Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
The email active link was missing a final character; when that was
included, the link works ok. And, I was successful downloading all the
data. I do agree the download command is somewhat hidden. You must click
the three-dots icon to find the download command. It will build a zip of
all the files in the folder and download that. Worked for me...
Larry I did all that, saw the .zip get built and then ? ? where the hell'd it go? Bill
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Re: Rescuing 500s from tube snatchers/scavengers - how much is it worth
I wonder how all of these vastly different tubes are all used in and every one "sounds wonderful" in his high-fi system? I don't know much about tubes, but I would think that each different tube would require careful tuning for each of the important characteristics of the circuit to get the best performance? Kind of like re calibrating a scope after major components are replaced?
-- Michael Lynch Dardanelle, AR In my view, the guy is a skank livin' large in audiophool La-La Land. Not that there aren't differences amoung tubes and not that some aren't demonstrably better than others but $US500.00 for a used, half-assedly 'tested' pair of unwarranted parts is daylight robbery. As to "tuning": audio circuitry is generally pretty simple and one or another variant of, say, a garden variety 12AX7 will meet spec perfectly well. That said, there are vast unit-to-unit differences amoung devices in respect of equiv input noise (often times an about 10 to 20dB range), microphony, heater to cathode leakage, grid current and vacuum quality in NOS parts. As well the thru-glass pins on 7- and 9-pin parts have a default hard oxide that messes up contact quality and sounds like hell. If w/o incurring righteous opprobrium I might dare link to a page on my site, you can see the difference between raw and my electropolished pins near the bottom of this page: In case anyone is interested: tubes range in equiv input noise between about 2 and 20nV/rtHz, numbers never spec'd back in the day. The top section of this page provides a wealth of information: Bill
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Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
The email active link was missing a final character; when that was included, the link works ok. And, I was successful downloading all the data. I do agree the download command is somewhat hidden. You must click the three-dots icon to find the download command. It will build a zip of all the files in the folder and download that. Worked for me...
Larry
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On 12/31/2020 4:38 PM, Bill Perkins wrote: Gosh, the link to the google drive Gerbers does not work for me. Anyone
have success downloading the various files?
Larry ????I just spent 10 frustrating minutes cursing the genius Google geeks who hacked that can o' worms together and fronted it as a done deal.
????Bill
--
Best wishes,
Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)
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Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
Jared,
Where did you get the extruded aluminum panels for the top and bottom of the unit? Were those reused from another module, or is there some way to get new parts?
-- Jeff Dutky
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Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
Gosh, the link to the google drive Gerbers does not work for me. Anyone
have success downloading the various files?
Larry I just spent 10 frustrating minutes cursing the genius Google geeks who hacked that can o' worms together and fronted it as a done deal. Bill
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Re: Tek 2465b two probes showing slightly different voltages and phases
A nanosecond just isn't what it used to be... :)
--Tom
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
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On 12/31/2020 16:27, Tom Gardner wrote: On 31/12/20 21:53, Tom Lee wrote:
Enjoy that scope, Mark -- it's an amazing instrument. Consider that it is so capable that the finite speed of light was the root cause of your delay problem! Nice to own a scope where you start complaining about light being too slow...
Here's a nice video of (Rear Admiral) Grace Hopper demonstrating the "size" of 1ns in vacuo: a piece of wire 11.8in long. In a cable it will be shorter, due to the reduced speed of light.
The 1972 portable Tek 1502 TDR is capable of resolving discontinuities 140ps apart, i.e. ~1.2in in a cable.
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Grid Bias Adjustment on 475A
I've been trying to run through the calibration process for the 475A that had a blown Z-axis amp, and I've run into trouble right off the bat. I was unable to get a visible spot on screen at the +15 V intensity level as indicated in the service manual. I had to crank the intensity up nearly to maximum, and then the trim pot (R1375) for grid bias had to be cranked to one extreme to see anything on screen.
I tried trimming up the power supply, even though everything was within spec (everything was a little low, but not out of spec, so I trimmed the +50 V rail up to +50.18V, just shy of the upper range in the service manual. All the other low voltage rails now look spot on.
I tried the same process on two other 475s (non-A) and was easily able to get a visible spot at the +15 V intensity level, as well as adjust the grid bias for a visible spot across a wide range of the grid bias trim pot.
