It is currently Tue Mar 17, 2020 2:52 am

All times are UTC - 7 hours



Post new topic Reply to topic  [ 15 posts ] 
Author Message
Post subject: BJR Valves gone, can I replace?
Posted: Thu Mar 08, 2012 3:21 pm
Offline
Hobbyist
Hobbyist
User avatar

Joined: Tue Jun 07, 2011 2:33 am
Posts: 31
Hi Guys, that my 5 month old Blues Jnr blown a valve! I got these replaced from the factory at the beginning of October. It has standard GT EL84-S and I need to know if I can just order these and replace them myself or does it have to go back to Fender again. I would think I would need to replace both at the same time!

I have hardly had it up past quarter to mark on the volume and master levels, so is this a normal time scale for valves?

Cheers
Indy


Top
Profile
Fender Play Winter Sale 2020
Post subject: Re: BJR Valves gone, can I replace?
Posted: Thu Mar 08, 2012 7:06 pm
Offline
Professional Musician
Professional Musician

Joined: Fri Jun 26, 2009 6:53 pm
Posts: 2252
Location: Harvard IL
Hi Indy, That time scale does not seem reasonable to me, unless you run the amp 8 hours a day, every day. The GT EL84-S, suggests they are Slovak(aka. JJ- usually a reliable company). Again, I wouldn't expect a failure in four months of normal use. IMO the amp needs to be checked by Fender. Yes, both power valves need replacement. But I wouldn't do that until the amp has been inspected. Art

_________________
None of Us are free, if One of Us is chained !


Top
Profile
Post subject: Re: BJR Valves gone, can I replace?
Posted: Fri Mar 09, 2012 1:44 am
Offline
Hobbyist
Hobbyist
User avatar

Joined: Tue Jun 07, 2011 2:33 am
Posts: 31
Hi, thanks mate, I thought 5 months is pretty short time for the valves to last, so I will send back to fender. They checked it out all when I got them replaced in October as well, I have emailed the tech at Fender UK and hopefully he will get back to me today.

I usually play it three times a week for about three hrs at a time, so not too long! going to miss this amp if I have to send it back for a couple of weeks, think I will need to get a spare lol


Top
Profile
Post subject: Re: BJR Valves gone, can I replace?
Posted: Fri Mar 09, 2012 11:35 am
Offline
Aspiring Musician
Aspiring Musician

Joined: Tue Feb 22, 2011 11:26 am
Posts: 500
Location: Lake Charles, LA
Try a small Mustang amp set to the '65 Deluxe Reverb model. Works pretty close for me. :wink:

_________________
Marshall JVM410H + 1960A Lead
Fender Mustang V + V412
Fender Mustang II
Marshall Lead 12 3005 MS
Gibson Les Paul Custom Silverburst
Gibson SG Faded Special
Fender American Special Stratocaster
Hagstrom Ultra-Swede
Custom Warmoth Strat


Top
Profile
Post subject: Re: BJR Valves gone, can I replace?
Posted: Sat Mar 10, 2012 12:05 am
Offline
Professional Musician
Professional Musician

Joined: Fri Jun 26, 2009 6:53 pm
Posts: 2252
Location: Harvard IL
Yes- 5 months, didn't count enough fingers! I know that it's a real inconvenience, Indy. But it really is their responsibility to provide a reliable amp. If you replace the valves every five months, that just doesn't seem reasonable to me. I would persevere with the inspection and valve replacement(if that is within the valve warranty). Good Luck & Keep Pickin' ! Art

_________________
None of Us are free, if One of Us is chained !


Top
Profile
Post subject: Re: BJR Valves gone, can I replace?
Posted: Mon Mar 12, 2012 4:12 am
Offline
Hobbyist
Hobbyist
User avatar

Joined: Tue Jun 07, 2011 2:33 am
Posts: 31
Thanks FFXlhealer, i will have a look at mustangs, looking for something to take out to BBQ's, so the wee mini one mights just do!

Aclempoppi..It doesn't seem right to me either and a real inconvenience, I've spent over 2 grand on a strat, amp and pedal and I can't get to play them now..very frustrating indeed! Fender have arranged a label for me to send back the amp by UPS, hopefully they will get it sorted this time. I have asked for a new one but they said they will need to look at it first to see what problem is. My worry is if it goes again and goes over warranty I will be snookered!


Top
Profile
Post subject: Re: BJR Valves gone, can I replace?
Posted: Mon Mar 12, 2012 8:01 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
indianabones,

Do you have the same symptoms as before? Buzzing, tubes with excessive glow, etc?

_________________
---> "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: BJR Valves gone, can I replace?
Posted: Mon Mar 12, 2012 9:03 am
Offline
Hobbyist
Hobbyist
User avatar

Joined: Tue Jun 07, 2011 2:33 am
Posts: 31
Hi Shimmilou, not the buzzing yet, but excessive glow yes, this is what happened last time, think the buzzing will start, but I haven't it played it since the drop in sound!


