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Re: PG506 fast rise time
Prof. Lee,
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Aha! Thank you very much, I'm happy to learn that my expectations were wrong and the PG506 is working properly. I hoped it was something straightforward like that. thanks again, Adam On Feb 3, 2024, at 22:25 , Tom Lee <tomlee@...> wrote: |
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Re: PCB extenders with a flexible ribbon cable - looking for suggestions on construction method
On Sun, Feb 4, 2024 at 2:31?AM John Griessen via groups.io <john@...> wrote:
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Re: PG506 fast rise time
The 284 is a 70ps instrument, so the 1ns reading you report is a measurement of your scope's rise time. When driving a 1ns rise time scope with a 1ns rise time pulse, you would expect to see a 1.4ns rise time, which is pretty much what you're seeing.
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Rise times add as rss (root-sum-squared), so you can use that fact to refine measurements of rise times that are similar to that of your scope. -- Cheers Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 420 Via Palou Mall Stanford University Stanford, CA 94305-4070 On 2/3/2024 9:32 PM, Adam R. Maxwell via groups.io wrote:
However, the rise time of the fast rise setting is ~1.3 ns, shown here with 10x and normal magnification. I was using the middle BNC of the three on the bottom of the PG506, which I believe is the rising edge. |
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PG506 fast rise time
Having replaced the bad tantalum caps and shorted transistor in my PG506, it's now working in all modes. I replaced all the tantalums on the fast rise board, since one was shorted.
However, the rise time of the fast rise setting is ~1.3 ns, shown here with 10x and normal magnification. I was using the middle BNC of the three on the bottom of the PG506, which I believe is the rising edge. Just to verify I'm within the scope capabilities, I checked my Type 284, and get about 1 ns rise time: The falling edge output is a bit worse. Any ideas on what might cause this, or are my expectations/measurements just wrong? I get the same results with the internal 50 ohm termination on my 2465A and an external thru terminator, as well as a few different cables. thanks, Adam |
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Re: Seeking Advice: Is Repairing and Calibrating a Tek 464 Worth the Effort?
Nik,
It is worth restoring and calibrating. This is like the others similar to it in that the condensers and some resistors should be replaced. Clean sockets and switches. I have a 466 which is similar to yours which I recapped and put in higher power resistors. I did get it adjusted right. The bridge rectifiers were replaced with 4A types. I found the 9V zener in the power supply was bad in mine that was replaced with a BZX85B9V1. Mark |
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High-Amplitude High-Frequency Oscillations in 7704A LV Regulator
Hi Barry! Your technique so far is spot-on for troubleshooting, the good board in the troubled scope works. However, it might be useful to put the "bad" board in the good scope, if there are off-board components (like pass transistors/wiring/big resistors) associated with it. If the "bad" board works in the good scope, then the problem is definitively off board. The only caveat is that you dont want the "bad" board to blow-up the good scope. I feel there is minimal risk of this as you have cross checked all the transistors on the board. Good luck.
Regards, J.Kruth |
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Re: TDS744 (NOT TDS744A) Option Resistors and Configuration
Hello guys,
I have a 744A type and wanted to do the same ..increase bandwidth.. By accident I met a technician of tektronix and talked about this mod. He told me that the input amplifiers of a 500MHz scope could go to 1 ghz but it is not shure for every scope it is possible... After the new callibration you can see if the mod was 100% succesfull ¡§failed or passed callibtrtion*..so think before you start regards, jac pe1kxh |
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Seeking Advice: Is Repairing and Calibrating a Tek 464 Worth the Effort?
Hello Tektronix enthusiasts!
A few years ago, I snagged a Tek 464 storage oscilloscope for a mere 25€, well aware of some existing issues. Now, I'm reaching out to the seasoned minds here to help me decide if resurrecting and calibrating this oscilloscope is a worthwhile endeavor. Current Issues: On startup, the screen stays blank unless I turn time/div to xy position, play with position and press beam finder. There is not backlight I did some measurements a year back, and as far as I remember, the voltage measurements were incorrect (I don't recall the specifics or how off they were). I identified at least one diode bridge with a missing corner and slight burn marks. Calibration Questions: How complex is the calibration process for a Tek 464, especially for someone with limited experience? Are there any common calibration challenges associated with this model? Can calibration be done without specialized tools, or are there alternatives for someone working on a budget? Current Situation: At the moment, the oscilloscope seems far from operational. However, I'm keen to know if not only repairing but also calibrating it is within the realm of possibility. This Tek 464 is currently my only oscilloscope, making the prospect of getting it back in working order and accurately calibrated quite appealing. Previous Actions: I've opened it up once before, identifying a burnt diode bridge and suspecting power supply issues. Yet, my knowledge is limited, and I'm uncertain about the complexities involved in both repair and calibration. (Note: added information about no backlight, line, etc.) Specific Questions: How challenging is it to repair a burnt diode bridge on a Tek 464? Are there common issues associated with this model that I should be aware of? Considering my limited experience, is this a reasonable project for someone looking to learn and improve their electronics repair and calibration skills? Future Steps: In about a month, I plan to revisit the oscilloscope. Photo of the 464 storage oscilloscope: (a link to the only photo I have from 2019. But its off) Your insights, advice, and tips on calibration would be incredibly helpful. Thank you for taking the time to read and respond! |
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Re: High-Amplitude High-Frequency Oscillations in 7704A LV Regulator
Hi Dave,
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I looked and for a 151-0136-03, it just states it is selected. Thanks for that reference, though. I didn't realize those parameters were listed there. Barry - N4BUQ Some 153- parts have matching criteria published in Tek's Common Design Parts |
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Re: PCB extenders with a flexible ribbon cable - looking for suggestions on construction method
John Griessen
On 2/3/24 15:16, cheater cheater wrote:
Someone smart just told me to use castellations on the edge of a boardWill you sketch that? Not getting a mind picture yet... |
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Re: Tek 2445B and 2465B power supply recap and Dallas NVRAM replacements?
