Atma-sphere S-30 lost channel--help!

Gopher · « **on:** 9 Nov 2010, 03:10 am »

I was just sitting down to some tunes after leaving the rig on to warm up but idling for about an hour. Things were sounding good when all of a sudden I heard a popping noise and lost the left channel on my s-30.

I'm not very tech savy, but as far as I can tell the tubes look OK...

Powering it back up and trying to check the DC offset the left side is unresponsive.

I'm pretty darn broke at the moment and this couldn't have come at a worse time... I'm hoping its something silly and small.

Ideas?

roscoeiii · « **Reply #1 on:** 9 Nov 2010, 03:28 am »

Besides calling ralph?

TomS · « **Reply #2 on:** 9 Nov 2010, 12:39 pm »

You can pull out an output tube at a time to see if maybe one of them went bad. It will run fine without all of them present. There is a visual inspection procedure here http://www.atma-sphere.com/support/visual.html that I might do first. Also, check the fuses if you haven't already. I had one go awhile back, replaced it, and never had a problem since.

Ralph can certainly help on the phone and is always more than willing to do so.

Tom

zybar · « **Reply #3 on:** 9 Nov 2010, 12:50 pm »

Quote from: TomS on 9 Nov 2010, 12:39 pm

You can pull out an output tube at a time to see if maybe one of them went bad. It will run fine without all of them present. There is a visual inspection procedure here http://www.atma-sphere.com/support/visual.html that I might do first. Also, check the fuses if you haven't already. I had one go awhile back, replaced it, and never had a problem since.

Ralph can certainly help on the phone and is always more than willing to do so.

Tom

When checking the fuses, look at the fuse closet to the IEC socket first. When a tube "pops" this is the fuse that protects things.

Ralph's phone support is excellent and I am confident that you will be fine and not out any major money.

George

Gopher · « **Reply #4 on:** 9 Nov 2010, 03:17 pm »

I will be calling Ralph shortly today, but had SOME progress with things.

The two fuses I can see through look fine, though the slowblo isn't translucent but I can't hear anything shaking it or see evidence of failure so I imagine its OK.

I flip flopped all the power tubes to the same position on the opposite channel and now both channels are alive, but things sound weird. I can dial in the DC offset perfectly for the right channel perfectly, but the left cannot be as the potentiometer doesn't turn anymore....

Prior to swapping the tubes I got no DC offset reading at all on the left side so I guess that is something... I didn't want to play with it to much out of fear of hurting my speakers so I kind of left it there and will call Ralph in the next hour or so.

jtwrace · « **Reply #5 on:** 9 Nov 2010, 03:20 pm »

Don't forget you can check fuses with a DMM with the audible Ohm setting.

Berto · « **Reply #6 on:** 9 Nov 2010, 03:44 pm »

Ive been playing around with less tubes and smaller fuse sizes and had two fuses pop (over a period of a few months). Like Zybar indicated it was the one next to the IEC. Once replaced , all was well.

jtwrace · « **Reply #7 on:** 9 Nov 2010, 03:47 pm »

Quote from: Berto on 9 Nov 2010, 03:44 pm

Ive been playing around with less tubes and smaller fuse sizes and had two fuses pop (over a period of a few months). Like Zybar indicated it was the one next to the IEC. Once replaced , all was well.

Why with smaller fuses?

TomS · « **Reply #8 on:** 9 Nov 2010, 03:51 pm »

Quote from: Berto on 9 Nov 2010, 03:44 pm

Ive been playing around with less tubes and smaller fuse sizes and had two fuses pop (over a period of a few months). Like Zybar indicated it was the one next to the IEC. Once replaced , all was well.

And you really need to test the fuses, as they don't always rattle when bad. I've even looked right at the clear ones with a magnifier thinking they were good and they were not.

zybar · « **Reply #9 on:** 9 Nov 2010, 03:53 pm »

Quote from: TomS on 9 Nov 2010, 03:51 pm

And you really need to test the fuses, as they don't always rattle when bad. I've even looked right at the clear ones with a magnifier thinking they were good and they were not.

This exact scenario just happened to me.

First time in almost two years of use that the fuse went. It went twice until I was able to identify and replace the tube.

