MORE Tube Amps 101 - Draining Filter Caps - DVD on Repairs, maintenance and more!

[LeviMan2001]

Do you recommend re-wiring these old gibson and epiphone amps to take 12ax7s instead of 6EU7s? I have an old gibson GA-15RVT that is really quiet and doesn't break up at allll. When you put a pedal through it it really gets loud though. I'm think the pre amp tubes are extremely worn out. They're 6EU7s. Anyhow, I was thinking of replacing them with 12ax7s. Also my reverb is extremely quiet, when the amp is all the way up (with the reverb all the way up too)you can barely hear the reverb Any tips?

[LeviMan2001]

@LeviMan2001 Oh and I nearly forgot, the amp is insanely bright. Almost no bass! Would a bad tube or two cause this?

[glprecycledsound]

@LeviMan2001 Like we say in our DVDs.... the reason to always suspect tubes first is because..........

ITs a Tube AMP! 6EU7s are generally available, so you can simply buy NOS. Rewiring for any 12 series tube would not be an easy task. But you don't comment on your POWER TUBES? Low Power most often starts there, followed by the Phase Inverter tube. Same deal with your Reverb, make sure your tube is a good one. Most Troubleshooting is wasted if not starting with KNOWN GOOD TUBES!

[glprecycledsound]

@LeviMan2001 Like we say in our DVDs.... the reason to always suspect tubes first is because..........

ITs a Tube AMP! 6EU7s are generally available, so you can simply buy NOS. Rewiring for any 12 series tube would not be an easy task. But you don't comment on your POWER TUBES? Low Power most often starts there, followed by the Phase Inverter tube. Same deal with your Reverb, make sure your tube is a good one. Most Troubleshooting is wasted if not starting with KNOWN GOOD TUBES!

[haz939]

I'm trying to fix my class A amplifier that that has a blown mosfet, It was not turned on for 3 days and the main filter caps still had a charge only 20v mind, but still enough to make you jump short out the capacitor. I'm going to make this cable to discharge caps properly so I don't shit myself lol.

[GtrDudeL]

ha! that was the exact solution I came up with... lol. works great!

[glprecycledsound]

What kind of half stack?? What kind of guitar - with what pickups?

What kind of speakers in your cab?

[fingerboy18]

Thanks for helping to save lives. Good way to do things!

[JedClampettJr]

Oh, come on man , just reach in there and grab it. It's good therapy!

[glprecycledsound]

Honestly, all the resistor does is prevent a SPARK from occuring when your connecting the clips. You don't really need it at all. If you follow our steps:

1. While playing, unplug the amp from the wall - keep playing til all sound dies out.

2. Leave Power and Standby switches in the ON position.

3. Remove the chassis and connect a jumper to the chassis and Pin 1 of your 1st preamp tube (12AX7 family).

4. Wait a couple minutes then test all filter caps with your meter for DC voltage.

[fuzzfreak1967]

Is that resistor good enough for any capacitor?

[jblah1]

Great video! Is a 1watt 100 ohm resistor ok? I just made made a discharge lead before I saw your video;-( Thanks for your great videos!!

[BayouBluesMan]

how do u discharge an ac30 man?

[Zanacek]

Translation by GOOGLE...

[Zanacek]

I apologize to You, but I thought so. I did not know that it is for beginners. Excuse me, please. Zanacek.

[2Langdon]

Thank you! Nice clear instructions and demonstration- just right for a newcomer. Appreciate it! Regards, Langdon

[glprecycledsound]

@2Langdon It is what we do in our DVDs. No technical joargon or "geekense", just easy to understand while you watch training. Our DVDs are aimed at beginners and full of all the info we found so hard to get when we started.

[glprecycledsound]

@2Langdon It is what we do in our DVDs. No technical jargon or "geekense", just easy to understand while you watch training. Our DVDs are aimed at beginners and full of all the info we found so hard to get when we started.

[glprecycledsound]

@Guinzarth The real danger is in not paying attention..... Keeping one hand in your back pocket, while probing with a chopstick is exceedingly safe..... as long as your not resting your bare arm on the chassis while doing so!

