something unbelievable oh i get it now look pin one is pin 33 and vice versa it's just upside down compared to the pcb ah it's obvious i've got the australian version of the schematic the moral to that story is like when you notice something weird follow it like i noticed that oh okay the voltage is like i wasn't getting the voltage i i wanted like i was measuring there's another uh pin on the chip which is a vp and i was like i was measuring that and i wasn't getting it i was trying to trace it back because you need a ground reference of course to measure it and i was choosing the connector over there and it wasn't right and then i thought something started going down the rabbit hole well is this ground yeah have i got a dry joint is there a bad link or you know in in one of the links because this is all a single-sided board so there's all these links in there it's got to jump all the ground has to jump over maybe one of those is bad or something so i was following her back and i could not buzz the ground pin of this i ultimately went right i'm checking that the ground pin of this goes over to the ground here and it didn't and then i kept following and then i realized don't the pin out's wrong so don't ignore that niggling feeling that something's up because well something could be up and something was up damn it okay i have determined a ground a reference point here that's the ground of the chip i have determined that this point up here is the 3.9 volts of the ah what do we get 3.5 oh is that near enough is that near enough i don't know maybe i have to read the data sheet but you know it's good enough for australia surely well no it turns out that that uh 3.9 volts there is not generated from the filament ac it's actually generated from a zener over here look 3.9 volt zener with an emitter follower there all right so let's actually check this emitter follower circuit here uh where five volts in we've already measured the five volts we know that's okay this is supposed to be i don't quite understand this is supposed to be a 3.9 volt zener there and it says that it's 3.9 volts on the output well you're going to get your drop you're going to get your pn drop in there so i'm not sure what the deal is there but anyway let's measure that make sure we got that rail there it's our 5 volts input as we expect and we're actually getting that's the zener voltage that's uh 4.2 instead of 3.9 so i'm not sure why um who knows they might have changed the part we might have an out of date schematic um anyway let's measure the 3.5 3.5 volt rail instead of 3.9 whether that makes a difference i don't know but that's kind of like the drop you'd expect it's not zero so i don't know is that good enough for australia three and a half okay so what i've done is i've measured all the caps on there i've made sure like there's no shorts anywhere everything looks fine the diodes measure fine everything's hunky-dory so next thing to do is check uh that the chip's actually getting um signals to it there's a couple of resistors down here so on one side there you go that's some sort of clockity-doo dart on the other side of the resistor just to make sure it's not being loaded down no yeah that's like data that's data that yep looks like data again yep that looks good and the other one's just a reset and that's permanently high i believe that is correct so it's not reset so chip's getting um data so but it's not displaying anything so is the four point whatever volts on the vacuum uh filament too low is it the has the magic vacuum escaped from the uh vacuum fluorescent display is the chip otherwise somehow dead the external components does that emit a follower circuit cause a is that causing an issue i kind of expected it to at least do something so i don't know well the next thing we want to do is uh there's another rail in here that's the vp pin on here and that comes from this diode circuit here which taps off uh the ac it's a bit convoluted the way it's all drawn you've got to follow it but it basically taps off the ac filament voltage so and you can see that that cap there goes down to that 3.9 volt rail and it's backwards so so negatives over here positive is over here so we expect uh that vp rail to be negative as opponent compared to 3.9 and that i believe is going to be the uh the driver voltage for the vacuum fluorescent so we should be able to see a negative voltage on there so let's measure vp uh it's 3.9 volts um what the heck the other side of the diode there six volts um okay okay let's get the crow on that and well there's our filament voltage okay so that's hunky dory and the other side over here well the wrong pin again there we go that's our filament voltage so there is our that's one side of the diode that's the other side i ain't seeing no negative voltage so something's going on there so what we're going to do is uh check that zener in there it's supposed to be an 8.2 volt zener that's one way 0.8 so regular diode drop the other way using 15 volt diode mode on the 121 gw there you go um that's bang on so nothing wrong with that zener you can see those two resistors in there 220 ohms each so that's just feeding that so we're supposed to get a negative voltage out of there when not so i'm going to check those caps well that 47 mic across the diode looks okay and the other cap in there that 10 mic that's just fine as well so yeah what the problem is is this uh vp voltage here it's supposed to be like significantly negative i.e tens of volts negative like you know minus 40 volts or something it's the pull down voltage for the vacuum fluorescent tube and we're only getting like positive two volts on there that's all we're measuring so everything else around here seems to be fine so i can only assume okay it's going in there that's 10k that's high impedance so it's nothing to do with that transistor there it goes vp does go over to here there is a cap there oh could that one be shorted oh i might have to check that but it does go somewhere over to the connector why don't i is it being generated over there i thought it was generated here from the but yeah we don't have enough voltage there hmm where's this going i'm going to follow the money there well yep um if i actually engage