Tube Amps 101 - repairs, maintenance and more!

[tomodrive]

i have an old tube amp ( silvertone ) that i yanked out of an old organ in my neighbors trash but it has no ground . do i just solder it to the chassis somewhere 

[ALFPARTZ1]

Three prong power cords that are 18 gauge are almost universal with most computer gear and the most common power cords available. You wanna get the Jap ones to use on the Fenders, because the insulation is generally a little thinner and they fit in the Heyco strain relief better. Good luck with that Fender Twin Death Machine :)

[James62]

The plastic "nut" for the lead is called a grommet.

When replacing the power cord as shown in the video, It's a good idea to shorten the active and neutral wires a little compared to the green earth wire. That way, if the power lead gets wrenched out of the chassis the earth may still be connected when the active and neutral wires have parted from their terminals.

[glprecycledsound]

Huge static noise is "usually" an indicator of tube socket problems. Wiggle each tube while it is making this noise and see what happens. If you can make it better (or worse) by doing this you need to clean and retension your tube sockets. This static is likely electric arcing at the tube sockets. We show you how to perform this repair in each of our DVDs - available at our website.

[5150VanAlien]

@glprecycledsound Thanks for the insight. I have an ENGL Savage and it is making loud buzzing/static noises, even with the stand by switch off. I also notice the power tube (6550) on the right starts to glow blue. I swapped around some pre-amp tubes, I plugged in my lead in the FX return but still the problem occurs. I assume, this could be the socket?

[glprecycledsound]

@5150VanAlien I really wouldn't expect a Savage amp to have this problem already, particularly if they use ceramic tube sockets. A blue glow in a power tube is not necessarily a bad thing. Watch your Power Tubes when it is making the noise, see if you see any internal arcing going on, watch your Rectifier tube too! ANY internal fireworks inside the tubes will require replacement of the tube.

[glprecycledsound]

@5150VanAlien I really wouldn't expect a Savage amp to have this problem already, particularly if they use ceramic tube sockets. A blue glow in a power tube is not necessarily a bad thing. Watch your Power Tubes when it is making the noise, see if you see any internal arcing going on, watch your Rectifier tube too! ANY internal fireworks inside the tubes will require replacement of the tube.

[5150VanAlien]

@glprecycledsound Thanks for the insight. When I look at the power valves, I don't remember seeing arcing just the right 6550 (right when standing in front of the amp) starts to light up blue. This is accompanied by a loud static noise even when only the power switch is on and the standby is off. Also, when I turn on the standby, and then turn off again, the speakers pop. Then when I turn the power off, the static sound continues for a few seconds. Could it be internal grounding?

[harpastatic]

great video!BTW,that grommet /strain relief nut would go in easier with a little lube like lemon pledge.

thanks for helping us beginners with learning!!

[glprecycledsound]

Just want everyone to know, we have started a TUBE AMP forum for discussions on troubleshooting, repairs and identification of tube amps.

Go to tubeamps.ning.com and join in!

[originalMOON3R]

i have an old stage amp and it doesnt work. i left it at a school's music class n someone plugged the guitar chord into the headphones jackport while the other end is connected to the guitar amp's output while it was on. i was told it just made a buzzin noise n died. im wondering if its fixable cause that old thing has a good tone

[glprecycledsound]

@originalMOON3R Is your amp DEAD as in it won't power ON or dead as in in everything looks right, but no sound? In the first case it may be as simple as a blown fuse.... in the second case you may have a blown output transformer. In either case it is easily fixable......... 

[originalMOON3R]

@glprecycledsound yeah like it wont make a sound even the LED wont light up when you flip the switch on. any advice on how to check either of them? i might make it worst

[glprecycledsound]

@3musicmakers You have to bear in mind our videos (and our DVD series) is for BEGINNERS! Why would you recommend that a DIY'r go out and buy a specialty tool for a one time use? We are trying to help people SAVE MONEY. Other tutorials won't even show you it can be done with pliers. They are why we started our series of DVDs for beginners - Tube Amps 101. After watching our repairs, inside of real vintage tube amps - you see and hear the symptoms and you watch us make the repairs.

[anwerpelut]

Hey, one thing, I´m buying a Bugera 333XL soon, but I wanted to change the Bugera tubes, or whatever they´re, and put a Mesa/Boogie 6L6 STR-440 tubes, will it work nice? the amp comes with 4 EL34 tubes fitted on it, but I can change them and put 6L6, it allows it,

but i wanted to put the M/B ones tell me if it´s possible please,

thank you a lot :D

[glprecycledsound]

@anwerpelut I haven't checked that one BUT if they say you can swap 6L6s with EL34s, then I assume they have a circuit designed to do so. After that, well a 6L6 is a 6L6 is a 6L6....that is the BRAND doesn't affect the tube. All 6L6s are internally connected the same way so you can't make a mistake by simply changing brands. You WILL need to RE-BIAS your amp however! 6L6s generally don't like as much bias voltage as EL34s.

