Sony TA-4650 V-FET Amplifier (Part 4 - Restoration Complete!)

[@whatcouldgowrong7914]

In the final video I will also go over common questions around tools, grease etc and give a parts list of capacitors and transistors used 😀

[@roerdomp16e]

Thanks a lot ! Although I have been restoring v-fet amps for many years, I still learned some things. And yes, the way you have done this one is the extreme version of a restoration ;-). For anyone who tends to save some money on the relay: change it! The riveted plastic holding bar of the fingers will crack over time! I have done dozens of 4650's and others. At least half of them have a broken relay when they come in. And although your power caps still seem to be fine, capacitance wise, I see many who have less than 50% of their original capacitance left.

[@whatcouldgowrong7914]

Yes it was overkill and I know it haha, I like to push the boundaries

[@roerdomp16e]

@@whatcouldgowrong7914 You certainly did that! especially opening most of the switches. I actually tried this on a filter switch from a junk board. I gave up trying putting it back together for an hour and losing one of the tiny contacts. My hands are to big and fingers to thick. I normally just put them in the ultrasonic cleaner.

[@PeterMilanovski]

Great job! That puffer jacket screams Melbourne! Good to see someone putting in so much effort who possibly lives local to me..... I think that the benchmark for amplifier restoration is held by X-ray Tony B, he also does a talk over while he's soldering which works better than just listening to an extraction fan or at least that's what it sounded like to me! Besides that! And apart from installing the new diodes which I probably would have sat them a little bit higher from the PCB to give them a little breathing room but the original one's didn't appear to be generating enough heat to burn the PCB so I guess that it's not important.... I really have nothing to complain about! Going up in the voltage rating for the capacitors was definitely a good call! I especially like to go up in capacitor voltage rating if they are located next to or above any heat source, the higher voltage rating is the equivalent of higher temperature rating and helps keep those capacitors live longer.... Which is always a positive for a proper restoration.... I'm looking forward to watching more!

[@mikemmikem2758]

I love your work ethic and attention to detail. Absolutely gorgeous restoration. I could easily watch an hour of your videos (and I'm sure I'm not alone in saying such) so don't shorten too much. Thanks again for another super cool video.

[@PeterDyall-bn7ut]

Certainly is stunning. You’re setting the bar very high!

[@whatcouldgowrong7914]

Thanks! 🙏

[@RegiPavan]

Absolutely gorgeous restoration

[@whatcouldgowrong7914]

Thanks! 🙂

[@petertimp5416]

XrayTony would be proud, good job. Just subscribed 😊

[@whatcouldgowrong7914]

Welcome! Thanks for joining :)

[@adrieltzu3565]

Absolutely beautiful job. Sometimes ocd is a good thing.

[@whatcouldgowrong7914]

It can be a blessing and a curse 🤣

[@batmandestroys1978]

You are a modest genius!

[@whatcouldgowrong7914]

Many thanks!

[@MrJohnBos]

Beautiful restoration, the amplifier is stunning indeed. Better than new. I think you could definitely cut way down on the time lapse. I'd much rather see and hear your thoughts on why you are doing what you are doing. Other than that, I loved the entire series on this amp, well done.

[@mistermac56]

Excellent work. The silicone pads are so much better for thermal than mica wafers and heat sink grease for the V-FETs.

[@whatcouldgowrong7914]

Yup I hate thermal paste!

[@LuizMoraes-fn5ir]

Fantastic work. Greetings from Brazil.

[@jackalterman]

Really well done! I enjoyed this video, including the sped up bits. (I also appreciate the cleanliness of your bench and work in general.)

[@ukrainehamradio]

Great job!

[@repsych]

Thanks; what is the solution that you use in the ultrasonic cleaning machine?

[@whatcouldgowrong7914]

Ambersil ultrasonic cleaner with some IPA mixed in :)

[@markwroblewski6500]

Nice clean job.What's the brand of the suction pump you are using.Looks very effective.

[@whatcouldgowrong7914]

It is very good, its a GOOT solder sucker, had it for over a decade. It has its bad days but its never has anything replaced on it and should probably get a new one. Only problem is it’s not single handed use but I just use my hip to reload it

[@markwroblewski6500]

Love your perfectionist approach.2 questions - What's the make of the green soldering iron you're are using so skilfully?As well you've mentioned pairing/coupling of transistors.How would you pair NPN/PNP output ones in a Class 'A' power amplifier[Krell for example].Many thanks in advance.

