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Re: 7D20 with unknown options or mods
Chuck Harris
As I recall, there was a variation of the 7D20 that was called
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the 7D20T, that fit in its own chassis, and was used in conjunction with computers to gather data. A picture is shown on page 338 of the 1984 TEK Products catalog. -Chuck Harris Richard Steedman wrote: I have a 7D20 with a couple of modifications or options added. Can anyone provide some information about these? |
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Re: WTD - P6201 Probe tips (Tek P/N 206-0200-00)
On 08/09/2020 11:57, Raymond Domp Frank wrote:
Hi Phil,At least one, ideally two. NL->UK shipping is fine, I can't see that being too expensive! How much are you asking for the probe tips? I've found a few ebay listings in the US but either the price or the shipping tends to be the killer (or both). Thanks, -- Phil. philpem@... |
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Help Troubleshooting 466, No +15VDC
This 466 worked great for years, then suddenly I smelled something burning, and the fan stopped. All low voltages good on interface board, *except* for +15VDC. Reads about 4VDC, (and about 4 ohms to ground with power off....). If I leave power on past about 15 sec, I can smell something burning again, so I only power up long enough the check the voltages.
I'm thinking tantalum cap, but wondering a good way to isolate the offender? Assume the the +15VDC goes all over the scope, to other boards, so would be a bear to lift all tant caps one at a time. Thinking of breaking the trace somewhere near the PS source. Any other tips or likely suspects? Thanks in advance! |
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466 Interface Bd 15V-65V short
Troubleshooting an issue with my 466, where both traces would get blurry (unfocus) intermittently. The problem appeared to be mechanical in nature, as it responded to taps on the case.
Opened it up and found a chalky, powdery bridge between C1737 (65V) and the 15V test point on the interface board. Cleaned it up, and appears to have cleared the problem. Has anyone seen this before? |
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7D20 with unknown options or mods
I have a 7D20 with a couple of modifications or options added. Can anyone provide some information about these? The first is a board sitting on top of board A11 above the vacant IC sockets U1230, U1330 and U1430. It has a connector P200, connected to J100 on the CCD board A5. It has three ICs - a dual 4-input NOR gate, a quad analog switch/mux and a dual op-amp. One of the 7D20 photos on Barry Johnson's website looks like it has the same mod . The second is a small board sitting behind the front panel in-between boards A6 and A7. It's connector has flying leads soldered directly to pins of the CCD chips on the underside of board A5. I have posted photos here. The 7D20 has a serial number in the B085000's and is running firmware F1.03. Any insights gratefully appreciated! |
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Re: P6249 Oscillation
fauffing
Does the probe calibrate? I am new to the 694C and have two probes that calibrate and one which does not. All have oscillation similar to what you've described, with the more pronounced oscillation on the probe which will not calibrate (and I cannot effectively set offset according to documentation on this probe either). Does anyone have a screenshot of a 694C on the calibration pins at various scales they'd be willing to share, so I can use for a comparison? I really don't know what to reasonable expect from a working vs. a non-working P6249 probes.
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Re: 10 EASY WAYS TO TROUBLESHOOT WITH AN OSCILLOSCOPE
Good day,?
