Tektronix Option 1E - Page 1
Forum section: electronics / testgear

author: George_Race
author_rank: Regular Contributor
timestamp: August 11, 2015, 01:15:33 pm
content: TEK has an option 1E, is marked on the options sticker on the back of my scopes, (2445B & 2465B) that provides for a 10 MHz external clock input. I can't seem to find any information on this option.Does anyone know where I can find the schematic diagram of how an external reference is connected into the scope?Would like to use my shop Primary Standard to drive my TEK Scopes.

author: miguelvp
author_rank: Super Contributor
timestamp: August 11, 2015, 04:34:03 pm
content: It would help if you specify the model of your scope.This doc has operation instructions for that option (I think)http://exodus.poly.edu/~kurt/manuals/manuals/Tektronix/TEK%202445B,%202455B,%202465B%20Operator.pdfThis link has info for manuals sometimes with diagrams and schematics:http://w140.com/tekwiki/wiki/Main_Page

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: August 11, 2015, 07:22:15 pm
content: https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg620497/#msg620497You will not find much, if any, 1E OPTION info in the main manuals for the 24xxB series scopes.You need to look in the 24xxB OPTIONS manuals, in particular the 24XXB OPTIONS SERVICE manual.more info is available feel free to ask...

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: August 11, 2015, 07:45:36 pm
content: modified content... bumped

author: timb
author_rank: Super Contributor
timestamp: August 11, 2015, 11:35:48 pm
content: I've got some info I'll post once I get to my desk! (Using this post as a reminder.)Sent from my Smartphone

author: George_Race
author_rank: Regular Contributor
timestamp: August 12, 2015, 12:24:13 pm
content: I have a copy of what is called a 2465B options/operations manual, can't find anything about option 1E there.Option 1E is mentioned in the 1989 TEK Catalog. Page 164 details Option 1E, for the 2465 series of scopes.The reason I am looking is that I would like to drive my 2465B with an external primary standard, in place of the internal 10 MHz crystal.Looking for the schematic diagram that shows how it was done by TEK in that model.Thanks for all those helping, appreciated.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: August 12, 2015, 02:37:16 pm
content: As mentioned, it is almost ALL in the 24xxB OPTIONS Service Manual. Not where I have access to it at the moment, and never found that on the WWW, only from ARTEC Manuals. I will try to remember to provide more details, but, J5990 is the CTT/TV Sync board connector you need to connect your BNC input to.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: August 12, 2015, 02:40:50 pm
content: http://www.ebay.com/itm/TEK-2445B-2455B-2465B-2467B-Options-Service-Manual-/390300987500

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: August 12, 2015, 03:35:21 pm
content: Here's the info for installing Option 1E into PRE B05xxxxx S/N 24xxB's. The later s/n scopes use different options boards so you still will want to peek at the later B Options Service manual.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: August 12, 2015, 03:50:13 pm
content: Quote from: George_Race on August 12, 2015, 12:24:13 pmOk, I see now you are assuming, as I was, that the EXT REF input somehow replaces the 10 Mhz Xtal on the control board. Not so. This Option has nothing to do with that, or the time base. It simply increases the accuracy of the CTT FREQUENCY Counter ONLY, by 1 extra digit (nothing else), and ONLY if you have a CTT board Option already installed. Still, a nice feature...

author: timb
author_rank: Super Contributor
timestamp: August 12, 2015, 07:49:57 pm
content: Quote from: SoundTech-LG on August 12, 2015, 03:35:21 pmNot entirely true. Here's a quick annotation I made up for Option 1E on scopes with Option 9:https://www.dropbox.com/s/7icevdgf4fq8zds/1e-mod.pdf?dl=0I have a pre-B05x 2465B with the CTT/WR option, so I already had the BNC on the back (which gives a trigger pulse out each time the word recognizer probe makes a match). For option 1E, you can change that output to a clock input by removing R6180 and adding C6180 (22nF).Edit: One more thing I forgot to add; for pre-B05x 246xB scopes, use the 2465A Options Service Manual, which is a lot closer to our scopes than the post-B05x manual.Sent from my Tablet

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: August 12, 2015, 08:05:32 pm
content: Umm...Which part of what, is not entirely true???

