Faulty JVC HIFI With Valves! | Can I Fix It?

I saw a faulty JVC HIFI on eBay for spares or repair. What caught my eye about it was it has a valve amplifier inside, but it has USB Bluetooth and other modern features.
It has a bit of strange fault where none of the front panel buttons or controls respond, except for the power button.
Come join me while I try and repair it.. and mistakes were made along the way!
I'm not an expert, but I do enjoy trying to fix things.
If you enjoyed this video, or found it useful or helpful, please consider subscribing. It's free and you'll be notified when I upload more videos.
Thank you for your support!
Some of the tools that I use:
The Famous Blue Mat: amzn.to/47bPNGK
170 piece electronics tool kit (security bits): amzn.to/3FGLWpr
Aixun T3A Soldering Station: amzn.to/3u2SBri
Infiray P2 Pro Thermal Camera: amzn.to/47c05Xm
Soldering Flux: amzn.to/3Qn8Yq7
Low Melt Solder: amzn.to/3QICZ5r : Cheaper Alternative amzn.to/3G4L3XK
Grinding pen: amzn.to/3QCHE7v
Component Tester: amzn.to/46UcHm6 alternative (slightly cheaper) amzn.to/49yZSzJ
Overhead Camera Mount I Use: amzn.to/3tX8Ar4
Microscope Light (I use on my Trinocular): amzn.to/3FEAPgy
AD409 Pro Microscope 10" Screen: amzn.to/3G0CI7P
Extra Long Torx Drivers(used on Milwaukee radio): amzn.to/40siUU3
DC Power Adapter plugs 38 PCS: amzn.to/49lCUMm
USB Power Meter Tester: amzn.to/3T1hD4J
#electronicsrepair #electronics #repair
Faulty JVC UX-D150
JVC valve amplifier repair
JVC valve HIFI repair

[@karlfell3768]

The issues were all centered around the conductive glue. It used to be called Sony Bond. As the name suggests, originally developed by Sony in the seventies. It became a plague over the following decades in many consumer electronics. A bit of a ticking time bomb. I always clear it out as soon as i find any. Very unusual to find it in something of that age. A great repair and patient fault finding. Karl

[@plasma453]

Interesting i'd never heard of it before but if you Google "Bond glue issues and pictures" there is a fair bit on it.

[@wisher21uk]

There was a range of Samsung TVs that suffered with that glue it turns brown and then get conductive, cleaned many boards and had to repair them, usually quiet a catastrophic failure ending is burning out

[@BuyitFixit]

Thanks Karl, first time I've came across it. Good to know and thanks for commenting!

[@t0nito]

I have an ols Yamaha AX-400 amplifier that would trigger the protection randomly, first thing I did before anything else was to scrape off all that nasty glue and cleaned with alcohol. It never triggered back since.

[@wisher21uk]

@@t0nito caught it just in time 😁

[@a2zme]

One thing I've realized from watching master electricians repair stuff on KZbin is the incredible PATIENCE required. This video just amplifies that point (no pun intended) .. great job!

[@BuyitFixit]

Thanks 👍much appreciated 🙂

[@DJ_Sycottic]

Amazing fix, you've got the patience of a saint. My sister had the same model, I loved it and was going to get the same but after an unfortunate incident I became disabled so couldn't afford one. When I saw your video I thought I could watch it and look for one with the same fault but after watching what you went through I think I'll stick with my 20yr old Sony hifi... 😂

[@BuyitFixit]

Thanks 👍I saw another one on eBay about a week or so after this one, it was a Sandstrom unit and it sold for £6!

[@jackbauer2698]

40 minutes for us, hours upon hours of diagnosing for you. Respect 🙏.

[@BuyitFixit]

Thanks Jack👍

[@adrianstephens56]

Nice video. Your patience and persistence are awesome. Weird how "what goes around comes around" - in this case valves. I started out with valves as a teenager, because I could pick up scrapped TVs and pull them apart for components. I used to have a box of fluffy wax capacitors, and I still have my box of EF80s, ECC82s and similar vintage valves. But to see a valve (hardly high tech) married to NFC truly boggles the noggin.

