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afterdawn.com > forums > home theater > receivers and amplifiers > reparing tube based amplifier
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Reparing tube based amplifier
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DarkJello
Senior Member
_ 		13. May 2007 @ 17:50 _ Link to this message    Send private message to this user   
Anyone know of any books/websites where I could read up on this, or care to share their knowledge of the subject with me?
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Indochine
Senior Member
_ 		13. May 2007 @ 23:46 _ Link to this message    Send private message to this user   
Be very careful - there are high voltages inside.

What sort of problem are you having?

What is your present level of electronics knowledge? If you are not already pretty advanced in electronics theory and repair, I advise leaving it to a professional.
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On m'a dit que je suis nul ŕ l'oral, que je n'peux pas mieux faire !

This message has been edited since posting. Last time this message was edited on 13. May 2007 @ 23:49
DarkJello
Senior Member
_ 		14. May 2007 @ 08:29 _ Link to this message    Send private message to this user   
From what I understand, the tubes need to be replaced. I don't have any intentions of tinkering with it until I was sure I knew what I was doing, and am aware of the risk associated with the high voltage. So I was just wondering if anyone could reference an article or book about the subject for me. I promise I won't kill myself :)
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Indochine
Senior Member
_ 		14. May 2007 @ 09:17 _ Link to this message    Send private message to this user   
Replacing tubes is very similar to changing light bulbs.

They get pretty hot, more so if they are old and failing, so don't handle them straight after powering down. Leave them for 30 minutes.

Sometimes as tubes age they take other components with them, eg screen grid resistors, and some capacitors may be getting leaky, depending on how old the rig is...

http://www.kbapps.com/tubeamptips.html

http://www.amazon.com/How-Service-Your-Own-Tube/dp/0962817007
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On m'a dit que je suis nul ŕ l'oral, que je n'peux pas mieux faire !

This message has been edited since posting. Last time this message was edited on 14. May 2007 @ 09:38
VanTwest
Newbie
_ 		28. May 2007 @ 02:33 _ Link to this message    Send private message to this user   
It's actually quite simple. I replace the tubes in my Messa Boogie bass amp every few years, to ensure reliability.(they would last for about 10+years but i'm picky)Very simple yet important tip dont handle the tubes with your bare hands, use a clean cloth or even the cardboard box that it comes with, oil from your fingers or anything else will cause the globe to get hotter then usually and can usually burn your bulb in a matter of seconds.

Have fun.
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Indochine
Senior Member
_ 		28. May 2007 @ 03:10 _ Link to this message    Send private message to this user   
Originally posted by VanTwest:
IVery simple yet important tip dont handle the tubes with your bare hands, use a clean cloth or even the cardboard box that it comes with, oil from your fingers or anything else will cause the globe to get hotter then usually and can usually burn your bulb in a matter of seconds.
Very good tip, and also applies to halogen bulbs and projector bulbs.

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On m'a dit que je suis nul ŕ l'oral, que je n'peux pas mieux faire !
ireland
AfterDawn Addict
_ 		28. May 2007 @ 15:36 _ Link to this message    Send private message to this user   
I am from the old school of Vacuum Tubes and i still repair them today..power the amp off,and change the tubes with the correct tube identification..

How Vacuum Tubes Work
http://www.vacuumtubes.net/How_Vacuum_Tubes_Work.htm


Tube Electronics
http://www.ccdemo.info/SportsAndHobbies/...lectronics.html


The Vacuum Tube Audio Page
http://www.austinstereo.com/vacuumpage.html

2 x 50 watts Tube Power Amplifier
http://www.klaus-boening.de/html/tube_amp.html

Vacuum Tubes Frequently Asked Questions
http://www.vacuumtubes.net/faq.htm


The-ResistorPage what the colors mean on the resistors
http://www.williamson-labs.com/resistors.htm

ELECTROLYTIC CAPACITORS
http://www.faradnet.com/deeley/book_toc.htm

and here
http://en.wikipedia.org/wiki/Capacitor
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This message has been edited since posting. Last time this message was edited on 28. May 2007 @ 15:47
Indochine
Senior Member
_ 		28. May 2007 @ 22:21 _ Link to this message    Send private message to this user   
I must admit that when I worked in a TV repair workshop in the 1970s we never worried about touching the replacement tubes with our fingers.

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On m'a dit que je suis nul ŕ l'oral, que je n'peux pas mieux faire !
ireland
AfterDawn Addict
_ 		29. May 2007 @ 08:36 _ Link to this message    Send private message to this user   
Indochine
i also admit this will give my age away..i worked on a CT-100's Color Television Receiver when i worked at RCA.15GP22 picture tube
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Indochine
Senior Member
_ 		29. May 2007 @ 09:31 _ Link to this message    Send private message to this user   
I was in England, we got colour TV in 1967, and for about 8 years after that a lot of chassis were hybrid - transistors up to frame, line and audio output, then pentodes of various sorts. I believe you call frame output "vertical output" and line output "horizontal output" in the US? I remember a British made GEC chassis, the 2040, that had colour difference drive to the CRT grids, with a pentode for each colour, they were a nightmare to set up if the tubes had aged. they had to be replaced as a set. We called them "valves" by the way. Also a beefy pentode with a top cap for line output, a similar sized booster diode valve, and a directly heated tube EHT rectifier in a lead glass sleeve to keep the X-rays in... Delta gun tubes with convergence boards that used to fry the potentiometers and burn up the tracks... happy days.


Now we don't have a domestic TV manufacturing industry, or a repair industry to speak of, all the old terms are fading away, and the US terms are used more and more.
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On m'a dit que je suis nul ŕ l'oral, que je n'peux pas mieux faire !

This message has been edited since posting. Last time this message was edited on 29. May 2007 @ 09:32
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DarkJello
Senior Member
_ 		29. May 2007 @ 11:04 _ Link to this message    Send private message to this user   
Thanks for the links guys, should be able to tackle the project this summer.
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