[Moh1Z]

Why not just unplug the power cord while the amp is still on? Works at least on my amp, there's no voltage on the filter caps after that.

[glprecycledsound]

@Moh1Z That DOES indeed work on many amps. I like to tell people to hit a great big power chord and hold it while unplugging the amp...... that fizziling note you get as the volume dies is the capacitors giving up their voltage! BUT.... you need to be aware enough to leave your power and standby switches in the PLAY position! AND I wouldn't retension tube sockets in ANY amp without using a voltmeter to test the caps for remaining stored electricity.

[glprecycledsound]

@Moh1Z See my answer to streakinginjanuary BELOW.....

[Finom1]

I am just starting out. I have 2-Sunn heads from 1969 and I would like to make them come alive.

Thank you for teaching the world on YT.

[glprecycledsound]

@Finom1 I can't say I would start out with old Sunn amps...... are they currently DEAD? Bringing a dead amp back to life is pretty straightforward... Breathing TONE into an amp that never had it is a bit more tricky!

[glprecycledsound]

No you can't, unless you are touching the chassis or are otherwise grounded and completing a circuit with your leads. Just watch what I do in the vid and you'll be fine. Bleed the caps into the millivolt range and you'll never feel a thing!

Better yet, invest in our TUBE AMPS 101 series of DVDs and gain 6 hrs. of comfort level troubleshooting, repairing or modding your tube amps,along with a ton of reference information!

[StreakingInJanuary]

Just for reassurance, can you be electrocuted by the capacitors through a voltmeter? Just in case I did this wrong. 

[mgp701]

If your first preamp tube is an EF-86 would you clip your lead to pin #6? This is the pin for the plate according to the pin-out I have,

[glprecycledsound]

@mgp701 Yes... leave your stand-by switch in the play position and it would be good to double check a few caps with your DVM to be sure it is draining before you begin work.

[EL34]

where do i buyyyyy?

[glprecycledsound]

Available at our website shown on the video.

Volume III will ready in a week or so. More troubleshooting, how to re-hab an old amp and MODS! We even show you how to do the Paul C mod, using a PRinceton Reverb as an example.

[widepass]

Some days when i am messing with my amps i don't Drain Filter Caps just because i am bored and thinking that a shock will snap me out of the boredom!

Shock me, make me feel better

Shock me, put on your black leather

Shock me, we can come together ,LOL

[StreakingInJanuary]

My amp's first Preamp Tube is a 12AX7, will I be able to discharge it by putting the clip on Pin 1, and then grounding it, and leaving it on standby?

[glprecycledsound]

@StreakingInJanuary Sounds like it....

Play your amp - while playing - UNPLUG it!! - The dying sound of your playing is the caps discharging...... then clip one end of your discharge wire to the chassis, the other end to Pin 1 of that 12AX7. Make sure you still have it the play mode. Then test it with your meter to be sure.

[glprecycledsound]

@StreakingInJanuary In MOST cases YES! You should double check with a voltmeter before starting your work!

[sawyerandjackfucking]

I usually find a resistor to ground somewhere and just jumper one of the tube plate pins to that resistor. I will find a 220K-100K. Also, if the amp doesn't have any, I'd add a bleeder resistor (again, I usually use 220K) to ground close to the cap.

[mafiagretel]

is any shielded wire used in these old amps? i'm building my own tube amp and just wonder not to see any...

[glprecycledsound]

@mafiagretel Shielded wire started to show up on Fender amps in the 70's. Before that it was pretty rare to see. If you're building your own... use it.

[andy92811]

One time before my amp was grounded I plugged in one day and my guitar became the ground and all the strings were vibrating with electricity. Talk about electric guitar!

[glprecycledsound]

That is why it is important to convert all your vintage two prong amps to 3 prong grounded power cords!! ANOTHER thing we show and explain in our DVDs.

[andy92811]

@glprecycledsound Yep it had it done years ago. You should post a video on how to re-tension tube sockets.

[glprecycledsound]

@andy92811 I hate to say it but If I keep posting How To's there won't be a need for the 4 hours of How Tos I have on our DVDs!! We DO show how to clean and retension tube sockets on both of our DVDs, along with a ton of other useful info. A THIRD Edition is coming soon that will include a rehab of a 1958 Tweed Deluxe and some other cool stuff.

