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Finally, Sansui G8000 restored

You are a very skilled craftsman, excellent work!!
But, How does it SOUND, please keep us updated.
Regards
Mike
 
falcon377 said:
You are a very skilled craftsman, excellent work!!
But, How does it SOUND, please keep us updated.
Regards
Mike
Click to expand...
You see, I still didnt say anything about how it sound; why? Because so many parts are changed, the sound is now similar to some Yamaha home theater receiver than to real Sansui sound. But, I know that will be changed after 30 to 50 hours of work and than it will be with warm Sansui sound but with clear and soft high. The same case I had with my G7000 what I restored last year.
But now, I can say something for sure, without signal on input, you can hear silence like in grave :yes: without hiss and brum!!

Regards!
 
G8k

Good job Kale, the G8k is one of the finest receivers ever made, and you have saved one to have it live again for many years of trusted service.
It's good for we in the US to see workshops in other lands, sometimes maybe we think americans are the only folks crazy enough to have the passion for vintage audio that we all do.
Will you veneer that case? I never cared for the vinyl that Sansui used on that series, LBPete did mine for me, and it really kicks the looks of that receiver up a notch.
Casey
 
nosirrah said:
Good job Kale, the G8k is one of the finest receivers ever made, and you have saved one to have it live again for many years of trusted service.
It's good for we in the US to see workshops in other lands, sometimes maybe we think americans are the only folks crazy enough to have the passion for vintage audio that we all do.
Will you veneer that case? I never cared for the vinyl that Sansui used on that series, LBPete did mine for me, and it really kicks the looks of that receiver up a notch.
Casey
Click to expand...

Casey, here in Europe, the prices of vintage receivers are much more higher than in States. I still dont know why USPS dont wish to make transport heavy items by boat, only by plane. I got my G7000 from USA to Croatia for only 70 US$, OK the shipping was three months long, but I can wait. Now, for the same receiver, I have to pay over 250 US$ for shipping by plane! Not good for us in Europe and not for you in States.

As I told before, I have another one G8000 which is not so good as this one, and it has some damage on wood case, so I will try to put real wood veneer on it. I can remember that gamalot made one fantastic case for G9000!

BTW, Aarons didnt answer to me about those screws what I asked you. I sent them the picture with dimensions of screws, but without answer.

And, one question for all: what is with Michael Percy Audio Store (www.percyaudio.com), I have written so many times to them for order some parts, but nothing, I send them fax order, again nothing. Very strange!

Regards!
 
Kale said:
BTW, here I wish to show you only one modification what I made in that receiver... On that receiver, I decided to do only restoration, but one thing, Sansui did on bad way. To correct that Sansui mistake, I have had a big help from another Croatian member ilimzn. So first about what I am talking here;
There, I am talking about connections of main capacitors. You know that G8000 has 4 pcs of 6800uF capacitors per channel, and that is very good, but Sansui made a mistake how they are connected. First of all, wire of ground is so long! Second, wires of power supply and wires of power stage are connected into one point.
So, we need to separate pair of power supply capacitors from capacitors of power stage, and make better ground wiring.
Click to expand...

Hello everyone. Kale asked me to explain tyhe modification to he capacitor conenction of his newly restored G8000.
What Sansui did in this case is not something i would strictly call an error, as much as a missed oportunity.
When constructing a non-regulated power supply for an amplifier, one of the main concerns is to separate the current loops of the rectification part and the load (in this case amplifier) part as much as possible. When there are only two filter caps, the best one can hope for is that this common path are the caps and the ground wire that connects them. Sadly, even for this simple case wiring errors are not uncommon - one of the more common ones is an overly long ground wire connecting the two caps, and several off-shoots of the ground to various places in the amp which result in a badly defined star ground center.
With two pairs of caps, it is possible to separate the current loops quite efficiently, by attaching the rectifier side to one pair, and the amp side to the other. Then, the two pairs are interconencted by wires that should not be too thick (a bit of resistance helps here because it forms a filter with the caps), by inductances (like kale did), or even by a common mode choke. Because the interconenction is 'lossy' for the current waveform in question, the majority of the high frequency AC spectra of each current loop goes through only it's respective capacitor pair, while the DC portion of the current still sees both pairs of caps in parallel.
Because the rectifier loop contains many harmonics of 120Hz, and the amplifier loop contains halfwave rectified output current, separating these loops prevents the intermodulation of these two signals, and the many previously non-existent frequency components that result, from feeding back into the amplifier, and into the mains. And all it takes is slightly altering the way the two filter cap pairs are conencted - even if it's simplified down to wire connections!
 
ilimzn said:
Hello everyone. Kale asked me to explain tyhe modification to he capacitor conenction of his newly restored G8000. ...[CUT]
Click to expand...
Thank you ilimzn what you found some free time to write that very good explanation about this power supply problem! And as always, yours text is very interested to someone who wish to learn something from you, so again thank you for that :thmbsp:!

Regards!
 
Thank you

ilimzn said:
Hello everyone. Kale asked me to explain tyhe modification to he capacitor conenction of his newly restored G8000.
What Sansui did in this case is not something i would strictly call an error, as much as a missed oportunity.
When constructing a non-regulated power supply for an amplifier,

<<snip>>

And all it takes is slightly altering the way the two filter cap pairs are conencted - even if it's simplified down to wire connections!
Click to expand...

Excellent description, Ilimzn. :thmbsp: Technical people always appreciate the "why" in any of these improvements.

Paul
 
Yes, Ilimzn, thank you very much for your lucid description of the work. Along with the pictures, and many repeated readings, I hope to fully understand it and one day apply this idea to an amp! It is really really helpful that you used the structure of the amp as a way of explaining it, rather than "the orange wire," so that new people like me can increase our learning!

Collin
 
Very, very nice, Kale. :thmbsp:

BTW, good luck with those screws and Michael Percy Audio Store, sorry no advice.
 
Kale said:
I know that the most members of AK dont like so many words, so my introduction will be short. That G8000 I have bought about one year and half beffore on ebay. I was lucky because at that time, USPS still made shipping by boat, and it was slowly shipping (about three months to Europe) but very cheap (about 80 US$). But when I finally got it, I was mad, look how it was looking:





















And finally:
Top_G8000.jpg


FrontG8000.jpg
Click to expand...

terrific work..enjoy!!!!
 
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