Big V-FET thread

[Wire Nut]

Big Sony V-FET thread

There are a lot of posts out there with different info on updating a Sony V-FET amp. I am going to try to make it easier for someone that wants to upgrade a 46-5650 integrated amp. I will include links to some of the threads I have found out there with a brief blurb on what it is mostly about.

This is the 5650 on the Vintage Knob- the info on the 4650 leaves a lot to be desired:
http://www.thevintageknob.org/sony-TA-5650.html

First you will need a manual, here are the manuals for the 5650:
http://www.hifiengine.com/manual_library/sony/ta-5650.shtml

And for the 4650: http://www.hifiengine.com/manual_library/sony/ta-4650.shtml

1. This one talks a lot about the electrolite caps in a 5650:
http://audiokarma.org/forums/showthread.php?t=268927

2. This one has two service updates from Sony and talks about testing the V-FET's: http://www.audiokarma.org/forums/showthread.php?t=386842

3. This guy replaced his RCA and speaker connectors- it also shows how to test the V-FET's with a multimeter: http://www.audiokarma.org/forums/showthread.php?t=476729

4. This one shows how a tech used the old output caps to mount the board that is on top of it: http://blog.kf7lze.net/2014/11/11/sony-ta-4650-vfet-stereo-amplifier-inspection-and-upgrade/

5. This one shows how to connect the death diodes in series (corrected):
http://blog.kf7lze.net/2014/12/18/sony-ta-5650-vfet-integrated-stereo-amplifier-overhaul/

6. This one talks about the diodes in more depth:
http://blog.kf7lze.net/2014/11/25/vd-1221-repalcement-substitute-diodes/

7. Here is a photo bucket of a 4650 before mods (in case you need to remember what it looked like before you took it all apart!):
http://s755.photobucket.com/user/anonieme/media/Sony TA-4650 V fet/SonyTA-4650Vfet008.jpg.html

This is a good start- if you have favorite links for the Sony's please include them on this thread. I will be starting my upgrade next week when my caps are done being cryo treated. This should be a lot of fun!
I will do my best to include photos of the work.

 

[Vinylcafe]

Nice to have this all in one place ... good idea.

On point #5, unless I am mistaken, those diodes go in series, not parallel

 

[Vint Age]

5. This one shows how to connect the death diodes in parallel

 

[Wire Nut]

Sony V-FET integrated amps

Yes you are correct- it was a long day. They are in series...

Unlike the other guys that made posts, I started with the 8650 and went backward. I just picked up a 4650. The 8650 is a different beast. The 46 & 5650 are quite similar. Alas- I got rid of my 8650 years ago in the 70's because it could not run my Ohm F speakers that I had at the time very well (the protection kept cutting the music off).

 

[Wire Nut]

I wanted to include a photo of the diodes and the location on the 4650. On the attached photo you will see two white spots, they have a red circle around them- those are the culprits!
Can anyone with experience comment on the best way to take them off (considering they have the thermal paste on them)?
Also the best way to install new ones and if direction (polarity matters)?

 

[kf7lze]

The thermal paste isn't an adhesive, it just comes right off; just unsolder the diodes from the board and remove like you'd do anything else. Put the two 1N4148s in series, bend back into position, and put a little thermal compound between them and the transistor as the original used.

The diode's polarity is marked on the silkscreen below the part, just observe that marking and you'll be fine. (In the small photo you attached, it looks like the cathodes point towards the outside of the board, based on the silkscreen.)

 

[Wire Nut]

In searching for something else- I found this repair job that has some great photos of a disassembled 4650:
http://www.vintageaudiorepair.nl/sony/uksony_ta-4650.html

Also - wanting to do something useful to the unit while I wait for the cryo to be done Monday, I decided to install an IEC connector for power.
The stock wire is 18ga which is tiny. I used my "Nibbler" and chewed away the metal where the old hole used to be and installed a gold plated Furutech with solder connections. Going from the Furutech to the first external component inlet I used cryo treated Neotech UPOCC 16ga solid core wire (yellow jacket).
16ga solid core has about the same copper mass as 14ga stranded.