[Juckey2008]

Can the chassis be floating when draining the caps? Or must there be an electrical connection to earth ground before draining the caps?

[glprecycledsound]

@Juckey2008

Yes, to use your word - the chassis can be "floating". Your disapating the DC thru the chassis.

[KrankySourPants]

This is an awesome video. I'm really digging tube amps now that I have my first one.

[glprecycledsound]

Ya gotta remember this is aimed at and FOR beginners! Too many instructional DVDs out there leave you with more questions than what they answer! After they are done fast talking.... you aren't sure what they said? This particular topic is VERY important to those that are new to amp work, so I thought it important to go slow! I appreciate your comments though!

[BigFishingShop]

What do you have your multi meter set on ??

[glprecycledsound]

When checking for adequate drainage of stored voltage - set your meter to DC Volts.

[peterm3964]

So the jumper clips are INSULATED right ???? oh theyre not .. hahahaha funny guy

[crittoprrr]

Yeah I was scratching my head over that one. Obviously he'd already drained the caps beforehand, maybe it just slipped his mind to make the vid with insulated clips.

[glprecycledsound]

I use the non insulated when I am testing caps to make sure they are drained clipped at the end of a chopstick. But YES - normally, for the jumper I leave hooked up while servicing - I do indeed use insulated clips.......

[MattTheGuitarGuy]

im very confused on something i bought a pedal and hooked everything up correctly and cheked every last detail but wen i strum the strings no noise comes out of the amp...... any suggestions?

[glprecycledsound]

Does your pedal have a light that tells you it is on? If so and no light appears, first check your battery. If your not using a battery check that you are using the correct polarity plug on your AC wall wart. If your getting a light and no sound, no check BOTH cables. Make sure they pass signal by plugging each one straight into the amp from a guitar. Advise what you find after checking the above.

[wags126126]

Great Vid! What tube amp books would you recommend for someone interested in learning more and possibly building one?

[glprecycledsound]

@wags126126 I recommend OUR DVDs. I have yet to read a book that doesn't leave me with MORE questions than I had to to start with. With all 3 of our DVDs and FREE printable reference material included, you can make your own over 300 page book! No need to buy someone elses!

[musicmaker85]

I have actually been shocked by an electrolytic (the canned plug in type) while it was unplugged. Wasn't payment attention and touched the leads with my hand. It hadn't completely drained and still had 95 VDC. It was not a pleasant experience and taught me a very good lesson that day.

[glprecycledsound]

Thats exactly why we put our DVDs together. Both Tube Amps 101 and MORE Tube Amps 101 are aimed at the beginner (and those with a little experience) for safety and ease of learning. Somehow it is very difficult to actually find the info we give on tube amp circuits, parts, troubleshooting and repairs. Thanks for the reminder - that there is indeed the possibilty of injury if you have no clue....

[angushetfield13242]

Rainin Fillter Caps!!!!!!!!!!!!!

[eddielang2]

Hey Greg! You give some very important information here that I didn't know. This has been a very good learning tool for me. Thanks! I look forward to your next production!

[glprecycledsound]

@eddielang2 Tube Amps Volume III is ready for Christmas! More great troubleshooting, how re-hab an old amp and now MODS are included too!

[8153max]

hi ...I have your first dvd on tube amp repair. It is great! and you gave some excellent insight on telling what the age and year an amp is by checking various components. You guys are great. Tube amp repair is a dying art these days. There are a lot of clowns out there that think they know what their doing. But thanks to you guys we can now figure out what amp tech guys really are good.....

[glprecycledsound]

@8153max Tube Amps Volume III is ready for Christmas! More great troubleshooting, how re-hab an old amp and now MODS are included too!

[pomod]

awesome

This is exactly what i was looking for. I'm mulling over an amp project but am nervous about frying myself in the process. I guess I should do some more reading on ground etc. but having a visual like this really helped.

thanks.

[glprecycledsound]

Our DVDs show you what you need to know and we give you printed instructions on how to build a Current Limiter - an indespensible tool for troubleshooting and amp building.