[@BuyitFixit]

Cheers Adrian 👍

[@rory9174]

My God you have great patience and amazing skill at finding the source of electronic failures. Brilliant video, thanks so much.

[@BuyitFixit]

Thanks Rory 👍🙂

[@fredwooding599]

You had me on the Valves thing.. We in USA call them Vacuum Tubes.. Great job kind Sir.

[@BuyitFixit]

Cheers Fred 👍I'll try to get a look at your device this week. I've been busy pulling the gearbox out of the van as the clutch failed.

[@wisher21uk]

Clean that brown glue off of the board near that crystal, may effect anything as it degrades more, it turns brown and conductive Nice fix Mick really appreciate your time and effort 😊

[@BuyitFixit]

Thanks Cucumber man, yes I had a bit of a nightmare with this one!

[@wisher21uk]

@@BuyitFixit Mick I forgot to say.. that was the video you mentioned with the shock !!!!! I thought that was quite an impressive crack I heard, it must of had a bit of a bite behind that one, I felt your pain 😁

[@en2oh]

Your persistence is admirable. We’ve come a long way from board level repairs to “remove & replace”. Not in a good way, but then again, time has become so expensive and boards so cheap… I suspect that this unit wouldn’t be worth repairing. Nicely done

[@BuyitFixit]

Thanks 👍I've repaired a lot of things that are perhaps not really cost effective, it's more out of interest and the challenge 🙂.I've had a few issues with manufacturers not willing to help too. I had this with the FLIR thermal camera I repaired and the solar inverter I repaired where the company wouldn't give me a service password after I repaired it! Ended up having to reverse engineer their software and write my own password tool which I've released freely to help others people. Both videos are on my channel if you haven't seen them 🙂👍

[@SuperHandyMan]

I have watched a number of your videos lately. You're quickly becoming one of my favorite channels. Can you tell me what type of flux you use and why? Tell us about solder selection as well. Keep up the excellent work.

[@BuyitFixit]

Thanks 👍The flux was just one I bought from Amazon, it was cheap and seems to work fine. The solder reel I normally use I've had for years, but I much prefer leaded solder. It's a lot easier to work with and doesn't require as much heat and isn't as brittle as the lead free solder.

[@personalPickle]

Another cracking video, great teaching too - I now know what a H bridge motor driver circuit is and I'm proper chuffed about it, thank you. 😊 That being said.. 'Girls with guitars' really?! 🤣..I think Brian Johnson's cap just shot off! Should have been a copy of ACDC High Voltage!! p.s This man should be at 100K followers already, come on guys!!

[@BuyitFixit]

Cheers 👍🙂 The "girls and guitars" is my wife's. It was the only CD I could easily lay my hands on for "testing" 😂😂😂

[@personalPickle]

@@BuyitFixit 😁 😂 'It's not mine it's me missus's' - that old chestnut eh.. 😆🤣

[@robtitheridge9708]

nice fix. the valves are only a buffer stage before a class d amp a bit of form ovetr function..that glue is becomingt a pain in lots of eqipment .

[@BuyitFixit]

Thanks 👍I was wondering about that as there seemed to be an amp chip under the heat sink on the main PCB. I've read a few other comments about the glue saying similar. Thanks for sharing 🙂

[@bobbaggs6149]

As a relative newbie to electronics I learn a huge amount from you. Your fault finding and descriptions of circuits etc are informative and educational. Always interesting and my goto electronics channel. Much appreciated.

[@BuyitFixit]

Thanks! I'm no expert, but I do seem to know enough to get by. Thanks for the kind comments 🙂👍

[@TheRealBobHickman]

Great fix! I would have thrown it across the room about half way through :)

[@BuyitFixit]

Thanks 👍Don't worry.. I was tempted 😂😂😂😂😂

[@marcyd2007]

Nice job Mick, as always. Nice to see a couple of old valves in there, you don't see them much these days. I've never worked on anything with them in personally. Cool that you can see the valves from the front when it's switched on too.

