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Re: 7000 plugin socket side covers?
It all depends on the particular connector's state. The "adding mechanical support" approach will only work if the contacts are in place and not bent, and the covers are just not "springy" enough anymore to stay in place but are not entirely crumbling - the external supports only cover the part of the side covers that remain exposed when the plug-in is seated, i.e. they mainly just hold the covers in place.
The transplant approach which I have documented on ("obscure"?) TekWiki was necessary in an extender that I had and in an early instrument (a 7503), where a number of contact fingers were beyond salvage, and some of the covers were cracked too much to create contact pressure even if held in place. It's a lot of work and the modern connector has much higher friction and insertion force (not designed for frequent insertions I guess), but it does conclusively fix contact problems. The contacts de-solder very easily and without danger to the multi-layer PCB, because the holes are relatively wide (I suspect they were slightly oversized by design to help assembly). You may be able to salvage covers and contacts to fix one of the remaining sockets like in my case where both V slots needed replacement but I was able to fix the H slot. BTW, at least once the contact fingers are off, you won't feel sorry about cutting up the remaining connector skeleton to hold the new connector. |
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Re: 2465 Calibration Completed but boot still fails
Great Job!!!
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Take gold star for the forehead out of petty cash. Ross -----Original Message-----
From: [email protected] <[email protected]> On Behalf Of jimbert4 via groups.io Sent: Monday, May 02, 2022 5:59 PM To: [email protected] Subject: [TekScopes] 2465 Calibration Completed but boot still fails After I successfully completed CAL 01-04, I still get a failure on boot-up. This is what it said on the scope: ALL 00 PASS XX<F77F> So it passes everything but fails. Huh? I found in the service manual that this happens from a Cycle Error that must be cleared by running Exerciser 03 diagnostic routine (Page 6-16,17 in the service manual). After running that routine the error cleared! Woo Hoo! My 2465 is fixed! Thanks to everyone in this forum who patiently answered my questions and offered suggestions. |
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Re: Saving 576 plots (again)
David,
What kind of sample rate did you use for the plots? All I have for comparison is a 7CT1N, but it's "sweep rate" is pretty slow: if you try to display more than a few curves in a family you can see the sweep with the naked eye. It really helps to have a storage scope. It should be able to be accurately reproduced with a pretty slow ADC: maybe as low as a couple kSps; maybe 20 kSps at most? You should be able to get a good reproduction using stereo audio input to any computer. -- Jeff Dutky |
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TDS3000B 50 Ohm Termination
Hi,
Has anyone here repaired a failure in the 50 ohm termination on a TDS3054B (or TDS3000B series)? I have a fairly nice unit in which CH 2 does not turn on the 50 ohm terminator. I'm assuming the resistor is shot, but could be the relay also. I do hear the relay clicking but the actual contacts could be bad. Thanks for any advice. --Victor |
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Re: Tek PS503A problem
I took a look at my notes for the non-A version from long ago (repaired a batch of these rescued from ewaste), and there's nothing in there about dificulties with lamp access, so just go slow.
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I routinely replace incandescents with LEDs whenever I have to open 'em up for service. Here I used T-1s and changed R48 and R148 to around 15k-18k from 1.2k. A 1/4W rating is fine. I did not change R55 or R155, so the max LED current is a little on the high side, but that hasn't caused any problems. These are nice little power supplies. The voltage-dependent glow is a more useful feature than I'd initially expected. --Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 5/2/2022 17:04, ghwerl@... wrote:
I just acquired a PS503a module, very clean. Upon first powerup there are two items. First. the CM7220 incandescent lamp in the positive side appears to be burnt out, resistance checks show about 62 ohms on the negative (good) lamp and over 10K on the positive lamp. Looks like a bear to get at to replace, essentially tearing down most of the front panel. Any words of wisdom here or just be slow and careful. |
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Re: Saving 576 plots (again)
This is my point exactly about feature creep on these threads, haha
Guys, it really shouldn't be that hard. As a little proof of concept yesterday (the post hadn't been approved yet and I was itchy to find a solution) I rigged up the worlds simplest curve digitiser with a super basic transistor curve tracer I got at an estate sale a while back (my 576 still hasn't arrived). Literally all I did was add a 1 ohm sense resistor to the emitter connection and then probed across that for current and the collector for voltage into a DSO. Saved as CSV and opened as a graph without issue, looked exactly like the trace on the screen at the time and included scale. Tried the same thing with a current probe instead of a sense resistor, result looked just as good. You can take these basic ideas and optimise them a thousand ways from there, but to be honest the results were good enough that I didn't see much point digging any deeper because I had clean curves saved for later recall, which was the goal. Based on that I ordered one of those little ICP12 boards I'd heard about on here, if it produces reasonable results I'll just stick one in each text fixture I make with a few resistors to scale voltage etc and the problem should be solved. |
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Tek PS503A problem
I just acquired a PS503a module, very clean. Upon first powerup there are two items. First. the CM7220 incandescent lamp in the positive side appears to be burnt out, resistance checks show about 62 ohms on the negative (good) lamp and over 10K on the positive lamp. Looks like a bear to get at to replace, essentially tearing down most of the front panel. Any words of wisdom here or just be slow and careful.