George

Ericus Rex · « **Reply #10 on:** 9 Nov 2010, 03:54 pm »

Quote from: Gopher on 9 Nov 2010, 03:17 pm

The two fuses I can see through look fine, though the slowblo isn't translucent but I can't hear anything shaking it or see evidence of failure so I imagine its OK.

Test those fuses with a multimeter using the continuity feature. That's really the only way to be sure about them.

Gopher · « **Reply #11 on:** 9 Nov 2010, 04:20 pm »

I've got an MM at home and will test the fuses tonight. FWIW I'm getting output from both channels though. Pretty low and NOT sounding properly, but I imagine if the fuse took out a channel I'd get nothing.

TomS · « **Reply #12 on:** 9 Nov 2010, 04:41 pm »

Quote from: Gopher on 9 Nov 2010, 04:20 pm

I've got an MM at home and will test the fuses tonight. FWIW I'm getting output from both channels though. Pretty low and NOT sounding properly, but I imagine if the fuse took out a channel I'd get nothing.

Actually it might still give faint output if I recall correctly

Berto · « **Reply #13 on:** 9 Nov 2010, 06:16 pm »

Quote from: zybar on 9 Nov 2010, 03:53 pm

This exact scenario just happened to me.

First time in almost two years of use that the fuse went. It went twice until I was able to identify and replace the tube.

George

Maybe I have a bad tube but can a tube light up and still be bad?

IRT to smaller fuses Gopher , what I mean is I was told by Ralph if I want to run 14 power tubes (in a MA-1) I need a 5 volt, 8 power tubes/p/side 3 volt and 4 power tubes/p/side a 1.5 volt. This lowers the power and I realized it also lowers the grip and bass of the sound. 8 tubes is really as low as I wanna go now since the SQ sounds less then divine w/less.

srb · « **Reply #14 on:** 9 Nov 2010, 06:38 pm »

Quote from: Berto on 9 Nov 2010, 06:16 pm

Maybe I have a bad tube but can a tube light up and still be bad?

Sure. "Lighting up" just means the heater (filament) is working, but doesn't say anything about proper operation regarding the cathode or plate.

Steve

Gopher · « **Reply #15 on:** 9 Nov 2010, 08:51 pm »

Spoke with a really nice guy (Adam I believe) over at Atma-sphere. He seemed to be 99% sure the issue is a tube or a fuse, but is confident its nothing serious. I'm going to try and do the tube visual inspection tonight, check the fuses with a multimeter and swap 2 tubes at a time to see if the problem can be remedied.

We shall see I guess.

Gopher · « **Reply #16 on:** 10 Nov 2010, 09:32 pm »

Spoke to Ralph this afternoon and he seems convinced there is no big problem to worry about. He suspects my problems are a combination of bad power tubes and bad 6sn7s in my driver position. I'm gonna shift things around when I get home and see if I can't bring things back to life the way it ought to be.

I will be holding my breath, but am hoping he's correct as I can't stomach/afford a repair bill at the moment.

TomS · « **Reply #17 on:** 10 Nov 2010, 09:41 pm »

Quote from: Gopher on 10 Nov 2010, 09:32 pm

Spoke to Ralph this afternoon and he seems convinced there is no big problem to worry about. He suspects my problems are a combination of bad power tubes and bad 6sn7s in my driver position. I'm gonna shift things around when I get home and see if I can't bring things back to life the way it ought to be.

I will be holding my breath, but am hoping he's correct as I can't stomach/afford a repair bill at the moment.

I had something similar happen and it was 1 fuse, 1 6AS7, 15 minute job to isolate which tube. Fortunately, these things are pretty bullet proof.

zybar · « **Reply #18 on:** 10 Nov 2010, 09:48 pm »

Quote from: TomS on 10 Nov 2010, 09:41 pm

...Fortunately, these things are pretty bullet proof.

BINGO!!

George

Gopher · « **Reply #19 on:** 11 Nov 2010, 12:45 am »

Alright I spoke to Ralph today and Adam yesterday and there is life to my amplifier, but its behavior is a little abnormal at the moment.

I've I've got 3 power tubes per side now and can't set the DC offset for crap. I've got a seemingly balanced channel output, but its saturating quickly at low volumes and just NOT sounding like I know it should.

I'll happily buy more tubes if that will get me operating as it should, but its sounding a little off, not just lower and my speakers are 16ohm 101db efficiency, so it doesn't get more perfect for matches...

I also threw some new fuses in there, just in case--