Sansui AU-X11 powers up but no sound

[Lari]

Hi there,
I've been reading your posts for a while and fellow vintage Sansui fan recommended to post a topic here.

I got nice AU-X11, which went for quick check-up/service. Quick inspection seemed ok. There was nothing alarming and ''All circuit elements appear to be working correctly'' but then there is no sound from speakers or from headphone. ''The unit is either in mute, which it doesn’t appear to be, or there is a broken signal path.'' We decided to call it quits for the repairs as it might be very expensive exercise for now.

We then talked about maybe keeping it powered on for a while and maybe I get something out. And I did after hour or two. Headphone output worked and kept it going for few hours. I turned it off/on at one stage to see what happens. No change...but when I kept it off slightly longer and moved it to a table, then I lost signal again. And haven't got it back yet.

I'm planning most likely to do full restoration someday but this is not cheap. I cannot put money into that at this moment. But I would like to enjoy it little before restoration.

I would appreciate if someone would like to advice what might be the possible cause here.

 

[Hyperion]

When you have the amplifier powered up but not giving any sound output, is it in 'protection mode' ? i.e. with the red power light flashing? - this would explain why you are getting no sound output. Leaving it powered on, and getting sound output eventually, suggests the amplifier has finally settled down and 'protection mode' has deactivated thus allowing sound output. However, if this is the case I would be very surprised that you haven't mentioned anything about the power light flashing. If the power light is steady (after a brief period of flashing), then it is very likely you do have a 'broken signal path', most likely caused by some signal path switching relays in this amplifier that become unreliable with age and need to be replaced.

The AU-X11 is quite a complex amplifier to restore, definitely not a job for a novice, it also contains some capacitors (nicknamed 'Black Flags' by an AK member) that can deteriorate over time and leave the amplifier in an unstable state. When this happens it is possible for the amplifier to be severely damaged, just by being powered on. So any use of the amplifier before these capacitors have been replaced risks damaging parts (output transistors) which are no longer made. In the light of this, your thought to "enjoy it a little before restoration" is one you should consider very carefully.

The AU-X11 is a very very nice amplifier indeed, it is rare, and good examples are expensive to buy. Properly restored it will give many years of listening pleasure.

How do I know this? - I have restored an AU-X1 and an AU-X11 and many other Sansui amplifiers.

Welcome to AK, the delights of Sansui ownership, and the thrill of owning an amplifier that many would give their eye-teeth for.

 

[Lari]

Thanks for your insight.
Power light also blinks few times in the beginning and I thought this normal for these. After that it is solid but I do hear few different ''clicks'' and I've been wondering if someone smarter could tell me if those are relays jamming the signal.

Yeah...I admit. It does sound little silly wanting to listen this amp before taking it for full service. I wasn't quite sure if that is possible either but according to my technician here, if all are ok then it might could be used for a while before proper service. He does vintage repairs for a living.

I've read about those black flag caps. Not sure though which one they are but I guess the big one's there in the middle.
I'm very new to vintage gear restoration but then again would like to know more as understanding makes listening and owning things more rewarding, like in everything else. Previously I have also helped friend to recap luxman amp. AU-X11 might be too scary to recap but I might give it ago. I don't have much to lose as restoration is so expensive that my other expenses won't allow me to do that for a long time.

 

[Lari]

Did little research and I can now I understand what those black flags are. I had my amp open here and there are plenty of those. Recapping this amp also is headache when accessing to all the boards is very complicated. It is really a puzzle and so many things must come apart. This might go to cabinet waiting for service or better days. Servicing this is just so expensive that it doesn't really pay off.

 

[Hyperion]

Servicing this is just so expensive that it doesn't really pay off.

Well, it should roughly double in value providing its been done by a recognised restorer. Note the word 'servicing' or 'serviced' has a bad reputation, as this is often used in ebay descriptions allegedly to mean 'good to go for another few years' or even implying 'restored' when no such thing has been done to the unit.