[anwerpelut]

@glprecycledsound ok, thanks, I deduced that I will have too re bias it, but, I will bring the amp to a music store, and then they wiill do the work, I´ll give them the amp, the tubes, and, they´ll change them ^^

THANKS :D

[glprecycledsound]

@anwerpelut Thats why we made our DVDs for Beginners on how to service your own tube amps........

[fthmusic80]

I just opened my amp. The internal fuse inside has blown. Do i fix my amp just by replacing it or it could be something worse? and, why did this happen?

Thanks !!

[glprecycledsound]

@fthmusic80 In our videos we show you how to use (and build) a Current Limiter. One of the best uses is for determining if you have a short, which blows fuses. When a fuse blows, the FUSE IS NEVER THE PROBLEM! Something caused it to blow. Make SURE you replace the fuse with the correct value (NEVER HIGHER) and give it another go......just to see if it blows again. If it does, you may have a bad Power Transformer...but I would also look at the Filament circuit.

[fthmusic80]

No, its just a normal new version of the 65 Deluxe reverb. I actually bought it new only 5 months ago therefore i guess all the components should be ok. Well its weird coz yesterday it was working perfectly and today i turned it on and it didn't...the only thing i saw was the rectifier tube on. Do you think it could be a tube or something like that? What should i do? What do u mean by PT? Thanks for such a fast reply !

[glprecycledsound]

@fthmusic80 PT = Power Transformer. I really think it is something with your 6.3 volt Filament circuit or in the PT itself. I'll have to pull a schematic for it to see what I can see. There may be an internal fuse for the filament? If you have some experience or at least have watched our 2 DVDs for beginners - Tube Amps 101 and MORE Tube Amps 101 - they can at least tell you how to safely poke around inside your amp. Otherwise you'll need to take it to a local amp tech. Go to

[fthmusic80]

Hi, i have a question. My 65 deluxe reverb does not turn on anymore. When i turn on the power switch the only tube that illuminates is the 5AR4 rectifier tube. Also the power indicator does not illuminate either. Whats wrong with my amp? How can i fix it?. Thanks and very nice video.

[glprecycledsound]

@fthmusic80 Is this a REISSUE '65 Deluxe Reverb? or a vintage model?

In a vintage DR, the power indicator is lit via a 6.3 volt tap from the transformer, which also lites ALL of your other tubes via the filament supply. Your Rectifier tube is lit by a seperate 5 volt tap from the Power Transformer.

I would want to see your amp, but it could be a broken solder joint or wire in your filament suply, between the PT and the power indicator or your PT could be bad.

or bad artificial CT resistors

[mellowb1rd]

Personally, I hate having the power cord permanently attached like that. If you are gigging you are going to break the wires in there sooner or later. I know some purists might not agree with this, but I always cut a hole in the chassis and fit a socket for a kettle lead. There's absolutely no reason to have it hard-wired in there if you can avoid it.

[glprecycledsound]

@mellowb1rd Personal preference is a wonderful thing! I can't say that I have ever run into a properly mounted hard wired cord come out... but they can be inconvenient. Then again, trying to keep up with an UNattached cord can be a hassle too! But like TONE and the FEEL of any given guitar, it's a matter of whatever inspires YOU to play - no matter what any so called expert says. While I do not claim to be an expert in anything - I include myself.

[mellowb1rd]

@glprecycledsound I don't mean come out. I mean constantly loading the amp into the back of a van and carrying the amp around tends to break the conductors inside the power lead at the point where it enters the chassis, so I find that for an amp that's going to be used at gigs, it's just worthwhile to install a socket, though it does mean cutting a fairly large hole. Only problem then is people stealing your leads.

[6L6tubeamps]

Good video!

Did you remember to remove the death cap from the ground switch? I hope so.

when upgrading to a grounded power cord, the ground switch no longer serves a purpose. there is a .047uF cap from the center pole of the switch to ground. It needs to be removed.

[glprecycledsound]

@6L6tubeamps Actually our DVDs and our FREE layout/written instructions show you how to wire around the polarity switch so you don't have to remove anything from a vintage amp. We use the existing ground switch like pin 1 of a 6L6....... as a place to tie the wires. Good point though and very observant!

[6L6tubeamps]

@glprecycledsound I agree, I never remove the switch, I just cut out the cap and leave the switch as the original connection point. I do the very same thing you do LOL, The Marshall 18g power cord works good in the old Fenders.

[glprecycledsound]

I'm not sure I understand the question BUT,

If you have two glowing power tubes, you can start by replacing them with the other two. Does the glowing RED follow the tube or stay with the socket? If it follows the tube - replace them and do yourself a favor and replace them ALL with a matched Quad. When you do that, replace your Phase INvertor tube too - the one right next to the power tubes. That should take care of you. Most EL84 based amps are cathode or self biased .

[glprecycledsound]

Well it's a tube amp! If you aren't using KNOWN good tubes, you should start by replacing them and see where that takes you. PArticularly if they are over 1 year old.

[kungfujews]

Really clear vid' thanks. I also have a question. I have a Mesa F100 and a Mesa Boogie MK 4 - the valves in the f100 are new...can I swap the valves in both? They both have stock 6L6s and 12Ax7s with fixed bias.

