Date   

Re: Waking a slumbering 475

Weathers, W
 

Ah, yes. My mistake. I had seen a portion of this procedure on 5-25, but somehow missed the low line indicator bit on 5-26. As a result, I thought that bit must have been somewhere else.


Re: Waking a slumbering 475

Weathers, W
 

Thank you Harvey for the explanation. You've given me a good jumping off point for more reading.


Re: CSA, UL/ULC and CE approvals for Tek gear

Roy Thistle
 

"excepted from" ... not "excepted form"


Stan Griffiths estate sale

David DiGiacomo
 

Sorry if this has already been mentioned, but Stan's daughter is trying to clear out his collection by February 27.

No connection except I read about it on Facebook:

https://www.facebook.com/groups/oldtekscopes/permalink/878380719616768

There are some photos there, and a note that there will be no shipping :(


Re: Tek 465B ch 2 var broken coupler repair

jhalbrecht
 

Hi All,

I've completed the repair of the Ch. 2 VAR coupler.

Cyanoacrylate  glue up didn't work, coupler broke again in the same spot surprisingly quickly.

I ordered a couple straight through couplers from The Robot Shop and ePay but they still haven't arrived, I became impatient and continued the repairs with what I had received.

I wanted to try some automotive vacuum tube, but found it too difficult to get it placed as I wanted to accomplish the repair without removing PCBs. I did loosen one PCB that gave me enough clearance to get the old part out and install the replacement.

Big thanks to Michael!
who sent me 1/3 of the coupler that matched up to the two thirds of mine that were undamaged. I had been apprehensive about replacing the coupler with the same part thinking it would probably fail as mine had. But I'm thinking someone just tightened that one too much, because with a gentle snug of the set screws the replacement coupler felt strong and functions fine.

Thanks everybody.

  - Jeff

On 1/30/2021 10:10 AM, jhalbrecht wrote:
On 1/27/2021 12:20 PM, jhalbrecht wrote:
I have a 465B that is looking good and running well, except that the coupler for ch 2 amplitude var coupler is broken.

Check these two tweets in a twitter thread for images of the broken part including an image from a USB inspection scope.
https://twitter.com/jhalbrecht/status/1353826933977485314?s=20
https://twitter.com/jhalbrecht/status/1354137517499400192?s=20
Check the above twitter thread for updated images...

Bottom line - so far - Nope :-( my JB Weld plus baking soda reinforced Cyanoacrylate not even close and certainly no cigar! :-(

I tried some _normal_ shrink wrap on the shaft, It was too easy to pull off.

I bought one of the two of two sold Tek couplers on ePay, not particularly optimist about using a used part of a poorly designed coupler.

I have some straight through couplers coming from the Robot Shop, and other source. Although the shaft is nylon providing electrical isolation there probably will be too much mechanical bind.

I think this would be a great new part, Yes I can afford $25 buck$, but I don't like it!... Check this part out. 1/8" id on both ends
https://www.huco.com/shop/couplings/oldham-coupling-1/oldham-coupling-2/500-06

Interesting McMaster-Carr page
https://www.mcmaster.com/flexible-shaft-couplings/clamping-vibration-damping-precision-flexible-shaft-couplings-11/

I have some other inquires out and will summarize if useful.

There were some great suggestions and discussion. Thank you all.
Keith suggested I could probably be forgiven if I tried glue. I didn't try... but glad for the first reply!
Quad suggested a cable time, which I hadn't thought of.., then linked to marine grade heatshrink with adhesive which I immediately bought to have on hand https://www.amazon.com/Wirefy-275-Heat-Shrink-Tubing/dp/B084GWYX42
Keith shared what I think is the proper new part to do the repair https://www.huco.com/shop/couplings/oldham-coupling-1/oldham-coupling-2/500-06 and he bought one and easily fitted it with a couple strokes of a file.
Quad shared a link to a brass traditional universal coupler https://www.ebay.com/itm/162691768380 I ordered a couple.
Jeff Dutky shared the now zero stock Tek part on ePay
Ed warned to be sure of electrical isolation. The shaft on my 465b is nylon
Eric suggested a part on Amazon, I couldn't find a 1/8" version. I'm pretty surprised I couldn't find it on Amazon, they had a lot of couplers..

O.K. the project is on hold until a few of these parts come in. Thanks again for the comments and suggestions.

  - Jeff

--
Jeff Albrecht KF7CRU @jhalbrecht


Re: Waking a slumbering 475

Mlynch001
 

On Wed, Feb 10, 2021 at 05:32 PM, Weathers, W wrote:


You mentioned that running the 475 up slowly on a variac is one of the
performance test procedures. Do you happen to know where this procedure is
documented? I would be interested in reading the procedure.
Look on Page 5-25 and 5-26 of the 475 manual. They do not tell you to start from 0 volts. You start at 115 and drop the voltage until the “low voltage” light illuminates on the front panel. Supposed to come on about 103 volts on the auto transformer. This is in the section that deals with LVPS ripple as well.