[@BuyitFixit]

Thanks Marc 👍

[@JimmysGarden]

I enjoy the way you fault find and determination to fit it. Cheers, 👍👍

[@BuyitFixit]

Thanks for that Jimmy 🙂👍

[@mattc3385]

Nicely done, sir! This one was up there with the FLIR repair. I commend your patience and ingenuity and will try my best to emulate it!

[@BuyitFixit]

Thanks Matt 👍🙂

[@NiddNetworks]

Love the variety of stuff you find - and the variety of faults you find in the stuff! Air gone out of a nailer? Check! Buck IC in a little valve stereo? Check! Can't wait to see what's next. I feel your pain with the "can't test without full reassembly" thing too... I'm working on an intermittent fault in my car, which has resulted in many a centre-console removal!

[@BuyitFixit]

Thanks👍 Yes, I do try to do a wide variety of stuff. I think it makes it more interesting! Best of luck with your car. I know exactly what intermittent faults can be like😂😂

[@MikeyMack303]

Good to see you got that working correctly again! Nice unit!

[@BuyitFixit]

Thanks!

[@captiveimage]

Great demonstration of tenacity ❤

[@BuyitFixit]

Thanks 🙂👍

[@mikecass8306]

Great repair Mick. You can't beat the sound of a valve amp 😀

[@BuyitFixit]

Thanks Mike 👍

[@koraypekericli]

Very good description of how this equipment works. Thank you! K.

[@BuyitFixit]

Thanks 👍

[@BPantherPink]

BRILLIANT fault-finding Sir 👌 👋👋👋

[@BuyitFixit]

Thank you 👍

[@chrisbartlett6022]

I love stuff with valves in. Took an old van to bits when we were kids and it had a valve radio in it. When I was in Redditch a mate and myself used to buy and sell a valve amp off each other when we needed money. Unfortunately he ended up with it when I came home. Had a gorgeous tone to it.

[@BuyitFixit]

I didn't know you could get car radios with valves. Interesting.

[@thetraindriver01]

Really nice job, great patience 👍

[@BuyitFixit]

Thanks 👍

[@victorclaudio3764]

wow, sounds amazing!

[@Js2060]

I really enjoy your videos. I tinker a bit. I like how you never give up. Been binge watching you.

[@BuyitFixit]

Awesome! Thank you!

[@Martyn-ey9lw]

Another excellent fix yet again, by far the best repair channel on KZbin, almost got a Vince "YES" at 39:46. Keep up the good work.

[@BuyitFixit]

Thanks, will do!

[@johnpartridge7623]

Good result mate 👍

[@BuyitFixit]

Thanks 👍

[@cymap]

It took time but what a satisfying fix and a lovely looking piece of kit with those valves glowing. Well done!

[@MattBrownbill]

I would laugh if the valves were purely cosmetic 😅

[@BuyitFixit]

Thanks👍🙂

[@BuyitFixit]

I'm not too sure, but if they were, would they go to the trouble of using a transformer and having a proper power supply section to supply 185v? seems a bit overkill. I think however they did add some LED's near the valves to make them more "glowy".

[@devshibhodia1738]

Well done, I that that was never ending with faults. you are very good, love watching your videos. well done keep up the work. you have definitely inspired me to look at faulty items to fix. Thank you

[@BuyitFixit]

Thanks 👍and good luck with any future repairs 👏👏👏

[@repairchannel]

Thank you, that was very inspiring!

[@BuyitFixit]

Thank you 👍

[@michaelclutton8446]

Thanks for the video, you did well fixing this unit, I have subscribed

[@BuyitFixit]

Thanks🙂 and Thanks for the sub! 👍

[@ISquishWorms]

This JVC unit didn't want to be fixed but little did it know that it would fall into your hands. It tried to beat you though which made for a good video. I like the way that you can see the valves through the front that is a nice touch. I would like to have a unit that used valves as they are before my time, and they just look nice like mini little candle lights. It also used a nice toroidal transformer too. The unit sounded really nice and was worth saving. Oh the when the caps got shorted out I jumped as well. Keep fixing looking forward to the next video.

