Bought a Sony TA-N7, and now?

Harolda · Feb 26, 2011

Hello Audokarma,

i am new here and i subscribed especially for the informaton on vintage amplifiers. I am an active Diyaudio member.

Last week i received my Sony TA-N7 V-fet. The Amp is in a very good condition and it plays very well. As far as i can tell it is still in its original shape. I am however keen on keeping this amp in a good shape and i wonder what to do. Next to the TA-N7 i also own a Sony 4850 Vfet.

Just use it and see how long it keeps working or take some measures to keep the v-fet's alive. I did not find all the information on restoring thess amps yet, but what i understand is that some parts should be replaced to avoid failure and consequent vfet failure.

Who can help me with some guidelines (posts/ threads) on this?

regards,

vincei · Feb 26, 2011

Welcome to AK, that is a nice amp you have. I am no expert, so I will leave the comments to them. My thinking would be that there would be some work that should be done and I am sure you will get some tips soon enough from the experts.

cdfac · Feb 26, 2011

there are some failure-prone components on Sony VFETs. a Google search will pretty easily turn up a list of what should be done as preventative maintenance.

MX117.MC7150 · Feb 27, 2011

First, welcome to AK. And, a wonderful amplifier. Do a search in this forum on the TA-N7 and TA-N7B and read all the old posts. Also, contact EchoWars and ask him directly. He rebuilt one for me and probably has more VFET knowledge and experience than anyone else in U.S. on Sony/Yamaha VFET gear. You might also post a pic or two and check out patrick66's and others VFET Sony gear posted over here:
http://www.audiokarma.org/forums/showthread.php?p=4434757#post4434757
Also, I have the the TA-N7 service manual in electronic format. If you need a copy send me your e-mail address via a PM. Also have a list of suggest mod's from Mirko, who is the 'German EchoWars' when it comes to Sony VFET gear and posts here occasionally.

Enjoy!!

Harolda · Feb 28, 2011

Dear all,

thanks for the support thus far. I have pdf of the service manual. I will try to post some pictures this week, if i can find the time. I will have to study the internals and look at the state of everything. I will capture everything on photo.

regards,

Fitzy · Mar 1, 2011

Welcome to AK! I also have an N7 and got the kit from Mirko. It made a huge upgrade to the sound of the amp and will hopefully give me another 30 years pleasure. Plenty of posts on V-Fets on here so I suggest you have a trawl. What pre are you using with it?

Harolda · Mar 2, 2011

Hello Fitzy,

Does Mirko supply a complete upgrade kit?

I will be using a TA-E86 as a pre or a tube pre which i am building now (aikido).

regards,

Harold

Jeff W. · Mar 2, 2011

Welcome!

Greetings Harold,

I just acquired a TA-N7B back in December. I started a thread about restoring/upgrading it here: http://www.audiokarma.org/forums/showthread.php?t=340050&highlight=vfet if you'd like to take a look. I let the thread stall temporarily. I did complete the work and test the amp :thmbsp:, but have been unable to listen to it yet :thumbsdn:. It is a 220v unit and I have no way to power it at home (yet) until I get some electrical upgrades done at my house. I am in the USA and we typically use 120v. As soon as I get the proper power to the outlet I will report.

I used Mirko's "kit" for mine. He doesn't supply one. However, I have his "list" as MX117.MC7150 mentions in post #3. It sounds like it's yours for the asking from him. I can supply it as well if you'd like to give a look. Just send a private message to either one of us and we can e-mail it to you. I can also tell you where to get the parts on the list and the part numbers from Digikey and Newark. Use the "Advanced Search" within Audiokarma with "Vfet" as a keyword and by Mirko's Audiokama user name: "Unda Maris" in the "User Name" box. I'm sure you'll find some good information. Substitute "Echowars" in the user name box next. Now you should have plenty to study. I'd be happy to help as far as my limited knowledge will allow. Best of Luck!

Fitzy · Mar 3, 2011

Harolda said:
Hello Fitzy,

Does Mirko supply a complete upgrade kit?

I will be using a TA-E86 as a pre or a tube pre which i am building now (aikido).

regards,

Harold

Hello Harold,

Mirko actually supplied a kit for my rebuild on the recommendation of Stoffie an AK member from Belgium who also used his kit. I have used an E86B in the past and more recently an E88B but have gone the passive route having tried a number of units and have settled on a ModSquad Line Drive DeLuxe. I use my N7 in a bi-amp set up driving top and mid drivers, sound wonderful!

Harolda · Mar 7, 2011

So i opened it, and noticed that it is (to my opinion) complete in it's original state. As you can see in the picture, the state is very good, only a minor scratch on the top of the faceplate. There is no sign of rust or other scratchs. Also the inside is very clean, almost no dust.