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while the author certainly had good intentions, the recommendation to probe live utility power per sections 2 and 3 without proper safety??precautions or links to the known safety standards & best practices?is unbelievably?risky and unnecessary.?Why pose such a risk for beginners? Why the author fails to?recommend some?low voltage probing as a start?is beyond comprehension. Cheers, Magnus Pete, Some (many young?) people think "scopemeters" are the Real McCoy, having never used a traditional oscilloscope and may think no one else alive has either. OTOH, The digital heads only think in 1s and 0s and somehow conceive that oscilloscopes are no longer needed because analog is dead and every signal running around inside a digital device is a clean high or low state (1 or 0). (I do agree with them that antenna theory is at least partly witchcraft) Many years ago (1980s?)I introduced the head of the electronics department at the best of the bunch area community college to a semiconductor curve tracer. He didn't know they existed. To his credit I could see a bright light flashing right through his eyes when I explained what he was looking at, and he was a relatively recent EE! Quite some time later, he informed me that he had requisitioned one for his department, got it in their lab, played with it for a few days, and procured several more. Curve tracing various types of semiconductors, and documenting the meaning of what is displayed became a required part of the degree path for his students. I suspect his graduate placement rate went up considerably. Sadly, he is only a few years my junior and may be on his way out, perhaps already retired. I can only hope he had a hand in choosing his replacement. Anyway, my point is that, previously, this same CC had been graduating students with an associate degree in electronics with the barest consideration of discrete component behavior beyond resistors and capacitors. Linear was nearly all opamps and digital was all logic probes on engineered student experiment platforms that had been carefully designed to produce precise, repeatable results. No Surprises! With that sort of mentality driving many of our schools, how can we expect the general public, even the smart ones, to know they don't know? It took me many years of study, and more than a few years learning, to realize how little I know. I don't even poopoo my friend who is in search of perpetual motion and/or free energy. I just tell him to build it and show me it working and let me play with it in my lab. If it still works after an inquisition, we'll become rich and famous unless, of course, were killed first to suppress it. Thomas Garson Aural Technology, Ashland, OR By my calculation, the? dynamic range of the universe is roughly 679dB, which is approximately 225 bits, collected at a rate 1.714287514x10^23 sps. On 9/7/20 6:24 PM, saipan59 (Pete) wrote:
Looking at the author's site, it *appears* that he has good intentions, and enjoys learning about a wide variety of things, but lacks actual expertise/experience (at least in electronics). |
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Re: Tek 4654M; No Trace, No +5V, No +95V; Help
Quick up-date. Disconnected the multiplier feed/connection to T550 pin 10. With this connection broken fuse F558 still blew upon powering up the scope. Am thinking that U550 has issues with more than just the multiplier. Was thinking of going back over some of caps again to see if one of the caps that goes to ground was bad and I missed it the first time around.
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Re: 1S1 sampling unit; (also 7B53AN & 7A18 plugins)
David Collier
A bit off -topic: today picked up Fairchild 765H Portascope with 74-13A timebase and 76-02 25MHz dual trace plugins, with probe, all for A$10!
Transistors with quite a few nuvistor tubes; EHT power via EL86 and 12AU7 tubes. Standard of construction not far behind TEK, if at all, with five fuses. Cleaning it up before gradually powering up in due course. Won't take 1S1 TEK plug in though. |
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Re: 10 EASY WAYS TO TROUBLESHOOT WITH AN OSCILLOSCOPE
Pete,
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Some (many young?) people think "scopemeters" are the Real McCoy, having never used a traditional oscilloscope and may think no one else alive has either. OTOH, The digital heads only think in 1s and 0s and somehow conceive that oscilloscopes are no longer needed because analog is dead and every signal running around inside a digital device is a clean high or low state (1 or 0). (I do agree with them that antenna theory is at least partly witchcraft) Many years ago (1980s?)I introduced the head of the electronics department at the best of the bunch area community college to a semiconductor curve tracer. He didn't know they existed. To his credit I could see a bright light flashing right through his eyes when I explained what he was looking at, and he was a relatively recent EE! Quite some time later, he informed me that he had requisitioned one for his department, got it in their lab, played with it for a few days, and procured several more. Curve tracing various types of semiconductors, and documenting the meaning of what is displayed became a required