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Sansui AU-D9 restoration

I made a small change at volume pot board:

PICT2293_zpshwz8cojq.jpg


Those black ground wires are not so nice to see, so I made the same thing but on some different way...

PICT2294_zps1z1gvbug.jpg


PICT2295_zpsl8p2fpz0.jpg


and afterr all... FINALLY!!!!

PICT2296_zpsdn96lqed.jpg
 
And first power up.... uf... the white smoke remained inside of the device :)
... or clearly said ... amplifier works as it should.

But during adjustment of phono preamp board I could not to adjust DC Servo to close to zero volts! No way!

And I have found why... previous technician changed 2SK146 dual diff. fet by two, not matched 2SK117!!!

It was good what I have some of NOS 2SK146 on my stock...

PICT2297%202_zpsk4pp4ods.jpg


But this time I wish to be sure, I temporarily soldered that 2SK146 on printed circuit side of Phono Board, and... yes... now it is all OK...

PICT2298%202_zpscpkkmjnk.jpg


On the next picture you can see a new 2sk146 and below it those not matched 2sk117

PICT2299%202_zpsq8rcsxlz.jpg
 
Kale said:
I made a small change at volume pot board:
Those black ground wires are not so nice to see, so I made the same thing but on some different way...
Click to expand...

This is typical for your work Kale!
Your attention to detail keeps amazing me.
Thank you for sharing.

-John-
 
It was not so easy to remove those 2sk117 and install a new 2sk146 to the that board when all wires are connected to the board. In other hand, I didnt wish desolder all those wires again and heat them again…

And we are close to end...

PICT2304_zpshnmnnsea.jpg


What was changed during this restoration:

PICT2302%202_zpskibpcobu.jpg


PICT2301_zpsjrzwhlfg.jpg
 
Kale said:
...

What was changed during this restoration:

PICT2302%202_zpskibpcobu.jpg
Click to expand...


Is that IC at far right an opamp? If so, which one have you replaced with? :scratch2:

Would be great to know the trannies you have replaced as well, although I understand it can be lot of extra work.

Beautiful work and pictures!! :tresbon:
 
About replacing small signal transistors… first if it is technically OK (by diode test) I am testing it to see how much it has Hfe, and if it is below Hfe rank for that transistor, I am replacing it (BTW I have some semiconductor tester)… in some critical places in amplifier (like here in Diamond-Differential circuit) I am replacing them all with matched new ones… or on the places where I noticed that some small signal transistor worked at high heat space, or when I notice that some small signal transistor has legs so much oxidized… I am making that decision depends of specific situation...

That IC on the end, is JRC4558 DC Servo op.amp. and because I could not adjust DC Servo, I replaced it by new jrc4580, but as you see later, the main problem was those 2sk117...
 
And now some pictures about testing amplifier….

First Phono input -> sinus 150Hz -> taken from speakers connectors

1_Phono_zpse6e506ci.jpg


then TUNER input -> 400Hz -> Square -> Tone Control Off -> taken from speakers connectors

1_400Hz_without_tone_zpskcbqsn43.jpg


TUNER input -> 400Hz -> Square -> Tone Control on -> taken from speakers connectors

1_400Hz_with_tone_zpslqmgy1v6.jpg


TUNER input -> 30kHz -> Square -> Tone Control off -> taken from speakers connectors

1_30kHz_without_tone_zps9px5pol1.jpg


TUNER input -> 100kHz -> sinus -> Tone Control off -> taken from speakers connectors

1_100kHz_without_tone_zps9zj6vtb6.jpg


All test signals was taken with dummy resistors 8 ohms 250 Watts connected on speakers terminal.

I did a clipping test (again with 8 ohm dummy resistors on speakers connectors), and it has just 90.6 w just before clipping which is good, because mains selector is on 240 V AC position (at Europe is 230 VAC standard, but Sansui has only 220 or 240 VAC)
 
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And at the end, some final pictures

PICT2313_zpswog6ezzi.jpg


... during listening test (source was Sansui Alpha CD 907)...

PICT2314_zps06ad6z8y.jpg
 
stevo1214 said:
Awesome work there,Kale. And BTW do you have any extra 2sk146BL for sale? I'm in need of one for my AU-D11.
Click to expand...

I am very sorry, but as you see, I had only 6 pieces and now I have just only 4 pieces, so I cant sell them. BTW did you see on eBay, I think there you can find some pieces.
 
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Kale said:
About replacing small signal transistors… first if it is technically OK (by diode test) I am testing it to see how much it has Hfe, and if it is below Hfe rank for that transistor, I am replacing it (BTW I have some semiconductor tester)… in some critical places in amplifier (like here in Diamond-Differential circuit) I am replacing them all with matched new ones… or on the places where I noticed that some small signal transistor worked at high heat space, or when I notice that some small signal transistor has legs so much oxidized… I am making that decision depends of specific situation...

That IC on the end, is JRC4558 DC Servo op.amp. and because I could not adjust DC Servo, I replaced it by new jrc4580, but as you see later, the main problem was those 2sk117...
Click to expand...
Thank you, Kale for the explanation. Actually I've tried doing the same lately... :thmbsp:
 
Kale! Yes, I saw some on ebay but they are from seller in China,so I don't know if I want to take a chance on those. The only place in the US that I can find is this searspartsdirect but I don't know if these are genuine parts or not and they are much cheaper too. I also see that Mouser has the IFN146, this FET is costing a bit of money.
 
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stevo1214 said:
Kale! Yes, I saw some on ebay but they are from seller in China,so I don't know if I want to take a chance on those. The only place in the US that I can find is this searspartsdirect but I don't know if these are genuine parts or not and they are much cheaper too. I also see that Mouser has the IFN146, this FET is costing a bit of money.
Click to expand...

I see that Littlediode has it, maybe you can try there?
 
Hi Kale - I see you left the large filter caps original. I assume they tested to their full rating of 12000 uf, yet they are still 35+ years old and must be closing in on their retirement years ;-) Just curious - thanks again for sharing this beautiful work. It is very inspiring.
 
stereofun said:
Hi Kale - I see you left the large filter caps original. I assume they tested to their full rating of 12000 uf, yet they are still 35+ years old and must be closing in on their retirement years ;-) Just curious - thanks again for sharing this beautiful work. It is very inspiring.
Click to expand...

I didnt replace them because first agreement between me and the owner was just to fix that amp, then when I opened it it was very dirty, plus it had issues, and we decided to go in restoration job but without changing main capacitors.
 
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