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Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?

Jared Cabot
 

I ordered my rotary switch from Digikey, looks like there are 100 in stock with a little bit of a price break for multiple purchases.
Might be worth looking around for cheaper prices, I didn't ask the manufacturer for direct pricing, but that might be worth the time spent to send an email to see if cheaper pricing is a possibility.

https://www.digikey.com/en/products/detail/grayhill-inc/71BDF30-02-2-AJN/98685


Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?

Larry McDavid
 

Six list members have said they want to participate in a group buy of these board sets. Those are:

ML
PA
SM
DC
HB
GL

I've asked Jared for clarification on some points and for help ensuring the order is placed correctly. I'm waiting to hear from him.

I'm inclined to place the order with the same board house Jared used. I'm not willing to go into a lot of competitive bidding on board cost! I don't know the cost of a set of four boards but it can't be that much...

I live in Southern California and am retired so I can manage a group buy, with reimbursement via PayPal Friends and Family. There is a very special PWB-mount rotary switch required; I may buy a lot of those to ensure availability so that would likely be part of the board set purchase. Be aware this is a $25 switch! Many of us have other standard parts available so I'm not enthusiastic about buying other parts.

So, think about really wanting to build one of these testers and let's see if we can make a group purchase work.

I'm currently building a GPSDO into a TM500 proto module. But, any non-working TM module can be bought and stripped to provide the chassis structure for this tester. The PWB set makes is easy...

I welcome your constructive comments. Note the cost of the rotary switch stated above.

Larry

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:
https://www.youtube.com/watch?v=Afwqtc6Fxd4

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.
https://drive.google.com/drive/folders/1yj52Z_BtGZ7Q9BB2jS9Lf2Uz39turS4-

Direct link to the new manual:
https://drive.google.com/file/d/1iqpcqheb01qMioQwcUhyWv6A37v2HPro/view?usp=sharing

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)


Re: Grid Bias Adjustment on 475A

 

I have not examined the grid bias trim pot (R1375) yet, so I don't know what voltages it sees. Like I said, if it turns out that the trim pot has drifted out of spec that would explain a lot of what I'm seeing. I'll see what I can measure straight away.


Re: Off topic inquiry

snapdiode
 

What do you mean by chip? 74LS logic and SRAMS can be tested with the TL866 II device programmer.


Off topic inquiry

ken chalfant
 

Greetings,

Allow me to seek some owner/user comments as well as alternate suggestions.

I am considering acquiring an IC tester/identifier instrument. Currently, on-line I have found a very limited selection - actually just one unit - a Chinese built YBD868.

I have been unable to find any useful information regarding this thing. The very few on-line videos are rather worthless. They are either void of any operational demonstrations or show the unit as completely unresponsive.

Does anyone have personal experience with this unit and if “yes” I would be very grateful for an accurate assessment.

Additionally, if there are other IC test and identification units available, which I have simply not discovered, I would greatly appreciate recommendations.

I wish all of us a much better 2021 than this year has been.

Wherever in the world you might live I hope 2021 becomes you best year thus far with many fantastic years to follow.

Regards and best wishes!

Ken


Re: Grid Bias Adjustment on 475A

Ananda
 

Sorry! that should be 50 volts. Not 150 volts!


Re: Grid Bias Adjustment on 475A

Ananda
 

On Thu, Dec 31, 2020 at 04:36 PM, Jeff Dutky wrote:


I also checked the voltage at the base of Q1332 which measured -1.75 V (as
indicated).
The diagrm I have for 475A has the Q1332 base grounded. I am not sure about the readings you have mentioned. I have not gone through the whole manual but just looking at the schematic only.

Also, do you have the 150 volts on one leg of the R1375 trim pot?


Re: Tek 2465b two probes showing slightly different voltages and phases

Tom Lee
 

Yes, it works better in US units -- "1ns per foot". "3.3ns per meter" just doesn't quite have the same mnemonic quality.

--Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 12/31/2020 18:41, Steve Hendrix wrote:
At 2020-12-31 07:27 PM, you wrote:
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. https://hackaday.com/2012/02/27/visualizing-a-nanosecond/
Wow, that brought back a memory - I attended her talk in person when I was a cadet at the USAF Academy, and that 11.8" has always stuck with me and been quite useful. That would have been about 1977.

Steve Hendrix



Re: Tek 2465b two probes showing slightly different voltages and phases

Steve Hendrix
 

At 2020-12-31 07:27 PM, you wrote:
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. https://hackaday.com/2012/02/27/visualizing-a-nanosecond/
Wow, that brought back a memory - I attended her talk in person when I was a cadet at the USAF Academy, and that 11.8" has always stuck with me and been quite useful. That would have been about 1977.

Steve Hendrix


Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?

Glenn Little
 

Me too.

Glenn

On 12/31/2020 6:31 PM, Dale Chayes wrote:
Yes,

-Dale


On Dec 31, 2020, at 18:12, Larry McDavid <lmcdavid@lmceng.com> 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:
https://www.youtube.com/watch?v=Afwqtc6Fxd4
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.
https://drive.google.com/drive/folders/1yj52Z_BtGZ7Q9BB2jS9Lf2Uz39turS4-
Direct link to the new manual:
https://drive.google.com/file/d/1iqpcqheb01qMioQwcUhyWv6A37v2HPro/view?usp=sharing
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)





--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@arrl.net AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"


Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?

Jared Cabot
 

To answer a few other questions:

I used a blank module kit to build this project, I lucked into one when buying a 'mainframe with modules fitted' at Yahoo Auctions so put it to good use. But I don't see why any old chassis from an otherwise unrepairable TM500 module couldn't be used.

The front faceplate PCB needs to be made from 1mm PCB rather than the usual 1.6mm, black silkscreen on white solder mask, but this is easily done by any Chinese manufacturer. I know PCBWay and JLCPCB can do it as they both manufactured this sort of thing for me in the past.

I can't comment on actual costs as such as the PCB's were sponsored, but matte black from PCBWay is rather expensive so the more standard colours (like green etc) will help save cost. The white for the front faceplate shouldn't raise costs much (or at all) though, so that shouldn't be much of a concern.
The large PCB does raise the cost a little, but it's not too bad from the Chinese manufacturers, and when divided out to a group buy, the individual cost should be pretty manageable.

I just uploaded the files to the files section here too, to make it easier to download for anyone having trouble with google drive (seems google groups isn't compatible with some of the URL's generated by Google Drive, who would have thought??)
https://groups.io/g/TekScopes/files/Tek%20TM500%20Power%20Module%20Tester%20067-1201-99%20New%20Ver.
Hopefully that link works, it's in the files section anyway. :)


Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?

Jared Cabot
 

Hi,

Wow, I didn't expect such a big response. :D haha

As for production of PCB's, I did use PCBWay as they are a sponsor of my Youtube channel, however, they are a slightly more 'premium' Chinese manufacturer.
Using JLCPCB or Seeed Studio (with 3 e's) will be cheaper and still have very good quality.

Gold plating is a good idea for the Main PCB, and a manufacturer that can chamfer the card edge connector is a good idea too. JLCPCB and PCBWay can do this (it's a minimal extra cost per PCB) but I think Seeed Studio couldn't last time I checked.
I have used JLCPCB extensively in the past, their prices and quality are quite good.

I'm not quite in a position to run a group buy myself as I live in Japan, so shipping and logistics would be more expensive and difficult than if someone in the USA did it instead. However, I am more than happy to provide 'technical support'.

Just let me performance check my unit first to make sure I have it all working 100%, I'm a bit paranoid that I might have a gremlin hiding somewhere. :D haha

Anyway, I'm glad you all like it. I have a few more ideas for some similar projects in the future so stay tuned. :)


Re: Fun with the type S plugin

Morris Odell
 

Thanks everyone for your comments.

