Asking about Tektronix 2465B, any experienced Tek tech or lovers jump in please - Page 1
Forum section: electronics / beginners

author: BravoV
author_rank: Super Contributor
timestamp: October 20, 2011, 05:08:02 pm
content: This is my first Tek scope, so please be patient and bear with this Tek newbie, hopefully any experienced technician or Tek lovers could share some experience and knowledge.Just got it recently this beast at a local tech surplus store, its made by Tektronix Guernsey, not at Beaverton like other popular 24xx series. This is what I got when powered up at the diagnostic screen, you can't see the bottom readout text since its sinking down there.Another view.Zoomed, looks like it says "ALL 00 PASS <0066>", but again, I'm not sure since can only identified half of them.When measuring.Zoomed, same here too.Few knobs are not fully pushed and having gap pointed by red arrows, while few others have no gap like those pointed by blue arrows, looks better right ?Same here at the front knobs at the bottom of the screen.Now, questions :Are scopes made at Tektronix Guernsey like this one, have the same quality built or reputation as those made at Beaverton ?What is that diagnostic message translate to ? Already read the user operation and service manual, still can't find it.The power on message is "DIAGNSTIC. PUSH A/B TRIG TO EXIT", is this normal ? Whats yours ? It should be "DIAGNOSTIC" right ? Instead of "DIAGNSTIC"The sinking bottom read out text, is it normal with that yellow color ?How to fix for the vertical readout text position problem ? I'm guessing and hoping it just needs an adjustment right ? Please, don't tell me I need to replace those hybrid.Those gaps at few knobs, is it safe if push it harder ? Just don't look pretty with those wide gap.Other questions might follow once I have the time to tear it down and inspect it's inner parts.Thanks.

author: lowimpedance
author_rank: Super Contributor
timestamp: October 20, 2011, 11:39:44 pm
content: BravoI dont have this model to refer to but do have a 2430 and the color of the text at the bottom is only because it is just below the phosphor no problem if it was higher up.Which seems to be a vertical geometry issue. Does the manual go into any detailed internal adjustments for that?. (the 2430 manual has a section for display adjustments using internal controls, ie have to take the cover off!).It appears to display an input signal so looks to be working.As for the knobs, well I wouldnt bother but if you want to see if pushing can seat it further well thats up to you.You should be able to run a full diagnostic after power up and get full info on what was tested and whether it passed or failed (this info should be displayed around the middle of the screen (the service manual should show which buttons to press)Good idea to take the cover off anyway to see if all is okay and to clean any dust/ dirt out. while your at it check the switchmode power supplies for any sus electrolytic caps (see your service manual for details on getting into this area)Looks like a tidy unit.Sorry I could not be more specific.Good luckJohn

author: gregariz
author_rank: Frequent Contributor
timestamp: October 21, 2011, 04:45:48 am
content: Quote from: BravoV on October 20, 2011, 05:08:02 pmI can't help you with most of the questions as I have just had a 2 second look and video of mine.1. dont know but I'd imagine the Guernsey quality should be good.2 & 3. I actually don't think I've ever read the manual! But as you will see mine doesn't have it unless your's was a different revision.4 & 5. The sinking text is not normal. It should be in a readable position on the bottom of the CRT. But your's is there so I'd imagine that may be adjustable somewhere's inside - you'll need to look through the service manual to see6. The knob gaps are normal! Tektronic knobs IMO were the weekpoints. Yours look fine but they are a two piece plastic design IIRC and the internal piece does crack if abused. If you scour around the web there were a few places selling factory leftovers but they were at extortionate prices. If you have that problem just use a bit of superglue to fix the internal clip.

author: tekfan
author_rank: Frequent Contributor
timestamp: October 22, 2011, 12:40:58 am
content: These scopes often have problems with the corroded hybrid contacts so they should be cleaned before anything else.

author: BravoV
author_rank: Super Contributor
timestamp: October 24, 2011, 10:39:53 am
content: Quote from: lowimpedance on October 20, 2011, 11:39:44 pmYeah, its still in very good shape, came complete with the top pouch, front cover and a tek 350Mhz probe.So your knobs are also like mine ? Thats a relieve, thanks.Quote from: gregariz on October 21, 2011, 04:45:48 amHey Gregariz, thanks for shooting that video, really appreciate that, and now I have a direct comparison against mine on how this thing behaves.About the read out position, after reading the circuit, thanks to Tek excellent documentation, I finally fixed it, its quite easy, only single adjustment on the vertical readout trimpot.Here how it looks like now :With measurement screen and 4 traces turned on, the text readout position looks fine right ? I mean compared to yours ?Btw would you do me another favor, hook up the probe at the calibration pin as your video, and push the the red "AUTO" button for automatic scale selection on horz and vert adjustment and watch for the result, does yours looks like this below ?About those gaps at the knobs. with both lowimpedance and your confirmation, guess I just have to live with that.Few other questions if you don't mind testing it for me :- When power up after pressing the power button, during the diagnostic where some of those leds at the panel was blinking, did you hear a single click sound ? It sounds like a relay, and only one time when powered up.- While pushing buttons or turning any mechanical switch at the panel, at my panel, other leds also flicker a bit too, not much though, only dimly blink when any button pushed or switch turned, does your 2465b front panel leds also experience the same ?Again, many thanks for your help, really glad that you have same exact Tek that I can compared to.Quote from: tekfan on October 22, 2011, 12:40:58 amThanks, yes, thats the plan too, planning to do a detail inspection and tear out, probably I will make a new thread for it, your excellent HP 1741A restoration thread really inspires me.

