It is currently Tue Mar 17, 2020 1:54 am

All times are UTC - 7 hours



Post new topic Reply to topic  [ 9 posts ] 
Author Message
Post subject: 2010 Blues Junior Tech Issue?
Posted: Sat Aug 11, 2012 1:40 am
Offline
Aspiring Musician
Aspiring Musician
User avatar

Joined: Mon Apr 21, 2008 1:37 am
Posts: 597
Location: Australia
G'day Ya'll, well this evening whilst jamming on my blues junior I heard a loud POP! :shock:

shortly after the POP sound, the clean sound level dropped and became distorted! :?: so I turned off the amp for 30 seconds and then turned it back on and the amp played normally again.

I have been using JJ Tesla tubes since I have owned it new from 2010.

Can anyone please shed some light on what this issue may be?

Kind Regards


Top
Profile
Fender Play Winter Sale 2020
Post subject: Re: 2010 Blues Junior Tech Issue?
Posted: Sat Aug 11, 2012 2:51 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14049
Location: Province de Québec, Canada
Did you check bias when you put new power output tubes ? It is a must.

You're amp could need new tube ( and bias check ) or some solder in power supply need to repair and some resistor check ( overheat )


Top
Profile
Post subject: Re: 2010 Blues Junior Tech Issue?
Posted: Sat Aug 11, 2012 3:01 am
Offline
Aspiring Musician
Aspiring Musician
User avatar

Joined: Mon Apr 21, 2008 1:37 am
Posts: 597
Location: Australia
stratele52 wrote:
Did you check bias when you put new power output tubes ? It is a must.

You're amp could need new tube ( and bias check ) or some solder in power supply need to repair and some resistor check ( overheat )


Thanks for your reply Stratele! Mate from what I know of BJ's there is no bias.. the JJ's have been used like nearly everyday for the past 2 years. I'm thinking I may have popped a valve!

I will have a look tomorrow.

Either way it's going to my amp tech.

I was just wondering if anyone else has experienced this with thier valve amps?


Top
Profile
Post subject: Re: 2010 Blues Junior Tech Issue?
Posted: Sat Aug 11, 2012 4:11 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14049
Location: Province de Québec, Canada
All amps have bias , you probably mean " no user adjustment pot " That is right ,but most of them need a tech to check and adjust .

Any kind of amp need a bias check when putting new output power tubes, even class A amp .


Top
Profile
Post subject: Re: 2010 Blues Junior Tech Issue?
Posted: Sat Aug 11, 2012 8:02 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
It could be an output tube arc inside the tube, or it could even be a solder joint issue, although I suspect output tubes in this case. If the output tubes are running hot, which they almost certainly are in a stock BJr, then two years of regular use is pretty good life for most types of output tubes.

It is always a good idea to check the bias when changing output tubes in most any tube amp. Although the BJr has no adjustment, the bias can be adjusted with a resistor change or by adding a bias pot, either of which will probably void the warranty. I weighed the possibility of needing the warranty against the likelihood of tube replacement every couple of years (I only had about 2-1/2 years left on the warranty), and went ahead and added a bias adjust. The warranty is now expired and I'm still using the same output tubes that I installed at the same time as the bias pot, approximately five years ago. Not a single glitch or hiccup in that time, and the amp still sounds great. No loss of tone by lowering the bias, and in fact the amp is much more versatile with the new bias setting, as I can get better cleans as well as the same distortion as before. Before the bias adjust, I could not get a lot of clean headroom, but much better now.

If you are concerned about keeping the warranty intact, maybe your best bet is to get a set of output tubes with a low current draw. Just ask the vendor that you buy tubes from if they can select a set with the lowest possible current draw. For the stock BJr, I would go with some sturdy output tubes, like some 7189, or EH or GT EL84. The 7189 is a mil spec tube that can take the punishment of the hot bias in the BJr, and they sound very strident and clean, described on the site below.

You can read about what I did to my BJr here:
http://shimmilou.mysite.com/Amps.html

Also, lot's of great info about the BJr on the Billm site:
http://billmaudio.com/wp/?page_id=2

_________________
---> "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.


Top
Profile
Post subject: Re: 2010 Blues Junior Tech Issue?
Posted: Sat Aug 11, 2012 6:01 pm
Offline
Aspiring Musician
Aspiring Musician
User avatar

Joined: Mon Apr 21, 2008 1:37 am
Posts: 597
Location: Australia
Thanks to both of you guy's, I sincerely appreciate your replies.

I will take the BJ to my amp tech and ask him to repair any issues be it valve or solder or other, but more importantly bias the amp with a new set of JJ's.

2 months after I first purchased the BJ, I couldn't put up with the brittle highs so in went the JJ's which made it the amp what I wanted! only thing I didn't do, was to have the amp biased with the new JJ's I put in back then.

It's done well after many small club gig's and almost day to day jams at home..

Thanks Again. :D


Top
Profile
Post subject: Re: 2010 Blues Junior Tech Issue?
Posted: Sun Aug 12, 2012 6:55 pm
Offline
Aspiring Musician
Aspiring Musician
User avatar

Joined: Mon Apr 21, 2008 1:37 am
Posts: 597
Location: Australia
lol I have sorted out my own problem.

I took out the JJ power tubes and the elements in them looked fried and brittle.

So I reinstalled the original factory GT's and whammo. Full power again with nice cleans and classic raw overdrive!!

Cheers.


Top
Profile
Post subject: Re: 2010 Blues Junior Tech Issue?
Posted: Sun Aug 12, 2012 7:03 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
Awesome! GTs rock! Always good to have spares.

_________________
---> "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.


Top
Profile
Post subject: Re: 2010 Blues Junior Tech Issue?
Posted: Mon Aug 13, 2012 1:19 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14049
Location: Province de Québec, Canada
kineman karma wrote:
lol I have sorted out my own problem.

I took out the JJ power tubes and the elements in them looked fried and brittle.

So I reinstalled the original factory GT's and whammo. Full power again with nice cleans and classic raw overdrive!!

Cheers.


Is possible the bias are corectly set for GT 's tube, not for your JJ's . Chance are a correct bias adjustment for JJ's have same result.

Bias check is always a must when replacing power tubes. Even with original GT's tubes. Today we are not sure ( original ) tubes are the same as those Fender put in your amp months or years ago.

And like Gerald Weber ( famous amp builder and tech in case you never heard about him ) said about a too hot bias; " ...amp sound always good before tubes blow ".
___________________________________________________________________________________
There also a chance your bias are good too. If your new GT are not red plating after one hour or more chance are your bias is not too hot , can I say good ?

Red plating is a overheating tube plate , you see the tube very bright and red . Tube's heater are red too , this is normal, but less than plate heating.
If not sure , put back your JJ's an see how they glow. If GT's are the same , they are working probably safely.

Enjoy your amp


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 9 posts ] 

All times are UTC - 7 hours

Fender Play Winter Sale 2020

Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: