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Hanging by a thread, aka restoring a Sansui AU-717 the Leestereo way!

AmbientNoise

AmbientNoise

AK Subscriber
Subscriber
So I'm brushing off the cobwebs and getting ready to restore my Sansui AU-717... It's been years since I've done repairs to electronics/guitars so to say I'm nervous would be an understatement. Please understand I never would have attempted this had I found a shop that I felt I could rely on, I'm sure they're out there. So after messaging the wizard "Leestereo" I've decided to take on the challenge myself. I've just received my BOM from Mouser and verified quality/quantities. I've also just started a new job and will only have time on the weekends to work on this. I'm questioning the sanity of creating this post to begin with, but I feel it will help me push through and hopefully inspire others with rusty skills.

Please note: I'll upload photos as best I can, but it will likely be before/after and any odd problems I run into along the way. Additional mods will include a new polarized 2 prong power cable and a set of new speaker terminals linked here: https://speaker-terminal.com/en/produkt/sansui-au-717-speaker-terminal/.

Also don't be discouraged if I don't respond to questions quickly, I've got a new job and the work will occupy a good bit of my time after I get home as there are several challenges I'll need to sort to be effective the next day/week.

Thanks in advance to everyone that's gone before me and any members that have/will contribute!
 
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I'm sure you will do fine. There are plenty of folks to help you along the way if needed.

Also, good luck with the new job.

Rob
 
So I'm still waiting on a couple of pieces to arrive, in the meantime I've decided to crack open the case and take a look inside.
Woof, I know it hasn't been submerged but wow look at that grime! I'm strongly considering ordering a set of Sanken output transistors
and possibly others if the corrosive glue has climbed up the legs of them. Anyone else have any luck with doing the same?
Huge thanks to Leestereo for the inspiration and knowledge base!!!




IMAG1042[1].jpg IMAG1043[1].jpg IMAG1044[1].jpg
 
Robisme said:
I'm sure you will do fine. There are plenty of folks to help you along the way if needed.

Also, good luck with the new job.

Rob
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Thanks Rob!, I'm heading out of town for 3 days starting tomorrow and will be back home late Wednesday night.
Any thoughts or advice is greatly appreciated!

Regards,
Anders
 
AmbientNoise said:
I'm strongly considering ordering a set of Sanken output transistors
Click to expand...
Even the Sansui Glue doesn't get that far, just look after the originals by not making any mistakes and you will be fine. It's true that some people change transistors with blackened legs, personally, I don't bother unless they are transistors on the 'known troublemaker' list.

What people sometimes do with particularly rare output transistors is substitute them with new (currently available) very similar transistors until they know everything works as it should. Then and only then, swapping back the valuable, rare originals. I am not immune from making mistakes and I have done this on more than one occasion with success and fewer grey hairs ;)
 
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Hyperion said:
Even the Sansui Glue doesn't get that far, just look after the originals by not making any mistakes and you will be fine. It's true that some people change transistors with blackened legs, personally, I don't bother unless they are transistors on the 'known troublemaker' list.

What people sometimes do with particularly rare output transistors is substitute them with new (currently available) very similar transistors until they know everything works as it should. Then and only then, swapping back the valuable, rare originals. I am not immune from making mistakes and I have done this on more than one occasion with success and fewer grey hairs ;)
Click to expand...

I'm going to at least clean them and replace the thermal paste/insulators, I'm going to be digging in and searching to make sure any PNP or NPN transistors are addressed if need be. I think after all the parts are replaced my biggest challenge will be aligning the channels as it's something I've never done.
 
So I've noticed a bit of corrosion around the edges of some of the boards, mind you I haven't plugged this amp in, in fear of damaging it. Anyone else see this during their rebuilds?IMAG1060[1].jpg
 
Hyperion said:
Looks like flux or possibly Sansui Glue to me - very unlikely to be corrosion as such.
Click to expand...

Thanks John! I'm going to be cleaning off each board with alcohol and non-acetone nail polish remover. Hopefully there is no trace damage, though I can repair if need be. Today is just removing panels and control knobs and getting a general look at what all is going on.
 
Looking forward to your restoration on your AU-717. I see what you mean on dirt, grime and cobwebs...lots of cleaning..!
...looks to be untouched and in great condition....good luck with your new job...
 
Thank you! Yeah everything seems to be original and untouched, which makes me happy!
I've got an option to buy a backup AU-717 for decent money, I might just grab it to restore and hold as backup.
Though I plan on reworking all the other pieces I've got before that. I'm thinking TU-717 next...
 
If you amp is working with the original outputs, then I would keep them, but remove them and clean the old heat transfer grease, and put new stuff in. However, I cannot say the same for the rest of the transistors. There are some small signal transistors that are prone to failing, this manifests itself as noise, but they could also do some serious damage. There are fusible resistors - "fusistors" that often go out of spec as well, and there's the electrolytic caps. The one I did, all four of the main caps were out of spec, so I would recommend changing them as well.

https://audiokarma.org/forums/index.php?threads/sansui-au-717-restoration-and-upgrade.875646/
 
Super Noob said:
https://audiokarma.org/forums/index.php?threads/project-sansui-au-717-restore-rebuild.893233/

https://audiokarma.org/forums/index.php?threads/project-sansui-au-717-bks.896463/

Did a couple of these... my builds were Ben Lee inspired. @Leestereo

Very nice integrated indeed.
Click to expand...

Thank you @Super Noob ,
I've already started looking over your thread(WOW!), any must do's other than the work Lee has done? I've already ordered my BOM that he supplied me with. To be honest there is a small part of me that wants to do a complete rebuild leaving no stone un-turned. Though I may just do the recommended on this unit, should I end up with the other unit that I have the chance to buy I'll definitely do a full rebuild.
 
@leesonic,

I've invested in the playbook and BOM from Leestereo and am fully committed to making it a beautiful beast once again. But you and Hyperion are strong on the original output transistors, I'm super curious why though? Please understand I'm coming from a place of genuine curiosity, are the new transistors from Sanken or others total crap? If you had to replace them which company would you go with?
 
AmbientNoise said:
@leesonic,

I've invested in the playbook and BOM from Leestereo and am fully committed to making it a beautiful beast once again. But you and Hyperion are strong on the original output transistors, I'm super curious why though? Please understand I'm coming from a place of genuine curiosity, are the new transistors from Sanken or others total crap? If you had to replace them which company would you go with?
Click to expand...

modern TO3 are not as fast... retain the output transistors. Recommend just the small transistors for this set. I did them all minus the outputs on BKs = so you have a reference if you go that route.
 
@Super Noob,
Thank you! I couldn't figure out what the deal was in regards to older TO3's, so the newer units are slower and affect the dampening rate?
It's crazy to think that no one makes those components to that standard anymore. Guess I'll keep an eye out for backups at some point.
 
Good Day,
+1 on Output transistors. Also if driver transistors are intact leave them alone and do not use MJE15032/33 (they are also slower). Best replacement for those driver transistors which are currently in production are Sanken 2SC4883A/2SA1859A . But those have isolated tab and will require creativity when installing them (you can see my "Another Sansui AU-717 restoration") Also if you do it for yourself look at my thread and see about Rubycon MU series film caps. Good Luck with the resto.
Here is the link to my resto https://audiokarma.org/forums/index.php?threads/another-sansui-au-717-rebuild.932752/
 
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