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Post subject: How to remove tube retainer on blues jr
Posted: Sat Mar 22, 2014 1:58 am
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I just picked up a used blues jr and for the life of me I can't find a good way to remove the metal retainer that holds the power tubes in place. It seems that if I try to pull it off, it pull the tubes with it. And how are you supposed to unhook and rehook the soigné without touching the tubes?

Seems like a simple thing, but I feel like I'm doing it the hard way and I'm going to put new tubes in soon, so I don't want to either break the tubes.


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Post subject: Re: How to remove tube retainer on blues jr
Posted: Sat Mar 22, 2014 2:24 am
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These one ? Just remove the spring on the top metal plate.Pull tubes out .

http://www.darrenriley.com/shop/cart.ph ... ail&p=1459

If you put new Output Power tubes , you have to check the bias . If you can't do this job, put same brand tubes , chance bias is ok , not sure .

Shematic here ;

http://support.fender.com/schematics/gu ... ematic.pdf


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Post subject: Re: How to remove tube retainer on blues jr
Posted: Sat Mar 22, 2014 6:35 am
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Problem is the top of the tubes actually get stuck in the metal bracket so I had to pull the tubes out by the bracket and then sort of twist the tubes free. It's seems like too tight a fit.

There is no bias control on a blues jr.


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Post subject: Re: How to remove tube retainer on blues jr
Posted: Sat Mar 22, 2014 6:47 am
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curlyjive wrote:
Problem is the top of the tubes actually get stuck in the metal bracket so I had to pull the tubes out by the bracket and then sort of twist the tubes free. It's seems like too tight a fit.
The only way is to pull the tubes . This bracket is just put on top of the tubes , may the two holes are too thight ? When remove , sand inside the hole mfor a easy fit .

There is no bias control on a blues jr. Like many amps you have to change one resistor if needed , a cost cutting? , it is a job for a tech or someone with electronic skill , but you must check and adjust bias each time you put new output tubes


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Post subject: Re: How to remove tube retainer on blues jr
Posted: Sat Mar 22, 2014 7:00 am
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Thanks. I think I will try and make the opening bigger.

I hear what you are saying about biasing. I know some people say you don't need to on these amps, others say you do not. Eurotubes addresses this by trying to match the tubes and select them according to how you want them to perform.

If it were a newer amp under warranty and you messed with the board to change the bias, you'd void your warranty I think.


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Post subject: Re: How to remove tube retainer on blues jr
Posted: Sat Mar 22, 2014 7:13 am
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curlyjive wrote:
Thanks. I think I will try and make the opening bigger.

I hear what you are saying about biasing. I know some people say you don't need to on these amps, others say you do. Eurotubes addresses this by trying to match the tubes and select them according to how you want them to perform.

People saying that it is because they are not able to do the job and they don't want to pay a tech for and they do not know electronic . I study electronic at school and I work in electronic all my life and I fix amp since manny many years . For me is very easy to see that tubes need bias check and many time a bias adjust .

If it were a newer amp under warranty and you messed with the board to change the bias, you'd void your warranty I think.

I don't know about warranty . To me it is no sense if you put some new tubes without a bias check . You may not need to adjust bias ,this will keep amp original, we can't say before check


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Post subject: Re: How to remove tube retainer on blues jr
Posted: Sat Mar 22, 2014 8:09 am
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Is it also safe to say the same problem exists for all blues jr out of the box? Since there is no bias control, fender just slaps tubes in and they don't adjust the bias or change the resistor. So doesn't it stand to reason that any blues jr new is technically not biased correctly?


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Post subject: Re: How to remove tube retainer on blues jr
Posted: Sat Mar 22, 2014 8:12 am
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I wouldn't say "not biased correctly"......just not optimized for the best amp tone.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: How to remove tube retainer on blues jr
Posted: Sat Mar 22, 2014 8:14 am
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Retroverbial wrote:
I wouldn't say "not biased correctly"......just not optimized for the best amp tone.

Arjay



Right, so is that any different than when you replace the tubes on a blues jr?


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Post subject: Re: How to remove tube retainer on blues jr
Posted: Sat Mar 22, 2014 8:19 am
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curlyjive wrote:
Retroverbial wrote:
I wouldn't say "not biased correctly"......just not optimized for the best amp tone.

Arjay



Right, so is that any different than when you replace the tubes on a blues jr?


Read my post few days ago ;

Post subject: Re: How to remove tube retainer on blues jrPostPosted: 22 Mar 2014 04:24


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Post subject: Re: How to remove tube retainer on blues jr
Posted: Sat Mar 22, 2014 8:49 am
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stratele52 wrote:
curlyjive wrote:
Retroverbial wrote:
I wouldn't say "not biased correctly"......just not optimized for the best amp tone.

Arjay



Right, so is that any different than when you replace the tubes on a blues jr?


Read my post few days ago ;

Post subject: Re: How to remove tube retainer on blues jrPostPosted: 22 Mar 2014 04:24


I saw your post. My question still stands: is a new out of the box blues jr likely have the same bias issues that you would have replacing tubes?


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Post subject: Re: How to remove tube retainer on blues jr
Posted: Sat Mar 22, 2014 10:29 am
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Yes .


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Post subject: Re: How to remove tube retainer on blues jr
Posted: Sat Mar 22, 2014 10:44 am
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stratele52 wrote:
Yes .



Ok so given that, replacing tubes doesn't leave me any worse off correct?

I agree, a bias mod is a good idea, but not something I'm willing to pay for now or feel confident doing myself.

But still these are pretty popular amps and most people do not add a bias mod, they just slap new tubes in and carry on. Has worked fine for fender, though it baffles me they don't just add the bias adjustment...how much would it really cost them?!

And while they're at it, fix the stupid hard to remove/ install tube retainer!!!


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Post subject: Re: How to remove tube retainer on blues jr
Posted: Sat Mar 22, 2014 11:19 am
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A correctly biased amp will run efficiently and maximizes the life of your tubes.

Under - biased amps will lack of punch and tubes will run hotter , shorter tube's life .
Overbiased amps will sound thin and brittle. with tubes running too cood for proper performance .
A correctly biased amps will sound clean and thight a moderate volumes., than at higher volumes breakup and distort musically .

2 power tubes are not expensive and if you just put it in with no bias check I don't think you do a big mistake . You may not have the best of your amp .

And when the amp is not at the best , you may want to buy a new one in few months , years ....
If you don't know a qualified tech ( do you know what is this ? ) to be sure he'll do the best job , keep your amps without bias check


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Post subject: Re: How to remove tube retainer on blues jr
Posted: Sat Mar 22, 2014 3:28 pm
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stratele52 wrote:
A correctly biased amp will run efficiently and maximizes the life of your tubes.

Under - biased amps will lack of punch and tubes will run hotter , shorter tube's life .
Overbiased amps will sound thin and brittle. with tubes running too cood for proper performance .
A correctly biased amps will sound clean and thight a moderate volumes., than at higher volumes breakup and distort musically .

2 power tubes are not expensive and if you just put it in with no bias check I don't think you do a big mistake . You may not have the best of your amp .

And when the amp is not at the best , you may want to buy a new one in few months , years ....
If you don't know a qualified tech ( do you know what is this ? ) to be sure he'll do the best job , keep your amps without bias check



Yes I completely understand all of this and that biasing is ideal. No question, it's the best practice. I do not have a qualified amp tech around to mod the amp or change the resistor.

My point is just that blues juniors have been made and used this way successfully for a long time. While it is odd fender did not include a bias control, they have and continue to be extremely popular and I doubt most people do anything other than swap tubes.


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