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I just purchased a used Tektronix 465B Oscilloscope and I am having some difficulty with the VOLTS/DIV knobs. Both channels have markings from 5mV up to 50V.

All of the settings work except for the 10, 20 and 50 volt settings. The knob will not physically turn to these settings. Its almost like its locked out or something. Has anyone had experience with this? I feel like I should be able to measure 120V on this hunk of machinery, however I am limited to a max of 20V. :(

Its also worth mentioning there is a x10 mag button located on the front. I don't think its what I am looking for. I have been able to locate a tech manual, but have been unsuccessful with an operational manual. Any experience with this would be greatly appreciated!

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    \$\begingroup\$ Unless you are trolling you should read the answers given and understand them instead of indicating that you intend to trash a very nice piece of equipment through gross stupidity.| You MAY mean you were going to use a 10:1 probe, but you didn't say so.| What Oli said is that the'scope does NOT have 10 20 50 Volt per division settings. He indicated that for convenience the scope has MARKINGS that show 10 20 & 50 V/div BUT these are for use with a 10:1 probe - so the scope sees 1 2 & 5 V/division respectively. | | At max setting the screen allows 40V p-p . Survival at 120VAC is a gamble. \$\endgroup\$ – Russell McMahon Dec 29 '11 at 2:18
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    \$\begingroup\$ The 465B is a nice scope - treat it with due reverence and it should serve you well. I have managed to place a screwdriver solidly between phase and a grounded chassis (long ago) - so doing damaging things through a lack of understanding is well understood ! :-) - but $ wise it's better to try this with a screwdriver than a 4565B input ;-). [FWIW the tip welded to the terminal with phase on and the arc from driver shaft to chassis eroded chassis and shaft until the arc went out. A regrind fixed the tip and a crater in the side of the shaft remindedme to think more carefully in future :-). \$\endgroup\$ – Russell McMahon Dec 29 '11 at 7:31
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I imagine the 10, 20 and 50V markings are for when the probe is set to 10x. The dial should have two bands to correspond to 1x and 10x settings.

I have an old tek scope which does this - the highest you can turn to for 1x is 5V/div.

I just googled for a picture of the 465b and it looks like this is the case - notice there are two bands on each knob. On the bottom knob you can see one is at 1V/div and one is at 10V/div, which would correspond with 1x or 10x setting:

Tek 465b

EDIT - I have added arrows pointing to the bands to clarify things.

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  • \$\begingroup\$ That's what I thought. I guess I will hook it up to 120 and see what happens! It just seems odd that they would make a knob with those values when its not possible to select them. \$\endgroup\$ – atomSmasher Dec 29 '11 at 2:04
  • \$\begingroup\$ I guess what I didn't understand is that I need a probe attachment. Which I did not know existed. I am guessing if you attach the probe it will turn on the second LED band that you are referring to. I apologize for my ignorance. But unless I missed something, that's why this site is here. Thanks for your help. \$\endgroup\$ – atomSmasher Dec 29 '11 at 2:41
  • \$\begingroup\$ @atomSmasher - not sure what you mean by "LED band". I have added some arrows on the picture pointing to the bands I am talking about. Also, not quite sure what you mean by "probe attachment" - most "standard" probes usually come with a switch set into them that sets it to x1/x10 (the x10 puts a 9 Megaohm resistor in series with the 1 Megaohm scope input impedance). There are many varieties though, I suggest a bit of googling and reading about probes/scope inputs. \$\endgroup\$ – Oli Glaser Dec 29 '11 at 5:46
  • \$\begingroup\$ To clarify these "bands" are little lights that shine through the plastic scale around the knobs (not LED but small bulbs). x10 probes from Tektronix have a special pin on the BNC connector. When you plug them in, the light for x10 scale lights up. When using x1 probes (or third party probes without the pin) the light for the x1 scale lights up instead. \$\endgroup\$ – Alex Jasmin Dec 23 '12 at 7:19
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Summary:

  • The Tektronix 465B oscilloscope has a MAXIMUM rated input voltage of 5V/division at the input terminals. That's 40V peak-peak max.

    You can legitimately observe a screenful of signal when the displayed region is "sitting on top of" quite a lot larger pedestal - see below. In fact, US 110 VAC mains IS inside the overall spec - but far to close to the when-brand-spanking-new limit to be safe.

    110 VAC is about 300 V peak to peak - over 7 times what you can usefully display.

    • I lie, of course: if you put zero at the bottom of the screen you can display the positive half of a 80V p-p signal, and you can display a smaller variation on a large "pedestal", but you get the idea.

    ie 110 VAC on a 1:1 probe into a Tek 4656b is a REALLY REALLY bad idea. The display will be well over scale (+/- 20V max, you would be putting in about +/- 160 V.

    Tek have designed it to survive this , but that was when it was new.
    Capacitors get old,
    dust build up,
    moisture happens,
    ants crawl, and die materials get tired with heat and time.

    IF mains does get through the front end and you are holding the probe or adjusting the scope then you may never get to see the magic smoke, or anything else thereafer.

    Yesterday's 500 V_peak-to-peak limit is Murphy's playground.
    Don't make his day.


The Tektronix 465B oscilloscope has a MAXIMUM rated input voltage of 5V/division at the input terminals.

The 10/20/50 Volt per division settings are for use ONLY with a 10:1 probe and signify the sensitivity as seen at the probe tip with a 10:1 divider so that the oscilloscope sees voltages 10% of what is at the tip.

