Stocking TESTED in OPERATION used tubes-saves a LOT of time

[ronl]

i posted this on arf and figured i should post this here.

Yup-seen many times a tube tests good and did not work in operation. even new ones. back in the day, i used to stock a "tested in operation"" used tube set for troubleshooting(after they passed a tube tester.). saved me a LOt of time.
once in a while,i would retest them in a known working set on my bench and tube tester just to be sure.

its a good tip forum-everybody should do this with common tubes. horz output and damper was still a little ify if you where troubleshooting width problems though-not perfect but helped a lot.
got some great responces:

1-Mr. Detrola said-I have always done that as well. There's a box of set tested tubes on the shelf next to the workbench, with all the common radio and TV types included for the range of sets that I normally work on.

I agree about the horiz output types, it's not unusual to find one that will make a 1" or more width difference in one chassis, but won't in another set.

2-AMStationEngineer said-I don't know about you guys, however, I can't count the number of times that I've had a tube which was suspect in one set (which I changed), held on to it, had it test good (Sencore Hybrider), and sometime later - came to find that it worked well in another set. Happened quite often in Chroma and Video IF sections. There were times that I'd go further into the circuit, mostly to find that everything was within or close to spec.

Likewise, I've had more than a few (especially GE) new tubes which arrived DOA-NIB.

my responce:

Great to hear that other techs have done this Mr. Detrola. it saves so much time.

i agree with you AMStationEngineer. there has been times when i didnt have a "tested in operation" tube but would dig through my used tube stock and find a tube that worked in the set im working on but not in others. ps- i always replaced the old "tester tube" with a new one because they were meant for troubleshooting only(always ran a tube tester on ANY tube including a new replacement tube before plugging it in just in cause of a short). tubes can be a "dark science"-lol
frankly, this should be a "sticky post" because it saves so much time.
all tube techs should read this imho. Admin?

3-Johnnysan said-In TVs I always used new tubes. Tested good used tubes just won't cut it in many applications in TV, because they are driven so hard that only a new tube will work well.

my responce:

i agree with that Johnnysan-(Tested used tubes just won't cut it in many applications in TV, because they are driven so hard that only a new tube will work well.)

but it still worked a lot of the time and if you didnt have much in the way of new stock tubes, was better than nothing at the time.
nothing beats a new tested tube for troubleshooting but even that, i found was not 100%.
i even found some new powertubes(eg: horz output/vert/damper/rectifier)brands didnt work perfect but a different brand did.
waisted some time over the years assuming new parts were 100% good-tubes or otherwise.
Never count on new parts being 100% good members-the "dogs" could be because of this.
thank you for all your comments members-the more opinions we get,the more we learn.

arf link http://www.antiqueradios.com/forums/...72632#p2472632

any further info/experiance with this issue here?
RonL

[Electronic M]

When I think there is a tube related problem in a tough dog I tend to borrow tubes from working sets when possible. I don't have enough cartons for all the unboxed used pulls bought cheap at meets I have rattling around (or enough storage space) let alone a set tested diagnostic tube set so it will be a long time before I have the luxury of keeping set tested tubes for what I most work on handy.