New guy 465b questions

[jmacqueen]

Old guy here that trained as a tech years ago, just getting back into electronics. I need to build a bench up on a budget. been reading this site for a while and decided to sign up.

I picked up an old Tek 465b the other day, along with an old  Sony/Tektronix 308 data analyzer/w probes and a little old heath sg1271 signal generator as a package for $200 bucks. Got it locally so I was able to briefly test the scope with the generator. Not a steal but not a bad price I think

Since then the generator that was working great has quit working after about an hour of use, power but zero signal out, should be easy to fix though as I have the manual.

The 465b works ok, it's pretty clean, no dents, all knobs and buttons intact, everything is functional, but spent some time in a garage, rotary switches and pots seem a bit oxidized but much better after a few rotations. Came with two sets of probes in the ziploc bags, and couple of other connectors.

Two issues I need to fix though that I would appreciate an opinion on from vastly more experienced folks here before I even open it up. First all the small push buttons stick pretty badly. They seem to switch electrically fine, it seems the springs just can't physically push the buttons back out. What should be cleaned and/or lubed and with what?

I know the service manual states to use IPA for the rotary switches contacts etc, easy enough, I don't know if I actually even need to clean them but the channel 1 vertical control seems loose, it can move up and down vertically when wiggled, with a corresponding reaction on the scope of intermittent connection. Anything specific to look for for that?

Then there's the probes not making contact good enough for good readings, and lighting up the proper 1x or 10x lights on the vertical, it uses the probes with that little pin to know what probes are in it and I have to wiggle em and hold my tongue just right to get a good connection it seems. What the best way to clean the BNC jacks and probe plugs for a good solid connection?

[PA7RG]

Look at the TekScopes yahoo group! http://tech.groups.yahoo.com/group/TekScopes/ and register!
In the file section info which deals with washing. And a lot of Tek scope wizards!

Robert

[PaulAm]

Are you referring to the Ch 1 vert position control?  That's right on the corner and those knobs (and shafts) have a tendency to get hit and bent.  The actual pot is about 6 inches behind the panel with an insulated shaft though, so it's pretty safe.  You might have a loose bushing in the front panel, the coupler might be loose or the pot might be dirty (or all 3).  You can take the cover off by removing the 4 feet and two center screws on the rear plastic trim.  Slide the case off the back and inspect.

Some of those push buttons are hard to get to unless you start pulling boards, but you can probably get a needle or long spout oiler in there with IPA.  A couple drops should loosen up the switches.  You don't want to spray contact cleaner around there.

Try using Deoxit or a tarnish remover on the BNCs.

Ditto on joining tekscopes.

[jmacqueen]

Thanks, I have seen that group or rather group of groups. I'm not a big fan of yahoo groups but I may join anyway.

I was afraid it might be tough to get to all those little buttons to free em up. I was kinda hoping maybe it would be a bit easier. They work just fine, I just have to pull them back out manually sometimes. I do have some 91% ipa and a few syringes though, I'll give that a shot.

Yeah it's the channel 1 vert that feels a bit wobbly, if the switch is a few inches back with a bushing up front then it would likely be the bushing I suspect, probably just wear then. The unit appears to have been treated ok, no signs of bent shafts or anything.

The guy I got it from stored it in his garage for a few years I guess wrapped up in a plastic bag.

I like the scope though, much more like what I trained with back in the late 70's than the digital models out today. I really need to brush up on things with an older analog anyway where I have to think a bit about the things modern scopes do for us automatically these days.

I'll likely open it up as soon as I have the signal generator troubleshot. I'll probably get on that tonight. Anyway thanks for the tips.

Still need to find a manual on the Tektronix 308 data analyzer, google is not being my friend on that.

edit: Found a good copy of the 308 manual from the tek forums.. Time to crack open that signal generator and see what happened to my output..

[Anson]

If the buttons on the 465b are anything like the 466 then you should have no problem getting them working. The 466 I have needed the invert switch rebuilt. Simple task other than the fact I de-soldered it from the board first figured out after I could have done it still installed. The grease inside became hard and fouled the contacts. The 400 series scopes are very serviceable. So they should be around forever. Just don't get transistor shock when you open it. There is a lot of transistors and other circuitry in there.

