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Post subject: Blues Junior - Sound level -significant drop
Posted: Thu Jan 01, 2015 11:37 am
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To date powering down and reseating tubes has rectified the issue. But I always see that EL-84 tube on left (viewed from rear) doesn't glow. I swapped the tube positions and it is still the left tube that doesn't glow. So, the tubes are OK. Before I start disassembling the amp can I confidently go with the tube socket as being the issue? Any heads-up about other culprits would be of great help.

I have a fair amount of electronics repair and my soldering is, I have been told, expert. lol: I have read other posts on similar complaints but they don't exactly fit.


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Post subject: Re: Blues Junior - Sound level -significant drop
Posted: Thu Jan 01, 2015 4:00 pm
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How old is the amp ?

Socket contacts on printed circuit board may need solder . The small circuit with tubes's socket

https://www.youtube.com/watch?v=c-XhTtQ0NAw

http://billmaudio.com/wp/?page_id=17


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Post subject: Re: Blues Junior - Sound level -significant drop
Posted: Thu Jan 01, 2015 5:12 pm
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The amp is 4 years old.

Are you thinking that I don't need to replace the socket just touch the connections with a little solder?


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Post subject: Re: Blues Junior - Sound level -significant drop
Posted: Thu Jan 01, 2015 5:31 pm
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dennyb wrote:
The amp is 4 years old.

Are you thinking that I don't need to replace the socket just touch the connections with a little solder?


You have to take some voltmeter reading and check why one tube don't glow ,after you fix what it need to be fix.

You have to check carefully solder first , better to not replace socket if they don't need , printed circuit are very fragile and four years old socket are almost new . You may have more problem .


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Post subject: Re: Blues Junior - Sound level -significant drop
Posted: Thu Jan 01, 2015 6:14 pm
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OK. Thank you for the response.


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Post subject: Re: Blues Junior - Sound level -significant drop
Posted: Fri Jan 02, 2015 12:11 am
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+1 stratele52

Likely poor solder joint(s), or maybe socket pins need re-tensioning.

_________________
---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


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Post subject: Re: Blues Junior - Sound level -significant drop
Posted: Fri Jan 02, 2015 7:40 am
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Thank you for the response. That's two opinions that fundamentally agree. I can easily manage that work.

Thanks again.


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Post subject: Re: Blues Junior - Sound level -significant drop
Posted: Sun Jan 04, 2015 5:33 pm
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OK I touched up the solder joints and there's no change. But the amp is working. Now here's a concept:-
As the tube in question is a power tube and in my venues I haven't needed to turn the Master and Level (both) above 4, is it possible there is circuitry in the amp that will only switch in the 2nd power tube when that power is needed? Grasping at straws.


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Post subject: Re: Blues Junior - Sound level -significant drop
Posted: Sun Jan 04, 2015 5:56 pm
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Beats me but I had a tube fall out of mine and it kept working.

Aren't there ribbon cables between the tube socket board and the main board? how they looking?


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Post subject: Re: Blues Junior - Sound level -significant drop
Posted: Sun Jan 04, 2015 6:05 pm
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dennyb wrote:
OK I touched up the solder joints and there's no change.
Did you see something broken ? Ohm reading ?

is it possible there is circuitry in the amp that will only switch in the 2nd power tube when that power is needed? Grasping at straws
No

.



You need to see a qualified tech


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Post subject: Re: Blues Junior - Sound level -significant drop
Posted: Tue Jan 06, 2015 2:45 pm
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Have you tried re-tensioning the output tube sockets?
Here's some info on how to do that. Remember safety if poking around, or take it to a tech.

http://billmaudio.com/wp/?page_id=171


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