[@BuyitFixit]

Thanks 🙂 Yes I did get a bit of jump scare out of it! and it does sound pretty nice. My wife has commandeered it now 😂😂😂

[@ISquishWorms]

A bargin then as it kept the wife happy too. 🤣@@BuyitFixit

[@lumbo101]

Possibly a factor in the buck regulator chip failures without the (10uF?) local ceramic decoupling cap would be voltage spikes due to the switching current in the extra parasitic inductance (a few cm of trace to the bulk electrolytic smoothing cap?). Great video, thanks.

[@BuyitFixit]

And thanks for your thoughts 🙂👍

[@jonnyduncan7056]

Great fix..

[@BuyitFixit]

Thanks 👍

[@mistersunny3636]

What an surprisingly massive power supply. Nice!

[@BuyitFixit]

Yes indeed 👍

[@ianbradshaw9704]

great Video, Keep em' coming. Cheers

[@BuyitFixit]

Thanks Ian 👍

[@markpirateuk]

Great repair & great patience, these things are so fiddly to work on, I make a point of marking the plugs & sockets with a sharpie, you never know how long it will be before it goes back together 😆

[@BuyitFixit]

Thanks👍 I know exactly what you mean. I've got a few things in bits which I'm waiting parts for..

[@JamieBulloch1]

great stuff. persistence pays.... i think the gunk was called 'oh dear, glue gone, buy new' strategy....

[@BuyitFixit]

Thanks Jamie👍

[@davidgordon796]

Great job 👍👍👍

[@BuyitFixit]

Thank you 👍🙂

[@peterd1083]

Very good! I wish I had your skills.

[@BuyitFixit]

Thanks Peter 🙂👍

[@cajuncoinhunter]

That circuit board glue reminds me of the Uniden / Cobra chassis etal. It is a light color when new and then turns darker with age and becomes corrosive and conductive , I've seen many an older radio in the 90's come into my shop with the 10.240 XTAL legs ate away and the big caps looked like they were leaking , but were fine ...... Great diagnosing on this one ...... Take Care Mon Ami.....

[@BuyitFixit]

Thanks Cajun👍. Yes a few people have mentioned about the glue and it all makes sense. It's the first time I've came across this problem, so good to know 🙂👍

[@WelshLad.]

What a great fix. I like the old tubes and I know how you feel with no reception we can't get DAB here too in Pontycymer

[@BuyitFixit]

Thanks, yes DAB and even FM reception is poor here. I don't bother with TV either because the transmitter here only has a few channels (freeview lite) so I just watch catchup or youtube via the internet. I use a 4g sim card for that as it was talking me 8 hours to upload a 20 minute youtube video when we had ADSL!

[@JaysElectronicTinkerShack]

Nice little bit of kit that hybrid valve amp there using the valves for a valve preamp sound prob has a rda chip for the actual speaker output may have a hint for one of these cause has a nice look to it , I’ve had issues in the past when something has burnt like that capacitor where the carbon on the board causes shorts too but what. A nice little fix

[@BuyitFixit]

Thanks 👍🙂 There is an identical unit, but it's badged Sandstrom. I saw a faulty one sell on ebay for £10 about a week or two after I bought this one.

[@markusallport1276]

Very nice troubleshooting and repair. I suspect the tubes are 12AX7 pre-amp tubes. they are plentiful and still produced in Russia and Ukraine.

[@BuyitFixit]

Thanks 👍yes one thing that I didn't look at, is what tubes it contained unfortunately.

[@deathventure]

One thing to note about capacitors on voltage regulation circuits, often enough they are there to prevent oscillation on the circuit. The oscillation on the circuits can cause any range of issues, including not letting the circuit work at all.

[@BuyitFixit]

Thanks 👍

[@stevedebeukelaer1424]

Nicely fixed rarethe motor failed never happened by me. Yea the glue if it old can be conducted. Good job.

[@BuyitFixit]

Thanks 👍yes not sure what caused the motor failure 🤷‍♂️

[@tomharris1457]

Agree with Karkfell, could not remember the name of the glue, but it turns nasty.

