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
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
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.
One thing I've realized from watching master electricians repair stuff on RUclips is the incredible PATIENCE required. This video just amplifies that point (no pun intended) .. great job!
As a repair technician in my younger days we were allowed 1 hour to diagnose what the fault was! If you exceeded this time you had to hand it to a senior technician who would ‘ have a look at it’ ! Time is money I was told! Have you checked this/that yes yes yes! I said finding the fault is like a detective hunting a criminal! You can’t wave a magic wand! I started keeping a record of all the faults found so that the next time a job came in you could save a lot of time by check this/ that!And it worked!😂
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.
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.
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... 😂
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
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 🙂👍
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.
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 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 😁
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.
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.
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.
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 🙂
Thanks for excellent video. I have one with no sound. I have taken it apart and can’t see anything obvious. I’ve removed all the old glue. I can hear sound very faint when I turn it up full. I’ve tested all caps with an est meter and all seem ok. I’ve removed the valves and check the pins all ok. Wondering is all sound sources routed through the valves before the class D amp?
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!
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😂😂
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.
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".
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.
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.....
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 🙂👍
Yep - at time index 20:36 what you are seeing is that glue that goes conductive as KarlFell suggested - Sony and some other manufactures also put that glue on certain items to keep them from moving - The older VCR's were notorious for this as well...
This diagnostic approach was awesome. Put the board in freezer and the bond should fleck off using dental tools or Harbor Freight small sculpting tools. After you are thru. Soak whole board in 99% IPA over night, then blow off with low PSI compressed air (3 psi) then let it sit on a heating pad for a couple of hours then plug it in. I don't like ultrasonic cleaners on old boards; the vibrations might cause solder issues. One other thing, as you know, leaded solder has lower melting point and this could cause problems on components that get hotter than 150°C.
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
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 😆
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.
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!!
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
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!
Can't help thinking those valves are just there for show..... there was a large chunk of that board you were working on that looked suspiciously like an audio amp and of course, the speaker terminals are on there as well, not to mention the large power cables from the transformer, the split rails, the fuses etc all on that board. And the final thing....who buys something like that? Great fix as always though. 10/10 for patience :)
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.
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.
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".
I think the valves on this unit work as a pre amplifier and it sends the low signal to the digital amp on the main board you was working on as I looks like the bigger heat sink is the amplifier.
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. ;-)
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..
@karlfell3768 is absolutely correct, that glue destroyed many a Ham & CB radio whenever it was used it would also become very acidic causing trace & component corrosion.
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.
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.
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.
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!
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.
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,
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?
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.
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.
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.
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.
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.
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 .
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.
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
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 ..
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? :)
Valves .... I play guitar ,and have a valve amp. 4 x 6L6GC, here you have only somepreamp valves, to introduce some "warmth" , what are they good for then???
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
Interesting i'd never heard of it before but if you Google "Bond glue issues and pictures" there is a fair bit on it.
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
Thanks Karl, first time I've came across it. Good to know and thanks for commenting!
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.
@@t0nito caught it just in time 😁
I agree! Your patience is awesome! I think an hour of this and I would have sent it to room 101 ! 😂😂😂
😂😂😂Thanks 👍
40 minutes for us, hours upon hours of diagnosing for you. Respect 🙏.
Thanks Jack👍
One thing I've realized from watching master electricians repair stuff on RUclips is the incredible PATIENCE required. This video just amplifies that point (no pun intended) .. great job!
Thanks 👍much appreciated 🙂
As a repair technician in my younger days we were allowed 1 hour to diagnose what the fault was! If you exceeded this time you had to hand it to a senior technician who would ‘ have a look at it’ ! Time is money I was told! Have you checked this/that yes yes yes! I said finding the fault is like a detective hunting a criminal! You can’t wave a magic wand! I started keeping a record of all the faults found so that the next time a job came in you could save a lot of time by check this/ that!And it worked!😂
@@elsaarmstrong-zp6ng Nice one, Thanks for sharing 👍
You had me on the Valves thing.. We in USA call them Vacuum Tubes.. Great job kind Sir.
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.
IN many places in the Eu also
Great fix! I would have thrown it across the room about half way through :)
Thanks 👍Don't worry.. I was tempted 😂😂😂😂😂
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.
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.
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... 😂
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!
My God you have great patience and amazing skill at finding the source of electronic failures. Brilliant video, thanks so much.
Thanks Rory 👍🙂
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
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 🙂👍
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.
Cheers Adrian 👍
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 😊
Thanks Cucumber man, yes I had a bit of a nightmare with this one!
@@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 😁
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.