--
Michael Lynch
Dardanelle, AR


Re: CSA, UL/ULC and CE approvals for Tek gear

Roy Thistle
 

On Wed, Feb 10, 2021 at 10:34 AM, walter shawlee wrote:


It is also why so much gear has an external wall-wart power supply (with an
approval), to avoid the need for specific equipment approval.
Usually... that gear falls under so called "Class 2" devices ... which are excepted form (and defined in) the jurisdictional regulatory requirements, here in the colonies.


Re: Tek 1A5 and 132 on eBay for 85 bucks

snapdiode
 

Now it says "This listing was ended by the seller because the item is no longer available."

The original listing is still visible and it is not a multiple item auction.

I'm sad that the bargain is no longer available.


Re: CSA, UL/ULC and CE approvals for Tek gear

Michael A. Terrell
 

John Williams wrote:
The organizations such as UL and CSA or CE were no doubt founded long before there were many imports of equipment. Now who knows where anything comes from, including your car. So I would imagine that enforcement would be next to impossible. But getting back to Walters op it would seem that all requirements for any domestic producers of test equipment would have the necessary approvals for any use, such as schools and labs. I also believe CSA and UL were not government organizations but some sort of independent entities. But I do not know that.
Yes, UL is independent The NEC (National Electric Code) was also created by insurance company to set minimum safety standards. They operate on the other end from UL but both are intended to prevent fires and electrocutions. UL doesn't test for other safety issuse, like sharp edges or corners, or parts that can break off unless that will expose voltages over 24 VAC.

It's no fun trying to educate fools, who claim they have been electrocuted many times.


Re: CSA, UL/ULC and CE approvals for Tek gear

John Williams
 

I would have to agree with you. A check shows my 2200 and 2400 scopes have UL and CSA stickers. However none of my older tube scopes have any stickers for either organization. I would have to surmise that they could indeed have some sort of exemption or even a blanket approval. A mystery indeed.


Re: Waking a slumbering 475

Harvey White
 

Variacs and regulators may or may not be a good idea.  Depends a lot on what kind of regulator it is, and what it does, when.

For a linear regulator, once the input voltage (courtesy of the variac) gets high enough, the regulator starts to connect, and essentially runs as a dead short (output too low!  decrease resistance!).  Since the output voltage of the regulator is way too low, the output becomes whatever the input voltage is, minus whatever drops there are in the regulator circuitry.

Generally, IMHO, the regulator doesn't care and this doesn't bother the regulator.  What the driven circuitry manages to do with the voltages (that are perhaps not balanced), that's up to that circuitry.

For a switching regulator, the subject is a bit different, and I'm simplifying.

For a switching regulator, there are two input conditions, generally:  1) input is too low, pass transistor turns on, never turns off and 2) input is acceptable (may be too low, but the transistor is switching).

For any pass transistor in a switching regulator, in general, the thing is either off (no power dissipation), or on (minimal, but designed for, power dissipation).  In these cases, the power transistor is likely to be fine.  The amount of on time vs off time controls the output voltage.  The closer you push the regulator to its limit (low input voltage) the more time the pass transistor spends on.

Now we have to consider the design of the regulator, sorry, but there are different designs and they behave differently.

If the regulator is on only for a certain time, then must switch off, then the regulator is generally going to be able to handle the situation *because* the transistor should be designed to get rid of that power....  Note the word should.

Now suppose that the regulator turns on the switching transistor, but only when the output voltage gets above the desired value. Next we have to assume (and it's not a bad assumption) that the regulator is running at a lower duty cycle, which means that it can handle the 75% or so on time, but over that, well, maybe not.

What happens in the last situation (and especially if there's no current limiting at all!) is that the transistor turns on completely, too much current flows, and the transistor overheats.

In the normal "turn on the power and see if it smokes" kind of situation, the input voltage goes through the "NOT WORKING" to the "ON FULL" to the "REGULATING" stage fast enough that the transistors involved don't overheat.

I'm sure that there are more scenarios, but this is one.

Each scenario does assume that the parts are rated for the worst case current, have sufficient power heat sinking for worst case situations, and so on.

A bunch really depends on the assumptions that the power supply designer made when he/they designed the supply.


Harvey

On 2/10/2021 6:32 PM, Weathers, W wrote:
Jeff,

Someone had suggested to me ages ago that powering a long-stored scope on a voltage ramp, as a one-time thing, would help reform the electrolytic capacitors. I am trying to ascertain whether that is a common practice. It seems there are various opinions on whether this is a good idea.

