Tektronix 465B Oscilloscope - workable?

[squigley]

There's a Tektronix 465B Oscilloscope for auction on a govt surplus site. I'm wondering if it's worth bidding on (starting at $50!) and cleaning it up.

I don't have a scope already, this would be my first/only. The reason I am asking for advice is the pictures show a large bright spot in the middle of the screen, ie not sweeping, which looks weird to me. Is this normal/settings, or something wrong? if so, is it repairable, and/or would the CRT have burn in as a result?

It also has a busted knob, wondering how easy they are to source/replace. Please see the photo..

(Edit: I just found a 2465 listed as well, which looks in better shape, I'm thinking that's a better bet?)

[Old Printer]

The 465B is a great old scope but even if it works will likely have on going maintence issues to keep it running, which usually requires another working scope. The 2465 is much newer and more feature filled, but also more complicated and has some difficult/impossible parts to go bad. Power supply capacitors on all these vintage scopes will be a concern. Question B is can you pick it up as they are heave to ship. I would want to buy locally from a known seller and be sure I got a working scope to start with. What are your scope needs?

[0culus]

On the bright side (heh), there are lots of resources for old Tek scope repair, both here and at the TekScopes list on groups.io.

[rhodges]

I was thinking the knob might be on XY, but nope...

For what it's worth, I have a 465 and 2465. I really like the 2465 because the voltage and timebase is on the screen. On the 465, it is hard for me to read through the clear plastic. The measurement cursors are nice, too.

[Stray Electron]

   Used Tektronix parts are widely available on Ebay.  As long as you don't mind paying $20 per knob!  The 465 is a great old scope, I loved using those back in the day (starting 50 years ago!).  However they seem to have a very serious problem with aging. The last one that I owned started acting up about 20 years ago and one circuit after another failed, over and over again. At about the same time I found a stash of about 25 of them and I went and checked every one and that had all failed in one way or the other.  All of these were good when they were put into storage but as I said They don't age well. Also everything is tightly packed in them and they use a zillion small capacitors so I finally gave up on them and I wouldn't recommend one today.

[med6753]

That delayed trigger switch assembly always gets bent/battered but with careful manipulation can usually be straighten out. The lack of sweep could be any number of things, hard to tell from your picture.

That said the older 400 series scopes are approaching 45 -50 years old. While great scopes they can turn into maintenance whores. I have two functional 465B's and a functional 475A plus a nonfunctional 465 and 465B parts mule. One of the biggest issues with them is the multiple beaded tantalum capacitors used plus issues with the attenuator switch decks. Once those issues are resolved they settle down with just minor and occasional issues. But getting there can take a lot of work. For a newb I don't recommend them.

The 2465's are a better choice but they have their own set of unique issues too. The 2465 (no suffix) is much more reliable than the later 2465A and 2465B. I have two 2465's here. You have to be proactive to recap the PSU and the cooling fan gets noisy and is difficult to service. But other than that they work well.   

[squigley]

I bid on the 2465 instead. It would be local pickup, no shipping cost, since I figured these would be heavy.

I figured I would be dismantling/cleaning/replacing capacitors/reassembling to get it into use.

I don't really know how to quantify what my needs are; I tinker with circuits trying to repair things, usually switch mode power supplies/LCD screens etc, which is not the easiest using a meter alone, and would be nice to see the outputs of PWM chips/input to FETs/transistors etc.

My mate also recently bought an RCA Victor 9K-1 radio which I would like to have a go at restoring, and to test the tubes and align the IF amplifier etc (though I think I also need a signal generator and a spectrum analyser for that).

[med6753]

If you do manage to win the bid on the 2465 you will find complete guide for PSU capacitor replacement here:

https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg1658102/#msg1658102

The same thread also has fan motor repair.

[Old Printer]

That is a great point about old TEK scopes, the service manuals are great and readily available and parts mules are plentiful and usually pretty cheap, until it is time to ship one. I just paid UPS $40 to ship a 13 lb package by ground from Florida to New York

[Dacke]

Speaking as somewhat of a newbie to electronics that just completely rebuilt a 475A and I finally got everything working after about two months of work,  I'd say avoid the 4** series altogether.   I wanted a repair challenge to hone my skills a bit so I got the 475A for $50 as non-working.   Now I'm not a masochist or anything,  but getting that scope fully functional was like playing some twisted version of whack-a-mole.  I would fix something and some other shit would break,  every time.  Eventually one rogue tantalum even decided to blow up in my face.   Now that it works,  I don't even use it (I have a better scope).  Get the 2465.

And actually,  if someone wants to do a local pickup in south Florida on the 475A,  I'll sell it for the $50 I paid.  It's fully functional,  I just don't have room for it and I'd rather give it to someone who needs it.

[med6753]

Similar experience with a 465 which became a parts mule because every time I fixed one thing something else would break. 3rd time on the power supply sealed it's fate.