part of the degree path for his students. I suspect his graduate placement rate went up considerably. Sadly, he is only a few years my junior and may be on his way out, perhaps already retired. I can only hope he had a hand in choosing his replacement. Anyway, my point is that, previously, this same CC had been graduating students with an associate degree in electronics with the barest consideration of discrete component behavior beyond resistors and capacitors. Linear was nearly all opamps and digital was all logic probes on engineered student experiment platforms that had been carefully designed to produce precise, repeatable results. No Surprises! With that sort of mentality driving many of our schools, how can we expect the general public, even the smart ones, to know they don't know? It took me many years of study, and more than a few years learning, to realize how little I know. I don't even poopoo my friend who is in search of perpetual motion and/or free energy. I just tell him to build it and show me it working and let me play with it in my lab. If it still works after an inquisition, we'll become rich and famous unless, of course, were killed first to suppress it. Thomas Garson Aural Technology, Ashland, OR By my calculation, the dynamic range of the universe is roughly 679dB, which is approximately 225 bits, collected at a rate 1.714287514x10^23 sps. On 9/7/20 6:24 PM, saipan59 (Pete) wrote:
Looking at the author's site, it *appears* that he has good intentions, and enjoys learning about a wide variety of things, but lacks actual expertise/experience (at least in electronics). |
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Re: Lot of 10 scopes (400s & 2400s) with 5 scopemobiles
Roy Morgan
Tek folks,
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The seller as acknowledged my offer and I will be making arrangements to get the lot. Most likely I will store them near Greenfield till they can be sorted and moved on to folks who want them. I'll keep the list posted. Roy Morgan K1LKY Western Mass 607-765-8867
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Re: 10 EASY WAYS TO TROUBLESHOOT WITH AN OSCILLOSCOPE
Looking at the author's site, it *appears* that he has good intentions, and enjoys learning about a wide variety of things, but lacks actual expertise/experience (at least in electronics).
He may not realize that a scope is NOT essentially an auto-ranging DMM, and that advising newbies to make AC line measurements is a Bad Idea. Pete |
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Re: Lot of 10 scopes (400s & 2400s) with 5 scopemobiles
Roy Morgan
Tek folks,
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I am working to put together a deal for these scopes (I am on western mass in striking distance of the NH seller) Goal is to get the lot and pass along scopes to interested list members, covering just costs. ) I will make offer to buy the lot and keep the list posted. Roy Roy Morgan K1LKY Western Mass On Sep 7, 2020, at 10:36 AM, David Berlind <david@...> wrote: |
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Re: Tek 4654M; No Trace, No +5V, No +95V; Help
Michael. Thank you for your pictures and explanation. Your repair looks very professional and obviously was effective. Unfortunately I don't have access to a 3D printer for the enclosure. I am thinking maybe I can use a craft store plastic container or a small pill bottle. I am not familiar with the Tek X Ref catalog but will search for it on line. Building a replacement circuit will be new for me. I haven't done that in the past. I am good at parts replacement. So circuit building will be new for me. From your pictures it appears your new circuit is spliced into the red line going to the CRT. Thanks again for the information. I was thinking of shelving the 465M because I didn't have a replacement U550 but you motivated me to perhaps carry on. My functional scope is a Tek TDS460A. The 465M is strictly a bench and learning exercise/project. The scope was given to me as excess and not working. I do have a "parts" 455 but I was trying to save it so that if I got educated and repaired the 465M I might be able to bring the 455 back just for the exercise. The 455 U550 doesn't seem any better so I haven't considered swapping it out. It did look good at one point but no longer. It appears to be blowing the F736 fuse. Don't know if that is the result of my probing or if something just gave up once it was powered up for a bit. Before it was blowing the F736 fuse It didn't have a trace but did have a beam finder. The 455 also spent some time under water years ago so that certainly didn't help it. Enough on the 455. Thanks again for the information. Harrison N1FAM
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Re: Tek 4654M; No Trace, No +5V, No +95V; Help
Hi Harrison,
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Yes, that all sounds correct. From the symptoms your scope is exhibiting as compared to mine and others, the multiplier is likely arcing inside when it gets up to working voltage. As far as I know, this is fairly common failure in the 465M's multiplier. Good luck with it. Thanks, Barry - N4BUQ ----- Original Message -----
From: "Harrison" <buma7@...> |
Raymond Domp Frank
saipan59 (Pete)
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