I am glad you now see how much work is involved in restoring one of those, they really deserve to be dealt with properly.

 

[Lari]

I agree. I would be tempted to start doing some minor work for this amp but I don't think I could ever complete or do the fine tuning for this so better just to forget, at least for now.

Impressive if you have serviced/repaired few of these. It must have been long process though?

 

[Hyperion]

It must have been long process though?

I've only done one AU-X1, and one AU-X11, but a host of others including three AU-919's. I haven't measured it exactly, and it depends if I am doing things like re-stuffing or changing main PSU capacitors or fitting replacement speaker terminals, but around 30 hours work for one of those. That's not including making up the order for parts, and any fault finding which can take some time too.

 

[Lari]

Very impressive so I guess you know your Sansui's very well then. You still have them or you passed them along?

This Sansui was actually supposed to be just a temporary amp until I get few other things sorted. My plans were to get Accuphase C-200V and P-300V combo.
But I didn't realise how expensive fixing this Sansui would be. Now then again I'm not sure how many years I would need to wait to be in situation I can spend money for Accuphase so I might keep this Sansui for a bit longer. I also wanted to hear big Sansui so I decided to get this one. It is quite ''plain'' looking and with few plastic knobs, not like Accuphase amps, but then again size of this amp is impressive.

Again, this recapping thing keeps bothering me. My mind keeps telling forget it but I feel I would like to do something for it. I want to restore this in a service shop but 30 hours of work is going to kill it. Labour is expensive here and couldn't be justified for now. But if I would try to do something myself, like maybe starting with speaker ports and moved slowly with capacitors then I'm sure I could save already heaps of money.

When you have done this in the past, would you happen to have list of capacitors needed, including the ''black flags?'' This would be tremendous help as I wouldn't need to pull everything apart just to know what I would need. Then I would also now pricings for those pretty easily and could think of this process more.

 

[Hyperion]

You still have them or you passed them along?

The AU-X1 is mine as is one of the AU-919's - and in my collection I have a total of 6 Sansui amplifiers. The others mentioned above belong to other AK members, or non-member referrals. As for 'very impressive', I'm just a 'shrimp' in comparison to some of the restoration & reconditioning Titan's that inhabit this site.

I am only an amateur, I don't feel the need to maintain components lists as volumes reconditioned here are very low. Also the electronic values of the parts installed very often varied over time, so a list generated for one AU-X11 won't necessarily be the same for another one produced at a different time. These amplifiers often had these component changes happening during production runs to improve performance, or stabilise instability. And the schematics contained in the Service Manuals also don't often reflect these changes, making the job of the would be restorer more difficult.

Just a note about output transistors, the originals are not available anymore, it is easy to make a mistake and damage OP transistors when restoring one of these, especially as these amplifiers are inclined to be unstable. There are substitute OP transistors available and they'll work, these particular amplifiers do sound marvellous, but only sound their absolute best with the original type of output transistors, many other amplifiers are not so picky.

 

[Lari]

Heh...I'm feeling you are trying very politely to advise me not to touch the amp.
If I would do recapping then it would require the daunting task of trying to check every capacitor but then again it would need to be done anyway.
Not sure, if I will do some work for this. It won't happen soon anyway so I can have time to process this.
Anyway, after any of the potential work it would first go to tech to check again and finish the job.

I've done little soldering earlier for Luxman and to few B&W and Kef speakers.
Would need to get proper soldering kit for this job though...and for any potential future works.
I would probably start with speaker terminals. Could you advise what replacement terminals you would recommend?

 

[Hyperion]

Could you advise what replacement terminals you would recommend?

Any decent 4/5 way speaker binding posts will do, loads of adverts on ebay for these - one thing I strongly recommend you buy 'fully insulated' types, as you may be aware shorting speaker terminals together is a huge no-no, and uninsulated ones make this much more likely.

 

[Lari]

Thanks, much appreciated, I will do some ebay searching. I will probably need to ask more advise when I get to somewhere with the fixings later on.