[@BuyitFixit]

Yes I thought it must have been the glue reacting! Thanks 🙂👍

[@piotrnowak4870]

Respect for your skills mate...Well done.All the best from Cleveland.Peter.

[@BuyitFixit]

Thanks Peter 👍

[@FixthisCD]

Dislike those little jam packed units. Good work

[@BuyitFixit]

Thanks 👍

[@luminousfractal420]

Nice nice. I picked up a really nice tascam CD/cassette rack mountable thing on a wish and a prayer, wish was granted, it's only issue was the tiny switch that let's it know the cd drawer is closed had somehow worn down or shrunk by about 1mm, enough for it not to close. I saved hundreds with a matchstick shaving and some superglue 😂 (but reality check I've also got several other repair jobs that are a bit more intense and above my head, but I want to bring them back to life. Sw. Radio is one. It was all crusted over with what looked like salt crystals and there's a couple of exploded components I had to identify from the body parts but life it will get, one day. I hate this thing of throwing quality equipment in a landfill only to be replaced by some cheaply made overpriced rubbish.

[@BuyitFixit]

Thanks 👍You might find one of those drawer switches on an old computer CD or DVD drive. The salt crystals could be the remains of either battery corrosion if it was battery operated or the remains of electrolyte from leaking capacitors? Yes I agree, we are such a wasteful society now. Even things that are fully functional (old Iphones for example) are now just tossed to have the latest model.

[@snipersquad100]

Nice little radio is that.

[@BuyitFixit]

Yes, my wife quite likes it 👍

[@keymad4]

brilliant

[@BuyitFixit]

Thanks 👍

[@yvesrochet3288]

Awesome Work as usual , Karl. How many hours in reality?

[@BuyitFixit]

Good question, I can't remember exactly but I thing it was a few!

[@josephlalock8378]

it's a habit of mine to clean up that glue on any unit that i repair/refurb. even if it has not yet turned "conductive brown"

[@BuyitFixit]

Good idea. It's the first time I've came across it.

[@vanderlinde4you]

I'd say that today's tech and "digital components" stuff blows out way faster then the old stuff. I had a soundbar - pretty much the same diagnose as in above. They can't handle long term power.

[@BuyitFixit]

Interesting. Thanks for commenting 👍

[@johnmchardy1229]

Yes I have found that as well. The glue is the problem.

[@BuyitFixit]

Yes, that's pretty much the conclusion I came to as well. Thanks for sharing 👍

[@SlartiMarvinbartfast]

Well done on the repair. I always really enjoy your videos but I'll never figure out why you put some electronic devices fully back together before testing, particularly in cases like this where more than component is obviously involved. In this instance for example you could have done some more testing without reassembling the case the first time (and even going so far as to put the screws in). You're either extremely confident in the repair or you just love using your screwdriver. ;-)

[@BuyitFixit]

Thanks 👍Perhaps over confident at times. I was sure that it was fixed, but then again I do get things wrong. I had to pretty much assemble it anyway to test it and the top cover was only 6 more screws..

[@ronwade5646]

Tubes, we call them hot, glowy things, TUBES!

[@kingey71]

Not to us who use proper English language 😂

[@chrisprobert6]

Sounded like lightning, when you removed the board first time. Good job it wasnt your fingers😅 I laughed for a while, we both jumped

[@BuyitFixit]

Yes, I actually jumped again watching it back 😂😂😂😂

[@andymouse]

Awesome work ! great to watch. However I'm a bit of a sceptic when it comes to hybrids like this as I think that the "power" side of it and all the HIFI stuff was under that heatsink probably a class D chip on the 'bother board' as the speaker outs and phono in were all on that board as well. So everything to do with the music was on that board and they used the Valves as a Pre Amp only, or as I have seen in headphone amps they only wired the Heaters up for effect and had an NE5532 (great chip) as the Pre Amp. If and I hope not ! you ever have to open it again I would love to Know exactly what those valves do !!....cheers.

[@BuyitFixit]

Thanks Andymouse. I had been thinking something along those lines too, as when I was looking at the main board which I had out, under the heatsink was a chip that did look like an audio amp.