One group member privately messaged me to say (I am paraphrasing here) that running the scope on a variac, well below the expected regulated voltage, was a bad idea. He noted that the regulators were not designed to run at exceedingly low voltages.

You mentioned that running the 475 up slowly on a variac is one of the performance test procedures. Do you happen to know where this procedure is documented? I would be interested in reading the procedure.

Ward





Re: CSA, UL/ULC and CE approvals for Tek gear

ron amundson
 

Back in the 80's, it was a rare piece of Tek equipment that had a UL, or CSA mark, as there were research / commercial exemptions. In some cases, there wasn't an easy way to meet safety requirements, and at the same time eek out the last bit of performance from some research gear. In other cases, it was market demand, ie certs for the most part didn't matter to users prior to the 90's. Once demand for certs picked up, especially in the European domain, good manufacturers went ahead and jumped the compliance hoops. Other manufacturers, invested in label printers. The Chinese Export sticker is nothing new. FP was selling UL electrical panels, even though their panels could not pass the test criteria... but they had good lawyers, so houses burned down, but they were never forced to recall them.

We had an inhouse safety lab at work, where we'd pre-qualify our gear before sending it out for agency approval. Every once in a while, we'd run some other manufacturers gear through the test sequence, some did really well, others, well, they blew in a spectacular fashion, where as others would just let the smoke out, even with the certifying labels/documentation.

I think if you need certs to donate gear, pretty much anything prior to 1985 is off the table, as would highly specialized gear even if its newer. Certifications and documentation make bean counters happy, as its a no-go type of decision, even though said equipment with a fake label can still be putting students at risk. Consider all the faked CAT III and CAT IV dmms out there, many of which are still being built and imported with ease.

On Wednesday, February 10, 2021, 05:28:21 PM CST, John Williams <books4you4@mail.com> wrote:

The organizations such as UL and CSA or CE were no doubt founded long before there were many imports of equipment. Now who knows where anything comes from, including your car. So I would imagine that enforcement would be next to impossible. But getting back to Walters op it would seem that all requirements for any domestic producers of test equipment would have the necessary approvals for any use, such as schools and labs. I also believe CSA and UL were not government organizations but some sort of independent entities. But I do not know that.


Re: CSA, UL/ULC and CE approvals for Tek gear

Roy Thistle
 

On Wed, Feb 10, 2021 at 03:28 PM, John Williams wrote:


organizations such as UL ... were no doubt founded long before there
were many imports of equipment.
UL 1894
ULC (independent organization, in Canada) 1920


Re: Waking a slumbering 475

Weathers, W
 

Jeff,

Someone had suggested to me ages ago that powering a long-stored scope on a voltage ramp, as a one-time thing, would help reform the electrolytic capacitors. I am trying to ascertain whether that is a common practice. It seems there are various opinions on whether this is a good idea.

One group member privately messaged me to say (I am paraphrasing here) that running the scope on a variac, well below the expected regulated voltage, was a bad idea. He noted that the regulators were not designed to run at exceedingly low voltages.

You mentioned that running the 475 up slowly on a variac is one of the performance test procedures. Do you happen to know where this procedure is documented? I would be interested in reading the procedure.

Ward


Re: Maybe OT? TELEQUIPMENT CT71

Stephen
 

Thank you Dave. Good points.
Is it still worth getting?


Re: CSA, UL/ULC and CE approvals for Tek gear

John Williams
 

The organizations such as UL and CSA or CE were no doubt founded long before there were many imports of equipment. Now who knows where anything comes from, including your car. So I would imagine that enforcement would be next to impossible. But getting back to Walters op it would seem that all requirements for any domestic producers of test equipment would have the necessary approvals for any use, such as schools and labs. I also believe CSA and UL were not government organizations but some sort of independent entities. But I do not know that.


Re: CSA, UL/ULC and CE approvals for Tek gear

Siggi
 

On Wed, Feb 10, 2021 at 5:11 PM John Williams <books4you4@mail.com> wrote:

I guess I am just dumb, but I fail to see what the problem is here. In the
United States electrical equipment needed UL approval to be sold in that
country. Same in Canada with CSA approval. These standards did not come
from lawyers and politicians, but from safety experts and engineers. They
were needed to protect consumers from shoddy products that endanger
people’s lives. Certainly you wouldn’t want your wife or kid to use
unapproved toasters computers etc.
The more salient example than toasters nowadays is phone chargers. I've
seen several dissections of phone chargers sold in North America that are,
if not directly lethal, only one failure away from plumbing mains into the
user's ear. After the first time I saw one of those I threw out all phone
chargers of unknown or questionable origin, and I will only buy name brand
chargers from verifiable sources since...