I didn't know you could get car radios with valves. Interesting.
BRILLIANT fault-finding Sir 👌 👋👋👋
Thank you 👍
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.
Thanks! I'm no expert, but I do seem to know enough to get by. Thanks for the kind comments 🙂👍
I really enjoy your videos. I tinker a bit. I like how you never give up. Been binge watching you.
Awesome! Thank you!
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.
Thanks Marc 👍
I enjoy the way you fault find and determination to fit it. Cheers, 👍👍
Thanks for that Jimmy 🙂👍
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 .
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 🙂
Thanks for excellent video. I have one with no sound. I have taken it apart and can’t see anything obvious. I’ve removed all the old glue. I can hear sound very faint when I turn it up full. I’ve tested all caps with an est meter and all seem ok. I’ve removed the valves and check the pins all ok. Wondering is all sound sources routed through the valves before the class D amp?
Very nice troubleshooting and repair. I suspect the tubes are 12AX7 pre-amp tubes. they are plentiful and still produced in Russia and Ukraine.
Thanks 👍yes one thing that I didn't look at, is what tubes it contained unfortunately.
The patience of a Saint comes to mind.... :) Bravo, a great repair!
Cheers Chris 👍
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!
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😂😂
Great repair Mick. You can't beat the sound of a valve amp 😀
Thanks Mike 👍
great stuff. persistence pays.... i think the gunk was called 'oh dear, glue gone, buy new' strategy....
Thanks Jamie👍
Great demonstration of tenacity ❤
Thanks 🙂👍
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!
Thanks Matt 👍🙂
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.
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 😂😂😂
A bargin then as it kept the wife happy too. 🤣@@BuyitFixit
Good to see you got that working correctly again! Nice unit!
Thanks!
It took time but what a satisfying fix and a lovely looking piece of kit with those valves glowing. Well done!
I would laugh if the valves were purely cosmetic 😅
Thanks👍🙂
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".
Very good description of how this equipment works. Thank you! K.
Thanks 👍
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.
And thanks for your thoughts 🙂👍
really good repair. I really like your pace in your videos. :)
Thank you very much!
What an surprisingly massive power supply. Nice!
Yes indeed 👍
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.....
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 🙂👍
Yep - at time index 20:36 what you are seeing is that glue that goes conductive as KarlFell suggested - Sony and some other manufactures also put that glue on certain items to keep them from moving - The older VCR's were notorious for this as well...
Yes, first time I've came across the issue of conductive glue. It's good as I've learned something new to add to the toolbox 🙂👍
This diagnostic approach was awesome.
Put the board in freezer and the bond should fleck off using dental tools or Harbor Freight small sculpting tools. After you are thru. Soak whole board in 99% IPA over night, then blow off with low PSI compressed air (3 psi) then let it sit on a heating pad for a couple of hours then plug it in.
I don't like ultrasonic cleaners on old boards; the vibrations might cause solder issues.
One other thing, as you know, leaded solder has lower melting point and this could cause problems on components that get hotter than 150°C.
Thank you and thanks for the tips 👍
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
Thanks 👍and good luck with any future repairs 👏👏👏
Agree with Karkfell, could not remember the name of the glue, but it turns nasty.
Yes I thought it must have been the glue reacting! Thanks 🙂👍
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 😆
Thanks👍 I know exactly what you mean. I've got a few things in bits which I'm waiting parts for..
Another excellent fix yet again, by far the best repair channel on RUclips, almost got a Vince "YES" at 39:46. Keep up the good work.
Thanks, will do!
Really nice job, great patience 👍
Thanks 👍
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.
Thanks 👍
Nicely fixed rarethe motor failed never happened by me. Yea the glue if it old can be conducted. Good job.
Thanks 👍yes not sure what caused the motor failure 🤷♂️
Sounded like lightning, when you removed the board first time. Good job it wasnt your fingers😅
I laughed for a while, we both jumped
Yes, I actually jumped again watching it back 😂😂😂😂
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!!
Cheers 👍🙂 The "girls and guitars" is my wife's. It was the only CD I could easily lay my hands on for "testing" 😂😂😂
@@BuyitFixit 😁 😂 'It's not mine it's me missus's' - that old chestnut eh.. 😆🤣
Thanks for the video, you did well fixing this unit, I have subscribed
Thanks🙂 and Thanks for the sub! 👍
Heya really nice hifi set after the repair you have there
Thanks 👍It's in my wife's sewing room. She really likes it 🙂
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
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.
brilliant
Thanks 👍
wow, sounds amazing!