author: timb
author_rank: Super Contributor
timestamp: August 12, 2015, 08:07:22 pm
content: Here's some photos:BeforeAfterRemove R6180, Add C6180Notice that the removed resistor and new capacitor both share the pad closest to the board edge, yet the other lead of the cap goes into a previously unused hole.Sent from my Tablet

author: timb
author_rank: Super Contributor
timestamp: August 12, 2015, 08:09:47 pm
content: Quote from: SoundTech-LG on August 12, 2015, 08:05:32 pmIt may not be a matter of *just* adding the BNC connector depending on which exact CTT option you have. You may have to remove a resistor and add a capacitor as well.Sent from my Tablet

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: August 12, 2015, 08:14:07 pm
content: For the earlier CTT boards. the 24XXB units SN B05xxxxx and later plug right in to J5990 for REF IN attach BNC, done.WORD Recognizer functionality needs additional plug/wiring. But if I recall, the OP was asking about the FREQ REF only.

author: timb
author_rank: Super Contributor
timestamp: August 12, 2015, 08:19:51 pm
content: Quote from: SoundTech-LG on August 12, 2015, 08:14:07 pmLook at the PDF I posted. It has schematics. Here's a photo with the relevant portions highlighted.(This is for pre-B05x serials.)Sent from my Tablet

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: August 12, 2015, 08:23:58 pm
content: No dispute on this end. Certainly don't see the "not entirely true" part...

author: timb
author_rank: Super Contributor
timestamp: August 12, 2015, 08:31:07 pm
content: Quote from: SoundTech-LG on August 12, 2015, 08:23:58 pmI was originally quoting the portion of your post that said it was a simple matter of just installing a BNC connector. That statement may *or* may not be correct, depending on if you have just the CTT option, or the CTT/WR option.I then went on to post about how to mod the CTT/WR option.I wasn't disagreeing with you, or calling you a liar or anything. I was simply adding more information to your post."Not entirely true" means "true, with the exception of..."Sent from my Tablet

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: August 12, 2015, 08:37:45 pm
content: Here's a newer, updated, and more accurate version of my original post back in Marchhttps://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg620497/#msg620497

author: timb
author_rank: Super Contributor
timestamp: August 12, 2015, 08:47:31 pm
content: ...I'm not disputing the accuracy of anything you said.In fact, you literally said:Quote from: SoundTech-LG on August 12, 2015, 08:14:07 pmWhich is true!All I did was post additional information about changing the WR-OUT port to EXT-REF on PRE-B05xxx scopes with Option 9. In which case, it requires a simple passive component change and not the addition of a BNC connector.The information you posted is correct, so is what I posted.Sent from my Tablet

author: timb
author_rank: Super Contributor
timestamp: August 12, 2015, 08:53:17 pm
content: Actually, I tell you what. I'll make up a PDF guide tonight incorporating all the info you've posted about 1E, including guides for converting both Option 6 and Option 9 and information about what it does and how it works.Because honestly, your original post in the 2465B thread is what got me looking in the service guide on how to convert my Opt9 to 1E.Before your post, I had thought 1E overrode the built-in reference. So, thanks for that.Sent from my Tablet

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: August 12, 2015, 09:02:44 pm
content: Yes, originally I thought it replaced the time base reference somehow. But that has nothing to do with it. The main thing is the CTT Frequency counter function, and increased accuracy by one full digit, from 7, to 8.I have the ARTEC Options service manual , so can also post relevant info for the later B05xxxxx serials. It details the functionality etc., whereas I have not seen it in earlier versions of the Options manuals.

author: George_Race
author_rank: Regular Contributor
timestamp: August 12, 2015, 11:02:36 pm
content: Boy, what an education you can get when you ask what was probably a dumb question, without a lot of good information from me to start with!This whole issues started with me noticing the options sticker on the back of both scopes. The 1E option is on the options label, BUT DOES NOT HAVE THE PUNCH MARK next to it on the options label. So my scopes DO NOT have that option!So my thought was that there must be a way to replace the internal 10 MHz xtal frequency standard with an external standard, if you only had that option installed. That is where my inquiry started, me thinking it was an option that could be easily installed in both of my scopes!With a spectrum analyzer, frequency counters, and signal generators all being driven by my house standard, it just does not seen right that when I ask a scope to give me the frequency of a standard 10 MHz waveform, it come up somewhat short of the actual 10.0000000 MHz that I would expect to see from the internal counter within the scope. So my quest was to find out how to make it happen, using an external standard in place of the internal xtal 10 MHz standard. And I don't see any easy way to adjust the frequency of the xtal oscillator that exists in each of the scopes.So Gentlemen, thank you so very much for all the research and explanations of the 1E option. I am sure that I am not the first to come across this issue, and together you all have contributed to this session which will be findable by others in the future. So with that, I thank you all for your comments and input to this particular topic, it was very helpful to me and will be to others in future.