Next, I followed the diagnostic procedure in the service manual for the Z-axis circuit on page 4-18. I set up the scope as indicated, lifted on end of CR1343, and measured TP1364 to be +6.05 V (as indicated in the SM). When I press BEAM FIND the voltage jumps up to +29.3V, which is higher than the SM's indicated +25 V. Next I checked the voltage across VR1362, which is +6.23 V, which is the indicated value. Next I removed Q1362 and checked the voltage at the base of Q1352 which measured +1.34 V, and the voltage at the base of Q1344 which measured +0.67 V, both as indicated in the SM.
After that I lifted one end of CR1341 and measured the voltage on the collector of Q1338 while turning the INTENSITY knob through its full range of travel; the collector voltage measured from +7.6 V to -1.1 V (the later being a little short of the indicated -1.3 V from the SM). I also checked the voltage at the base of Q1332 which measured -1.75 V (as indicated). I then removed Q1332 and disconnected J1333 and J1334, and measured the collector voltage on Q1338 again as I turned INTENSITY through its range; again +7.6 V to -1.1 V
So I'm seeing a slightly higher than expected voltage when pressing BEAM FIND at TP1364, and a slightly narrower than expected range of voltage at the collector of Q1338, with the "top" of the range falling about 200 mV short of what the SM indicates. I'm not sure that any of this explains why I can't do the grid bias adjustment as indicated in the manual.
Just for good measure I also swapped the CRT from one of the 475s that I was able to successfully perform the grid bias adjustment on with the CRT in the 475A (they happened to be exactly the same part number, even though the SM for the 475 says that the CRT should be PN 154-0677-00, what I found in my donor was 154-0677-10, which is the correct part for a 475A), but the trouble did not follow the CRT.
I guess I could still check to see if the trim pot (R1375) appears to be in spec (if it isn't it would explain a lot), but I'm otherwise at my wits end.
Any help or advice would be appreciated.
-- Jeff Dutky
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Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
Ok, I'll ask OSH Park for a quote and compare quotes.
Larry
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On 12/31/2020 4:22 PM, Jim Ford wrote: Yes, I have used OSH Park before as well.? Not sure where they are located, so I hesitated to mention them.? I try to avoid sending any of my dollars to China these days.? ?JimSent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Harvey White <madyn@...> Date: 12/31/20 3:50 PM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] I built a TM500 mainframe tester, and updated the design. Someone...
--
Best wishes,
Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)
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Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
Why would using Chinese made boards require a different physical design?
The author, Jared Cabot, used PCBWay, surely fab'd in China, and provided Gerber files for each of the four PWBs. Since several here want boards sets, the simple thing seems to be order them from PCBWay. Delivery timing is really not an issue and shipping cost for blank boards can't be that much... I will ask PCBWay for a quote.
Larry
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On 12/31/2020 3:50 PM, Harvey White wrote: Oshpark is very good, with 3 board per order for the price of 5 dollars per square inch.? I should point out that the board set I saw would be rather expensive.
Their boards are purple, and ENIG (gold plated)
The typical Chinese made boards may have a size limitation for lowest cost, and the lowest price will be for HASL (Hot Air Solder Leveled) boards.? On the other hand, a 100 mm square board can be had for 4.90, and that's for 10 of them.? Shipping with DHL is likely 20 to 25 dollars, but that price range covers 5 different boards, all 100 mm in size or less.
Using Chinese made boards will require a different physical design.
Harvey
On 12/31/2020 6:33 PM, Michael W. Lynch via groups.io wrote:
Are there any US PCB? Houses that we could contact?? Or are they all in China?? I have never done boards before.? I would be willing to help out with the process.
--
Best wishes,
Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)
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Re: Tek 2465b two probes showing slightly different voltages and phases
On 31/12/20 21:53, Tom Lee wrote: Enjoy that scope, Mark -- it's an amazing instrument. Consider that it is so capable that the finite speed of light was the root cause of your delay problem! Nice to own a scope where you start complaining about light being too slow...
Here's a nice video of (Rear Admiral) Grace Hopper demonstrating the "size" of 1ns in vacuo: a piece of wire 11.8in long. In a cable it will be shorter, due to the reduced speed of light. The 1972 portable Tek 1502 TDR is capable of resolving discontinuities 140ps apart, i.e. ~1.2in in a cable.