This plugin was an interesting mix of tube and transistor circuitry. I think it is one of Tek's first attempts to use transistors in their instruments wherever possible.
It certainly uses some early Ge pnp transistors in less critical areas. The lowest 2N number in it is a 2N270 which is an emitter follower for the shift voltage applied to one side of the vacuum tube differential output amplifier. The multivibrator transistors were 2N1377's and the trigger amp is specified as a 2N1631 which had been replaced with a AC128 which is a lot slower but seems to work. All the tubes in the plugin were OK despite their age.

The "magic" in this plugin is contained in the mercury wetted relay sealed inside the glass vial. I not so sure it is pressurized.
It is pressurised and both the S and 109 manuals warn about the explosion risk. The 109 manual mentions the limited lifetime but not the S. I checked the Tek part numbers in the manuals to see if they used the same part and it was indeed the same one. It would have been an interesting challenge to try to make up a substitute fast rise pulser using modern parts if the reed was faulty.

I switched on first time my "R type" plug in which measures transistor risetimes.
I have one of these too. I last used it to check the transfer times of optocouplers I wanted to use to transfer video pulses to a CRT grid.

Even though the unit seems to work well there are some glitches and I suspect some of the precision resistors in it have drifted over the years. Replacing them will not be easy and I might not do it at all. Where does one find a 43.4K or 69.5K precision resistor these days?

Cheers,

Morris


Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?

Harvey White
 

On 12/31/2020 7:32 PM, Larry McDavid wrote:
Why would using Chinese made boards require a different physical design?
money, simply money.

using SEEED studio as an example, a 113 mm by 246 mm board, HASL (roughly a complete inside of plugin, is 65 dollars for 10, 48 dollars for 5.  ENIG goes to 94 dollars/10 and 75 dollars for 5.

a 4 by 4 board, HASL, is $4.90 for 10.  same price for 5.


The board interface to the frame, 113mm by 52 mm, is roughly 23 dollars HASL lots of 10, 19.00 HASL lots of 5.

The main board can be done as a 100mm by 100 mm board,

The front panel board can be made within the 100 x 100 mm range.


So: HASL, 6.50  for the main board if full size.  otherwise 2.30 and 50 cents for board connector (can be used for different designs), and main board.... $2.80.

and if you don't get it exactly right the first time, the costs mount up.

This neglects the front panel board(s) which will fit within the 100 * 100 mm promotional price.

Harvey




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


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.




Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?

Larry McDavid
 

The downloaded files go into your Windows Downloads folder; check near the top of the folder tree in Windows Explorer. If you are using an Apple computer, you are on your own...LarrySent via the Samsung Galaxy S10

-------- Original message --------From: Bill Perkins <sales@pearl-hifi.com> Date: 12/31/20 5:03 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] 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


Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?

Harvey White
 

Some minor fitting and stuff says that either the TM500 shell will work (best), or the TM5000 shell (likely less available).  I think that the 5000 series scope extrusions are the same width and have the same slots in them (but are likely to require some machining), and the 7000 series scope frames, while too long (and can be cut down), would need more machining.  What you do for latches is up to you.

The TM500 "universal" shells have brackets punched and bent in to support the boards.  They may need to be bent a bit.

The 7000 series have the same basic punches (across the 7000 series), but different holes and spaces.  Some different adjustments need to be made.

Harvey

On 12/31/2020 7:39 PM, Jeff Dutky wrote:
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





Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?

J Hunt
 

Michael,

I have for many years and many projects used Sunstone Circuits, located in Mulino Oregon. They do excellent work and have great customer service. They accept Gerber files and also have their own free layout software, PCB123. They are setup for prototype and production quantities.

John Hunt
Portland, OR
**********************
Michael 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.

--
Michael Lynch
Dardanelle, AR


Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?

Bill Perkins <sales@...>
 

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


Re: Rescuing 500s from tube snatchers/scavengers - how much is it worth

Bill Perkins <sales@...>
 

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:

https://www.pearl-hifi.com/03_Prod_Serv/Cryo/Cryo_Intro.html

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:

https://www.pearl-hifi.com/03_Prod_Serv/Cryo/CryoValve_Tech_Info.html

Bill


Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?

Larry McDavid
 

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

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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