author: w2aew
author_rank: Super Contributor
timestamp: October 24, 2011, 04:08:39 pm
content: A couple of quick comments...The measurement screen looks normal to me. The same as I see on mine.The knob gaps look normal to me too - typical of the dozens of these scopes I've seen and used over the years.The calibration waveform looks exactly like that on my scope if I use the Auto function. On these scopes, the calibration signal frequency varies with the horizontal timebase setting. You would typically use the cal signal to adjust the compensation of your 10x probes. However, in order to do that, you'll probably want to adjust the timebase to something between 200us to 1ms / div. For more info on 10x probes and their compensation, you might want to check out this video:

author: Omicron
author_rank: Regular Contributor
timestamp: October 24, 2011, 05:25:48 pm
content: Quote from: BravoV on October 24, 2011, 10:39:53 amThis seems to be quite common among 2445B and 2465B models. Earlier models don't seem to have this quirk. And even not all B models have it. I have one 2465B that has this flicker as well and I have another one that doesn't. Maybe it's a firmware difference. I was planning to investigate this a little further myself but haven't found the time yet. The LEDs are driven via a serial to parallel shift register. It shouldn't be that hard to hook up a logic analyzer on the serial input and clock lines of the shift register and see if the firmware is actually commanding the LEDs to "flicker" or not.PS: if you open up your scope check out the vertical PCB on the side (the A5 PCB if you have the service manual). If your version is built with SMD components then you need to replace the electrolytic capacitors on this board. I think there are 4 or 5 of them. They are known to leak and the electrolyte will sooner or later destroy the board beyond repair. There is much info on this on the TekScopes yahoo group. If your A5 board is an earlier version built with trough hole components then you have nothing to worry about.

author: gregariz
author_rank: Frequent Contributor
timestamp: October 24, 2011, 09:09:34 pm
content: Quote from: BravoV on October 24, 2011, 10:39:53 amYes that looks exactly like mine.Quote from: BravoV on October 24, 2011, 10:39:53 amYes mine is exactly the same, and its normal. On the cal hook you will notice a recommended cal timebase (I mentioned it in the video). The Cal output on the 2465B is a little bit fancy compared to other scopes. On timebase ranges down to 100nSecs the scope automatically changes the cal frequency (You'll notice when I changed the timebase in the video that the display seemed to remain constant). What Tektronix did was to make the cal output frequency such that each half a cycle takes up exactly one horizontal graticule. On many simpler scopes the cal output frequency is fixed (ie 1khz etc) and doesnt change as you adjust the timebase. Taking up one graticule makes it easy to quickly check that your scope is in cal.So you notice your cal output looks crapy on the 50nSecs range. This is because the timebase setting is below the 100nSec's limit of the cal adjustment. You should not use less than 100nSecs timebases to compensate your cal probes.Quote from: BravoV on October 24, 2011, 10:39:53 amThe one click sounds normal. I don't really see blinking in the other leds however someone mentioned above some do this and some not so if so I wouldn't worry about it.With regard to the startup message "Diagnstic. Push A/B trig to exit", I just had a quick look in the manual and notice that message continues to appear if at some point in the past the scope had failed a startup test. On my scope I can enter the menu by pressing the delta-time and delta-volts buttons simultaneously. When you go into the diagnostic menu you should select exerciser 03 "Cycle Error Clear" to see if you can make that go away. See page 6-18 of the service manual.good luck.