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Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
Yes, I have used OSH Park before as well.? Not sure where they are located, so I hesitated to mention them.? I try to avoid sending any of my dollars to China these days.? ?JimSent from my Verizon, Samsung Galaxy smartphone
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-------- Original message --------From: Harvey White <madyn@...> Date: 12/31/20 3:50 PM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] I built a TM500 mainframe tester, and updated the design. Someone might find this useful? Oshpark is very good, with 3 board per order for the price of 5 dollars per square inch.? I should point out that the board set I saw would be rather expensive.Their boards are purple, and ENIG (gold plated)The typical Chinese made boards may have a size limitation for lowest cost, and the lowest price will be for HASL (Hot Air Solder Leveled) boards.? On the other hand, a 100 mm square board can be had for 4.90, and that's for 10 of them.? Shipping with DHL is likely 20 to 25 dollars, but that price range covers 5 different boards, all 100 mm in size or less.Using Chinese made boards will require a different physical design.HarveyOn 12/31/2020 6:33 PM, Michael W. Lynch via groups.io wrote:> Are there any US PCB? Houses that we could contact?? Or are they all in China?? I have never done boards before.? I would be willing to help out with the process.>
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Re: Spectrum analyzer Tektronix 7L13 on mainframe Tektronix 7603
Yes, finding oddball crystals is a challenge. I very much doubt that you will find 52.5 (or 55, for that matter) MHz crystals as standard stock items, so your choices are limited. If you can't find them as off-the-shelf or surplus items from the usual sources (including ebay), you'll have to have them made.
So, your next question would be: Who makes custom crystals? The number of good answers is unfortunately diminishing with time, as vendors disappear. About the best recent discussion I've seen is a couple of years old:
Scroll down near the bottom of the first page. A poster "drussell" offers a comprehensive list of potential vendors. Warning: Custom crystals tend to be rather expensive. You may spend as much or more just for the crystal than for a nanoVNA. :)
In discussions with potential vendors, let them know that you would be happy with a third-overtone crystal, if they ask. Fundamental-mode crystals for that frequency range exist, but are incredibly expensive. Plus, the TR50x gens already use third-overtone crystals. No need to pay a surcharge on top of a surcharge.
Good luck!
-- Tom
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
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On 12/31/2020 12:16, Attilio wrote: Hi everybody,
where can i find the 52.5 MHz crystal? It is hard to find!
Thanks and happy new year
Attilio
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Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
Oshpark is very good, with 3 board per order for the price of 5 dollars per square inch.? I should point out that the board set I saw would be rather expensive.
Their boards are purple, and ENIG (gold plated)
The typical Chinese made boards may have a size limitation for lowest cost, and the lowest price will be for HASL (Hot Air Solder Leveled) boards.? On the other hand, a 100 mm square board can be had for 4.90, and that's for 10 of them.? Shipping with DHL is likely 20 to 25 dollars, but that price range covers 5 different boards, all 100 mm in size or less.
Using Chinese made boards will require a different physical design.
Harvey
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On 12/31/2020 6:33 PM, Michael W. Lynch via groups.io wrote: Are there any US PCB Houses that we could contact? Or are they all in China? I have never done boards before. I would be willing to help out with the process.
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Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
Several at least here in Southern California.? For just this type of small order.? For volume production, China is of course the 800 pound gorilla.? Check out Advanced Circuits, TTM, or Summit here in the States.? HTH.? Jim Ford?Sent from my Verizon, Samsung Galaxy smartphone
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-------- Original message --------From: "Michael W. Lynch via groups.io" <mlynch003@...> Date: 12/31/20 3:33 PM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] I built a TM500 mainframe tester, and updated the design. Someone might find this useful? Are there any US PCB? Houses that we could contact?? Or are they all in China?? I have never done boards before.? I would be willing to help out with the process.-- Michael LynchDardanelle, AR
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Re: Rescuing 500s from tube snatchers/scavengers - how much is it worth
On Thu, Dec 31, 2020 at 12:19 AM Roy Thistle <roy.thistle@...> wrote: On Tue, Dec 29, 2020 at 09:50 PM, Bill Perkins wrote:
Good, clean data on the 5687/6900 is available here
Posting a link to tube datasheets ... together with links to tube sellers
who freeze tubes... that won't cause me to conflate scientific evidence
with anecdotal evidence... or believe without any scientific evidence
whatsoever... that freezing vacuum tubes makes them sound better.
If we take the tubes out of our 500s (sans the CRT) and cryogenically
treat them... will the signals displayed on the 500 screens look better?
I tried cryogenically treating the tubes in a 561A Now all my sine waves look like so... I'm not sure if I want to calibrate it back out..... :-)
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Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
Are there any US PCB Houses that we could contact? Or are they all in China? I have never done boards before. I would be willing to help out with the process.
