S1 45 serious issue

THE NEW #1. Series One Amplifiers.
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6strings
Posts: 12
Joined: Wed Mar 21, 2012 1:00 am
Location: Stoke, UK

Fri Sep 28, 2012 12:56 pm

Aup guys!

Writing here hoping u can help me again. My S1 45 developed a serious issue during yesterday's rehearsal.
After about an hour of usage it started cutting out, then I heard a long sequence of popping and rattling.
All this ended with a very loud sound you might know from a spectrum or commodore 80's 'computer' when loading a game
from tape, that noise continued even with master volume down to zero! When I tapped the top of amp more to the side
where the master volume and power switch are the noise disappeared for a short while but came back straight after
playing a single note. Switched the amp off for 10mins, back on, no noise for few seconds then all the nightmare again.
All this still with master down to zero, even then that noise is extremely loud and insane.

Power tubes have been swapped for a pair of matched JJ's few months ago, job done by a tech. They glow nicely
and seem to be ok. Preamp section is still stock. Didn't power it up again after taking it back home,
dunno if this could damage the amp, so thought I might ask u guys first for advice. Please help!

User avatar
Sonofarich
Posts: 617
Joined: Thu Feb 24, 2011 1:00 am

Fri Sep 28, 2012 2:48 pm

6strings wrote:Aup guys!

Writing here hoping u can help me again. My S1 45 developed a serious issue during yesterday's rehearsal.
After about an hour of usage it started cutting out, then I heard a long sequence of popping and rattling.
All this ended with a very loud sound you might know from a spectrum or commodore 80's 'computer' when loading a game
from tape, that noise continued even with master volume down to zero! When I tapped the top of amp more to the side
where the master volume and power switch are the noise disappeared for a short while but came back straight after
playing a single note. Switched the amp off for 10mins, back on, no noise for few seconds then all the nightmare again.
All this still with master down to zero, even then that noise is extremely loud and insane.

Power tubes have been swapped for a pair of matched JJ's few months ago, job done by a tech. They glow nicely
and seem to be ok. Preamp section is still stock. Didn't power it up again after taking it back home,
dunno if this could damage the amp, so thought I might ask u guys first for advice. Please help!
Popping/crackling is usually a symptom of tubes. If you can't get it to the tech and have access to preamp tubes, I would replace them and see if that solves your issue.

IM4Tone
Posts: 505
Joined: Sun Aug 07, 2011 12:00 am
Location: Emporium, PA

Fri Sep 28, 2012 5:22 pm

Sonofarich wrote:Popping/crackling is usually a symptom of tubes. If you can't get it to the tech and have access to preamp tubes, I would replace them and see if that solves your issue.
^^ yes, OR a cold solder joint.

User avatar
6strings
Posts: 12
Joined: Wed Mar 21, 2012 1:00 am
Location: Stoke, UK

Sat Sep 29, 2012 2:23 pm

Thanks guys! I was actually hoping that it's just the preamp tubes, the easiest and relatively cheap fix to the problem. But a cold solder joint as suggested by IM4Tone
seems like more possible in this situation - gentle tapping on top of amp stops the noise for a short while, so it looks like something's gone loose inside.

Is it possible to locate that cold joint by myself (have a bit of experience with soldering) or should I rather try new tubes first and if it doesn't work
then take it to a tech?

IM4Tone
Posts: 505
Joined: Sun Aug 07, 2011 12:00 am
Location: Emporium, PA

Sat Sep 29, 2012 3:21 pm

6strings wrote:Thanks guys! I was actually hoping that it's just the preamp tubes, the easiest and relatively cheap fix to the problem. But a cold solder joint as suggested by IM4Tone
seems like more possible in this situation - gentle tapping on top of amp stops the noise for a short while, so it looks like something's gone loose inside.

Is it possible to locate that cold joint by myself (have a bit of experience with soldering) or should I rather try new tubes first and if it doesn't work
then take it to a tech?
I'd try new pre-amp tubes first...relatively inexpensive as you've mentioned.
Is the amp under warranty? If so, after trying new tubes, I'd take it to an authorized rpr. cntr. if it's still a problem. If not under warranty, you could try to troubleshoot and locate the possible cold solder joint if you're experienced in such, but if intermittent, it can be a real challange. I don't know if I'd rely on "a bit of experience with soldering" on circuit boards (I'm not familiar w/ S1 series and am assuming it uses PCB's and isn't PTP or eyelet board.)

User avatar
6strings
Posts: 12
Joined: Wed Mar 21, 2012 1:00 am
Location: Stoke, UK

Thu Oct 04, 2012 6:12 pm

New preamp tubes fitted, problem still there. So I tried some random el34's I had at home and 'voila' - amp sounds like new. I only wonder how come that the pair of power JJs gone so quickly?
Anyway taking the amp and new tubes to a tech. At least now I've got a better sounding amp with new preamp section;) Thanks for replying guys.

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