Tek 465 CRT Testing - Page 1
Forum section: electronics / beginners

author: Anthony Brady
author_rank: Newbie
timestamp: March 22, 2016, 11:06:40 pm
content: I was wondering if there are any testers for checking an oscilloscope CRT the way regular tubes are checked? There are CRT testers/rejuvenators out there from the old CRT TV days such as the Sencore CR70, CR143 and CR7000 testers. B&K has their 465, 466, 467, 490A and 490B CRT testers. But, are any of them capable of testing/rejuvenating a Tek 465 oscilloscope CRT?

author: danadak
author_rank: Super Contributor
timestamp: March 22, 2016, 11:17:38 pm
content: There are a couple of Yahoo Tektronix groups you might consider. There areexperienced senior Tek engineers, many retired, that support those sites.Regards, Dana.

author: tggzzz
author_rank: Super Contributor
timestamp: March 23, 2016, 12:03:05 am
content: Testing and rejuvenating are two very different things. You can always test a tube by putting it in a functional 465.Myvery limitedunderstanding is that rejuvenation sometimes works, but only for a short time.

author: rastro
author_rank: Frequent Contributor
timestamp: March 24, 2016, 01:49:56 am
content: Anthony,I used a Sencore CR70 to rejuvenate the CRT on a Tektronix 2755AP spectrum analyzer with a low brightness. It did a good job recovering the dim tube. Don't recall all the settings but I do know it boosted the cathode voltage and Grid briefly. I think I tried checking the grid current but did not get any usable results so I just proceeded with the rejuvenation. Most CRT's used in test equipment are not well documented on the Sencore and BK CRT testers. Most importantly you want to find out what the CRT's cathode voltage runs at on the system as a basis for the setting. You will need to use what is called a universal adapter - basically hook clips on the pins of the CRT. The 2 labeled "F" are filaments and the "G1" is typically the Grid. You can hook the rest up but these three are the key connectors.I did come across a write up with some information that may be of some interest.http://www.thegleam.com/ke5fx/crt.htmlFortunately in your case there are there were plenty of 465's manufactured for potential spares - It's harder to source Tek's SA CRT's.-rastro

author: jh15
author_rank: Frequent Contributor
timestamp: March 24, 2016, 06:09:18 pm
content: My Sencore cr70 has a separate switch setting for 'scope tubes. I have a 465 no suffix scope with either a circuit issue or crt is not wicked bright. Its been usable, but I always wanted to go through it eventually.I'll have to look into at least trying to test the CRT. I'm not sure if 'scope tubes are listed in my setup book, what is the CRT number?

author: tggzzz
author_rank: Super Contributor
timestamp: March 24, 2016, 06:42:50 pm
content: Quote from: jh15 on March 24, 2016, 06:09:18 pmBefore potentially damaging your CRT, I suggest you see if there are any problems in the HV or DC restorer circuits - the diodes and capacitors are a frequent failure point.N.B. a month ago I have never been near a CRT, but I had brightness problems with a 465. In my case the tube was internally terminally faulty; the grid was disconnected.I strongly suggest you have a look at the Yahoo! TekScopes group. Their archive is searchable, and the denizens wereveryhelpful and welcoming to me.

author: woodchips
author_rank: Frequent Contributor
timestamp: March 25, 2016, 07:27:58 pm
content: If you do need a new CRT then don't just look for 465 ones, possibly any side plate 10x8 CRT will work. The 2445 series are probably too short unless you get the screen, but there are lots of TV video CRTs now available but most aren't side plate.Even HP, Philips etc CRTs will possibly work.

author: rastro
author_rank: Frequent Contributor
timestamp: March 25, 2016, 08:06:14 pm
content: I agree with tggzzz eliminate all possible problem sources before touching the CRT.Rejuvenation should be at the bottom of the list since there is always the possibility of damaging or shortening the life of the CRT.-rastro

author: tggzzz
author_rank: Super Contributor
timestamp: March 25, 2016, 08:11:03 pm
content: Quote from: woodchips on March 25, 2016, 07:27:58 pmhttp://www.reprise.com/host/tektronix/reference/crt.aspcontains CRT to Instrument Cross Reference Database, plus other useful information.

author: tggzzz
author_rank: Super Contributor
timestamp: March 31, 2016, 01:38:07 pm
content: In my case the 465 tube was terminally damaged: the grid was internally disconnected. Rather than throw it out, I decided to chop it up and put the pretty bits in my display cabinet.The results, including pictures of the hidden metal mesh lens, can be seen athttps://entertaininghacks.wordpress.com/2016/03/09/rescuing-a-broken-tektronix-465-crt/Those interested in the Burr Brown equivalent of the Pirelli calendar can look at pretty scans of thick-film hybrids athttps://entertaininghacks.wordpress.com/2015/07/07/images-of-late-70s-burr-brown-thick-film-hybrid-ics/(Yes,otherpeople have described them as "geek porn")