[@jasejj]

It's a valve buffer - the idea originally was to match up impedence between source and preamp, or preamp and power amp better by placing the valves in-circuit, the addition of "valve warmth" being a side effect. Complete waste of time on an all in one system like this though! I have one of the original valve buffer devices from Musical Fidelity and it does clear up the stereo "imaging" effect on a good hifi setup. There's a guy who puts these valve buffers into CD players which are claimed to transform the sound over mass-produced op-amp based output stages - look up "Lampizator".

[@coyote_den]

That little capacitor goes to a pin marked BST. It is a bootstrap capacitor and the DC-DC converter isn't guaranteed to start without it. That component glue is awful. When it turns brown it gets corrosive and conductive. Every single failure you found was under that stuff.

[@BuyitFixit]

Yes, that glue is awful. The capacitor that was blown was going to gnd and pin 2. The other capacitor seemed fine going between pin 1 and pin 3.

[@apollorobb]

I deal with that stupid Sony Bond glue all the time. It becomes conductive and corrosive if it doesn't short the component its on it will eat the legs and pads on the board . i do a ton of Vintage Receivers for a living and this is super common .

[@BuyitFixit]

Thanks 👍First time I've came across this problem so good to know🙂

[@jasonhale4639]

conductive glue that they used on that board I bet that is causing shorts and corrosion. It was a known issue with certain electronics. The glue became conductive and acidic with age.

[@BuyitFixit]

Thanks 👍a few people have said the same. I'd not came across it before but at least I know now 🙂

[@herby4215]

I'm lucky to find them working in 😅

[@MarvinHartmann452]

I thought they were done putting that glue. I've rebuild some older sansui products from the 70s and 80s completely because of that. They put silicone now.

[@BuyitFixit]

Thanks 👍a few people mentioned the same, so I'm going to take it apart again and remove all traces of the horrible stuff...

[@tim0steele]

Maybe a visual inspection of that board might have helped earlier on? :)

[@ralphj4012]

Well done, not a straightforward fix, good. The brown gunk (in two places) looks suspicious and I wonder whether it shorted what looked to be the input noise decoupling cap on the regulator. Probably an illusion but part of the crystal looks to be eaten away (36:50). £30 including postage, large letter it is not. Love the thumb on chassis power supply testing technique, ho, ho.

[@BuyitFixit]

Thanks👍I've been reading the other comments and it seems the glue goes conductive and causes short circuits, a common issue with plenty of other devices apparently!

[@LinusJohansson-yu7cy]

Chip killed by "death glue"... Make sure all that glue gets removed from every board on that unit! Once it turns dark like that, it also turns conductive and corrosive.

[@BuyitFixit]

Thanks 👍a few people have suggested the same. I'll be taking it apart again it seems 😂😂😂

[@iantyler4045]

That brown goo absorbs moisture and becomes conductive over time. All traces of it need to be removed or it will eat away at the PCB. Many VHS VCR's succumbed to it.

[@BuyitFixit]

Thanks, a few people have said the same. I think I'll take it apart again and remove it. Any suggestions on what's the best way to remove it Ian?

[@iantyler4045]

Scrape off most of it with a pick or small screwdriver then clean the rest off with isopropyl. @@BuyitFixit

[@BuyitFixit]

Thanks Kevin 👍I've got some freezer spray 🙂

[@leewright6101]

its a valve preamp and main amp is a class d amp we used to fix these all the time valves used to come out all the time, was common issue from currys when we used to buy pallet loads of currys faulty goods, but yeah, keep your videos comming,

[@BuyitFixit]

Thanks Lee, I was wondering about that as there did seem to be a chip on the main PCB (underneath the large heatsink) which looked like an amplifier .

[@SPINNINGMYWHEELS777]

You need a hybrid power supply for that hybrid unit.. I call it a sledge hammer.

[@BuyitFixit]

🤔

[@peterfindlay5820]

What product do you use to clean off the resin or clean up the boards? Isopropyl alcohol or acetone?

[@BuyitFixit]

I have both, but use Isopropyl alcohol mainly 👍

[@tanjem]

yoy might want to visit Thailand second hand market ...largest in asia to find and repair stuff there . I am sure your skills will be put to the test ..

