tek 465 sweep switch - Page 1
Forum section: electronics / testgear

author: chucksue
author_rank: Newbie
timestamp: February 15, 2015, 05:47:49 pm
content: I have a tek 465 and I have the operators manual. For the life of me I do not understand how the sweep switch works for both channels. I know you pull it out to unlock it. can anyone explain this to me?

author: Howardlong
author_rank: Super Contributor
timestamp: February 15, 2015, 09:53:02 pm
content: I have a 465B here. I am not totally sure what you're asking, but I will try to explain.There are two timebases, A and B, and most of the time you'd just use the A sweep for both channels. The B sweep is also often known as the delayed sweep; it's an additional feature of the scope, not all old school CROs have it. The B sweep is typically used to zoom in to see detail on a signal that otherwise would be too fast to see on the A sweep alone. Newer DSOs can achieve the same thing, but operate in slightly different way reflecting the different technology in use.When you pull out the timebase knob, it controls the B sweep timebase. When it's pushed in it controls the A timebase. If are using the B sweep, the B sweep trigger conditions only come into play once the A trigger conditions have been satisfied.Please note that both channels trigger off the same timebase settings, there isn't any fixed correlation between channel 1/timebase A and channel 2/timebase B. However, you can trigger sweep A off either channel, and similarly sweep B can be triggered off either channel.There is a good treatise here from w2aew, it's for a 485 but it applies to the 465 too although the button layouts are slightly differenthttp://youtu.be/J-7MycqHPOsDelayed triggering with dual timebase is not the easiest concept to grasp on an old school scope, but once you've figured it out you'll wonder what all the fuss was about.

author: chucksue
author_rank: Newbie
timestamp: February 16, 2015, 08:51:35 pm
content: I watched the video and saved it so I can watch it at home and see if I can do the same on the 465.

author: tautech
author_rank: Super Contributor
timestamp: February 16, 2015, 09:07:18 pm
content: Quote from: chucksue on February 15, 2015, 05:47:49 pmHoward has given a good explanation of A & B timebases.Mostly you will use ONLY the A timebase and the setting (s/div) you apply will becommonfor both channels.Remember timebases apply to theselectedTrigger source.Experiment with the B timebase and there will be times when it will provide you with the information you need.

author: w2aew
author_rank: Super Contributor
timestamp: February 17, 2015, 12:48:47 am
content: Quote from: chucksue on February 16, 2015, 08:51:35 pmHoward already gave you a link to one of my videos on the topic of dual/delayed timebases on analog scopes. This is the way we did "pan and zoom" in the days before DSOs. There are several additional videos on my channel that use the dual timebase of the scope. Check out the one on analyzing an RF Power Detector, and another on the scope bandwidth considerations.If your scope is a 465 and not a 465B, then the delayed timebase works a little different than the 485 (in the above video), it essentially expands/magnifies the sweep to the B setting after the Delay expires - this is the "Mixed" setting on the horizontal mode switch.

author: chucksue
author_rank: Newbie
timestamp: February 17, 2015, 10:35:01 pm
content: I made alot of progress after everyons help. I also discovered that the scope never syncs the wave form. The red lamp never comes on either.I have been reading about the trigger on several sites. They talk about the tunnel diodes may be bad. I am printing out the manual that I found. It is operators /maintence /repair/calibration. I have never attempted anything this involved. I can't stand having something that doesn't work right. I will have to tape the schematics together since they will print out in several sheets.I would appreciate any guidance.

author: w2aew
author_rank: Super Contributor
timestamp: February 18, 2015, 02:27:04 am
content: Quote from: chucksue on February 17, 2015, 10:35:01 pmDo any of the trigger modes/sources work? What have you tried? I also have a video on the trigger controls on the 465B, which is virtually the same as your 465. Have you watched that one?

author: chucksue
author_rank: Newbie
timestamp: February 18, 2015, 04:56:37 pm
content: I will attempt to answer your question. When I have the switch for channel 1 with an input from my B&K at 1 K HZ I can adjust the sweep switch and it responds. The 1 K HZ never stops running and the red light for trigger never comes on. I want to do some more trials before I even think about opening the case. I hope this helps answer your question. If you need more let me know what to do.I can set the scope up and move the trigger from the top of the trace to the bottom and i9f I exceed the upper or lower peak the trace runs wild like in the video. Thanks .

author: Electro Fan
author_rank: Super Contributor
timestamp: February 18, 2015, 06:47:02 pm
content: Quote from: chucksue on February 18, 2015, 04:56:37 pmI don't have a 465 and each Tek model has it's own layout and operating style but here are some ideas from looking at a photo of the 465.If the signal is connected to CH 1 make sure the button column on the left side of the display is set to CH1 and set the source lever on the lower right side trigger area to CH 1 or Norm.You can try both AC and DC coupling for the CH1 signal input (upper left) and the trigger setting (lower right) but it should work either way. (Start by trying DC on both.)With the 1 kHz signal from your B&K signal try to make the amplitude cover most of the screen - just adjust the VOLTS/DIV knob until the signal covers at least two graticules (up and down) in the center of the screen or all but the top and bottom graticule (so the signal doesn't run off the screen top and bottom). A tall signal will make the signal easier to find with a trigger.Key steps after everything else is set right: 1) Set the TRIG MODE to Auto (you can also use Norm but stick with Auto.) 2) Use the grey A Trigger knob on the lower right side - turn it slowly back and forth smoothly - all you are trying to do is to get the trigger's vertical level (which isn't readily apparent - but it is going up and down as you turn the knob) to overlap with the signal trace - at which time the signal should trigger (remain stable on the screen) and the trigger light should illuminate.Make sure the trace intensity is turned up so the signal is bright enough to see - kind of obvious, but it happens to get dim sometimes. (Also, on older units sometimes a knob is dirty inside and a signal can be intermittent - it can happen on the TIME/DIV knob - so if you lose the signal try turning it left and right occasionally).Likewise if you can't see a signal make sure you have centered the trace with the vertical position button in the upper left hand corner.Keep the big TIM/DIV knob pushed in (so it is not in Delay Time mode). You can play with the Delay Time (pulled out setting) after you get a basic trigger to light up.As an alternative to using the B&K if you have a probe you can hook the probe to the front panel calibrator - again turn up the VOLTS/DIV knob to cover most of the screen or at least a good portion of the middle of the screen to help the trigger find the signal.If none of this works perhaps the trigger light isn't working but probably it's fine and it's just a matter of getting familiar with the settings. (Although if you can use the trigger knob to stabilize the signal you might have an issue with the light.) The Delay Time procedures will be easier after you get the basic triggering process running consistently.Let us know what you find.

