Sansui AU-X301i troubles (noise,super quiet output)

A

auxym

New Member
Hi, a couple weeks ago I picked up this amp (AU-X301i) on craigslist for what appeared to be a good deal (30$). Guy assured me it was working fine.

Well, I just got around to trying it, and apparently I got screwed. >.<

It makes this constant "NRRRRRRRRRRRRRRRR" noise. This noise is directly influenced by the volume, so you can't hear with the volume way down, but as you turn it up it gets louder and louder (pretty damn loud, too.) It makes this noise whether there is an input or not.

If I do connect an input, I can hear it, but it's very, very quiet. As in, I have to turn the volume halfway up just to be able to barely hear it.

Playing with the controls also makes weird things happen. By playing with the Rec Selector knob or repeatly turning on/off the Tone switch, the noise sometimes goes away, or only in one channel, or one channel completely dies. The music however stays quiet.

Finally, I am not sure if this normal or not, but the Protector LED stays lit when the amp is on. It blinks during the first few seconds, then when the amp clicks, it stays lit.

Am I looking at something that is repair-able here? If so, is it something that is worth repairing, or should I just ebay it for parts or something?

TIA!
 
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I had one of those. They don't sound that good. I compared it to an AU-517, and the 517 was worlds better.

I gave it to a kid.

It was not made in Japan. If your sticker is missing, it says made in Taiwan.

I also had the TU-X301i tuner. it was made in Japan and was a decent tuner.

Is the noise in both channels?

Probably not worth repairing. IMO

Rob
 
Alright, well thanks for your thoughts.

Hypothetically, if I wanted to investigate a little bit into this, do these symtpoms usually point to a particular problem? Bad cap? Blown transistor? Ground issue? Or oxidization of controls or something?

As for the AU-517, as much as I'd love to pick one up, it's a bit out of my budget. I'm a college student and was looking to put together a really cheap setup for listening to music (heh, couldn't be worse than 20$ computer speakers, in any case). Looking on CL again, some guy has a Sansui A-9 also 30$. Provided I actually try it and make sure it's in working condition, is that a decent amp?

Edit: Sorry, yes the noise is in both channels and also for both speaker outputs (speakers A/B). It sounds kind of like a ground loop buzz I guess?
 
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auxym said:
Alright, well thanks for your thoughts.

Hypothetically, if I wanted to investigate a little bit into this, do these symtpoms usually point to a particular problem? Bad cap? Blown transistor? Ground issue? Or oxidization of controls or something?

As for the AU-517, as much as I'd love to pick one up, it's a bit out of my budget. I'm a college student and was looking to put together a really cheap setup for listening to music (heh, couldn't be worse than 20$ computer speakers, in any case). Looking on CL again, some guy has a Sansui A-9 also 30$. Provided I actually try it and make sure it's in working condition, is that a decent amp?

Edit: Sorry, yes the noise is in both channels and also for both speaker outputs (speakers A/B). It sounds kind of like a ground loop buzz I guess?
Click to expand...

Try a good cleaning of the controls, and if that doesn't fix it do as Rob said and discard it.
the A-9 isn't any better.
On a budget try to find one of the receivers, a 2000X maybe.
Your computer speakers won't sound good with anything hooked up to them...
Keep watching, good deals will come up, but you gotta jump on em quick!
Casey
 
Alright, well I actually made some progress with it. At the moment it's sitting in pieces on my table. I got my hands on the service manual and adjusted the DC offset (was around 12mV instead of 5). I actually get sound now! And the buzzing is already quite a bit quieter. Pretty cool :)

However, I still have a couple weird things happening. I've narrowed it down to two controls: volume knob and Tone push-button

First of all the volume knob. Simply making contact with the actually metal "stick" (on which the knob would go) makes the noise appear, as soon as I let go it goes away. Similarly for those 3 contacts/leads coming out the side, touching them makes the noise vary. I guess this is somehting contact cleaner could fix.

And then there's the tone switch. Just slightly wiggling it makes a bunch of things happen: one channel going out, noise coming or going away on one or both channels, etc. Another thing: it seems that the bass in really over-emphasized in the right channel and completely lacking in the left. At very moderate volumes, I'll actually see the right woofer thumping with considerable amplitude on each bass drum hit (only a moderate difference in sound though, so it must be only very low frequencies doing this). At the same time, the left channel seems to be completely lacking bass. Mids/highs on both channels seem decent. Wiggling the tone switch makes this problem worse or better (never completely goes away though). The actual position of the tone button (on or off) does not seem to make a difference.

Now the thing is, this tone switch does not seem to have any exposed contact. Would this be a matter of maybe replacing the button? Or would there perhaps be a way to fix it?

Picture for reference (click)



Anyways, I'll pick up a can of contact cleaner tomorrow and update you guys.

In the meantime, could anyone confirm whether the Protector light behavior described above is normal? (Blinks when turning on, then stays lit when the relay clicks).

Oh and by the way, I wasn't planning on hooking it up to my computer speaker ;) I'm in the process of re-foaming an old pair of Boston speakers. And thanks for the recommendation on receivers, I'm keeping my eyes peeled.
 
Well, I might be replying to myself here, but I'm making some great progress with this :)

I got my hands on a can of Deoxit D5 (set me back 20$ but hey, good investment I guess), and cleaned every single pot and jack. Wow! Pretty much all the issues are gone, including the hum, and weird channel intermittency.

One small-ish issue remaining: the right channel is significantly louder than the left. I mentioned only for the bass in my previous post, but upon double-checking, it seems to be across the range. I'd say, by ear, it's about twice louder in volume. To have equal volume from both channels, I have to set the balance knob about halfway left. I say it is a small-ish issue because, worst-case, I can just leave the balance there and be happy.

But, since I'm curious, what could be the cause for this?
 
Does the loudness button work for both channels?
Try turning the balance all the way to the right and hit the loudness button.
Then all the way to the left and hit the loudness button.

I had a receiver that acted that way. it turned out to be a short.

Just something to try.

Could be the volume pot is out of whack.

Rob
 
Thanks for the ideas.

Loudness button seems to work the same on both channels.

As for volume pot -- could I test that with a DMM set to resistance check?
 
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