Videokarma.org

Go Back   Videokarma.org TV - Video - Vintage Television & Radio Forums > Vintage TV & Radio Tech Forum

We appreciate your help

in keeping this site going.
Reply
 
Thread Tools Display Modes
  #1  
Old 05-03-2015, 03:43 PM
TheShanMan's Avatar
TheShanMan TheShanMan is offline
VideoKarma Member
 
Join Date: Sep 2014
Location: Hillsboro, OR
Posts: 88
Important to test tubes after recapping a non-working TV or radio?

Just wondering if I run any risk of damaging components if I try firing up a radio (1946 Westinghouse) or TV (1956 Packard Bell) after recapping the chassis if the condition of the tubes is unknown? I don't have a tube tester myself although I may be able to get them tested locally. If there is little to no risk of damage then I'd like to fire them up and see what happens and only mess with testing/replacing tubes if I still have a problem.
Reply With Quote
  #2  
Old 05-03-2015, 05:22 PM
Eric H's Avatar
Eric H Eric H is offline
Administrator
 
Join Date: Jun 2002
Location: So. Calif
Posts: 11,565
Not much risk of damage but it's nice to know if your tubes are in top condition or not.
They can often have shorts or be weak and still basically function.

I just finished recapping an Admiral but the vertical wouldn't lock, turned out to be a weak Sync tube, it also had four bad 6AU6 tubes in the i.f. section, performance was greatly improved after replacing them.
Reply With Quote
  #3  
Old 05-03-2015, 06:45 PM
zeno's Avatar
zeno zeno is offline
VideoKarma Member
 
Join Date: Mar 2013
Location: New Hampshire
Posts: 4,672
You are on the right track IMHO. Just be sure things are coming
up as they should, audio on the radio & HV on the TV.

Keep in mind the only bigger liar than a tube tester is a
politician ( both parties). They have there uses but its
best to deal with problems one at at time & not look for
miracle cures. You learn more that way anyhows. Many of the
low level tubes can be bought cheap also & they are the ones
that can bring a set from working OK to working like new.
Subbing a known good tube is the best checker.

We had a top-o-line B&K checker at the shop and never used it. It
was for the customers & the best salesman we had. Back
then there was 60%-90% mark up in tubes and that was for name
brand ones ! We did use a little checker. Plug in a tube & if
the light lights the filament was OK. Saved time on series filament
sets.

73 Zeno
Reply With Quote
  #4  
Old 05-03-2015, 07:04 PM
TheShanMan's Avatar
TheShanMan TheShanMan is offline
VideoKarma Member
 
Join Date: Sep 2014
Location: Hillsboro, OR
Posts: 88
Thanks guys!
Reply With Quote
  #5  
Old 05-03-2015, 07:14 PM
Olorin67 Olorin67 is offline
VideoKarma Member
 
Join Date: Feb 2014
Location: Milwaukee
Posts: 927
If you later run into issues , its good to test the tube in that stage, or swap another tube in if you have one. One reason i use my tube tester is when i buy something off ebay, sometimes tubes develop shorts from being bumped in shipment, so I will usually run the tubes past my checker mainly to look for shorts, and weed out some weak ones as a side benefit. Radios and hifi rarely run the tubes hard, and often seem to work fine with rather weak tubes. Many TV circuits seem to be less forgiving of tubes, and may need a strong tube to work best.
Reply With Quote
Audiokarma
  #6  
Old 05-03-2015, 07:42 PM
Jon A.'s Avatar
Jon A. Jon A. is offline
Don't mess with Esther.
 
Join Date: Jun 2013
Location: Canada
Posts: 4,267
Quote:
Originally Posted by zeno View Post
Keep in mind the only bigger liar than a tube tester is a
politician ( both parties).