Top
Profile
Post subject: Re: BJR Valves gone, can I replace?
Posted: Tue Mar 13, 2012 6:38 pm
Offline
Professional Musician
Professional Musician

Joined: Fri Jun 26, 2009 6:53 pm
Posts: 2252
Location: Harvard IL
Shimmy, What are you thinking is the problem ? Five months isn't reasonable is it ? Art

_________________
None of Us are free, if One of Us is chained !


Top
Profile
Post subject: Re: BJR Valves gone, can I replace?
Posted: Tue Mar 13, 2012 8:21 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
Not reasonable at all, even in a BJr, especially with the S version of output tubes. Last time, I thought it might be just a tube issue. But the same symptoms twice, might indicate an amp problem. I would check the bias circuit and bias for starters, and the usual solder joint inspection. Wasn't the amp sent back to Fender or some place for service before? We're just guessing here as we can't put eyes and meter to amp, but the service center should have physically inspected it, and I would think that they would have checked the basics....? It is possible that it might just be a bad tube, having been shipped with tubes installed after repair, but again, seems necessary to check the amp.

indianabones,

Any experience, or desire to check some things yourself?

_________________
---> "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: BJR Valves gone, can I replace?
Posted: Wed Mar 14, 2012 7:47 am
Offline
Rock Star
Rock Star
User avatar

Joined: Sat Jul 03, 2010 2:18 pm
Posts: 6544
One thing I notice on the Blues Junior circuit versus say the Peavey Classic 30... is the Fender puts only (-10.7VDC) bias voltage onto the two EL84 grids (with 329VDC B+). While the Peavey puts (-14VDC) onto its four EL84. Plates at 332 VDC.

Since the bias power supply runs in parallel with the output tubes, the total negative voltage needed to roughly center the idle bias should be about the same. If same output tubes are used. Regardless of number of pairs of tubes. (Rough guesstimate).

So maybe, dropping the negative voltage down to ~ (-)12-14 VDC would allow better idling point. Or adding an adjustable pot to do the same thing.


http://www.blueguitar.org/new/schem/fender/blues_jr.gif

http://www.blueguitar.org/new/schem/peavey/c30schem.gif


Top
Profile
Post subject: Re: BJR Valves gone, can I replace?
Posted: Wed Mar 14, 2012 9:28 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
That's what I did to my BJr, the tubes were running hot at around 13 watts idle, but my tubes lasted a couple of years before the adjustable bias was added (GT EL84 R, white label). From my own experience, your numbers are right on, mine was 10.86 volts on the grid from the factory, and my final grid voltage was close to -13 VDC when I finished, at about 330 Plate volts (approx 8.5 watts idle).

http://shimmilou.mysite.com/Amps.html

It seems that there are some BJr amps that have a hotter bias than others. Mine was certainly scorching, but many must be low enough to work fine, hence the need to check the bias.

_________________
---> "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: BJR Valves gone, can I replace?
Posted: Wed Mar 14, 2012 10:43 am
Offline
Professional Musician
Professional Musician
User avatar

Joined: Sun Sep 16, 2007 7:32 pm
Posts: 1384
Location: uɐʇsıʞɔnuɐɔ 'puɐlʇɐlɟ
Is it the heater element that is glowing excessivly, too much juice on the heater circuit?
Or is it the plate that is glowing, which is a very different problem.
indianabones wrote:
Hi Shimmilou, not the buzzing yet, but excessive glow yes,!

_________________
Keep on Truckin, Going full speed ahead down the highway to hades.


Top
Profile
Post subject: Re: BJR Valves gone, can I replace?
Posted: Thu Mar 15, 2012 2:37 am
Offline
Professional Musician
Professional Musician

Joined: Fri Jun 26, 2009 6:53 pm
Posts: 2252
Location: Harvard IL
Peterp, kind of seems like it's the plate overheating. But like Shmmy says, it's hard to say, without the first-hand inspection. Beemer makes a good point. Not being intimately involved with these amps, I'm just on the observation side of things. Peterp, you probably have experience with these units, and that's the"real deal". It's just that the valve-life didn't seem right to me. Art

_________________
None of Us are free, if One of Us is chained !


Top
Profile
Post subject: Re: BJR Valves gone, can I replace?
Posted: Fri Mar 16, 2012 12:26 pm
Offline
Professional Musician
Professional Musician
User avatar

Joined: Sun Sep 16, 2007 7:32 pm
Posts: 1384
Location: uɐʇsıʞɔnuɐɔ 'puɐlʇɐlɟ
No first hand experience with a BJr for me either.
When I first went looking for one there were none to be found at least in Ontario, that is when I ended up with my first BDri.

I have had tubes last decades (in an old Traynor), and others that seem to have died overnight.
But to have them repeatedly die after only a few months seems unreasonable to me, I'd be suspecting something not right with the grid/plate circuit.

Here is a picture of a el84 red-plating, is this what your's looks like?
Image
http://www.marshallforum.com/members/so ... ating.html

_________________
Keep on Truckin, Going full speed ahead down the highway to hades.


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 15 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: