#1
Well as title says , only one local store near me, and charge about 120$ to change the tubes and rebias it etc. And well, i'm not rich.

Now i'd experiment without thinking twice, but i don't plan to die so young . Can anyone give me an idea on touching what and what would kill you ?

Like for example i've read the one hand in pocket rule, but my amp has stiff metal things that need to be held down to pull the tube up, now that can't be done with one hand.

Can i pull / put a tube out/in with 2 hands?
Can i hold that metal protector for the tube?

Thanks.
#2
If you change the power tubes to exact same ones as before, rebiasing should not be needed. So you can safely change them yourself because you dont need to open your amp. Thats where the dangerous stuff is, inside. The tubes are tight but they should come out with some effort.

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Line6 Pod X3
#4
Yea, which amp do you have? I changed the power tubes on my Princeton without a problem and without having to rebias the amp but I did use the same tubes.

Carl
Fender Telecaster and HSS Stratocaster - Epiphone Les Paul 1960 Tribute Plus
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#5
A Blackstar series one 100, and i plan to change the kind of tubes, tubes, so biasing will be required, so again how do i not kill mself
#6
Check out eurotubs.com they have a very helpful page that tells about an amp and how to rebais them. I'm not sure if that have that model but you can call or email them and there vary nice and will help you. They also have the best price I have found on jj tubes I have found.
#7
pull them out and put new ones in. you need to find the bias adjustment for your amp. its different for every amp.
#8
Step 1: UNPLUG THE AMP FROM THE AC OUTLET!!!

Step 2: WEAR MECHANIX GLOVES (OR LEATHER - NOT COTTON) IN CASE YOU BREAK A TUBE. Getting glass in your hand(s) makes playing really hard!

Step 3: DO NOT JUST PULL THE TUBE! GENTLY rotate or rock it it as you pull it out.

Notes:
1) 12AX7 can be directly changed to a 5751W or vice-versa
2) IF you are changing the type of output tube (6L6, 5881 whatever) to a different type you should re-bias unless the amp does that "automatically" - few do. That is best done by someone with experience. You can read how online.
#9
Don't be afraid of getting electrocuted by changing tubes, there's nothing live on the outside of the amp that can hurt you. Buy a matched set of power tubes. Obviously turn it off and unplug it from the wall and let it cool down and you'll be fine. Handle the tubes by the base so they don't fracture.
I read the manual for your amp and didn't see anything about biasing, so unless you can see some test points on it or email Blackstar for a definitive answer, you might not have to bias it.

Quote by emad
jthm_guitarist
Warned for trolling!


Quote by metal4eva_22
Didn't you say that you had a stuffed fox that you would occasionally fuck?

Quote by Axelfox
It's not a fox,it's a wolf.
#10
Quote by jthm_guitarist
Don't be afraid of getting electrocuted by changing tubes, there's nothing live on the outside of the amp that can hurt you. Buy a matched set of power tubes. Obviously turn it off and unplug it from the wall and let it cool down and you'll be fine. Handle the tubes by the base so they don't fracture.
I read the manual for your amp and didn't see anything about biasing, so unless you can see some test points on it or email Blackstar for a definitive answer, you might not have to bias it.


NO!

Be afraid, just don't be so afraid you can't function. The task is not inherently dangerous, but it is hazardous. (Danger is out of our control, hazards can be mitigated.)

People who forget to be afraid of things that can kill them are often the ones that end up dead. Always treat any electrical repair with a healthy respect.
“Ignorance more frequently begets confidence than does knowledge.”
Charles Darwin
#11
Quote by Arby911
NO!

Be afraid, just don't be so afraid you can't function. The task is not inherently dangerous, but it is hazardous. (Danger is out of our control, hazards can be mitigated.)

People who forget to be afraid of things that can kill them are often the ones that end up dead.

Great advice man, you really saved the OP by correcting me and added valuable information specific to what we're talking about.

Quote by emad
jthm_guitarist
Warned for trolling!


Quote by metal4eva_22
Didn't you say that you had a stuffed fox that you would occasionally fuck?

Quote by Axelfox
It's not a fox,it's a wolf.
#12
Quote by jthm_guitarist
Great advice man, you really saved the OP by correcting me and added valuable information specific to what we're talking about.


Thanks, it's nice to be recognized.


“Ignorance more frequently begets confidence than does knowledge.”
Charles Darwin
#13
Quote by dkcol
Step 1: UNPLUG THE AMP FROM THE AC OUTLET!!!

Step 2: WEAR MECHANIX GLOVES (OR LEATHER - NOT COTTON) IN CASE YOU BREAK A TUBE. Getting glass in your hand(s) makes playing really hard!

Step 3: DO NOT JUST PULL THE TUBE! GENTLY rotate or rock it it as you pull it out.

Notes:
1) 12AX7 can be directly changed to a 5751W or vice-versa
2) IF you are changing the type of output tube (6L6, 5881 whatever) to a different type you should re-bias unless the amp does that "automatically" - few do. That is best done by someone with experience. You can read how online.

This is pretty good, I just have a few clarifiers.

Yes, unplug the amp. Keep in mind that most tube amps will hold a charge even after unplugging from power


So yes, be very careful.

I have a Blog in my profile on biasing amps that has lots of detail and safety tips

Also, you don't technically rotate the tubes out. You pull them.
What helps is to rock them back and forth a bit as he said and the contact cleaner will help moving forward.
Last edited by 311ZOSOVHJH at Aug 12, 2013,
#14
Thanks so much for the tips / steps guys, i've went through your profile 311z , couldn't find that blog since you have so much ;p , so if you could pm me a direct link, i'll be grateful.
#16
If you're that worried then rubber gloves while you do it. Just make sure it doesn't have any holes
My Name is Cameron.
Quote by Cathbard
For me, bedroom levels is a cranked plexi half stack.

Now get off my ****ing lawn.


#17
Quote by weirdzaid
Thanks so much for the tips / steps guys, i've went through your profile 311z , couldn't find that blog since you have so much ;p , so if you could pm me a direct link, i'll be grateful.



http://profile.ultimate-guitar.com/311ZOSOVHJH/blog/80083/

There are 2 parts (2 blogs). 1.) My Amp Bias Tutorial (for my amp) and 2. My Amp Bias Tutorial (Continued)
#20
unplug it, make sure the tubes are cooled down (if you were just playing wait maybe an hour or so) don't touch any capacitors which you shouldn't run into anyways and just pull those suckers out and put the new ones in
#22
I was the one that may have scared you in the other thread. I was referring to when it came time to bias.

His bias test port(similar to marshall) is a few millimeters away from V5. If he goes to check his bias mV V5 is looming large right next to 2 connector. All it takes is a misplaced hand he will have a bad day. Nothing like getting hit with 300vDC.

TS, you can stick a nonconductive "blanket" over V5 to shield yourself from an accidental slip. Something like a thick rag, rubber or piece of plastic.


General rules you shouldn't break to get you on darwins list:
Don't stick anything in the tube sockets
Don't work on a live amp with wet hands
Don't grab the chassis with one hand and then touch the back of a tube socket with the other.
Quote by DeathByDestroyr
See, it's important that people clarify when they say "metal", because I pretty much always assume they are a Cannibal Corpse fanboi.
#24
Quote by 311ZOSOVHJH
I told him to get a bias probe which he is ordering - but all good advice


You can still zap yourself with a bias probe. Make sure its plugged into your meter before turning the amp on....
Quote by DeathByDestroyr
See, it's important that people clarify when they say "metal", because I pretty much always assume they are a Cannibal Corpse fanboi.
#25
Quote by R45VT
You can still zap yourself with a bias probe. Make sure its plugged into your meter before turning the amp on....

I realize that. I never said a bias probe will make things completely safe. The safety tips, which he's read, specifically deal with safety using a meter. I was just pointing out that he's getting a probe so the proximity of the test points shouldn't be an issue anymore. Why Blackstar set those test points up like I have no idea. If I remember correctly - this is a S-1.

#26
Yeah it is , Blackstar series 1 100 , one good thing though, is i've realized i don't need to open up the amp to reach the Testpoints ( Which i won't have to access anymore since i'm going to be using a probe ) and the bias trim pot are accessable by opening a small hole in the bottom, so here's one good thing blackstar did ;p
#28
One last question , Regarding bias probes, like the ET One i'm going to order. Is this what i'm going to do?