 

[absolve2525]

Cool thread! What speakers are you using with yours? I have a couple 4650 myself, with the diodes replaced. I'd like to recap mine at some point. Has anyone done theirs? Did you notice a sound difference going to the new power cable?

 

[Sam Cogley]

Those damned varactors are the mark of evil. Spent years chasing a gremlin in a PS-X70 turntable and it turned out to be two of them causing the problems.

 

[Wire Nut]

I will probably use this amp in my shop with KEF 103.2 spekers. I also just got a Accuphase E-202 that had the oddest accident. I set it on top of the washing machine while I was painting the side panels and the damn spin cycle threw it to the ground and killed it. It was working and I was just going to recap it- it is now way beyond my powers of medicine & is in "Amplifier Surgery". That will power my B&W "pregnant penguins" the first B&W speaker to use phase correction and a Kevlar speaker. I LOVE those speakers!

 

[Wire Nut]

Absolve, my 4650 works- I had it on for all of less than a minute. I checked both channels for output, I put on a turntable and checked both channels for output and turned it off. I will never have a comparison of before and after as I am afraid of the death diodes.

Last evening I installed some very tasty Vampire gold plated solid copper RCA's for the phono 1 section. I am also going to run some 28ga solid core Neotech UPOCC wire to the phono connectors. I am not a fan of tinned copper wire.
I also made some speaker cables from Analysis Plus 12ga speaker wire with Vampire BAR connectors on one end and AQ bananas on the other- which I may replace with pins for the KEF's.

 

[Wire Nut]

I am going to hard wire my phono section. I want the best performance possible from my record players. I built a wiring harness with 28ga UPOCC wire, I twisted the pos and neg per left & right, then twisted those pairs, then twisted the phono 1 & 2 pair. Should be pretty good at EMI/RFI rejection. I put the whole thing in clear Techflex.
Hopefully tomorrow I can start putting in the new caps.

 

[Wire Nut]

I started putting in the caps, I was short six of the 10uf caps so that part is on hold, which is OK as I am waiting on the diodes and the big output caps. I didn't like the speaker posts so I ordered some gold plated copper ones that I will install- on the A speakers I will also run direct solid core 18ga Jupiter 4-nines cryo treated wire.
The speaker wire runs around the transformer- what a bad design! I made a shield for the new wire and attached a ground wire which I will connect to the chassis.
The photo below is of both of the new wiring harnesses.

 

[Wire Nut]

Since I want this to be easy on everyone and for you to be able to do this stuff correctly - here is a little advice on diode polarity:

 

[roger2]

^^^ silly picture, the diagram shows cathode on the right then the actual diodes are oriented the other way

as this is meant to be educational, you'd think that they would have the diagram and and the actual diodes facing the same way. could be confusing to someone learning this for the first time

 

[kf7lze]

I started putting in the caps, I was short six of the 10uf caps so that part is on hold, which is OK as I am waiting on the diodes and the big output caps.

Which caps did you order? I've had trouble finding drop-in replacements for the big caps with the right screw spacing. Got a PN, or are you making an adapter/jumper for them?

 

[Wire Nut]

I got Nichicon Gold Tone, I like them a lot. I will need to make "stand offs" out of wood. I will include pix when I get to that.

 

[Wire Nut]

Don't forget- there are three diodes that need to be replaced.

 

[GuyNoir]

Timely - thank you.

 

[Wire Nut]

I ordered some caps from Digikey, they sent me 12 of the wrong ones. Somehow it is my fault and they want me to pay shipping to send them back! I found the customer service reps there to be some of the worst I have encountered anywhere. I would be careful buying from those guys.
On the other hand, I have encountered some terrific service from Partsconnexion, the only issue with them is it takes a while to get parts from them if you are in the US.
As an owner of a web based store I have accounts with both, I will be giving less business to DigiKey in the future.