Hi Luca,
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I think 2465B and 2467B share the same supply schematics. Based on my experience with 2467B: - Component diagram may have C1132 and C1115 swapped (wrong). While desoldering take a note of the original value to make sure. - NTC resistors RT1010 and RT1018 drifted quite a bit on my unit and most importantly R1010 was open circuit with a burn mark, check R1019 too. I replaced them with flameproof resistors. Ozan On Sat, Feb 3, 2024 at 01:22 PM, Luca wrote:
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Re: High-Amplitude High-Frequency Oscillations in 7704A LV Regulator
Some 153- parts have matching criteria published in Tek's Common Design Parts Catalog. Look in the Diodes and Transistors volume archived at w140.com .
Dave Wise ________________________________ From: [email protected] <[email protected]> on behalf of n4buq <n4buq@...> Sent: Saturday, February 3, 2024 12:23 PM To: tekscopes <[email protected]> Subject: Re: [TekScopes] High-Amplitude High-Frequency Oscillations in 7704A LV Regulator Yes - I noticed they were selected as well but, like you say, we don't know the criteria. New 2N3053s have a range of 50 to 250 for hFE so I suppose it's a crap-shoot as to what one gets. Thanks, Barry - N4BUQ On 2/3/2024 1:11 PM, n4buq wrote:I have three transistors with which I can use to test for Q32143:I am late joining this thread, and although I have look at the previous |
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Re: PCB extenders with a flexible ribbon cable - looking for suggestions on construction method
Someone smart just told me to use castellations on the edge of a board
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to solder the flat cable to. What are your thoughts everyone? I guess I would just span the ribbon across the castellated edge, and then burn the hell out of it with a hot bar until it's soldered. Think the melting / burning insulation would pose a problem with the solder joints? Bear in mind this is just for audio. On Sat, Feb 3, 2024 at 10:49?PM Leo Potjewijd <pe1rhx@...> wrote:
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Re: PCB extenders with a flexible ribbon cable - looking for suggestions on construction method
This is a transit connector:
@John: Bin d'Aire-Dunndad, works reasonably well. Just not for 100+ pieces (= 200+ cable ends)... FPC has the disadvantage of being less flexible. For the housing: 3D printing can be succesful if the material is chosen wisely. For 200+ housings one might even be looking at injection molding,the molds can be relatively cheap if they do not need to last long. Clever design would mean a housing built with two identical parts. |
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Re: Tek 576 Curve Tracer repair
emissionlabs:
I have bad experience of silicon grease in combination with switches. The silicon floats around after some years and may end up in the contacts. This is easily seen with the silicon thermal paste that sooner or later covers a big part of the cooling flange. I saw in the HP service manual for 8340A, vol 3, page 56, that HP specify oil based thermal compound and warn about using silicon based thermal compound due to reliability issues as the TO-3 transistors are mounted in small pin-sockets. The oil based will dry with time though. The microwave oven I still have, has this silicon grease in the mechanics. After some years it became more and more difficult to set the cooking time. I who likes to see "whats inside", took the rotating digital switch apart and found this. After cleaning thoroughly it worked fine for many years until fairly recently the same thing happened again. I took it apart again and now it works just fine again. I'm not 100% sure it really is silicon in the switch, but it looks like it is. At my work we were also warned not to use it. These Tektronix push switches I have seen before in some other old equipment, and even took one switch apart for some forgotten reason. Cannot even remember where and when, quite some time ago. I think they are "standard" and you specify what combination and functionality you want. From what I understand, there were at least two US manufacturers, compatible but slightly different (color?). Bo |
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Re: Tek 2445B and 2465B power supply recap and Dallas NVRAM replacements?
Hi all
Thanks for all your inputs. I found some Excel sheets about the capacitors and will go through the boards first. Maybe I'll also do the big main board.. I don't trust any late 80s until early 00s capacitors anymore I've seen too many failed ones. When I'm done with this or hit a snag I'll come back to this thread. Regarding the Dallas, good idea recording the calibration data. I got a video with the data for the 2465B. I hope I can do the same with the other scope after I get it running again and nothing is lost yet. The DS1230Y/AB still has batteries, that would have been to easy... I found this document with several solutions for replacing the Dallas chips (after going through that PDF I'll try to find the reasoning against and then make a decision) |
Jean-Paul
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