Tektronix 2465B repair advice

[705jas]

HI All

Just 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

[Ice-Tea]

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.

[David Hess]

That screen display is caused by a problem with the z-axis blanking.

[SoundTech-LG]

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.

[SoundTech-LG]

It doesn't appear to be much more in the Z-axis ckt. than U950.

[SoundTech-LG]

https://www.ebay.com/itm/273535129705

[SoundTech-LG]

It could be just another symptom of this issue...

https://www.eevblog.com/forum/repair/tektronix-2467b-flicker/msg2679009/#msg2679009

[SoundTech-LG]

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 quiet
honor to talk to him.....

I did ask him about about a problem o had, the screen was acting
erratically and sometimes go away, I swapped all the modules, checked every
part, but I couldn’t find it, he right a way told me check a coil with 4
feet near by the Zaxis vertical maybe, he said one of the foot has cold
solder, I was shocked he was right !! I resolder it and worked fine, and I
did ask hi about the U800 problems too, it is a customs complex IC they go
bad over time because of excessive heat, he said when......"
https://groups.io/g/TekScopes/topic/64372210

[med6753]

Set aside a few hours and read through this thread.......

https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/

[705jas]

Hi All

Thanks 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

[siggi]

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.

Set aside a few hours and read through this thread.......

https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/

[Mark Krass]

Hello 705jas,

Did you manage to nail down this problem after all? It looks like I've got the same issue.

HI All

Just 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