#1
Hey guys and guyettes.

I have a small problem with my valves (bought the amp new a bit less than a year ago), it's not affecting the sound at all really, but I can tell there's something wrong from the burn mark on one of my power amp valves (if you can't see it, it's near the writing on the valve).


So, the question is, what does this mean? Do I have to replace my valves? Stop asking so many questions?

Cheers guys.
"Breathe, breathe in the air
Don't be afraid to care"

Fender Strat/Tokai LS80>few pedals>Orange Rocker 30
#4
There's a lot of power going through those things....sometimes, it can burn the valve. If the amp is still playing fine, then there really is no need for a tube swap, but if they've been in use for about a year now, I think it would be time for a routine tube swap, so now might be as good a time as ever.
#5
Hey thanks guys, Tubey, I went on the link, and yea, that's describing some of the problems, I also get "Crackle or noise coming from the speakers" aswell as the burn mark on the valve too.

And it probably is time to replace the valves (probably just power amp ones...)or all?, I'll look around at how to do it and so on....
Any websites recommended for replacing valves?
"Breathe, breathe in the air
Don't be afraid to care"

Fender Strat/Tokai LS80>few pedals>Orange Rocker 30
#7
Might be worth changing them all. Different valves will change your sound so it might be worth chatting to someone who knows a lot about them so you can choose what valves you want. It's not really worth changing them yourself just take your amp to your favourite guitar store. Try

http://216.239.59.104/search?q=cache:4LTTNSQ7J9sJ:www.universal-total-guitar-plus-center.com/tubes.html+burn+mark+on+guitar+amp+valve&hl=en&gl=uk&ct=clnk&cd=1
#8
It's a Fender Blues Jr
It has....
2 EL84's(6BQ5's)
3 12AX7's

Oh yea, keep in mind that I'm in England, so no USA valve sites please!

Cheers.
"Breathe, breathe in the air
Don't be afraid to care"

Fender Strat/Tokai LS80>few pedals>Orange Rocker 30
#9
^Sorry, couldn't really tell from your 'location'
I'd replace all of them, good EL84s and 12AX7s are dirt cheap.
#10
Haha, nobody ever get's my location... They're Oasis lyrics.... Oasis=Manchester.

I'm not gonna' cheap out on valves really, so I'm gonna see what prices for which brands and so on.

And I'm not sure if I can take that eurotubes website seriously from that pic on the first pagehaha, and that's in dollars too...

Any more UK sites please guys?
"Breathe, breathe in the air
Don't be afraid to care"

Fender Strat/Tokai LS80>few pedals>Orange Rocker 30
#12
When the tube heaters light up, does the glow spread to any other parts?
I'm not very active here on UG currently.
I'm a retired Supermod off to the greener pastures of the real world.
#13
Yeah, i'll admit, the eurotubes website is kinda sh*tty, but i emailed and called them up, they know what they're talking about. They're people persons, very nice. Plus the prices on their tubes are good, with a flat ship rate of something around $6-7, with no sales tax, I'm prob. gonna buy from them again.
#14
^Yep, that dude pwns. They're in the same city as me too.
I'm not very active here on UG currently.
I'm a retired Supermod off to the greener pastures of the real world.
#15
Cheers everyone, I'll email the guy at EuroTubes, but it's still in USA prices, is it gonna' be about the same as UK prices anyway?

And Pink, I'll check if the glow spreads anywhere else.
"Breathe, breathe in the air
Don't be afraid to care"

Fender Strat/Tokai LS80>few pedals>Orange Rocker 30
#17
Quote by R_H_C_P
Cheers everyone, I'll email the guy at EuroTubes, but it's still in USA prices, is it gonna' be about the same as UK prices anyway?

And Pink, I'll check if the glow spreads anywhere else.


Yeah, probably it's old tubes, but it might be biased too hot(too much current in the tube.) If the glow spreads it means there's too much current, and an amp tech should look at it. You could too, but it's not the recommended first electronics project.
I'm not very active here on UG currently.
I'm a retired Supermod off to the greener pastures of the real world.
#18
If you want tube advice from an expert, e-mail Bob at Eurotubes (www.eurotubes.com). That guy is extremely helpful and his tubes kick ass.
#19
I'm assuming, from what gear you have posted in "post pictures of your gear", that you have a Blues Jr. If so, according to Bill Machrone, who has come up with a lot of mods for this particular amp, he says that the Blues Jr. produces a lot more heat then a lot of amps in it's range, and that it's caused by too much current flowing to the EL-84's. Which, because of this, would need to be replaced more often.

Check out his site he has lots of useful info and mods. And if you already knew this sorry for wasting your time. The mod for the "over heating" is under the bias, or bias and tone section.

http://home.comcast.net/~machrone/bluesjunior.htm

EDIT: If you want to you can e-mail him, he responds very quickly and is always ready to help.
Hai UG!
#20
^Wow thanks man, I didn't know that at all, very helpful site!