my brain i would have known that yes that negative vp voltage is like we should have checked that and we should know when it was negative and we should have like could have saved a bit of time there anyway um yeah this is actually on the uh video switch board so over here here you go there's our plus five so a plus five volt display we've actually yeah we've got that no problems whatsoever but the negative vp there is actually it's generated down here there you go there's a 30 something volt zener and there you go it's supposed to be negative vp it's actually uh marked as minus 35 volts so we're clearly not getting that that's why it ain't working so now believe it or not we're actually going back to the transformer tap board over here and i've measured it um because that vp comes from a separate tap it's a 39 volt i'm measuring 39 volts uh ac on there so anyway we have to get to the video switching board which is now under here and that's like really annoying like why couldn't they have put this stuff on the actual uh display board itself ah these bloody multi-board designs just put stuff around willy nilly have oh that's a standoff post there we go there you go there's a ribbon cable there now access a video switching board down there which has our negative vp generator on it and here's where it starts becoming a gigantic pain in the ass because here's our negative uh vp here this comes from our ac tap down here and uh this stuff here is unfortunately on the bottom of this board down here we don't have easy access anymore there it is there we're looking at uh zener diode 36 volt zener diode 9005 and 9001 down there there's 9005 down there this is the bottom side the solder inside of the board but we can actually access uh 9001 that's actually on the top side that's i think those three pins in there so that's a to92 and but basically yeah um we're getting like it was easy before we could measure this thing all powered up and everything's hunky-dory but now it's integrated with this sideboard over here and it's all interconnected and oh it's just no i think the only way to get this board out because it's got like you can't just lift it out because uh it's connected right angle into this ball which is then connected down there and it's got its own standoffs and everything else i think we have to get this back panel off pull this off and hopefully these boards that are connecting to the speaker jacks there because like i can't yeah you can't get those yeah i have to unscrew all those unscrew the entire back panel and hopefully the back panel comes off and then we can pull this board out and then up okay i think i got every screw out and then i had to take the mains cord grommet out hey there we go that's actually very nice how that pulls out there now that ball's just flapping around in the breeze now they're all just flapping around in the breeze but yeah i should be able to pull that off now and access my surface mount parts on the bottom unbelievable yeah there we go we can now access the stuff on the bottom but uh yeah i don't see how we got like we probably can't just power this up on its own because uh then you don't have the connections through to the front panel and the soft power switch and all that although i think by default it does power on um so maybe we don't need that anyway and these ribbon cables too you can't just pull them out they've actually got like a locking mechanism on the side of these so you can't just can't just whip them out but anyway so i might have to bring the soldering iron to the job now unfortunately it doesn't look like we can power this thing up externally there's just too many um interconnected boards and everything i mean i'm just measuring like the basic 12 volt rail coming out of the tap there and it ain't working so yeah i can't just like power this thing up and probe around and everything maybe i could hack the soft start circuitry to make it actually switch on and make it work but oh geez it's getting messy now anyway um yeah the the problem here is that we don't have our negative 35 volt rail and i did find it's on one of the actually the only place that's the voltage is ever marked for our negative vp is on the uh overlay for one of the pcbs one of the pcbs that it passes through it's got minus 35 volts on it so it should be at that and that's the only rail that we don't have so unfortunately like i've tested the uh diode in here i've tested the transistor well it's you know as far as i can without taking out a circuit they all seem okay so i'm not sure what the heck's going on hmm and sure enough that uh 2sc 2235 transistor tests okay at least at a basic level in a tester like this doesn't mean there's not some high voltage breakdown or some other you know aspect to it but it's a transistory so uh as far as this video is concerned um it it's a bit of a diminishing returns i mentioned this on twitter um doesn't mean i'm not going to fix it it just means the effort required to go through it's going to take many many more hours probably to dick around with this thing to try and uh get to the bottom of this anyway yeah i'm calling it quits for this video so consider this a part one we've found the fault but it's just not easy to test and get back up and running that's all so yeah i'm just going to leave it here for the time being i need to get on with other stuff sorry if you don't like these repair videos that you know oh dave only released the video when you finish the repair what are you hopeless or something oh look you know come on this is just ridiculous anyway i hope this video was interesting enough so i'm going to leave it there for the part one i think we got to an interesting point where we've discovered what's actually wrong with this thing it's just a matter of fixing it and with all the paths that are going through all the different boards on this it it really is a pain in the butt and just not being able to power it up is just really annoying and oh god anyway ah i've had enough for part one catch you next time [Music]

Channel: EEVblog

Views: 56,089

Rating: 4.9208164 out of 5

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Id: YMC3R86_2h0

Length: 35min 12sec (2112 seconds)

Published: Thu May 20 2021