Tektronix 2465B repair advice - Page 1
Forum section: electronics / testgear

author: 705jas
author_rank: Contributor
timestamp: May 28, 2021, 06:25:54 am
content: HI AllJust picked up a 2465B and it powers up and seems to do what it should eg. Auto works on a signal, all 4 channels are there and measuring works etc but the main issue I have is the strange screen display (see video(https://youtu.be/SbDoiq8P4Bs) and pics). All voltages have tested ok. Initially, I had no display but a slight tweak of the Grid Bias and the display was there. Still has all original caps etc. Should I recap it as a matter of course and then start the troubleshooting again? Suggestions on where to get a cap "kit" from? Sorry for the newbie questions but just starting my journey with this beautiful old scope. I would love to get it fully working. Any advice appreciated.cheers....705JAS

author: Ice-Tea
author_rank: Super Contributor
timestamp: May 28, 2021, 06:36:16 am
content: You can start a six year flame war with the question "should I recap", so i'll gracefully stay out of it except for this: at least the power supply has a number of RIFA timebombs onboard. Excavate those at your earliest convenience.

author: David Hess
author_rank: Super Contributor
timestamp: May 28, 2021, 11:59:44 am
content: That screen display is caused by a problem with the z-axis blanking.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: May 28, 2021, 01:58:19 pm
content: I can see the intensity control is max CCW, so no control over intensity. I have a 2467B that does this on an intermittent basis, usually when warmed up good. All I can do is power off/start up again. I am afraid to walk away from the scope for fear of burning the screen.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: May 28, 2021, 03:19:22 pm
content: It doesn't appear to be much more in the Z-axis ckt. than U950.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: May 28, 2021, 03:36:02 pm
content: https://www.ebay.com/itm/273535129705

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: May 28, 2021, 03:53:57 pm
content: It could be just another symptom of this issue...https://www.eevblog.com/forum/repair/tektronix-2467b-flicker/msg2679009/#msg2679009

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: May 28, 2021, 04:33:47 pm
content: more... but have yet to see what U950 problems develop, and any list of symptoms.https://groups.io/g/TekScopes/topic/64372210"Once I had a talk with the engineer who developed the 2465, it was a quiethonor to talk to him.....I did ask him about about a problem o had, the screen was actingerratically and sometimes go away, I swapped all the modules, checked everypart, but I couldn’t find it, he right a way told me check a coil with 4feet near by the Zaxis vertical maybe, he said one of the foot has coldsolder, I was shocked he was right !! I resolder it and worked fine, and Idid ask hi about the U800 problems too, it is a customs complex IC they gobad over time because of excessive heat, he said when......"https://groups.io/g/TekScopes/topic/64372210

author: med6753
author_rank: Super Contributor
timestamp: May 28, 2021, 05:14:19 pm
content: Set aside a few hours and read through this thread.......https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/

author: 705jas
author_rank: Contributor
timestamp: May 30, 2021, 11:23:21 am
content: Hi AllThanks for the advice so far. The only way to get a display at all was to tweak the Grid Bias initially. I have checked all voltages and they are ok. Ripple is a bit all over the shop (I think). I tried to do the Cal 08 procedure but when trying to turn the Grid Bias down to get the dot on the screen to match the others, unfortunately, everything on the screen dims at the same time so I cant move past that part of the procedure. I have also tried replacing the U950 with a working one from a 2465 that I have here as well but it made no difference at all.The pic attached is what I have on screen. Note the rows of horizontal dots top and bottom and the whole display flickers ever so slightly. Ideas?cheers..Allan

author: siggi
author_rank: Regular Contributor
timestamp: May 30, 2021, 04:59:53 pm
content: Your display problem is most likely due to problems on the A5 board. The 2465X scopes are all drive-by-wire, and the versions that have SMD capacitors on the A5 board are infamous for the caps leaking, which wipes out the reference for the DAC. This in turn takes out the intensity controls and creates a whole host of other problems.Read through the thread as suggested here, and you'll find plenty of A5 trouble.Quote from: med6753 on May 28, 2021, 05:14:19 pm

author: Mark Krass
author_rank: Contributor
timestamp: December 25, 2022, 01:42:04 pm
content: Hello 705jas,Did you manage to nail down this problem after all? It looks like I've got the same issue.Quote from: 705jas on May 28, 2021, 06:25:54 am