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hello all groups I have to replace it in my oscilloscope tek475 part TEKTRONIX 152-0246-00 DIODE SILICON 400piv 200 ma , cd12676
help me
Roberto

Thanks, Egge Siert. I found the manual and in fact useful schematic to use this floating connector. .

OK. I uploaded another series of pictures. Same folder: /g/TekScopes/album?id=79121

I used a different 2N3055 than in the previous pictures.

Settings:
- Vertical: 50mA/Div
- Horizontal: 5 Collector Volt/Div
- Step/Offset: 0.1mA
- Max Peaks Volts: 25V
- Variable Collector %: 100%
- Series Resistor: 120 Ohm

I took a picture for every step increase. What's interesting is that "odd" numbers of steps seem to have less of the retracing issues than "even" numbers. The flickering of the display is also more pronounced with even numbers. I ran all samples with the fastest step rate.
Another questions since I have no experience with this instrument - is it "normal" that I get two traces even with just a step count of "1" ("number of steps" knob fully ccw)?

Thank you again, Wolfgang

On Fri, Nov 23, 2018 at 05:11 PM, Chuck Harris wrote:

I have to wonder what were your settings for H Voltage, and
V Current, Supply voltage and load impedance, and your step size.

You can curve trace a 3055 at amps of current, or you can trace
it at microamps of current. Capacitance is much more evident at
lower currents.

-Chuck Harris

OBTW, there is no z-axis blanking on these curve tracers.

Wolfgang Schraml wrote:

Still working on my 577 (see my other post regarding power supply

restoration). Voltages are all good now (after replacing all electrolytic caps
and tantalums on the power supply and collector supply boards).

I read the other posts regarding retracing of curves but can't seem to get

anywhere. In my case, it seems to be a lot worse that what I saw with the
other posts so I think my problem must be different (especially since I
already replaced the caps that were mentioned in one other post).

Here are some pictures I took with a 2N3055 at various step settings:

/g/TekScopes/album?id=79121

I am going to dig deeper into the collector supply board but appreciate any

thoughts/feedback.

Thank you,
Wolfgang

good point ... didn't write down the settings. I think I used pretty low current for the step setting. Let me run another series of traces with documented settings. Maybe I am chasing a problem that doesn't exist ...

Thank you,
Wolfgang

Hi Craig. The question of isolation transformer never really goes away. If you continue earthing of say an isolating transformer case to a ‘consumer’ case when servicing consumer/appliances you increase the likelihood that protective devices intended to be operated under earth-fault conditions will function or alterrnatively that contact with mains voltages could kill the person.or cause injury to him/her or property.

The purpose of an isolation transformer is, however, to NOT connect to the consumer/appliance device frame to the earthing, so that there is a greater degree of safety for a person working on the equipment when it is ‘alive’. Nothing will protect us from A-N hook-up but …presuming we are insulated from such environments as a cement floor or metal appliances or pipes going to earth, contact with an active will not lead to death.

The primary earthing ”MEN”… to the greater mass of earth...done at the sub-station or local supply transformer identifies which mains cable is ‘neutral’ at the incoming mains. That 'general' connection is supplemented by proper earthing and MEN at your distribution board. and thereafter the MEN identifies which sub-circuit wire is the neutral, and it must be so arranged in GPO (power outlet) and connections using it.....The MEN is bypassed when RCD’s are used.One relies on colour coding and testing to see all is well there. Connecting an RCD neutral to earth will interrupt it.

When the isolation transformer case is earthed, the person accessing the consumer mains areas must for safety ensure they cannot/do not contact the transformer case.as that would defeat the purpose of isolation from earth…which is what isolation transformers are ‘about’ as well as some dc effect blockage and give some lag to voltage fluctuations and noise…secondary/tertiary by-products.

Operating equipment which is permanently connected to an isolation transformer…? Craig I agree with you entirely and I see that as very bad practice. Bear in mind that not all transformers are Intended to be ‘isolating transformers’ and your warning still stands. Some specialist-only laboratories may have floating equipment, if designer, user energy authority and Standards Engineer approved but other hazards arise in quasi-laboratories .

When electronic 'genius' on say you-tube electronics sites advising adulating followers that the presenter does not earth their equipment is not an 'exception to the rule' I have seen in any Standards. It risks a following of that behaviour when doing making the statement at the time of advising strongly that their followers permanently use isolating transformers.

Here, for example, when operating 110V USA gear from 250 volt mains we either change the unit transformer (or its own connections where possible) to run from our mains….More often a 250-110/115 volt transformer is used, with a 2 lead only connection to the 115 v side.then running to the consumer through those (flimsy) US leads and 2 pin, unpolarised plug. In that case solid earthing should be ensured at the voltage lowering transformer and be solidly passed to the consumer (appliance) through a 3 pin US style socket and a replacement cable, doubly insulated, 3 pin with the correct polarity.

The 115v outlet and the consumer together must ensure earthing devices can give at least the minimal protection required by the standards….That actually rarely happens looking at the many 250/115 transformers which have passed through my hands.

Earth loop impedances are one thing test-required to meet our installation-Standards but over-riding that is that earthing-dependent protection MUST operate on the earthing system, which itself must not exceed the maximum earthing impedance laid down by the appropriate Standards.

It is a requirement of Standards (here) that doubly insulated tools or appliances must not be earthed, but bear in mind, without the suggestion being puerile, they do not suddenly become doubly insulated by being carried onto a construction site. Periodic testing of gear and distribution boards is supplemented by mindfulness, observation and alertness of stakeholders. metal shrouded tools...including sabre saws, drilling machines and so forth must meet the Standards requirements, design requirements, site requirements and environmental requirements.


--
Jack

I have to wonder what were your settings for H Voltage, and
V Current, Supply voltage and load impedance, and your step size.

You can curve trace a 3055 at amps of current, or you can trace
it at microamps of current. Capacitance is much more evident at
lower currents.

-Chuck Harris

OBTW, there is no z-axis blanking on these curve tracers.

Wolfgang Schraml wrote:

That again.
No it's not an absolute requirement that there is a ground connection
to the output of an isolation transformer.
In fact european standards absolutely demand that there not be one.

The isolation transformer makes a class 2 (double insulated) device
out of a class 1 (earthed chassis) device.
All exposed metal parts of the powered device end up connected
together, but floating.
You may not connect more than one appliance to an isolation
transformer (each needs a separate transformer).
You may not connect any other external sources to devices powered by
an isolation transformer.

I agree there are many cases in which an earth connection on the
output is better.
Especially if you ignore the rules about external power sources such
as is often done when floating scopes.

ST


On Sat, Nov 24, 2018 at 12:25 AM Craig Sawyers
<c.sawyers@...> wrote:

Sometimes there are good reasons to disconnect that ground and make a measurement that is not
relative to the AC power input ground.

This link will take you to a Tektronix ?white paper? about making floating measurements.

This has, as one recommendation, using an isolation transformer. However, it is an absolute
requirement that there is ground continuity between primary and secondary of an isolation transformer.

Think about it. The scope has line, neutral and chassis connections - a three wire system. An
isolation transformer has a primary and secondary only. The only way to connect the oscilloscope (or
any connected equipment) with a chassis connection safely is with ground continuity from chassis to
safety ground.

Which means you have a non-floating scope with transformer isolated line and neutral.

I'm really surprised that Tek missed that, because it has been part of electrical codes for longer
than that note was written.

For site use of site power tools isolated line and neutral is just fine - because connected power
tools are double insulated or even intrinsically safe.

But test equipment, like the vast majority of Tek test equipment, requires a hard chassis ground
irrespective of isolation transformer.

Craig

For whatever it might be worth, I tried six variations of 2N3055 on a 577 that has had only enough repairs to keep it functioning.
The 3055's varied with a 3055H and a 3055HV mixed in with epitaxial and non-epitaxial 3055's, including an actual Tektronix 151-0140-?
All of the traces looked like what you would expect, and nothing like what Wolfgang is seeing.
The gain of the 3055's varied widely, with the 3055HV having the lowest gain as you might expect.
All of the above means absolutely nothing in this current discussion, but any discussion about my favorite curve tracer model needs to be followed and looked at.
tom jobe...