author: BravoV
author_rank: Super Contributor
timestamp: October 25, 2011, 06:49:08 am
content: Great, more 2465B owners.Quote from: w2aew on October 24, 2011, 04:08:39 pmThanks for the confirmations on the knobs and auto measurement result, I feel qute happy now. About those knob gaps, again, since this is my first Tek, so I was sort of suspecting whether it was refurbished and tampered before, cause it looks like those knobs are not installed properly, I guess Tek didn't care bout these minor details.And yeah, I had my probe's compensation calibrated already, also again, thanks for the video !Quote from: Omicron on October 24, 2011, 05:25:48 pmAnother great information, thank you, so its normal, breathed a sigh of relief.Yeah, probably some changes at the firmware between both, since you have two 2465B there, are both have the same ROM version ? Btw, mine is Guernsey made.Here is mine, accessed through diagnostic excercise routine at EXER 04 to show the rom info, and the codes occupied at 3 locations, and all are version "01", whats yours ? Especially at the one that flickers ?1st location2nd location3rd locationQuote from: Omicron on October 24, 2011, 05:25:48 pmMy A5 board is SMD version, it has only 2 electrolytic caps, other are tantalums. Yeah, I'm aware of that leaky cap especially the smd version at A5 board from yahoo tekscope group, and strange part is it has only 2 instead of 4 or 5 as yours ?I'm planning to do a complete re-cap at all electrolytic type in this scope, and also few non electrolytic type if I'm not mistaken that are in the power supply section, that are known to crack and cause trouble. Any more tips or hints on the re-cap ?The A5 control & logic board, 4 red circles are the those 7 caps locations, you can see there are only two blue electrolytic caps at the upper right red circle :Close up at the upper right circle, two electrolytic caps and 2 black tantalum, these tantalum won't leak right ? Or they're known to cause trouble as well ?Quote from: gregariz on October 24, 2011, 09:09:34 pmThanks again, at least now I'm sure that my auto is behaving as it should at the cal signal.Lol, yeah, I was quite surprised and very confused too when I did test the cal signal for the 1st time, cause my previous scope has a fixed frequency, and that was before I read the operational guide, until I noticed and spotted the fine printed label at the cal terminal that says "5 Hz - 5 MHz", have to admit that cal circuit its quite fancy.Quote from: gregariz on October 24, 2011, 09:09:34 pmHey Gregariz, this solved the problem ! Thank you Sir !I was heavily concentrated and occupied at those circuits diagrams from the 1st time I got this scope, and only briefly skimmed through the written text part of that service manual. Heck, I even printed all those wide scanned circuit diagrams at A2 sized papers for easy reading, but not printed the text part yet, go figure.More questions to 2465B owners :The power on hours and cycle counts, looks suspiciously low isn't it ? I guess someone did a reset or may be not at all ?The vertical measurement cursors, both vertical location are not correct right ? I guess they should be at same height as the red line I draw there, how is yours ? Time to hunt down the circuit that handle these vertical position for these cursors, and just fyi, the text readout vertical adjustment as I did previously for fixing the text is not affecting them.The pic of the notorius, unobtainium U800 or 155-0241-02 hybrid ic , and this toaster is really scorching hot, verified it with my own finger at the ic's black body.Took a peek under the pcb using bright flashlight, these two bolts are not attached to anything at all under the pcb, or to any metal body/chasis, and they just sort of soldered at the pcb, so the heat dissipation path is only from the metal lid from the ic at the right bolt, and that tiny short bolt is acting as the primary heatsink.From the power distribution diagram, this poor little ic is working at+87 V, and its the brain of the whole scope's horizontal section, no wonder its easily burned and screwed.Planning to put a copper heat sink there with a high quality Shin-Etsu non sticky thermal pad, and add two more nuts on top of at that two bolts to fasten the securing steel wire clip, that will hold and press the heatsink at the ic. The problem is I can't find those nuts here locally cause all nut & bolt measurement are using metric system instead of imperial system.Or I just use a double sided sticky 3M thermal pad, and let the adhesive pad do the work on holding the heatsink ?Please share if you've done something to cool this chip and what exactly did you do to it ?.

author: BravoV
author_rank: Super Contributor
timestamp: October 27, 2011, 05:34:23 am
content: While doing all capacitors inventory for the major re-cap job, found these and wonder if its ok that they will be replaced with other quality electrolytic cap ?This is a non polar type, isn't it ? Can't find any polarity marking.Watch the upper left blue cap that is using ordinary electrolytic cap, and still Tek used these big unusual cap, what is so special about this type compared to electrolytic cap ?While both above caps are in the main A1 board, these below are at the switching PS section, and as you can see in the middle, there is an ordinary electrolytic cap under these gray metal caps.Why use this type instead of common electrolytic ? Is there anything that I should aware of before I order the replacement caps ?.

author: Omicron
author_rank: Regular Contributor
timestamp: October 27, 2011, 11:31:09 am
content: I wouldn't touch the large capacitors on the main board, especially the ones marked "Tektronix". They are high precision and critical to the correct working of the scope. As far as I know they do not cause any problems and you will most likely do more harm than good trying to replace them.The capacitors in the power supply you can replace. They look funny but they are just quality electrolytic caps. You can find some type suggestions in this document:http://www.condoraudio.com/wp-content/uploads/Projects/Tektronix-2465B-Oscilloscope-Restoration-Repair.pdf

author: tekfan
author_rank: Frequent Contributor
timestamp: October 27, 2011, 01:30:06 pm
content: Quote from: Omicron on October 27, 2011, 11:31:09 amExactly! Don't touch the big Tektronix marked capacitors. As far as I know they are film capacitors and not electrolytics built to very exact tolerances. They are used for the horizontal sweep timing so replacing them would seriously alter the horizontal accuracy of the scope.BTW every instrument from Tektronix either it was built in Beaverton or Guernesy Islands went trough the same testing procedures and used the same spec parts as the ones made in the US

author: rigmo
author_rank: Newbie
timestamp: August 15, 2020, 06:20:36 pm
content: Hi how to see power on hours and cycle counts?