author: Howardlong
author_rank: Super Contributor
timestamp: February 18, 2015, 07:25:15 pm
content: Adding to what's already been said, it sounds like it's not triggering from what you say. Sorry, from your OP I thought you were referring to the functionality of the delayed (B) sweep which is when you'd pull out the timebase knob.Bearing in mind what's been said so far, I'd steer well clear of the B sweep settings for now.A trick I am sure I picked up from one of Alan's videos (w2aew) is to set the selector switches to the upper most selections available to start with, this is like the default settings if you like.There is a good video of Alan's on basic triggering herehttp://youtu.be/OFGm-Pel4HgCan we assume that you have a trace, with some vertical component, but it is not triggering?If so, assuming that you only have Ch 1 selected and that's what your signal is on, set the following:On thebottom right quarterof the front panel...o Horiz Display: Ao Trig mode: Auto (sounds like you alrerady have this)o Coupling: ACo Holdoff: fully counter clockwiseo Source: Norm or Ch 1 (NOT to be confused with the Norm on Trig mode)o On the Level outer ring, adjust this to get a stable trigger... we hope!

author: w2aew
author_rank: Super Contributor
timestamp: February 18, 2015, 10:30:25 pm
content: If you're getting a stable trace (until you move the Trigger Level too far up/down, then you ARE triggering properly, and it could be as simple as the "Triggered" indicator is toast. I think that on the early 465 scopes, these indicators were incandescent, and weren't LEDs until the 465B (or maybe late production non-B).

author: Howardlong
author_rank: Super Contributor
timestamp: February 18, 2015, 10:59:20 pm
content: Quote from: w2aew on February 18, 2015, 10:30:25 pmI bow to the master!Howard (G6LVB)

author: chucksue
author_rank: Newbie
timestamp: February 19, 2015, 07:19:37 pm
content: This is what I have done -----CHANNEL 1 .5 V/DIV.AC COUPLINGSWEEP SWITCH – 10 MICRO SEC.B& K GENERATOR SET AT 50K HZ / 1 VOLT ACHORIZONTAL DISPLAY - A LOCKS KNOBSA TRIGGER – COUPLING ACSOURCE – NORMALTRIGGER HOLD OFF – FULL CCWThe trigger light does not come on.When I turn the level control I get + rise and – rise.Level control moves the trigger point from peak to peak.A trigger coupling in Lf REJ /Hf REJ./DC //all sync and can move sync point.In sync sep I can sync the wave.When I change the trigger mode to normal POSITION all couplings Lf REJ/Hf REJ.AND DC sync.Channel 2 responds the same way as channel 1.THRU ALL OF THIS THE RED TRIGGER LAMP DOES NOT COME ON.CAN I ASSUME THE LAMP IS BURNED OUT?I think most of my problems are operator error mixed with not understanding the scopes full potential.The next thing I noticed was the wave kind of flickers at low HZ but that may be common at low HZ.I sure appreciate the help. I have a degree in Electronic Engineering but that was way back when Noah landed the ARK on Mount Ararat.I BELIVE THE TRIGGER LMP IS SHOT AND THE SCOPE TRIGGERS.MAYBE I WILL GET BRAVE AND TRY TO REPLACE THE LAMP.

author: tautech
author_rank: Super Contributor
timestamp: February 19, 2015, 07:26:40 pm
content: Quote from: chucksue on February 19, 2015, 07:19:37 pmI would.QuoteEntirely up to you.You may find you can live without it....make a note and paste it next to the lamp.ORStudy the trigger lamp circuit,it and convert it to LED.

author: Paul Moir
author_rank: Frequent Contributor
timestamp: February 19, 2015, 07:42:28 pm
content: The OP has referred to the indicator being red, so it may be a LED already. I think all the earlier 465s with lamps had untinted lenses. So it may be a 465B, a late one like w2aew said or possibly someone may have converted it already?chucksue: Does it say 465 on it and not 465B? Are the other lights (uncal, x10, etc) coloured or white/orangeish?

author: chucksue
author_rank: Newbie
timestamp: February 19, 2015, 08:30:10 pm
content: All the other lamps are white and they all work.I need to look at the mechanical drawings and see how involved it is to open the scope to check the lamp.

author: chucksue
author_rank: Newbie
timestamp: February 19, 2015, 08:31:52 pm
content: The scope is labeled 465 on the front.

author: Paul Moir
author_rank: Frequent Contributor
timestamp: February 20, 2015, 12:10:53 am
content: So the trigger light is different from all the rest? If so that would indicate(...) that it's been modified by someone for some reason. Originally it was white like the other white ones. (The uncal ones and 10x use neons rather than bulbs so they're a little orangish)