What I'm gonna do is email both these guys and see what they have to say.

And Pink, no, the glow isn't spreading in the valves, I checked before.

Suggestions still very welcome.
"Breathe, breathe in the air
Don't be afraid to care"

Fender Strat/Tokai LS80>few pedals>Orange Rocker 30
#21
^Well, LedZep up there says there's too much current, which is indeed overbiasing, so I was right in my assumptions.

Take it to a tech, bring him a set of JJ tubes, and he can install the tubes, and bias the amp for longer life in the future.

I'm not very active here on UG currently.
I'm a retired Supermod off to the greener pastures of the real world.
#22
Cheers mate, how much d'ya reckon that would cost?

Now I've just gotta find some amp techs in Manchester....*goes off searching*

Also, Bill Machrone emailed me back (rather fast...) and he's also saying that it's because BJ's are biased too hot from the factory, and he's recommended a few mods to do (which I def. wouldn't be able to do), reckon I should just take it to an amp tech? Or buy the mod stuff and then take it to the tech?
"Breathe, breathe in the air
Don't be afraid to care"

Fender Strat/Tokai LS80>few pedals>Orange Rocker 30
Last edited by R_H_C_P at Jun 18, 2006,
#23
Well, you could always just send it in to Bill and tell him what you want done. Here's a list of stuff, with prices, from one of the emails he sent me.

"Blues Junior Modifications

Basic mods, green board: $80

1. Modified tone stack with Orange Drop capacitors
2. Rewired reverb, larger coupling capacitor (cream board spec), shielded input jack
3. Cooler fixed bias, optional bright cap (no extra charge)
4. Retwisted and rerouted AC leads for hum/hiss reduction

The mods aren't difficult, but getting to the back of the circuit board is
time-consuming. That's why the basic charge is what it is.

Basic mods, cream board: $60

1. Modified tone stack with Orange Drop capacitors
2. Simple (no bias balance) bias adjustment
3. Retwisted and rerouted AC leads for hum/hiss reduction

Additional mods:

Presence Control with bright/dark switch (green board only) $30

Pull-up potentiometer will be mounted on control deck in front of Fat switch unless otherwise specified. Connects to circuit board with Mogami low-noise coaxial cable.

Presence Control (cream board only) $20

Potentiometer will be mounted on control deck in front of Fat switch unless otherwise specified. With the presence cut, it sounds a great deal like the green board Blues Junior. Connects to circuit board with Mogami low-noise coaxial cable.

Individually adjustable bias: add $50.

Output tubes are individually adjustable for overall bias and can be balanced. Customer tubes will be biased to 24-25ma unless otherwise specified. Includes biasing instructions for future tube replacements.

Adjustable bias (cream board only): Now included in basic mods.

Output tube bias can be adjusted through a large range, but not individually. Requires use of matched output tubes. Customer tubes will be biased to 24-25ma unless otherwise specified. Includes biasing instructions for future tube replacements.

Clean Boost module: Add $45

This 1x1" circuit module installs inside the amp and gives you a volume boost that's about the same as that of the Fat switch, without the fatness. Its volume adds to that of the Fat switch, and can be wired to go on with the Fat switch or by itself on a pull-up on the presence control (if you choose the presence option). See http://home.comcast.net./~machrone/bjr/cleanboost.htm for more information.

Metal replacement input jack: $20

Switchcraft jack with isolating washers to prevent ground loop hum. Connects to circuit board with Mogami low-noise coaxial cable.

Auxiliary speaker jack: $25

Plug in an additional 8-ohm cabinet for bigger tone. High-quality Switchcraft jack.

Other mods or repairs: Parts plus labor.

Power supply stiffening, gain modifications, etc. E-mail for quotation.

You can save on shipping by just sending me the chassis and tubes. The
shipping fee is usually under $20; you pay both ways. Priority Mail is only $14-$16.

Terms: Payment due upon completion. Amp will be returned upon payment. Preferred payment method: Postal money order, cashier's check, or PayPal.

----------------

To remove the chassis,

1. Unplug the amp
2. Lay the amp on its face
3. Remove the back panel
4. Remove the tubes
5. Unplug the speaker
6. Unplug the two reverb wires
7. Unscrew the reverb wire clip
8. Pad the space between the speaker magnet and the chassis with a small towel or T-shirt (prevents the magnet from grabbing the chassis)
9. Remove the four screws (two top, two sides) holding the chassis
10. Lift out.

Keep the power tube retainer and springs, the case screws, and the reverb wire clip/screw in a safe place until I return the chassis.

Use bubble wrap to pad it and send me just the chassis and the tubes
(separately wrapped/protected). You can roll up pieces of bubble wrap to make "bumpers" that immobilize the chassis in the box and provide a cushioning layer between the metal and the box. Please don't use Styrofoam peanuts

Send the chassis to

Bill Machrone

18 Briarcliffe Drive

Scotch Plains, NJ 07076

and be sure to include a note with the mods you want done. "
Hai UG!