I have the following Vfets voltage pinch off:

Left Channel:
2SJ18 - 3 x JC-25
2SK60 - 3 x JC-26

Right Channel:
2SJ18 - 3 x JC-26
2SK60 - 3 x JC-25

All the caps and resistors are original.

more pictures to follow

Harolda · Mar 7, 2011

More pictures:

MX117.MC7150 · Mar 8, 2011

Hopefully those outputs are all fine and will remain so. One thing that is important with VFET devices is that they must match in 'rank'. Thus, if one is bad you can't simply replace with another one. You replace with one that has similar rank. For instance, a rank 55 should be replaced with a rank 55. Makes finding replacements very difficult. Think I have a couple should someone need, and Mirko has them, as well. A few years back several TA-N7 owners purchased a large lot (40, or so) of larger filter caps that fit in the cans. If I recall correctly, they were 20,000uf and and made by Chemican. Largest that would fit into the cap-cans. AK members Kristof or Patrick66, who seemed to have missed this thread thus far and own several of these amps, will likely remember better than I. If you will post a pic of your amp over in that "Show Us You Sony" thread I referenced above, and post a link to this thread, you will get several other knowledgeable TA-N7 owners, like Mirko (Unda Maris) to join in your discussion.

Harolda · Mar 8, 2011

MX117.MC7150 said:
Hopefully those outputs are all fine and will remain so. One thing that is important with VFET devices is that they must match in 'rank'. Thus, if one is bad you can't simply replace with another one. You replace with one that has similar rank. For instance, a rank 55 should be replaced with a rank 55. Makes finding replacements very difficult. Think I have a couple should someone need, and Mirko has them, as well. A few years back several TA-N7 owners purchased a large lot (40, or so) of larger filter caps that fit in the cans. If I recall correctly, they were 20,000uf and and made by Chemican. Largest that would fit into the cap-cans. AK members Kristof or Patrick66, who seemed to have missed this thread thus far and own several of these amps, will likely remember better than I. If you will post a pic of your amp over in that "Show Us You Sony" thread I referenced above, and post a link to this thread, you will get several other knowledgeable TA-N7 owners, like Mirko (Unda Maris) to join in your discussion.

thankx for the info. I will post my amp in the thread you mentioned.

regards,

Harold

Stoffie · Mar 9, 2011

I have nothing much to add as pretty much all the valuable info has already been shared

Unda Maris or Echowars are your guys when it comes to the technical low-down! (although I'm sure patrick66 knows a lot about these as well)

Safest is to replace all caps, fusible resistors, a resistor here and there, the pots, all the heat pads, the bipolars, and a little mod here and there.

I've been enjoying my amp for more than three years now (although last year or so it hasn't seen much use because of a severe lack of time), and it still plays beautifully.

The large filter caps we purchased were 80V 27000µF (as opposed to the 71V 22000µF stock ones) made by Nippon Chemicon if I recall correctly. I never got around to fitting them (as it already had new ones in there), still sitting in my closet. It does require a little bit of handy work to make them fit right, as the fit isn't 100%, and the holes in the copper strips on top need to be enlarged as the screw terminals are 6mm instead of the old 5mm.

Be sure to check the foam pads that support the L & R circuit boards, as mine were rotted out into a conductive mushy mess, frying some resistors on top in the process.

Good luck restoring your amp, I'm sure you will love it once it's done. I play mine with a TA-E88B and SS-G333ES speakers, and it's just awesome!

Harolda · Mar 29, 2012

Hi Guys,

starting on the amp soon, just collecting the info on the parts to order. I already send a pm to Unda Maris today on a parts list.

- The berquist pads are ordered
- The main PSU caps will come from Cornell Dubilier or Panasonic from Digikey, although the Panasonic are expensive and non stock
- Other parts to be ordered as soon as i have all the required information.

Does it make sense to replace all the electrolytics in this amp?

regards,

MX117.MC7150 · Mar 30, 2012

Have you checked with these guys? They may have something in stock.
http://www.tedss.com/electronic-parts/Capacitors/browse

Good luck making contact with Unda Maris. Stoffie may have his phone number.

Harolda · Apr 1, 2012

MX117.MC7150 said:
Have you checked with these guys? They may have something in stock.
http://www.tedss.com/electronic-parts/Capacitors/browse

Good luck making contact with Unda Maris. Stoffie may have his phone number.

Already looked at their store, nothing suitable. The Cornell dubiliers from Digikey are fine, they are the right size, but they do not have screw terminals. I could also get Nippon Chemi-Con 22000uF 100V Caps, but they are 51mm x 130mm, i will have to measure if those will fit.

I dismantled most of the "body work" of the amp, but can someone tell me how to get the cap off the big cans?

regards

Harolda · Apr 4, 2012

I started to dismantle the sony.

- Vfets unmounted for new pads
- I measured the large 71V 22000uF Cans. There is 135mm room for the Cans plus the copper bars, screws and small caps. So the 130mm ChemiCons will be too large.
- I have to make a list of all parts to be replaced now

i will keep you posted on the progress

Harolda · Apr 6, 2012

Today i dismantled the PCB's as much as possible from the enclosure and i cleaned the inside with soap, hot water and dried it with compressed air.

Parts removed from the pcb's
- all electrolytics
- 4 pots for the offset and bias
- loudspeaker clamps were broken, so i have to find a nice replacement, maybe the cardas binding posts. Have to check if these fit.
- next step is to remove the fusibles

Any ideas on which diodes to replace?

Harolda · Apr 9, 2012

Left power almost completed.
- Electrolytics replaced by Panasonic FC.
- Almost all fusibles replaced. Still searching for R127/R227. My Service Manual states that this is a 4.7R fusible.
- Pots replaced by Bourns Pots, 100R and 50K (i.s.o 22K).
- All solder points reflowed
- Wire connections solder added
- double Diodes MV12N to be replaced

Same goes for central power supply board

Next step is the right power board.

Bought a Sony TA-N7, and now?

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