73 Zeno
We have more than two to deal with here, ugh.

Anyways, that's a piece of equipment I likely won't add to my collection no matter how much tube stuff I get.
Reply With Quote
  #7  
Old 05-03-2015, 09:56 PM
Olorin67 Olorin67 is offline
VideoKarma Member
 
Join Date: Feb 2014
Location: Milwaukee
Posts: 927
For the money you might spend to aquire and restore a good tube tester like a Hickock, you could get a stock of spares for most tubes. Can still pay to keep an eye out for em though, i found one hickok in an antique store for $40, and got another from a co-worker cleaning out his dads estate.
Reply With Quote
  #8  
Old 05-04-2015, 12:27 AM
old_coot88 old_coot88 is offline
VideoKarma Member
 
Join Date: Sep 2009
Posts: 2,541
Very often the best tube tester is the TV or radio itself. There's the "seven seconds off" test which is useful for showing up borderline weak tubes.
With the set running and warmed up, turn it off for about 7 seconds, and back on.
Is the width slow to fill out? That'd be a borderline Horiz out tube.
Vertical slow to fill out? Weak vert. out tube. Horiz sync slow to lock in? Hor. oscillator weak. Pic comes in snowy, then clears up? Weak RF amp tube in tuner. Etc.

Then there's the 'tap test' useful for showing intermittent tubes. Tap each tube gently with something like a screwdriver handle while watching the pic (use a mirror if necessary).
Intermittent heater-cathode shorts in the CRT often show up by tapping the neck.
Damper tubes are notorious for arcing, and will almost always respond to the tap test (no mirror necessary).
Reply With Quote
  #9  
Old 05-04-2015, 12:04 PM
Electronic M's Avatar
Electronic M Electronic M is offline
M is for Memory
 
Join Date: Jan 2011
Location: Pewaukee/Delafield Wi
Posts: 14,758
Unless a tube has a BAD short it is unlikely to do harm if bad and ran in a set....The one big exception in TVs is the horizontal oscillator tube...If bad (or the circuit it is in is bad) the horiz. output tube will red plate which which if allowed to persist for any significant period of time (more than half a minute) will destroy said output tube and possibly the flyback.
__________________
Tom C.

Zenith: The quality stays in EVEN after the name falls off!
What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4
Reply With Quote
  #10  
Old 05-11-2015, 05:34 PM
AUdubon5425's Avatar
AUdubon5425 AUdubon5425 is offline
VideoKarma Member
 
Join Date: Aug 2008
Location: Picayune, Miss.
Posts: 1,769
I test them for shorts after two bad experiences.
__________________
AUdubon5425 Youtube Channel
Reply With Quote
Audiokarma
  #11  
Old 05-12-2015, 06:51 AM
Reece's Avatar
Reece Reece is offline
VideoKarma Member
 
Join Date: Jul 2004
Location: Cleona, PA
Posts: 2,178
One thing to check: be sure each socket has the right tube in it! Somebody ahead of you may have just stuck tubes into sockets without regard for matching tube numbers to chassis position. Wrong tube means set doesn't work, OR fireworks!
__________________
Reece

Perfection is hard to reach with a screwdriver.
Reply With Quote
  #12  
Old 05-12-2015, 09:52 AM
Kamakiri's Avatar
Kamakiri Kamakiri is offline
Administrator
 
Join Date: Jun 2002
Location: Buffalo, New York
Posts: 5,109
Gotta say, I disagree with those that don't use a tube tester.

No, it's not an absolute, but I'll say this....I'd rather play it safe than sorry. I have a big drugstore type tester. If I see something with low or no emissions, it saves me a lot of potential diagnostic work after a recap. That, and the aforementioned short test.

I don't see how anyone can reliably use vintage sets regularly without one. It's kind of like restoring sets without owning a meter.
__________________
"Restoring a tube TV is like going to war. A color one is like a land war in Asia."
Reply With Quote
Reply


Thread Tools
Display Modes

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

Forum Jump


All times are GMT -5. The time now is 10:28 AM.



Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
©Copyright 2012 VideoKarma.org, All rights reserved.