author: soren
author_rank: Regular Contributor
timestamp: August 13, 2015, 02:30:34 am
content: There seem to be several people in this thread who have the 2465B options service manual, which is not currently freely available as a PDF.It would be great if someone could scan it.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: August 13, 2015, 04:47:34 am
content: The late S/N (B05xxxxx up) Options manual does not seem readily available other than ARTEC. I have some small clips here, but want to encourage interested parties to buy it from them at a very reasonable cost.

author: George_Race
author_rank: Regular Contributor
timestamp: August 13, 2015, 07:19:55 pm
content: To completely remove any doubt that you cannot use an external 10 MHz Standard Frequency to increase the accuracy of the Parametric Measurements in the 2465B, I spend several hours going through the pages of "Theory Of Operation" and looking at schematic diagrams of the area around the 10 MHz xtal oscillator.It was soon apparent that using the Parametric Measurements to measure Frequency or Time, do not depend on the 10 MHz clock signal. What determines those readings is the information that is stored in the battery backed up NVRAM that is calibrated with the procedure in the CAL 09 - Parametric Measurements procedure. Once calibrated, that data provides the standards for measurement of signal frequency and time. It is just that simple!To prove that to myself, once and for all I did a small experiment!First I severed the tiny circuit board link between Pin 2 & Pin 3 of U2440A & B of the microprocessor clock circuit. I then carefully ran two cables out to a small switch that was wired to either reconnect pins 2 & 3, or allow the injection of my 10 MHz standard into Pin 3 to drive the Microprocessor Frequency Divider at 5 MHz. That 10 MHz signal out of Pin 4 of U2440B also feeds other parts of the scope with it's 10 MHz signal.Using the Parametric Measuring to measure frequency of my standard 10.000,000 signal showed 9.967 MHz with a Period of 100.3ns. Flipping the switch to inject the 10 MHz Standard in place of the internal 10 MHz Xtal, gave EXACTLY the same readings! Proving once and for all that it is not possible to use an external standard to get more accurate readings out of the TEK 2465B.Picture of area of interest attached.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: August 13, 2015, 11:59:31 pm
content: Great job George!At one point I was considering trying that!There is no substitute for critical experiment.I assume your scope is standard, (without the CTT board Option).

author: George_Race
author_rank: Regular Contributor
timestamp: August 14, 2015, 01:48:10 am
content: Thanks for the comment, appreciated. No CTT Board Options, just a standard 2465B.Certainly is an easy instrument to work on, everything is pretty much in the open and can be gotten to.Hopefully this conversation will be of help to others, who may have the same idea about an external standard.

author: FireDragon
author_rank: Regular Contributor
timestamp: December 18, 2015, 09:24:57 am
content: This thread has been very informative! I just ordered a 2465B CT on eBay which is supposedly functional. Should get it Monday. I plan on picking up a GPS frequency standard in a month or so and wanted to run the scope from that. I also wanted the scope to replace the need for a separate frequency counter. Clearly, the first is not an option. However, the scope provides the frequency counter. The only thing left is to upgrade the accuracy. My scope's serial number is B010xxx, so it is a very early "B" version. My understanding from this thread is that all I need to do is remove R6190 and insert C6190 which is 22nF. I have some questions...1. What is the voltage requirement for C6190?2. Is a ceramic capacitor ok?3. Since this is a very early "B" model, is the removal of R6190 and addition of C6190 still the correct change?Thanks.

author: FireDragon
author_rank: Regular Contributor
timestamp: December 22, 2015, 06:27:20 pm
content: I plan on using theC412C223K1R5TA Kemet 0.022uF MLCC, 100V, 10%which I think will do the trick. Without the service manuals, I can't be sure. If anyone has another suggestion, please share!