Hello to All, I'm new in the group and I should introduce myself. I'm 62, from Italy. Electronics has always been my passion although I'm doing something completely different for a living, as a university researcher and teacher in biochemistry. Some knowledge in Electronics comes handy for fixing laboratory instruments. It happens sometimes, and I'm sure you are aware, that a blown fuse is the reason for trashing even rather expensive equipment. But o many occasions the fix was much more difficult, different and rewarding. Speaking of fixing, I have a quite strange story to tell, for which I am asking advise in the group. I have bought at an auction a Tektronix 2465 (plain, no letters) for a couple hundred Euros (no probes, though). It was advertised as functioning and it did indeed turn on and it displayed trace and readouts fine. After one minute there was a bang and thick smoke filled the room. I already knew what it was, a RIFA capacitor in the primary of the power supply that failed just at that moment. I took apart the whole machine, cleaned it, recapped not only the safety capacitors but also most of the electrolytics. Checked most active components in the low voltage power supply, they worked, and reassembled the scope. After switching on, it looked that it worked fine with all 4 channels, but I immediately noticed something weird: the readout text was mirrored and flipped, as if the CRT was rotated 180°C. But I did not do anything to the CRT! I don't know if it is possile to post pictures, but I think you get the idea of what this is about. Do you have any idea of what could be causing this? I'm really lost. please help! Thank you very much and best wishes

Hello *, is it possible to replace the cavity 2nd LO A20, Part No. 119-1022-00 and 119-1022-01 in an older 492 (B03XXXX) by a 650-0296-01 2nd Local Oscillator to get a better performance especially the better shape factor at 100 Hz resolution? As I've seen in the manual the only thing would be a new 100MHz connection. Regards Colin

The following photos have been uploaded to the 130 L-C meter project ( https://groups.io/g/TekScopes/album?id=296248 ) photo album of the TekScopes@groups.io group. * Range caps guts.JPG ( https://groups.io/g/TekScopes/photofromactivity?id=3808531 ) *By:* ed breya <eb@...>

After calibration fixed the A triggering, I tested and found a bad FET (Q1012A/B) in the B trigger circuit, part #151-1042-00. The only source I found was in Eastern Europe, so I looked at substitutes and procedures used by others. After getting incorrect parts from Amazon (I should know better!), I found the BF256B at Digikey, and after swapping a few around to get a reasonably-matched pair, the circuit worked and calibrated just fine. I appreciate all of the help here on the TekScopes group! Maybe I can return the favor in the future. Chris W6ATV

I got an SG504 where the LEMO connector for leveling head has only two pins (instead of regular 4 pins). Pictures uploaded in (afraid you'll have to go backwards, from last to first, to have some logic - not sure why they arranged themselves in that order): https://groups.io/g/TekScopes/album?id=296499 Sure I'd like to hear if someone else is aware of this variant (maybe unique?) and what details could share - for my benefit, but maybe for others too. Specially the leveling head, what schematic or solution was used to rely on only two pins. Thanks for attention Titi

Hello group, My „new“ 7613 has a X-deflection issue. See posted 2 photos about two weeks ago. The X-deflection seems to depend on the Y voltage. At higher Y voltages the X voltage seems to shift to a righter position (later in time). One photo shows staircase lines where you can clearly see the funny effect. With increasing Y voltage the lines start right (later) shifted. The second photo shows a square wave signal. The falling edges are tilted in „negative“ time direction. The 7613 therefore can measure/shows negative time! The rising edges are tilted in positive time direction. The rise time of the square wave therefore seems to be worser than it actually is. I checked the X amplifier for any influences by the Y voltage, but everything seems to be ok. All calibration work and geometry settings are done. Nothing helped. It seems that deflection plates in the CRT are tilted, but this can happen only in the production process, or not? Any ideas what I can do to rescue the poor 7613 which is in an excellent condition otherwise. Regards Loetroelli

Hi, Does anybody know where to get the obsolete Software CAT200 for the 22x Series of portable scopes. The scopes (yellow ones) are called powerscout. I have 2 222's in perfect working order and one 224 with a bad CH2 Thanx

My 475 is now triggering with a new U520 chip, but not perfectly. As recommended on here, I found the 475 SN B250000 and up service manual that includes voltages at various points in the trigger circuit and tested them. Everything looked good until I got to one of the tunnel diodes, CR556, where the schematic states the anode should be at 0 Volts. At turn-on, the voltage on the anode of CR556, the arming tunnel diode in the A Trigger circuit, rises to 0.02 Volts and climbs as high as 0.04 Volts over 30-40 seconds. Then, it starts jumping around rapidly and ends on ~0.410 Volts where it remains. This is repeatable with each turn-on cycle. Is this the typical behavior of a failing tunnel diode? There are several components connected to this circuit point. I swapped transistors Q556 and Q566, and that made no difference. I don't know much about the normal behavior of the thermal resistor RT559. I work a lot more with vacuum tubes, but this looks like the behavior of a semiconductor that works when cold and then fails as it warms up. How risky is it to swap the tunnel diodes themselves between A and B Trigger circuits? I see they are socketed and not soldered. Thanks for helping a newbie at scope repair. I'm working on the learning curve.

Hi, I am starting to look for a probe or two for my 2GHz TDS794D. It has fixed DC coupled 50ohm inputs, which may make things a little more interesting to figure out. Does anyone have any experience with using 2GHz+ capable probes with these scopes that can provide any suggestions? Thanks! Jared

Hello everyone Does anyone have a scan of a Tektronix 145 PAL signal generator schematic and/or service manual? It was picked from a "free" pile and the plan is to give it a second life if it's not an unobtanium part and if it turns out economically unviable we'll part it out. Symptoms are low voltages and a scorchingly hot transistor on the power supply board. Thanks Luca

Hi all, I recently acquired a 7S12, plus an S-4 and S-53, and was able to play around with it more or less successfully with the Type 284. The biggest hurdle was figuring out 7S12 doesn't use the S-4 internal trigger pickoff, plus a minor mechanical reassembly of the DC offset pot. Unfortunately, the trace got really noisy and started drifting upwards while I was playing with it, kind of like when a 475 etc. gets a dirty vertical attenuator switch. I figured it needed a switch cleaning, so blew the dust off with compressed air, cleaned the rotary wafer switch with a few drops of DeOxit, then cleaned the cam timing switch with paper and alcohol. Unfortunately, the trace is now entirely offscreen (vertically upwards), and the only way I can bring it into view is by rotating the variable attenuator ccw. Once it's in view, DC offset moves it +/- a minor division or so. I'm baffled, as usual. Baseline correction is turned off (switch set towards the front of the scope). I can actually see the square wave from the Type 284 and it's quite sharp, but amplitude is very wrong (284 is set to 1V output thru 2X GR attenuator, per S-4 manual). Photos here: https://groups.io/g/TekScopes/album?id=296251 For extra fun, I don't have the S-52 and S-6 that the 7S12 manual calls for, let alone plugin extenders and card extenders, so I'm not sure if waveforms shown with the schematic will be comparable. I found Q620 (151-1021-00) is bad; for the moment I replaced it with a J112 (the only JFET I had on hand) with no change. I'd have expected this to be a timing/horizontal problem, anyway. For the moment, I'm assuming the S-4 isn't dead; I've been paranoid about static (wrist strap, termination on S-4 when not in use), and it was working (showed correct rise time for Type 284 pulse). Is that my most likely failure? I haven't tried testing the diode bridge yet. A few other oddities, which may be totally normal, or may be clues to the problem: - if I remove the S-4 head, the trace sits about 3 divisions below zero - on the mρ scale, I can't bring the trace in view - when it was working, I noticed that bringing DC offset below a certain point would cause the trace to collapse vertically thanks, Adam

This is my first post to this group after being guided to it by someone who told me this was the mother lode of Tektronix scope expertise. I am a professional audio tech with expertise in Hammond Organs, Leslie speakers, Rhodes & Wurlitzer Electric pianos, combo organs, guitar amps, and some synths and HiFi. I stay busy all the time and frequently use a scope, but usually only at audio frequencies except for the occasional poorly-wired amp that's oscillating at high frequencies. People sometimes give me things, and I was given this 1974 Tek 475 in very good physical condition. But I'm currently in a clean-out cycle of my shop, which means things are either going to get fixed or they're going to go. So I put this Tek 475 on the bench to see if I could resurrect it. I have found and fixed some power supply issues such as a dried out/open circuit C1412 and a burned tantalum cap on the +15 rail (no surprise). CRT seems strong. And I got the fan going. Most controls appear to do what they're supposed to do. But I can't get it to trigger. I've injected a 1kHz sine wave test signal into Channel 1. Adjusting the A Trigger knob has no effect. I can get the trace to stabilize somewhat and show a sine wave if I adjust the A Trigger Holdoff control. Pushing the Trigger View button shows me a display that's a good bit higher in vertical deflection than the test signal, but the same frequency. It also looks clipped/distorted. That's as far as I've gotten. I've read different strategies for how to approach this, one being to reseat connectors and transistors and/or do some cleaning with isopropyl alcohol. The other approach is to get into the circuit in detail to see if the fault can be found. I do have a working B&K scope to use for signal tracing. However, if I'm obviously out of my depth here, feel free to tell me. I do it to people who try to work on organs all the time. And I don't have laboratory-grade equipment to use for calibration -- because nothing else I work on requires it. If I can't get this 475 working, I'll give it to someone else. But it needs to work if it's going to stay in my shop. What should my next step be?