[@BuyitFixit]

Maybe one day!

[@Irilia_neko]

This glue is well know to create short circuit

[@voodler]

Yup, that glue has become hygroscopic and is now mildly conductive. That probably blew up the capacitor by shorting it and was corroding the other components. It should really all be cleaned off I think.

[@BuyitFixit]

Thanks for that. I've read a few similar comments so I might take it apart again and remove all of it. Thanks again👍

[@EsotericArctos]

I dont really like these modern attempts at hybrid amplifiers. Most of the time the "valves / tubes" are nothing more than low voltage buffers and do little to introduce any valve sound and most of the work is still done be solid state, like op amps and d class amplifier chips.. Fun to make a video on, but definitely nothing I would purchase for my own use.

[@BuyitFixit]

Yeah that seems the case, most of the work seems done by a chip and it seems more of a gimmick. It actually doesn't sound too bad and the wife seems to like it 🙂👍

[@brakeless9709]

I would be curious to know if you tested the inductor you removed, after you had it off the board? Do you think it may have played a role in the downfall of the first two chips?

[@BuyitFixit]

Yes, I tried my component tester on it (I don't have a LC meter) but the component tester showed both inductors as low value resistors with the same resistance.

[@screen-protector]

I've got exactly the same model with no power. I found one thing shorted, replaced it, but still no power only no short. I don't have time now, but, would love to fix it one day. If I won't be able to find schematics, would you do some readings for me, please? :)

[@BuyitFixit]

Could do as I probably need to get into it again to remove the rest of that glue.

[@TechGorilla1987]

@35:54 - That transistor lead soldering looks kin of cracked and shite. I'm probably wrong.

[@BuyitFixit]

No, I thought the same when I was editing the video. The other side of the board looked soldered fine though.

[@dannyhawkins7229]

Those valves look a lot like tubes lol.

[@BuyitFixit]

Those tubes also look a lot like valves 😂😂😂😂

[@simontay4851]

The main amplifier is class D. You can tell by the inductors near the speaker outputs and the large heatsink, which the chip will be under. So what are those tubes even doing? They seem to be just a gimmic for show. Is there even high voltage on the cathode.

[@BuyitFixit]

I didn't measure it but on the AC from the transformer it was marked 185v I think they are a pre-amp from what other people have said. I've also seen two tube pre-amps on Ebay.

[@allen5976]

A cotton swab is the last thing I'd go for to clean a pcb, its too risky and can pull components off the board, can't beat an old toothbrush or artists brush and ipa

[@BuyitFixit]

I use the old toothbrush too 🙂 I find it doesn't mop up the flux residue though and just spreads it around the board.

[@aliwho]

Wow

[@BuyitFixit]

👍

[@Popeyes66]

That job nearly kicked your A*$ Mick,but i knew that you would sort it out. Nice little unit.

[@BuyitFixit]

Thanks 👍

[@LuxAudio389]

They use a nice low noise toroidal transformer and then put a horribly noisy switch mode power supply behind it and ruin the noise floor. 🤦‍♂️

[@BuyitFixit]

Good point!

[@zedcarr6128]

35:17 The H Bridge Driver circuit is incorrect. The NPN / PNP pairs should be active on opposite sides. With the circuit show in the video, the transistors will ''crowbar'' the supply, destroying the transistors.

[@BuyitFixit]

Thanks 👍 I just did a C+P from the interwebs for a diagram, thanks for pointing it out!

[@proluxelectronics7419]

Spare or repair Rokit amp speakers have the same glue killer..

[@BuyitFixit]

Interesting, Thanks for letting me know👍

[@H2Dwoat]

Hi, just found your channel and have subscribed. just curious but is £30 a reasonable price for a non working JVC amp? What would a working amp cost? How do you mitigate any risks from charged capacitors, especially when they are in situ in a confined space?