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
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!
great Video, Keep em' coming. Cheers
Thanks Ian 👍
Can't help thinking those valves are just there for show..... there was a large chunk of that board you were working on that looked suspiciously like an audio amp and of course, the speaker terminals are on there as well, not to mention the large power cables from the transformer, the split rails, the fuses etc all on that board. And the final thing....who buys something like that?
Great fix as always though. 10/10 for patience :)
Thanks 👍The valves seem to be just a pre-amp. I've not tried it with them removed as they might well be just for show 😂😂
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.
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.
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".
Brilliant job very interesting video 👍👌
Many thanks
Very good! I wish I had your skills.
Thanks Peter 🙂👍
I think the valves on this unit work as a pre amplifier and it sends the low signal to the digital amp on the main board you was working on as I looks like the bigger heat sink is the amplifier.
Correct 🙂It looks like the main amplifier is a class-D.
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. ;-)
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..
Tubes, we call them hot, glowy things, TUBES!
Not to us who use proper English language 😂
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"
Good idea. It's the first time I've came across it.
Thank you, that was very inspiring!
Thank you 👍
Good result mate 👍
Thanks 👍
Nice little radio is that.
Yes, my wife quite likes it 👍
Dislike those little jam packed units. Good work
Thanks 👍
Awesome Work as usual , Karl. How many hours in reality?
Good question, I can't remember exactly but I thing it was a few!
@karlfell3768 is absolutely correct, that glue destroyed many a Ham & CB radio whenever it was used it would also become very acidic causing trace & component corrosion.
Interesting, I thought it must have became acidic or alkaline or something. I guess moisture reacts with it over time causing a chemical reaction.
Great fix..
Thanks 👍
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.
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.
love this channel!
Thank you 👍😊
Great job 👍👍👍
Thank you 👍🙂
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.
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!
nice fix. too much power supply failure in electronics.
Thanks 👍
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.
Thanks 👍a few people mentioned the same, so I'm going to take it apart again and remove all traces of the horrible stuff...
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,
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 .
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?
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.
Hi, thanks for your quick response. I enjoyed your video and admire your perseverance 👍.
No problem and thanks for your kind comments 🙂👍
What product do you use to clean off the resin or clean up the boards?
Isopropyl alcohol or acetone?
I have both, but use Isopropyl alcohol mainly 👍
13:57 it bitten me 😳😱
How dare you ,,, take this...💥💥💦🦄🥳
Super nice repair 👍👍👍👍👍👍👍
😂😂😂😂Yes it did make me jump a bit! Thank you 👍🙂
That job nearly kicked your A*$ Mick,but i knew that you would sort it out.
Nice little unit.
Thanks 👍
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.
Thanks 👍a few people have said the same. I'd not came across it before but at least I know now 🙂
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.
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.
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.
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?
Scrape off most of it with a pick or small screwdriver then clean the rest off with isopropyl. @@BuyitFixit
Thanks Kevin 👍I've got some freezer spray 🙂
I'm lucky to find them working in 😅
Respect for your skills mate...Well done.All the best from Cleveland.Peter.
Thanks Peter 👍
It says, hello & bye bye, at least its polite !
😂😂😂😂👍
Those valves look a lot like tubes lol.
Those tubes also look a lot like valves 😂😂😂😂
you are some kind of wizard or sorcerer
😂😂😂😂I ain't no Harry Potter 🤣🤣🤣
@@BuyitFixit close enough 🤣
Maybe a visual inspection of that board might have helped earlier on? :)
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.
Interesting. Thanks for commenting 👍
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 .
Thanks 👍First time I've came across this problem so good to know🙂
Ha ha, looks like it’s stuck in Dad mode 😎
😂😂😂😂
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.
I didn't investigate too much on the valve side, but hopefully they used sockets so the heat shouldn't be a problem.
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
I use the old toothbrush too 🙂 I find it doesn't mop up the flux residue though and just spreads it around the board.
You need a hybrid power supply for that hybrid unit.. I call it a sledge hammer.
🤔
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 ..
Maybe one day!
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?
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.
@35:54 - That transistor lead soldering looks kin of cracked and shite. I'm probably wrong.
No, I thought the same when I was editing the video. The other side of the board looked soldered fine though.
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? :)
Could do as I probably need to get into it again to remove the rest of that glue.
Spare or repair Rokit amp speakers have the same glue killer..
Interesting, Thanks for letting me know👍
Valves ....
I play guitar ,and have a valve amp. 4 x 6L6GC,
here you have only somepreamp valves, to introduce some "warmth" , what are they good for then???
@@norbertsmallegange6331 As you say to introduce some warmth I guess? I just try and fix stuff and unfortunately not an audio electronics designer.