Newbie question: what's making this staticky noise in my restored Sansui?

[gadget73]

re-read this and noticed OP said its not volume-dependant, so that means its after the volume control. Also its in the left speaker

Pull V11, a 6AQ8 and see if it stops. Its shared between both channels, but it will tell us if its at that stage or not.

 

[Viskus]

re-read this and noticed OP said its not volume-dependant, so that means its after the volume control. Also its in the left speaker

Pull V11, a 6AQ8 and see if it stops. Its shared between both channels, but it will tell us if its at that stage or not.

You mean pull it and turn on the receiver without the tube there? Is that copacetic? Never done that with a guitar amp.

 

[gadget73]

yes, it won't hurt anything, but with the tube out no signal will pass. I'm just curious if the noise is present with the tube in but not with it removed. If it still there with the volume all the way down its after the volume control. That 6aq8 is the next thing in line.

 

[Viskus]

yes, it won't hurt anything, but with the tube out no signal will pass. I'm just curious if the noise is present with the tube in but not with it removed. If it still there with the volume all the way down its after the volume control. That 6aq8 is the next thing in line.

I just tried it, twice.

Result:

Without V11, very soft hum in both speakers, and slight static/white noise in left.

With V11, louder static, plus popping and crackling in left speaker. Same soft hum in both.

 

[Mr Boochie]

I just tried it, twice.

Result:

Without V11, very soft hum in both speakers, and slight static/white noise in left.

With V11, louder static, plus popping and crackling in left speaker. Same soft hum in both.

Check the recap job done on the main power supply. I'm thinking maybe a cold solder.

Post close-up photos of the circuit board. Especially the work that was done. It helps the diagnosis.

Kinda like these.

Thanks!

 

[gadget73]

ok, so there may be something around the triode section of the 6BM8. Pulling the 6AN8 will skew the bias on the triode section of the 6BM8, but the fact that it didn't shut up completely makes me think it may be after that point.

Hum in both channels does imply power supply issue.

 

[Viskus]

Here are the photos. If these don't do it, I can break out the proper camera!

I did try probing around a bit more with the chopstick. No love.

 

[Viskus]

Does it do this on all sources? Does the volume control affect it?

Missed this earlier, but yes, this happens on all sources, and it isn't affected by the volume.

 

[Viskus]

I just cleaned the pins and sockets on V11 plus the four 6BM8 tubes. No change.

 

[Mr Boochie]

Here are the photos. If these don't do it, I can break out the proper camera!

I did try probing around a bit more with the chopstick. No love.

You may want to resolder all those electrolytic and non-polar caps that someone has replaced.

 

[Viskus]

You may want to resolder all those electrolytic and non-polar caps that someone has replaced.

This is the point at which I have to ask whether it's worth it. I can return this within the next two days, or I can pursue fixes. I don't have a lot of spare time -- if it's simple and straightforward, I might be fine. But if it's likely to be an ongoing effort to find something, I might do better to simply buy another receiver instead of this one.

 

[Mr Boochie]

This is the point at which I have to ask whether it's worth it. I can return this within the next two days, or I can pursue fixes. I don't have a lot of spare time -- if it's simple and straightforward, I might be fine. But if it's likely to be an ongoing effort to find something, I might do better to simply buy another receiver instead of this one.

If it were me, I'd return it. And look for a better alternative.

This is one rabbit hole/potential money pit to avoid (my humble opinion).

 

[wparks]

I guess it depends upon what you paid for it, and what level of functionality (and guarantee) it was advertised as. If they said it worked perfectly, it has definitely failed to live up to that and you are within your rights to return it. (Keeping in mind that something could have shaken loose in shipping and handling, so it may not actually be the seller's fault.) However, you understand that vintage equipment is filled with vintage components, that may be working today but will probably need ongoing attention. You could return it, and get another that has other, or more, or worse issues, or will very soon. It's like adopting an old dog. There are no guarantees. If it were mine, I would (or have someone) go through it all and make sure it's actually right, otherwise you really don't know.

 

[Viskus]

I guess it depends upon what you paid for it, and what level of functionality (and guarantee) it was advertised as. If they said it worked perfectly, it has definitely failed to live up to that and you are within your rights to return it. (Keeping in mind that something could have shaken loose in shipping and handling, so it may not actually be the seller's fault.) However, you understand that vintage equipment is filled with vintage components, that may be working today but will probably need ongoing attention. You could return it, and get another that has other, or more, or worse issues, or will very soon. It's like adopting an old dog. There are no guarantees. If it were mine, I would (or have someone) go through it all and make sure it's actually right, otherwise you really don't know.

I paid around $300. Advertised as fully restored, with no issues. It's a good deal I think, but I'm not attached to it. I think I'm going to hold out for eventually finding a 500 or if I'm lucky, a 500A. If I'm adopting an old dog, might as well go for a Beagle. And then I'd find all extra trouble worth it.

 

[Mr Boochie]

I paid around $300. Advertised as fully restored, with no issues. It's a good deal I think, but I'm not attached to it. I think I'm going to hold out for eventually finding a 500 or if I'm lucky, a 500A. If I'm adopting an old dog, might as well go for a Beagle. And then I'd find all extra trouble worth it.

Return it. If you really like it, have the seller fix the issues — as it is not "Fully Restored."

 

[Viskus]

Return it. If you really like it, have the seller fix the issues — as it is not "Fully Restored."

Yeah, that's what I'm going to do. I'm drawn in by the challenge, and I think it would be fun to fix. But I just don't have the time. I really appreciate all the helpful guidance here. I would have been utterly at-sea on my own.

 

[Mr Boochie]

Yeah, that's what I'm going to do. I'm drawn in by the challenge, and I think it would be fun to fix. But I just don't have the time. I really appreciate all the helpful guidance here. I would have been utterly at-sea on my own.

If you are looking to learn about how tube amps work, maybe a nice DIY single-ended headphone amp starter kit?

Since I play guitar, I started out fixing 1960s-70s-era starter-level Fender Champ and Vibro-Champ amps. There are new parts available, along with many good online how-to sites and YouTube videos.

 

[Viskus]

If you are looking to learn about how tube amps work, maybe a nice DIY single-ended headphone amp starter kit?

Since I play guitar, I started out fixing 1960s-70s-era starter-level Fender Champ and Vibro-Champ amps. There are new parts available, along with many good online how-to sites and YouTube videos.

Yeah, same here on guitar -- I have four tube guitar amps, and have read an entire book on amp design (which didn't stick, clearly). One of those amps is a very simple Valco design (see my avatar). I mostly just want to enjoy the sounds these days, as I'm very short on spare time.

 

[Mr Boochie]

Yeah, same here on guitar -- I have four tube guitar amps, and have read an entire book on amp design (which didn't stick, clearly). One of those amps is a very simple Valco design (see my avatar). I mostly just want to enjoy the sounds these days, as I'm very short on spare time.

One thing that I like about guitars and guitar amps is that you spend some time and money to fix them (hopefully correctly ) — and usually they sell for the investment spent. If not more.

Some of my amp porn.

 

[Viskus]

One thing that I like about guitars and guitar amps is that you spend some time and money to fix them (hopefully correctly ) — and usually they sell for the investment spent. If not more.

Some of my amp porn.

Very nice! I'm mostly a Vox guy myself. Though I've heard a few Fenders that I'd buy if I could justify any more amps.

I've got a '90s AC30, a modern AC10, and a customized take on the original AC15.