[@BuyitFixit]

Thanks 👍Re price, I'd think so, seems audio stuff even broken seems to fetch a decent price. Someone else has one advertised currently for £50 broken, but I saw one recently sell for £6.99 similar model (Sondstrom). A working one (used) on Ebay anything from £50 to £180 ish. Usually capacitors have a bleeder resistor fitted that automatically discharges them, but not in this case it seems.

[@H2Dwoat]

Hi, thanks for your quick response. I enjoyed your video and admire your perseverance 👍.

[@BuyitFixit]

No problem and thanks for your kind comments 🙂👍

[@willtucker2774]

Why does that machine only have a a live and neutral feed? It should be earthed too. If its got external inputs it could be nasty or at least cause a hum loop. Cheers for the videos. Will.

[@BuyitFixit]

Thanks Will. Good question. I kind of remember back in the day when I had HiFi separates that things like the cassette deck and tuners either had a 2 core hard wired cable or a figure of 8 lead 🤷‍♂️

[@ScottGrammer]

Most home hifi units in America have two wire power cords, to avoid ground loops and hum.

[@geoffisaac3511]

I have this model i had in currys about 3 years ago am i right in saying that it is a bit con that it his not a true valve amplifier?

[@BuyitFixit]

Yes, it seems the valve part is a pre-amp which then feeds a class D amplifier chip which gives the output to the speakers.

[@henkkalter3892]

Once again the glue causes problems. The glue used to glue the capacitors becomes conductive after a while.

[@BuyitFixit]

I thought that might be the case, I might have another look in the future and remove what's left of it.

[@leso204]

originaly made by SANDSTROM . bought mine about 8yr ago must have been bought out by JVC' tube pre-amp solidstate power just like Marshall did with they're hybrid .....P/s never fire up an all tube amp without a load on the output ,,,,,,,,,,,,,,,

[@BuyitFixit]

I did see another unit which looked almost identical on eBay. It was a Sandstrom, the only difference I could see what the antenna input was located in a different place (more near the top of the case and towards the speaker outputs). That one only sold for around £6 www.ebay.co.uk/itm/186095082032

[@scratchback2001]

I know some people will disagree here but I hate PCBs. They flex and crack and in valve amps, heat only hastens the inevitable. I'm a point to point guy. PCBs have their place but in low voltage low heat environments.

[@BuyitFixit]

I didn't investigate too much on the valve side, but hopefully they used sockets so the heat shouldn't be a problem.

[@karlkuttup]

they are a nightmare a guy i know had 1 it came on but no sound ,checked everything still no sound he put it away as spares ,then 9 mnths later he found it was a pins on the valves were loose

[@BuyitFixit]

Interesting. Thanks for letting me know 👍

[@ncooper8438]

Have you ever calculated your average hourly rate based on the time to repair, parts cost and resale value? IMO repairs are probably uneconomical but done for reasons of interest and job satisfaction.

[@BuyitFixit]

No, but I doubt I make a profit or break even. Mostly it's just a hobby, although there is probably some profit in a few items.

[@echelonrank3927]

ha ha THE VALVES IN THERE PROBABLY NOT EVEN HOOKED UP TO ANY AUDIO

[@BuyitFixit]

I might check this as I plan to take it apart to remove the remaining glue.

[@echelonrank3927]

​@@Kevin-mp5of UR EARS DISAGREE

[@muppetpaster]

23:06 look inside the coil .......😉

[@BuyitFixit]

27:43 different inductor 😉

[@matthiasmartin1975]

It is funny how you said "ploog ed en." instead of "plug it in".

[@BuyitFixit]

Either my accent or stress 😂😂it's quite hard sitting talking to people that aren't actually there at the time while trying to fix things 🙂👍

[@matthiasmartin1975]

it is enjoyable to listen to@@BuyitFixit

[@handsomemann1]

It was a long video. So I fast forwarded it. Could not find the part you resolved it. But I enjoyed your accent. Sounds a bit Scottish. Is it? Can you tell me what went wrong with the unit?

[@BuyitFixit]

My accent is Northeast England. There was a couple of problems with it. The buck converter IC seemed to have failed, but it was still unstable until replacing a capacitor where the burnt out one was. Then the CD didn't work as the motor had burnt out.