[@whatcouldgowrong7914]

It’s a Thermaltronics TMT-9000 inductive soldering iron, had it for a decade :) Inductive soldering irons will change your life, no waiting for joints to heat up / turning up or adjusting temperature etc

[@adaboy4z]

You have a parts list for the power supply!? Enjoyed the series!!

[@whatcouldgowrong7914]

Yup capacitor / transistor subs will be shared in the final video once I confirm everything is happy and nothing goes wrong after a burn in / testing. Doesn’t include the resistors but I just took those off the PCB service manual list which was accurate 🙂

[@garygranato9164]

noob question but why would he change out good components ? particularly the resistors ?

[@whatcouldgowrong7914]

Good is debatable these days, amplifier is almost 50yrs old and everything degrades. Capacitors are mostly fine still, transistors have drifted too much and needed to be changed / some are known to be problematic. The other resistors, some were a service bulletin, some had failed and the others i changed were in the signal path with high modern high precision resistors to try and improve thermal noise. Was it working before I started, sure. But as I said you get one shot with the VFETs and if something fails absolutely damages them, the amplifier becomes useless unfortunately.

[@waynemarc77]

I OWENED ONE OF THESE!!!

[@holtonaudio623]

I bought one of these amplifiers brand new back in late 1978 for $600AUD if my memory serves me correctly. A friend of mine in the day had the TA8650, much bigger amplifier power wise and it sounded great on a pair of La Scarla Klipsch loudspeakers.

[@johnny-z]

Wow! A Brit w/ a toothbrush. I didn't think that had those in Jolly ol' England.

[@supernovaf1]

Huh? He's not a Brit!

[@EliteRock]

@@supernovaf1 Yanks! All got tin ears.

[@MonHackintosh]

Please give me some circuit diagrams.

[@whatcouldgowrong7914]

All the documentation is on HIFI engine / google :)

[@savvassidiropoulos5952]

Those time lapses are not doing justice to the work. I understand the reasoning behind wanting shorter videos, but I don't mind long good ones. Perhaps showing important details for each section in real time? Or including chapter marks so people can jump these sections if they are bored with details? Anyway, it was my first time watching your work and I need to offer my compliments to a job well done.

[@whatcouldgowrong7914]

I agree, I’ll ponder how I can strike a better balance, split more videos or something, unfortunately I can only go off KZbin analytics and long videos seem less popular. Thanks 🙏

[@ABC-rh7zc]

It clearly takes up too much space on your bench. Happy to take it off your hands, no charge.

[@whatcouldgowrong7914]

That’s very gracious of you 🤣

[@jagrutbhatt3301]

So disappointed ...not found any sound demo in the end🫤😟🙁☹️🥺🥹

[@whatcouldgowrong7914]

A final video is coming 🙏I need to do it justice and spend some time with it

[@iceberg789]

except bare boards and cabinets everything got changed. 🤔

[@whatcouldgowrong7914]

Its a 50yr old amplifier… the boards are original, everything was changed based on ensuring it keeps working for another 50yrs

[@ian-c.01]

When you speed up the video so much it's not possible to see what you are doing so it gets to be just a blur, I had to skip those bits to get to the commentary because it's kind of annoying trying to figure out what's happening. Having said that I do realise there are people who will run the video at slow speed so they can see as much detail as possible and would prefer to watch a 2 hour video of desoldering, installing and resoldering components !

[@whatcouldgowrong7914]

Hence why I asked the question, it’s not really possible to accomodate every who wants reasonable length videos and time lapses as these videos take place over many hours of work and are already cut down 🙏

[@ian-c.01]

@@whatcouldgowrong7914 If you had a second channel showing uncut 4 hour videos of the entire process there are people who would love it ! They would probably complain you didn't upload enough for them too !

[@BaskaranBaskara]

Rummy circle vilambaram podaathadaa they..., paiyaa

[@AN-ce1nd]

Yeah but here’s the fact. More components in line with the inputs, added electronic distortion. Pretty but a complete failure. $2.37 tops and that includes shipping.

[@whatcouldgowrong7914]

Well it measures better than it did before I started so.....