[megawzrd]

Any tube amp gurus out there?

Are there any books, instructional videos out there that teach the proper safety methods of tube amp service and repair? Other than by trade or under the guidance of a seasoned professional how would someone learn this?


I have had a pignose gv40 guitar tube amp for about 5 years now and I was never really completely satisfied but it worked for my needs. I figured I could always tweak it since it is a basic tube amp design...and that was my idea 5 years ago. Fast forward...I have replaced the speaker with a vintage eminence and I have replaced the cheap stock 12ax7 preamp tubes with the drop in 5751 NOS which are the tamed 12ax7's to smooth it out. Now I am moving closer to the sound I am searching for...she sings nicely now.

I have come across some mods and some small tweaks but of course all of the mods and tweaks carry the "high voltage' disclaimer associated with servicing tube amps.

I would first off like to change out the cheapo stock 6L6 output tubes to something a little higher quality. I understand that changing these output tubes requires biasing to set it up properly. Which means opening up the chassis and knowing the dangers inherent.

I would like to know how to safely work on my tube amp (before just settling on paying someone to do the work for me). I would like to start with biasing, then go into tweaking some of the circuits to accomidate some different tubes say 12at7's (changing/adding resistors). Any advice is much appreciated.




Oh yeah I think this is post 100...woot

 

[megawzrd]

http://www6.head-fi.org/forums/showthread.php?t=167374

wow what a coincidence...posted right before me.

Its stuff like this that is informative. Most of the books or internet sites I have found when they talk about biasing they basically say unless you know what your doing you should have a professional perform this step. At least I now have an idea and images to what I would encounter in biasing thanks to the above post.

I just don't want to end up fried is all

.

 

[Voodoochile]

Antique Electronics Supply has a nice selection of books on tubed guitar amps- both design, and repair.

Working with tubes is pretty serious stuff, but if you understand and abide by some basic safety rules, you are good to go. The consequences of a slip-up in protocol can be grave, so you do need to excercise pretty strict discipline.

 

[bhjazz]

You should also spend some time and throw some questions around at the forum on Bottlehead. Link to the forum from the main page. Lots of intelligent people over there. Not that I want to steer anyone away from being here, but just to help you learn some more.

 

[rickcr42]

Discharge ALL power supply caps with a 100K/1W resistor across the caps before attempting any servicing and you should be fine.Best way I have come across is to use some black electrical tape to attach the resistor to the end of a wooden tongue depressor (any pharmacy) so you can reach into the gear without exposing any skin to High voltage DC-deadly stuff

When you fire that puppy up to make any bias adjustments put your left hand in your pocket and leave it there until finished...really.
The DC current can not make a circuit from your right to left hand after going through your heart unless YOU complete the circuit.
All probing should be done with clip on probes so you can do any adjustments without having to juggle between the probes and the meter AND the actual adjustment.A single moment of not paying attention is all it takes

[size=small]BZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZT !!!!![/size]

Want some bacon with that Head-Fi toast ?

 

[megawzrd]

I had read about being "the one handed repairman"...and about that capacitor discharge recommendation (the tongue depressor is a good idea). These are some golden tips that could save ones behind.
...keep em coming

In the meantime I ordered this book...I saw the description on the kendrick website and it looked to have some pretty expansive information. Hopefully it will have some good visuals and walkthroughs:

http://www.amazon.com/gp/product/096...lance&n=283155

I definately want to learn as much as I can and be thorough with safety "to the T" before I get into this.