Second, both the positive and negative side adjust only to +/- 15 volts at full cw rotation. The dual tracking control operates properly as described in the manual. The module recognizes being in a high or low power slot, however the operation is the same. I am wondering if a prior owner may have been working in OpAmps and internally adjusted R45/145 down so as not to inadvertently exceed max supply voltage for these parts. Or there might be a common problem in the reference supply, I have not yet checked any board level voltages. Anyone have any thoughts? I do have an extender cable, to work on the module. Thanks, gwerl |
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2465 Calibration Completed but boot still fails
After I successfully completed CAL 01-04, I still get a failure on boot-up. This is what it said on the scope:
ALL 00 PASS XX<F77F> So it passes everything but fails. Huh? I found in the service manual that this happens from a Cycle Error that must be cleared by running Exerciser 03 diagnostic routine (Page 6-16,17 in the service manual). After running that routine the error cleared! Woo Hoo! My 2465 is fixed! Thanks to everyone in this forum who patiently answered my questions and offered suggestions. |
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Re: 2465 Calibration
On Sat, Apr 30, 2022 at 11:21 PM, si_emi_01 wrote:
I have no overshoot when terminated at 50 Ohms and just a little when at 1 MOhm. So I did the whole vertical calibration using a 50 Ohm terminator plug and then just doubled the voltages from the waveform generator. That worked, although I had to tweak a couple of the voltages to eliminate the dreaded limit error. So I completed the calibration. But more on this below. |
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Re: Help with diagnosis of Tek 2465 Power Supply Problem
On Tue, Apr 26, 2022 at 05:39 PM, <lylejlarson@...> wrote:
1) The board layout is a nightmare. Component placement is scattered, and 90%The cross reference table listed on 4 pages before the Schematic 9 are for this purpose. It is pretty easy to locate components on the board and on the schematic this way. I found the scanning quality for Tek 2467 service manual better for this purpose. See 2) It's a complex board, conceptually. Easily one of the most challenging thatNo disagreement here! I am trying to understand it and I hope I am getting getting closer. Luca |
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Re: Help with diagnosis of Tek 2465 Power Supply Problem
How does current that initially charges C1025 flow? Is it like the following?
T1020 PIN4 -- R1020 -- C1025 -- CR1035 -- R1046 -- T1020 PIN6 This is not the only path, but seems the least resistant one. There is also a path through CR1072 and C1072, but that path will only allow C1025 to be charged to about 10V, because C1072 is about 30 times smaller than C1025. Luca |
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Re: Help with diagnosis of Tek 2465 Power Supply Problem
On 2022-05-02 5:05 p.m., lpb612 wrote:
Thank you so much Mark.If your ordinary iron is hot enough to melt it, you can remove just about 100% of the existing solder with desoldering wick. --Toby Thanks again - Luca |
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Re: Help with diagnosis of Tek 2465 Power Supply Problem
Thank you so much Mark.
I have replaced a few capacitors that I can tell or measure to be bad. I have not gone systematically, because of the limited supply. I have order a bunch of more generic ones to replace some other capacitors as needed. I am also ordering a desoldering gun. Without it, it is very hard to put the new capacitor back on, because of the remaining solder. Thanks again - Luca |
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Re: 7000 plugin socket side covers?
I almost like the idea of replacing them with modern connectors. The current "patient" is a 7514 and I don't know if it's the case with the Main Interface board in that scope, but in my 7704A, I ran into a problem with a multi-layer board for which I was not able to get a solid connection to one of the inside layers that ran from another hole to two of the pins on slots 1 and 2. I ended up having to run a separate jumper which I really didn't like but it works. if the 7514 has a multi-layer board, I'd be somewhat more hesitant to replace the connectors.
