How to test a tube - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 6th April 2005, 07:01 PM   #1
diyAudio Member
 
Join Date: Sep 2004
Location: casablanca
Default How to test a tube

hello

I need to repair a non working sansui au111 and want first to check if the tubes are working or not .
Do not know how to test at least if tehy work or not ?
I leave in Casablanca so I can't go to a specialised workshop .

Thank for help
Ger56
  Reply With Quote
Old 7th April 2005, 07:09 AM   #2
PRR is offline PRR  United States
diyAudio Member
 
PRR's Avatar
 
Join Date: Jun 2003
Location: USA
If it does not work at all, the power supply is bad.

The power supply is simple. You should have HIGH VOLTAGE A.C. on one side of the rectifier tube, HIGH VOLTAGE D.C. on the other side. Figure out which tube is the rectifier (it might not have a tube rectifier) and look-up the pin connections. And be careful.
  Reply With Quote
Old 7th April 2005, 08:55 AM   #3
diyAudio Member
 
Join Date: Sep 2004
Location: casablanca
Well the power suppply is ok but it won(t start as some resistor and do on are missing .

I have to check everything, change the bad resistor , most of caps should be changed but do not know how to check the tube to see what has to be replaced this is my problem by now .

ger56
  Reply With Quote
Old 7th April 2005, 10:33 AM   #4
Yvesm is offline Yvesm  France
diyAudio Member
 
Yvesm's Avatar
 
Join Date: Jul 2004
Location: Ardeche
Hi !

Yes tubes may be bad .. or may be not !
Testing tubes outside your amp means using a tube tester, and if you have not, it's simpler to check voltages against the schematic.

Here is what I've found about Sansui AU111:
http://www.bonavolta.ch/hobby/fr/audio/sansui.htm

If this can help ....

Does the tube glows ?
If not, what is voltage at pins 4, 5 and 9 ?

What is the voltage at the tube's anode ?

... just to start ...

Yves.
  Reply With Quote
Old 7th April 2005, 10:59 AM   #5
diyAudio Member
 
Join Date: Sep 2004
Location: casablanca
Thank you yves

In fact I am french from Paris .

I will check the output once I change the resistor and others in order to start .

In fact I have the schematic for the amp!

Just wanted to know if there is a way to test tube without havig a tube tester ? continuity or something like .

Regards

Gerard
  Reply With Quote
Old 17th August 2005, 04:45 PM   #6
JDeV is offline JDeV  South Africa
diyAudio Member
 
Join Date: Oct 2002
Location: Cape Town
Default Same subject:

The question have been asked earlier, but I could not find a clear answer:

Are there any method to test a tube without a tube tester, any of the parameters?

I am bussy repairing an old stereo Sansui radio/amp combo, using ECL82 tubes. The 1 old set of tubes I got , work well on both channels. I bought another set, which turned bright orange after 3 minutes. Took back to tube guy and exchanged for another "new" set. Now I notice a blue glow between the plates of both new tubes. All voltages compares correct to the service manual.

Any suggestions on this problem and tube testing?
__________________
"Be carefull who's advice you buy, but be patient with those who supply it."
From Baz Luhrmann's - Everybody’s Free (To Wear Sunscreen)
  Reply With Quote
Old 17th August 2005, 05:00 PM   #7
karma is offline karma  Canada
diyAudio Member
 
karma's Avatar
 
Join Date: Feb 2003
Location: hamilton,ontario
the new set turned bright orange because everytime you replace tubes u must bios the amp. blue glow is fine gassy tubes or new tubes do that.

if you wana test tubes get a tube tester. just one of manny


http://cgi.ebay.ca/LAFAYETTE-TE-55-T...QQcmdZViewItem
  Reply With Quote
Old 18th August 2005, 02:40 AM   #8
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
Normal failure in a tube creates lower to no current flow. Odd times elements may short, but the plate will have burn or "cook" marks on it. The best way to check a tube is in circuit and measure the terminal voltages.
Other parts will get you more often. Coupling caps are prime here. Run the unit up with no tubes (except rectifier) to about 70% ac voltage. The grids should measure 0V. Some power tubes are biased with a negative voltage. Some regulators "float" at some positive voltage.

With negative supplies for outputs, look at the ripple. There should be none.

-Chris
  Reply With Quote
Old 18th August 2005, 01:39 PM   #9
JDeV is offline JDeV  South Africa
diyAudio Member
 
Join Date: Oct 2002
Location: Cape Town
Default Build your own valve tester:

Quote:

if you wana test tubes get a tube tester. just one of manny

http://cgi.ebay.ca/LAFAYETTE-TE-55-T...QQcmdZViewItem


How about this, anybody got expereince with it / build and used it??

Build your own
__________________
"Be carefull who's advice you buy, but be patient with those who supply it."
From Baz Luhrmann's - Everybody’s Free (To Wear Sunscreen)
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
How to test a subminiature tube dayveshome Tubes / Valves 4 23rd August 2009 04:16 AM
Tube 6550 to test aduri Tubes / Valves 2 12th February 2009 10:19 PM
Need Help 12BH7 Tube test. Serratoga Tubes / Valves 1 6th March 2008 09:43 PM
tube test numbers - what do they mean? cbutterworth Tubes / Valves 5 27th February 2007 02:33 AM
Need help with tube test data - fast HugoR Tubes / Valves 15 7th November 2005 10:24 PM


New To Site? Need Help?

All times are GMT. The time now is 07:45 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2