--
Michael Lynch
Dardanelle, AR
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Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
Yes,
-Dale
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On Dec 31, 2020, at 18:12, Larry McDavid <lmcdavid@...> wrote:
?Anyone interested in buying sets of boards to share?
Larry
On 12/31/2020 11:27 AM, Jared Cabot via groups.io wrote:
Hi all,
I have been accumulating TM500 modules and mainframes for a little while, so I recently finished building an 067-1201-99 TM500 mainframe tester from the Tek construction notes floating around.
I updated the design somewhat and designed it for simplified construction (Not a single wire to strip and solder!) and I thought someone here might be interested in taking a look or even building one themselves.
Here's a link to the youtube video:
And here's a link to the google drive with all the gerbers and schematics and stuff. I went so far as to rewrite the manual with the alterations and corrections included.
Direct link to the new manual:
Let me know what you think, and let me know if you see any errors that need correcting. :)
Regards
Jared.
--
Best wishes,
Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)
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Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
The final "-" was missing in the hot link; with that added, the link works.
Larry
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On 12/31/2020 3:12 PM, Larry McDavid wrote: Anyone interested in buying sets of boards to share?
Larry
On 12/31/2020 11:27 AM, Jared Cabot via groups.io wrote:
Hi all,
I have been accumulating TM500 modules and mainframes for a little while, so I recently finished building an 067-1201-99 TM500 mainframe tester from the Tek construction notes floating around.
I updated the design somewhat and designed it for simplified construction (Not a single wire to strip and solder!) and I thought someone here might be interested in taking a look or even building one themselves.
Here's a link to the youtube video:
And here's a link to the google drive with all the gerbers and schematics and stuff. I went so far as to rewrite the manual with the alterations and corrections included.
Direct link to the new manual:
Let me know what you think, and let me know if you see any errors that need correcting. :)
Regards
Jared.
--
Best wishes,
Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)
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Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
Larry,
I am interested in a group buy of the board set.
Thanks,
Shaun M.
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-----Original Message----- From: [email protected] < [email protected]> On Behalf Of Larry McDavid Sent: Thursday, December 31, 2020 16:13 To: [email protected]Subject: Re: [TekScopes] I built a TM500 mainframe tester, and updated the design. Someone might find this useful? Anyone interested in buying sets of boards to share? Larry On 12/31/2020 11:27 AM, Jared Cabot via groups.io wrote: Hi all,
I have been accumulating TM500 modules and mainframes for a little while, so I recently finished building an 067-1201-99 TM500 mainframe tester from the Tek construction notes floating around.
I updated the design somewhat and designed it for simplified construction (Not a single wire to strip and solder!) and I thought someone here might be interested in taking a look or even building one themselves.
Here's a link to the youtube video:
;data=04%7C01%7C%7C40227a80b85e43231ba308d8ade187f9%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637450531445615030%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=zMJHqQdwdPvoSuICx%2BoFCyeirkm22N4SoXlBrecdNjs%3D&reserved=0
And here's a link to the google drive with all the gerbers and schematics and stuff. I went so far as to rewrite the manual with the alterations and corrections included.
;data=04%7C01%7C%7C40227a80b85e43231ba308d8ade187f9%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637450531445615030%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=m4yXNeErC6GNMwHIouWyCxe1FLYNKYdY%2BvngHZQzZMU%3D&reserved=0
Direct link to the new manual:
;data=04%7C01%7C%7C40227a80b85e43231ba308d8ade187f9%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637450531445615030%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=A%2B%2F%2Boa%2F3G4jzT18wrWcEhZ%2BYEsAAReNBeDCyXSy6dM0%3D&reserved=0
Let me know what you think, and let me know if you see any errors that need correcting. :)
Regards
Jared.
-- Best wishes, Larry McDavid W6FUB Anaheim, California (SE of Los Angeles, near Disneyland)
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Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
Yeah, I could be convinced into a set.
Board costs aren't so bad, but the shipping can rack up some charges. If you
can get a quantity at least it works out to something reasonable per board.
Then there's the Dennis problem - distribution to the individual member :-)
Paul
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On Thu, Dec 31, 2020 at 03:22:33PM -0800, Michael W. Lynch via groups.io wrote: On Thu, Dec 31, 2020 at 05:12 PM, Larry McDavid wrote:
Anyone interested in buying sets of boards to share?
Larry
I would be. I would want someone with experience dealing with a PCB House to make it happen.
--
Michael Lynch
Dardanelle, AR
--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@... | Unix/Linux - We don't do windows
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Bill Perkins
Michael W. Lynch
Shaun M