Looking for some advice/comments from anyone who owns/owned/serviced a Sansui AU-20000. Picked one up late last year and it is in my queue for detailed testing and restoration in the next few weeks. Unit appears to be original and was well taken care of by the previous owner. So, I must admit that prior to the purchase, I fell a bit for the hype on these, but I also had an AU-9900 that I restored with assistance from several AK members and am very happy with in terms of design and performance. After more considered research, I am reaching the conclusion that the AU-20000 is a much different beast and may be beyond my technical skill set. What I have is part of the first release, 1976 mfg date and does not include the factory mods in the newer revisions. For those that own/owned one, is this truly the "holy grail" worth the time and effort to restore and possibly pass on to those younger in the family, or am I looking at a bottomless money pit? Thanks in advance for any response.
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Plimpington2
Super Member
I have a been kicking the tires on one as well over the last 60 days or so. It is local to me, and not likely to go anywhere unless I buy it. The one I am looking at is also an early serial number. I have done my share of rehabs/repairs of Sansui's (and a few Pioneers and Kenwoods, Luxmans as well), and I feel that I am equipped to manage this 20000 no matter the vintage. My feeling is that if you were able to work through a 9900, you can tackle a 20000. I suspect the only "new" challenge for you will be the pass-throughs (I cannot remember if the 9900 has passthroughs).
Thank you for the positive response. Yes the "passthroughs" caught my eye and not something I have run across on other Sansuis.
Plimpington2
Super Member
Yes, I have not done passthroughs either. I have a derelict CA-3000 that has something like 40-50 passthroughs in it, which I have not yet started to tackle. But I think just steady as she goes - there's no reason why they should be a special challenge.
DEFTECHY
Well-Known Member
I own a AU20k that Ive been plucking away on the last year or so, got some great help from an AK member on testing some basics, theres a few other members here that are very knowledgeable on these, plus quite a few past threads on restoring them here & other audio forums out there.
I'm an amateur but have above average soldering skills, have worked on a few vintage amps & other gear, just recently did a full recap of a AU719 and replaced some other parts like bad output drivers & black flag caps, that was my first Sansui and was happy to find how easy the boards are to remove & work on... the AU20k is also a modular design and most the boards come out pretty easy so its not very difficult to work on, just be patient and realize how everything comes apart.
Get the service manual & study it to get familiar with the boards, then do some research on how others work on each board and what areas need attention like some vd1212 diodes, or the boards with the bad glue that needs to be removed, there are 3 of them. I havent got into the pass throughs yet but after looking at a few other resto threads it doesnt look too difficult, removing the heat sinks & separating them looks more involved than repairing or reflowing the pass throughs.
The Au20k has a lot of boards & parts to replace so how much you do depends on its current condition, some say every single part needs replaced, but as with many things, I follow the "if it aint broke dont fix it" approach for the most part... i left all original parts in the 719 besides the lytic caps and other items known to have problems or failures like black flag caps, but the rest of the transistors, resistors, etc tested good &/or work & sound good so I left them alone, nothing wrong with a complete replacement of all parts though if thats what you want to do.
Best of luck!
I'm an amateur but have above average soldering skills, have worked on a few vintage amps & other gear, just recently did a full recap of a AU719 and replaced some other parts like bad output drivers & black flag caps, that was my first Sansui and was happy to find how easy the boards are to remove & work on... the AU20k is also a modular design and most the boards come out pretty easy so its not very difficult to work on, just be patient and realize how everything comes apart.
Get the service manual & study it to get familiar with the boards, then do some research on how others work on each board and what areas need attention like some vd1212 diodes, or the boards with the bad glue that needs to be removed, there are 3 of them. I havent got into the pass throughs yet but after looking at a few other resto threads it doesnt look too difficult, removing the heat sinks & separating them looks more involved than repairing or reflowing the pass throughs.
The Au20k has a lot of boards & parts to replace so how much you do depends on its current condition, some say every single part needs replaced, but as with many things, I follow the "if it aint broke dont fix it" approach for the most part... i left all original parts in the 719 besides the lytic caps and other items known to have problems or failures like black flag caps, but the rest of the transistors, resistors, etc tested good &/or work & sound good so I left them alone, nothing wrong with a complete replacement of all parts though if thats what you want to do.
Best of luck!
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The thing you need to pay attention to is unfused live power rails in the AU-20000. Before touching these, the power filters need to be discharged and disconnected. These are not an easy restoration if done properly.
However one really doesn’t have a Sansui collection without one
However one really doesn’t have a Sansui collection without one
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It has been a while, but I finally started on the restoration of this beast. First off, I've had it running for several weeks, with no issues to report, but at low volume, say 30% of volume full scale, the top of the case did get noticeably warm. Found that one of the two 220 ohm, 15 w, cement resistors, at the back of the power regulator and driver boards, plug in chassis board, is running hot, say 80 deg C compared to 45 deg C for the other resistor. Per the attached photo, the top one runs hot. Also the overall current draw, at idle state, is close to 1 A, which is much more than I have measured on other units. Bias adjustments were made with only minor changes. The other observation, is that some modifications were made to this unit. Even though it is an early build. June 1976, the driver boards temperature sense circuit is on the driver board, per the newer design revisions. The addition of the two 220 ohm resistors, is also part of the redesign. Plan to proceed with a refresh on the power regulator board followed by driver boards. Hopefully that will identify rogue component(s) that may be causing the temperature anomaly.
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The Sansui serial number database shows AU-20000 production from October 1975 to December 1977. 1975 is considered "early production" with "early design" features through at least November production. I would expect a June 1976 unit to have all the later revisions in place, but @richardpp has a lot of knowledge on the 20000, and he may weigh in with some insights.