Re: TDS510 or TDS460A or 485 scopes as upgrade

Giuseppe Marullo
 

485 if still available is about 220-40USD (local pickup).
I usually wait for a unit with an issue at a lower price but the reason I get them is I like the puzzle of the debug so it may or may not work for you. I paid $60 for a unit with a power supply short, later it turned out it had dirty switches and a bad >>timebase capacitor.
Honorable intentions but I am past that, I am even past the drawer syndrome where you buy a new just released MCU and by the time you decide finally to use it, it has been superseded by another one or two generations.
I need something "reliable" in a sense that, despite old, comes in my hands working. If and when it will break, then it will become "another interesting project", and the debug/swap board fest will begin. For example I have a HP8640B in this situation, spare parts available but it's there waiting since three years ago.

This one seems okay, sold by an ham. If I will be able to lower the price a bit, it could be a nice addition to a Rigol that can't show much at higher frequencies. Cursors are nice, but as you know Rigol does way many measures that sometimes you have to wonder how much screen is left for the waveform. A clean screen could be even relaxing, in the end not so much money if it works. I see it has a respectable size, but there is always room as soon as the wife is distracted.

My comment above applies, you may want to wait for the right unit these prices seem too high for just a hobby unit.
I understand, but keep in mind that availability of units in Italy and in EU is just a fraction of what is available in US for example. Shipping charges/Freight, customs and *Fantastic* Ebay Global shipping program adds up to the costs considerably so what is available in EU could be sold higher.

How to tell 2465b from a pimped/fake 2445b?
There was a message chain in eevblog about it (you can search "fake 2465B"). I don't remember the details.
Thanks!

Since there is no ADC you can't read back the signal or take a screen shot from GPIB.
Okay, I was expecting it but I asked just to be sure.

At the moment, the 485 may fit the bill, else I will start looking for cheaper 2265b/2267b.

Thanks, I will post any progress here.

Giuseppe Marullo
IW2JWW - JN45RQ


Re: Maybe OT? TELEQUIPMENT CT71

Dave Voorhis
 

On 10 Feb 2021, at 22:41, Stephen <stephen.nabet@gmail.com> wrote:


On Wed, Feb 10, 2021 at 11:32 AM, Dave Voorhis wrote:


On 10 Feb 2021, at 21:54, Stephen <stephen.nabet@gmail.com> wrote:


What do you guys think of this curve tracer compared to other “real” Tek
ones?
What would it compare to in the official Tek line? Is it worth it?
I’ve never used a curve tracer before, and I don’t own one, I’m just
curious.

I have one.

It has neither the range of features or the industrial build quality (or the
storage capability) of my Tek 577 D1, but it’s still a nice, capable curve
tracer.

On the plus side, it has an illuminated graticule, which my 577 doesn’t
have.

Storage?
What kind of features would you say it’s lacking?
Build quality isn’t good? From the pictures it looks like any other good Tek gear to me.
Telequipment that was owned by Tektronix from the late 60’s through the 1970’s, I think. They made relatively low-cost equipment targeted at the service market, rather than the higher-end engineering market targeted by Tek.

Some differences:

The CT71 is technically simpler than the 577 and generally light-weight construction and cheaper circuit boards, lower power (10 watts max compared to the 577’s 100 watts), and a fixed front-end with multiple device adaptors, instead of a front-end plug-in (several available) with multiple device adaptors on the 577.

The 577 has a multi-turn precision vernier for offset and switchable aid/oppose, whereas the CT71 is a standard 1-turn pot and aid-only.

The 577 is switchable 1 - 10 or 1 - 100 (?) steps; the CT71 is 1 - 10 steps only.

The 577 has single-sweep and pulsed modes, which the CT71 doesn’t have.

The 577 D1 (but not the D2 model) has analog storage, which reduces flicker with slow sweeps and allows you to easily observe curve shift over time due to heating and such, which the CT71 doesn’t have.

The 577 has a front-panel circuit breaker to cut out the collector supply if the DUT is shorted; with the CT71 you replace a fuse.

Etc.


Re: CSA, UL/ULC and CE approvals for Tek gear

Michael A. Terrell
 

satbeginner wrote:
Hi Walter,

It could even be worse, a while back in The Netherlands there was a documentary about fake CE approvals.
It looks like CE, but the font is a bit different, and the spacing is a bit wider, and suddenly it means Chinese Export...

https://support.ce-check.eu/hc/en-us/articles/360008642600-How-To-Distinguish-A-Real-CE-Mark-From-A-Fake-Chinese-Export-Mark
Some refer to it as 'Can't Enforce' since there are no numbers to follow to the certification, it is too easy to fake.

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