[jmacqueen]

If the buttons on the 465b are anything like the 466 then you should have no problem getting them working. The 466 I have needed the invert switch rebuilt. Simple task other than the fact I de-soldered it from the board first figured out after I could have done it still installed. The grease inside became hard and fouled the contacts. The 400 series scopes are very serviceable. So they should be around forever. Just don't get transistor shock when you open it. There is a lot of transistors and other circuitry in there.

I'm having a hard time with that invert switch myself. I opened up the scope today and cleaned up contacts with some IPA, got most of the switches working fine.

My issue with channel 1 vertical flakiness turned out to be very simple.. A spider had gotten in there and built it's little cocoon nest right across the switch gang at some point. Cleaned that up and no more flakiness from channel 1. 

I also cleaned up the BNC jacks with just IPA and a paper towel wrapped around a screwdriver tip, didn't want to get any more abrasive than that in scrubbing them, shot some ipa into the plug and jack and worked em on and off and spun em around and get smooth contact now.

Then channel 2 just quit working after I put it back together and was checking it out,  it just gave me a straight line DC ground signal, had me in fits for a bit and just about to take the cover back off when I discovered it was the invert switch not making contact and I could get it to work intermittently. Seems all my push button switches are suffering from old dried up lube, but that one is going non operational. I may try a couple of drops of light lube in it and see if it will soften the old lube back up.

Overall it looked real good inside, no visible oxidation on component legs and such, I'm happy. According to the little digital signal gen I have it's pretty well n cal as well, it was last calibrated in 1991, built in '81 I believe it said inside.

I believe the signal generator has a bad 15v regulator, measures 3.9ohms to ground on the input when not running and only giving out 3-4 volts, gets quite hot, and there is no short on the circuit it is feeding. Ordered one today so we'll see.

[jmacqueen]

Well I think I got the scope running about as good as I can, cleaned the contacts on the vertical switches with alcohol and a piece of paper between the contacts, no more twitchiness or obvious contact issues when switching the vert switches now.

I put a couple drops of deoxit gold which is mostly a switch/pot lube in each of the push button switches, seemed to loosen up the old lube nicely and they work great now, feel like new and seem to make excellent contact.

One problem I'm going to have to live with is the teflon or ptfe or whatever that insulates the 10x detector ring from the bnc ground shielding in the channel 2 input jack  is faulty and the bnc innards move around in it. I originally thought the jack was loose, but it isn't. That is giving me intermittent issues and I have to tap the probe a little on channel 2 sometimes. I don't think I want to mess with trying to replace that jack unless the issue gets worse. I cleaned the jacks outside with deoxit d5, as well as the probe bnc plugs and made a huge difference.

The heath signal generator is working fine now too, the new 15v regulator IC did the trick.

I haven't played with the tek data analyzer yet, but I think I'm happy with the three for $200.

[Anson]

The BNC you need is part# 131-0679-02 There seem to be a number of places that claim to have them but only one I have found gives a price. For $15 plus shipping this place has them. http://4gte.com/tektronix-131-0679-02-bnc-connector-isolated-bulkhead-mount.html It shouldn't be to hard a task to change.

[jmacqueen]

Thanks for the link, I think I'll pick one up and just hold on to it for later though.

I discovered yesterday evening the problem wasn't the jack at all. I opened it up to take another look, and really didn't see how it being loose would affect it, the connections are all separately soldered to the jack layers. I also noticed when I was looking at it opened up with the RF shield off I couldn't get it to act up..

Then I put the shield back over the attenuator and it went all flaky, took it off, it was rock steady... So I took a qtip with some deoxit on it and went over the contact fingers and points on the shield where it contacts the other half of the shield and around where the screws mate, put it back on as far forward as the screw holes would allow, and the thing is rock steady and working perfect now even with a wiggly jack. Go figure...

Anyway it's working great all around now, to the point I can rely on it for measuring now.. which I couldn't before, and the buttons all work like new now. It was too frustrating to even use when things were flaky and jumping around, and I couldn't tell what buttons were even activated, or whether I was at x1 or x10 with the probe detect all flaky. I'm pretty stoked at how well it's doing now.

I think I'll grab that jack anyway though, just a matter of time till I have to change it.

Time to move on to fixing a couple of stereo receivers, my sisters dead PC, an old pioneer reel to reel, and an old tube Heathkit RF generator that doesn't appear to be modulating that are waiting to be dug into.