Restoring a "mighty" AU X1 / output transistor replacements

Ronito6 said:
I wonder if this is indeed the 330nf capacitor added by Mr. Kuehne to solve that DC drift issue.
(At least it would be part of his solution.)
index.php


You can see another black cap under the small blue one. That black cap seems to be a replacement for the one Sansui used to bridge diode 07 and uPA68hl.

Mr Kuehne, is that small blue cap part of your solution? If so, then the duo FET you refer to is the uPA68?
Click to expand...

Just picking up on this, there were 2 Black Flags on the print side of my Flat Amp board, the small blue one (in the pic) looks like a replacement for one, but also in the pic I see what looks like a Black Flag just below it?
 
Hyperion said:
Just picking up on this, there were 2 Black Flags on the print side of my Flat Amp board, the small blue one (in the pic) looks like a replacement for one, but also in the pic I see what looks like a Black Flag just below it?
Click to expand...

That threw me off too.

Only one person can solve this mystery.

This guy...

MartinKuehne New Member
 
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Sansui chose films, and so did Martin K - good enough for me - and no reason to use anything different.
 
Hi, I've only just come onto this thread because I have an AU-X1 here that has stability problems in the left MM phono. I swapped the black flag caps from the left MM board to the right channel, and vice versa. Now the instability has swapped channels so I know for sure the black flag caps need to be replaced. I decided to order NP0 ceramic caps to replace them. I'll let you know how it goes.
Colin.
 
Hi, I've only just come onto this thread because I have an AU-X1 here that has stability problems in the left MM phono. I swapped the black flag caps from the left MM board to the right channel, and vice versa. Now the instability has swapped channels so I know for sure the black flag caps need to be replaced. I decided to order NP0 ceramic caps to replace them. I'll let you know how it goes.
Click to expand...

Swapping or losing channels may be a symptom of failing small signal relays.

How does the instability show itself? Does the channel without sound make any sound?

Does the bad channel have super low volume or perhaps a dreadful hum?

If the problem persists after installing new np0's, look to those relays.
 
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On MM input the left channel buzzes prominently, slightly lower volume than normal playing volume. When MC is selected the buzz is reduced in volume. After swapping the black flag caps from channel to channel now the right channel buzzes, but quieter than when they were in the left channel. The relays seem to be fine, the volume is normal and balanced in both channels, apart from the constant buzzing.
I still can't believe how good the sound is on MC input! Zero noise, calm, serene and dynamic at the same time, with loads of depth.
 
Welcome to AK ColinF !

It would be a good idea to start your own AU-X1 thread, otherwise it can get confusing which AU-X1 is being discussed.
 
We have a surprising number of X1's popping up.

The detail in Harold's thread here and it's expansion of the X1 information base is proving needed.
 
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Ronito6 said:
We have a surprising number of X1's popping up.

The detail in Harold's thread here and it's expansion of the X1 information base has proved needed evidently.
Click to expand...

Yep, there is a surprising number of 'looks' at all the recent AU-X1 threads - which can only be a good thing. :thumbsup:
 
Not all the 'lookers' are AU-X1 owners. There is an abundance of experience and knowledge here and one never knows when some little tidbit will bail you out of a jam.

Thanks - - -
 
ghazzer said:
Not all the 'lookers' are AU-X1 owners.
Click to expand...

I think you have made a bit of inference. (...but he who is without sin...eh?)

X1's are rare, and showing the huge amount of work needed to get one back to "fighting fit" is an education.

BUT you got to admit ...Since Vintagear posted his X1 thread last year there has not been more X1 restorations shown anywhere else since Kale showed his work 3 or more years ago.

Just within the last 12 months X-1 restoration threads have been started by Vintagear, Harolda, Hyperion, and Willy6.

I think that is more X-1 restorations than ever seen on any website outside of Amp8s site.
At least as a window of time goes.
 
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It was a magnificent amp when it came out. The one I'm working on has been owned by its current owner from new. In the past (the 90s) it had suffered poweramp failure and I'm told it took over a year to repair it. Since this thread is an output transistor thread, is it worth stocking up on output transistors before they become really hard to get, or just rely on current production TO3P LAPTs? I think I'll also change the 33p caps to 47p in the poweramp. AK threads do help!
It would be great if Sansui could get back into proper audio and remake the X1 with surface mount parts. That way the circuit can be made more compact and its maximum operating frequency could increase. A current production X1 in today's prices would be very expensive.
 
The correct output transistors for the AU-X1 have long been out of production. However, they do come up for sale every now and again - possibly removed from units being parted out? so, the idea of 'stocking up' is a non-starter. Any you do see (especially on ebay), with original type number indication on them, should be viewed with extreme suspicion, as they could very easily be counterfeit.

You need to get rid of ALL the Black Flags in the AU-X1. If I may be very blunt, changing one or two here and there isn't going to get the job done.

ColinF, Please tell us about your AU-X1 in your own thread - it is always very useful to see how others do things, oh, and we like pictures very much ;)
 
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Hi guys,

No progress here. Amp is really performing, unlike anything I have heard. We moved into another house (intermediate) and most of my equipment is packed and will remain so for at least a year. Starting on building my dream house in September. Also my ns2000 remain packed. I have the amp driving some JVC sx3. I also restored these some time ago. Very nice combination. The amp is really unbelievable, and I still have to do some things like putting the phono boards in the amp. I didn't find much time to take part in the discussion here, but i'll be back ;)

Btw i use the amp with bypassed flat amp, much more detailed in my humble opinion
 
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