Whereas oscilloscopes made by and for mere mortals usually require the user to work out this 10% or 1000% scaling (depending on which way you are looking) for themselves, the superheros at Tektronix added a nice touch which allows the scope scale to adjust by a factor of 10 when a 10:1 probe is adjusted.

The scope still sees a maximum of 5 Volts per division.

HOWEVER (bugles and horses hooves, stage off, right ...)

The guys & gals at Tektronix are real engineers and saw Y'All coming - so they have rated the input divider at 500VAC peak peak as noted here at up to 1 kHz. This means that US Americans CAN connect a 1x the probe directly across US 110VAC mains and reasonably expect it to survive. Note that reasonableness and certainty are variably correlated in the real world. Whether it will do so 30 or so years on is TBD.

This also means that an Antipodean Kiwi or Australian, or most Europeans, people in Taiwan & mainland China and anywhere else with 230 VAC (or 220 or 240) can reasonably expect to get magic smoke if they connect via a 1X probe directly across mains AC.

Knowing Tektronix it's possibloe that even antipodeans may get away with doing this (230 VAC = 650 V peak-peak) but Murphy says that 30 years or so on I should not connect my 465B across the mains to see what happens.

Note that peak-peak includes any spikes and local trash that may have come along for the ride.

Doing it with 110VAC is also not very smart, spec notwithstanding.


50+ page oscilloscope tutorial from Tektronix - The ABCs of oscilloscopes - useful.

5 page 'scope tutorial - OK.

Some more 465B specs


Printout use:

ABCs: http://testmart.com/webdata/appnote/1603.PDF
5 pages: http://www.aoc.nrao.edu/~pharden/hobby/Scope1.pdf
500 Vpp: http://www.testequipmentdepot.com/usedequipment/tektronix/oscilloscopes/tek465bspecs.htm Specs: http://testmart.com/sp.cfm/ANAOSC/TEK/465B.html

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  • \$\begingroup\$ Thanks for your detailed comments and link! I am new to the field so I am still learning all aspects of the field. Even a scope. I haven't had the chance to use fully until now. I have only used a scope and signal generator once in my school career! I am hoping to get a head start now before the next round of classes take off this spring. I can understand your frustration. Just please remember some of us have to learn. I am sure this will not be my last question. I like stack and I find it extremely helpful. Some of us are still babies! Thanks again for your help. \$\endgroup\$ – atomSmasher Dec 29 '11 at 7:53
  • \$\begingroup\$ @russellMcMahon, your edit did not go in the answer, it was related to running the site, please take it to meta to discuss or take it to chat to talk to the person directly. \$\endgroup\$ – Kortuk Dec 29 '11 at 9:59
  • \$\begingroup\$ @atomSmasher - No problem. I'd only be frustrated if you blew up a fine instrument and, just possibly, killed yourself as well (no knowing where the mains goes next when you zap the front end and are holding a scope probe ! :-). Helping people learn and helping them stay alive are high on my list of "passions" as a browse of this site (or others) may indicate. Some here seem keener on being seen to be "polite" than keeping people alive and my warnings had a few of their attention grabbing teeth pulled. No hard dome this time round as you now seem to be aware of what's needed. Just in case ... \$\endgroup\$ – Russell McMahon Dec 29 '11 at 10:18
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    \$\begingroup\$ @RussellMcMahon - I'm sorry to have vandalized your post; I didn't think it lost much with the removal of a couple words. It received an "offensive" flag from the community. It wasn't offensive to me, but I could see how someone could be offended by the targetting of certain nations, so I removed the word "stupid" from it in two places. Sorry to have bothered you. \$\endgroup\$ – Kevin Vermeer Dec 29 '11 at 14:07
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    \$\begingroup\$ @KevinVermeer - Thanks :-). It's a shame "the community" doesn't actually read what's said. That was a 230VAC targeting - NOT a racial one.||Viz: This means that US Americans who are stupid enough to do so CAN connect a 1x probe across US 110VAC mains and... survive. ... This also means that a stupid Antipodean Kiwi [ie from NZ as I am] or Australian, or [ALL 230VAC !!!!!!] most Europeans..Taiwan..mainland China.. anywhere with 230 VAC .. magic smoke with a 1X probe directly across mains AC. Would it be stupid to connect 230 VAC to your Tek directly. Oh yes! May we say so? Apparently not. \$\endgroup\$ – Russell McMahon Dec 29 '11 at 14:22
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I have been able to locate a tech manual, but have been unsuccessful with an operational manual.

The best resource I have found for older Tekrronix scopes is this forum: TekScopes ยท All about classic Tektronix CRT o'scopes . They have extensive information on the 465B including links to download a users manual. I have a 466 which is extremely similar (the 466 has a storage scope that the 465 doesn't); it is an extremely well made piece of test equipment and if not abused should give you years of excellent service.

I highly recommend you get some proper probes and calibrate them as well as taking the time to learn how to properly use an oscilloscope.

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  • \$\begingroup\$ Sounds good! Thanks for your input. I always take good care of my things... I drove two hours to get it, it's my new baby! It's as heavy as a tank. I imagine we will become very close through-out school. Thanks again. \$\endgroup\$ – atomSmasher Dec 29 '11 at 7:49
  • \$\begingroup\$ The link is not loading. Do you have an update? \$\endgroup\$ – D. A. Oct 10 '14 at 2:00
  • \$\begingroup\$ Try this link: groups.yahoo.com/neo/groups/TekScopes/info \$\endgroup\$ – JonnyBoats Oct 11 '14 at 3:52

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