1) Have everything switched off, and keep the amp connected to the speaker
2) Take out the old tubes, and put the bias probe in any of the 4 tube sockets.
3) Put one new tube on the bias probe. and 3 other new tubes in the other sockets
4) Switch the amp on , let the tubes heat up. That will show the plate voltage on the meter.
5) Assuming el34L's which have a dissipation of 25watts, divide the wattage by the plate voltage, so assuming it read 600, so 25 divided by 600, that's 0.41, multiply that by 0.7 , which would give me 0.28. so i'd adjust the trim pot till the top reading on the same meter reading of 28 ma. and that's it, remove the tube from the probe, put it in regularly and i'm done?

Thanks so much for all the help you've been giving me . Saving me over 300$ ( They charge 120 for the process, and the drive there and back , over 2 times ( since they want 2-3 days ) would cost me about 400$
Last edited by weirdzaid at Aug 16, 2013,
#29
You asked me that exact same question in your PM this morning.

(or are you looking for a second opinion?)


Anyway, here is my response via PM:


Yep. Most of that is on track but you want to run the amp with all 4 tubes all the time, not one at a time. What I would do is before you put the new tubes in, go ahead and check your current plate voltage. This shouldn't change but good to know up front. Then I would go from tube to tube and get a reading on the mA of each one. Out of curiosity. They should be fairly close. Anything with a variance of more than +/- 5mA is considered unmatched by most. Take notes and even label them if you want with a sharpie. These can be your spares and having them labeled will be good down the road. Not sure on the Blackstar (ask them) but these tubes work in pairs. Sometimes it is the inner and outer pair, sometimes it the two right ones and left ones. Once you get this down you can basically just use the 2nd and 3rd tube sockets because you'll catch the bias either way.

Then put the new tubes in. Play the amp for a good 15-20 minutes to get things warmed up real good. Take note obviously of the tone. How does it sound. Now, following the safety procedures, check the plate voltage again. Then check the mA of all the new tubes. Again, they should be within +/-5 mA. If they are and they are in your target range (28 - 30) then you may need to do nothing. Sometimes it is easier to leave the probe socket on either the 2nd or 3rd tube socket and then just swap the tubes in and out that way. That is how I do it.

Remember, the biggest risk I see in this part is people pulling the leads out of the meter or pulling the probe off the socket while the amp is turned on.

Don't ever do that. It is a bit tedious turning the amp on and off and all that but not doing that could be really bad. Also, don't drink while you do this

Also, get yourself some good leather gloves or even those oven gloves with the grippies on it. You don't want to burn your fingers.

I blew the resistor pretty easily in my Eurotubes probe which is why I went with the TA Weber probe the second time.

Good Luck,

311
#30
The only real reason to check plate voltage was on old Marshalls because there was such a difference between units. (10v doesn't make much difference with 300+ plate voltage)

If you know what the plate voltage should be from BlackStar (ask them) then you don't need to worry about flipping your meter between current/voltage.

I'm not sure which probe you got, some are voltage based and others current.

Post a link to your meter and perhaps we could give a little more insight.
Quote by DeathByDestroyr
See, it's important that people clarify when they say "metal", because I pretty much always assume they are a Cannibal Corpse fanboi.
#31
Pussies! Electrocuting yourself is a rush.


I joke of course - but it is.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#32
Perfect =] Thank 311 and R45 , and no , the question was to you 311 :P But for some reason UG isn't showing me neither sent nor received msgs, so i didn't think you received it, good think i had it copied ;
#33
Quote by Cathbard
Pussies! Electrocuting yourself is a rush.
I joke of course - but it is.


Yeah, the first few times....

I suffered a good dosage of three-phase at work and decided that was enough
#34
I'm an old tech. I've been zapped by all sorts of shit for decades. My pinky finger should be a charred stump by now. It's always the ****en pinky finger.




One thing. You may have noticed that most techs don't wear metal jewelry. There's a good reason for that. Rings, bracelets, watches - get rid of them. I worked with a guy that lost a finger when his wedding ring shorted out a mere 50V. Burnt it clean off. Put that shit away before you go anywhere near a live circuit.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band