[glprecycledsound]

Yes sir, you can.....

[Chrysalis0808]

Great videos! I have a question that I wondered if you could help me with. I currently use a Laney Klipp which works fine at low volumes yet when the master volume is turned past about 5 it blows one of the power tubes, is there anything that would explain why the increase in volume is causing the tubes to blow? Many thanks!

[glprecycledsound]

Hard to say without seeing it BUT,if one power tube is taking the load, I would look at the bias section and or the phase inverter signal splitter area of the amp. There is a current problem in that one tube is getting more than the other - it should be balanced.

[varone6t9]

I have a question hopefully you can tell me what to do....I have a vox ac15 and i love it but im wanting to get more dirt naturally rather then having an OD pedal, I was told there are certain tubes that have a natural distorted tone when heated up. WOuld you happen to know any tubes that have that natural dirty tone in them?

[glprecycledsound]

Well EL84s are "naturally dirty". At least they tend to break up earlier than 6V6s for example. Otherwise from a brand perspective you can order Groove Tubes in HOT - MEDIUM - COOL ranges. The HOT would break up soonest.

[Vitotesta]

Nice enough video BUT you don't actually show the soldering of the black and white cables from the inside nor do you address which side is white which is black...the whole reason I'm looking for instruction vid! Thanks for posting anyway..

[glprecycledsound]

Ahhh BUT - I Include a complete drawing of the specific wiring in the BONUS CD.

The vid just helps you along.

[Vitotesta]

Hi thank you for your reply. I find your videos very informative and helpful. I did not know about the bonus CD!

[joeypinter90405]

hi, i want to bias my fender hot rod deville, what is the best (easiest) way

thanks

[dude794]

hey I dropped my amp and now it doesnt work. if i put finger to the chassis and a metal part of my amp, it works. is there any advice u could give me to how to fix this?

[jazzfusionforall]

first of all, don't touch it again unless you want to die. Thats a good way to figure out which components store a charge.

[dimeguitarsrock]

ABSOLUTELY.

ive got a 1963 fender amp i inherited.

every component inside uses the case as a negative or return path.

all you have to do is touch the guitar strings and the metal front of the amp to get the full charge through you.

Ive solved the problem for myself anyway, by just knowing never to do that.

bottom line is that putting yourself anywhere on a high voltage circuit as a test or to complete the connection, etc is a good way to die.

[dimeguitarsrock]

Btw, does anyone know how to modify an old school blackface amp to correct the shock factor?

is it able to be done in a removable way?

i dont ever see myself selling or thinking of selling this amp, but you never know the future with the way things are going.

[glprecycledsound]

Your Blackface amp likely has a 2-prong power cord. Change it to 3 prong grounded. Our first DVD - Tube Amps 101 shows you exactly how to do this along with a drawing to show you how to rewire the polarity switch and fuse. Our 2nd DVD - MORE Tube Amps 101 also shows this procedure with a little more detail.

[glprecycledsound]

If your putting a finger to the chassis to make it "work". YOU are completing the circuit. You don't want to be a part of an electrical circuit. You have obviuosly knocked something (or several things) loose. Without seeing it, I would take it to a competent technician for repair.

[wags126126]

Great Vid!

[markito787]

Hey...im having trouble with my pilot light jewel... it wont tighten. How do i fix this?

[glprecycledsound]

On a FENDER amp the nut for the light assembly is inside the chassis. If the whole light is spinning - stop twisting it. The pilot is lit from an extension of your filament voltage - you don't want to break that off.

[markito787]

ok. the light isnt twistin ...the jewel is... so how do i open up pro reverb in order to tighten the jewel?

[Gtrplyr1]

Hello... I have a problem with My Marhsall tube amp... My gf accidentally bumped into it causing it to make a loud disturbance sound. Now the amp will not play out of the simulated out. Can you suggest a possible idea of defect? I do not have a cabinet yet as i just bought the amp..Thanks

[glprecycledsound]

Tough to test without a cab...... but if the amp was HOT and got hit hard enough it is possible you knocked some of the insides of the tubes loose. When hot they can be like a light bulb in that the metal parts inside can be somewhat delicate.

[Gtrplyr1]

ok what is the safest way to fix then? Im new to tube amps and i know they could be quite dangerous. Should I unplug from wall before i touch? I don't want to end up with a an Einstein haridew :)

[glprecycledsound]

These things used to be thee amp to have or control room, I have seen good running 300's sell for $60, so I don't know that I would waste much money on this one. They are known for blowing OTs and could well be your problem here, with low or no output. They are known for passing DC on to the speakers when they start to fail. That will fry your speakers in a hearbeat. It doesn't seem to be worth it?? My DVD or a tech will help you determine if the OTs are bad. Hope that helped?

[strontiumdog9]

Just trying to help. Look forward to more videos. No matter how much you know, there's always something else to learn!!

[strontiumdog9]

There's a special tool for reseating that grommet. I have one, sure makes it alot easier to put back!

[alowishus1979]

Great vid. Where can I find your videos?