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I'm still wondering of Shapeways' SLA Accura? Xtreme? 200 might work and intend to look into that. Otherwise, I'll probably opt for some extra clamping pressure that's, perhaps, similar to what the fellow did with the FR4 material. It's too thick to fit inside where the plastic guide slides over the socket but I think if it is at least as far forward as possible, it could work. Thanks, Barry - N4BUQ ----- Original Message -----
From: "Jeff Dutky" <jeff.dutky@...> On Mon, May 2, 2022 at 09:38 AM, n4buq wrote:Yes, I had not seen this page either, and nobody mentioned it a few weeks back |
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Re: Help Needed - 547 Horizontal Timing/Trace
On Fri, Apr 29, 2022 at 07:34 PM, Stephen wrote:
----Hi Stephen, [I didn't (re)read the whole previous repair story.] Are you sure now that the sweep generator itself is not the problem? If A and B sweeps show the same problem then the problem is likely further on in the horizontal chain. To be sure you can use another scope with 10X probe to observe the waveform at the "A Sweep" front panel bus. That signal immediately follow the Miller circuit. In my 547 the sweep duration is about 10.5 ms (as should be) with amplitude about 90 V while the dead time between sweeps is about 2 ms. That's with the 547 at 1 ms/div and VAR in calibrated position, fully CW. The sweep time increases (up to 2.5X or so) when VAR is rotated CCW. Here¡¯s a short video of a 1KHz from a Type 184. You can clearly see theAlbert |
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Re: 7000 plugin socket side covers?
On Mon, May 2, 2022 at 09:38 AM, n4buq wrote:
Yes, I had not seen this page either, and nobody mentioned it a few weeks back when I was asking similar questions, so it must be fairly obscure. I'm especially interested in the possibility of replacing the connectors with modern card edge connectors, which seems like a much more permanent solution to the problem. 3D-printing the aligning end pieces seems much more doable that printing the side plates. Oddly, I have some compunction about carving up the existing connectors, even though I would be entirely replacing them in the instrument. I don't think I understand how the first fix on that page ("Adding mechanical support") was implemented: there doesn't appear to be space for the reinforcing plates between the existing side plates and the guides on the back of a 7k plug-in. The pictures are too blurry to give me a good idea of what was done, and I found the description difficult to follow. -- Jeff Dutky |
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Re: 7000 plugin socket side covers?
As a thought...
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Would the covers be 3D printable with a resin type of printer? Resin types (allegedly) have much better print resolution, but I don't know if the prints would have sufficient strength. (I don't own that type of printer, or I'd give it a whirl...) I can see where a bog standard FDM 3D printer might have resolution difficulties... David On Mon, May 2, 2022 at 8:24 AM Joel B Walker <joelandjoyce@...> wrote:
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Re: Saving 576 plots (again)
Since you have all of the "bits" needed with an LCD Display, it would be nice to be able to have an on-board USB Interface and application software with storage and overlays to display it on a desktop or laptop.
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Imagine the ease at which devices could be compared, documented, etc... I only wish Simmconn Labs had added that to my HP-8566 Spectrum Analyzer LCD kit. Ross -----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Zentronics42@... Sent: Monday, May 02, 2022 8:56 AM To: [email protected] Subject: Re: [TekScopes] Saving 576 plots (again) John, In putting in this effort in to a 576, retrofitting it for an LCD display rather than a CRT. A requirement for this project in my mind will be to delete the need for the HV transformer. This would open up the field significantly if a display could be fabricated as well as not need the -4kv and 200 Vdc supplies. It would extend the life time of the units significantly. Zen -----Original Message----- From: [email protected] <[email protected]> On Behalf Of John Griessen Sent: Monday, May 2, 2022 10:48 AM To: [email protected] Subject: Re: [TekScopes] Saving 576 plots (again) On 5/2/22 08:30, Eric wrote: I think in the rigol world last time I tried it the best resolution I Your earlier idea of using an LCD screen instead of borrowing a scope screen leaves off the electrostatic CRT display and limitations of 60 Hz AC sweeping. Two ADCs are needed, one for V one for I. and some code to overlay the up and down sweeps of collector voltage, then stop acquiring til next sweep, display the curve with "graticule" scale marks and V/div, I/div labels, and make this available to output as text data, or as an image file over the USB port. The text data is easier, (less code to write), and just pipe the data to gnuplot at the computer connected to the curve tracer. The culture shock schematics can give you an example system that is similar to look at for ideas. The HV board layout is helpful to see how the HV is divided down to record it: |
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