Dear friends; I recently aquired a AM 501 op amp plugin module, I would like to do the expirements in the user manual ,but forgive my ignorance,I am only a hobbiest wanting to learn more. The Am 501 user manual shows an arrow and cable to a Differential comparator, I'm confused by what the manual is refurring to by Differentia comparator, Iam familiar with all the Tek plugins and have never seen or heard of a Differential comparator, I know of the Am 502 Differential amplifier and I think 7A13 Differential anplifier, also there is a Tek Defferential probe, can anyone shed some light on what Tek is refuring to here also what they are trying to demonstraight with these expirements?? Meny Thanks in advance Dave

Is anyone making replacements for the teardrop knobs used on lever switches on the 453 scope and many others? Bruce Gentry, KA2IVY

Hi all. I'm currently on the hunt for a front cover for my TDS794D scope. Any front cover from a TDS500, 600, or 700 series scope will fit. If anyone has a spare one of these in reasonable condition, and can post it to Japan at my expense, please let me know. I have Paypal at the ready. :) Thanks! Jared

Loetroelli <tek@...> updated the photo album 7613 X-Deflection fault ( https://groups.io/g/TekScopes/album?id=296099 ) : Faulty X-Deflection of my "new" 7613. With increasing Y-Values the X-Deflection shifts to the right side. The effect is independent from Y-Frequency and X-Time. The measured X-Deflection voltages seem to be ok. Any idea?

Egge Siert <eggeja2@...> added the photo album Training Board 3 ( https://groups.io/g/TekScopes/album?id=296456 ) --- The following photos have been uploaded to the Training Board 3 ( https://groups.io/g/TekScopes/album?id=296456 ) photo album of the TekScopes@groups.io group. * Training Board 3 Bottom.JPG ( https://groups.io/g/TekScopes/photofromactivity?id=3806936 ) *By:* Egge Siert <eggeja2@...>

Hi to All, Acquired this Training Board 3. Posted in the past this request on eevblog. No replies. Asked Tektronix Support about it. The only they could find was an 1 page Document (071-1645-00). Therefore also on this Forum this request, hoping that it rings a bell with a former (or current) employee of Tektronix. Documentation on this TB3 is scarce as hen's teeth. There is also a Training Board 2, for which a 26 pages Document (071-1137-00) can be downloaded. This TB2 has some similarities with the later more advanced TB3. A picture of the TB3 (page 152) can be found in the very informative (394 pages!) Lab Exercise Book for the MSO5000/DPO5000 Series. Also it is mentioned on page 159 (Series Analysis Laboratory Section) of the RT-Eye Serial Compliance and Analysis Application Document (077-0021-00, 265 pages). In the later adapted (for CSA/TDS7000B Instruments) Version (HP022210) of this Document the TB3 isn't mentioned any more? And that's it. Anybody with some more information? I shall upload Pictures of the Board. Greetings, Egge Siert

I picked up a 7M13 Readout Unit as a package with some other things, As I was playing around with it , I noticed that the lower field will only display numbers. Different numbers for all characters, but always the same. The number buttons display correct 0-9. The frame counters work as described in the manual. Upper field displays all characters correctly. Have never used one before, is this normal? I also got with the package a temperature probe P6430 that I don't have a use for $30 shipped USA. Any takers? Mark W7HPW

So I have a Tek 2465 and it works perfectly fine with no issues. I replaced my 2230 with this scope as it has more untility functions as an analog scope. My only irk with it was how the focus of the trace varys around the display. In the middle, the trace is pencil sharp with a very clear display. But as you go farther from the edge the trace becomes less in focus. It's not really all too noticeable but it's there. I also happen to have 7613 main frame with has the same issue, except the magitide of focus variation is much greater. Like the 2465, the middle display is pecil sharp, but halfway to the edge of the display, it becomes thicker until the edge where it is about 4x as thick as the middle part. Is this normal? Is there a way to midigate the issue? I feel like this is just a limitaion of the CRT, but my 2230 does not have this problem what so ever. All areas on the display are pinpoint sharp and in focuses. No variation in focus. Thanks, Benjamin