Hi All
The CATS (Crawley Amateur Transmitting Society) rally is correctly known as the CATS Bazaar, it was not last month but is was held on the 15th November.
If you are into Amateur Radio or T&M kit it is a must go to event.
Just for the record I have nothing to do with the organising of the event.
73 George G6HIG

Here are some pictures I took with a 2N3055 at various step settings:
/g/TekScopes/album?id=79121

I'm not at all surprised - a 2N3055 is a power transistor with a very large junction area. So it has a
very high capacitance.

I'd have to look it up, but one of Tek's curve tracer manuals sets out a procedure to match the
looping with removing the transistor and putting a capacitor instead. When the capacitor looping
matches the transistor looping, the capacitor value is the same as Ccb of the transistor.

Craig

On Fri, 23 Nov 2018 15:17:15 -0800, you wrote:

Still working on my 577 (see my other post regarding power supply restoration). Voltages are all good now (after replacing all electrolytic caps and tantalums on the power supply and collector supply boards).

That part is good.

I read the other posts regarding retracing of curves but can't seem to get anywhere. In my case, it seems to be a lot worse that what I saw with the other posts so I think my problem must be different (especially since I already replaced the caps that were mentioned in one other post).
Here are some pictures I took with a 2N3055 at various step settings: /g/TekScopes/album?id=79121

That is a bit on the nasty side. I'm more concerned not with the
doubling of traces (which could be argued), but the lack of blanking
showing through.

Is there a blanking waveform? Is there scope blanking for traces? If
so, what's the waveform look like and what should be generating it?

Harvey

I am going to dig deeper into the collector supply board but appreciate any thoughts/feedback.

Thank you,
Wolfgang

Sometimes there are good reasons to disconnect that ground and make a measurement that is not
relative to the AC power input ground.

This link will take you to a Tektronix ?white paper? about making floating measurements.

This has, as one recommendation, using an isolation transformer. However, it is an absolute
requirement that there is ground continuity between primary and secondary of an isolation transformer.

Think about it. The scope has line, neutral and chassis connections - a three wire system. An
isolation transformer has a primary and secondary only. The only way to connect the oscilloscope (or
any connected equipment) with a chassis connection safely is with ground continuity from chassis to
safety ground.

Which means you have a non-floating scope with transformer isolated line and neutral.

I'm really surprised that Tek missed that, because it has been part of electrical codes for longer
than that note was written.

For site use of site power tools isolated line and neutral is just fine - because connected power
tools are double insulated or even intrinsically safe.

But test equipment, like the vast majority of Tek test equipment, requires a hard chassis ground
irrespective of isolation transformer.

Craig

Still working on my 577 (see my other post regarding power supply restoration). Voltages are all good now (after replacing all electrolytic caps and tantalums on the power supply and collector supply boards).
I read the other posts regarding retracing of curves but can't seem to get anywhere. In my case, it seems to be a lot worse that what I saw with the other posts so I think my problem must be different (especially since I already replaced the caps that were mentioned in one other post).
Here are some pictures I took with a 2N3055 at various step settings: /g/TekScopes/album?id=79121

I am going to dig deeper into the collector supply board but appreciate any thoughts/feedback.

Thank you,
Wolfgang

Hi,

It is a 5L4N Accessory. Some clues are given in its Manual.

Greetings,

Egge Siert

I bought a Hantek dual trace 200 mhz scope about a year ago. It cost about 350 bucks. I also have a couple of 465 scopes. The Hantek has its advantages in some situations. Of course be reminded it is no Tek 465. I can work on stereos with that Hantek. It it immediately syncs to the signal and automatically adjusted to the right vertical scale. It gives an automatic readout of P-P voltage, offset voltage and frequency. Probably more that I don't remember. The trace on this Chinese product is not beautifully smooth and crisp like my Tek scopes. This is actually a matter of aesthetics rather than function. I just love seeing that beautiful crisp display on a 465. I got an update a couple of months ago for this Chinese scope. It corrected a problem for me. This scope would try frantically try to sync on an SSB signal that was being modulated by my voice and would just show garbage. The update fixed this. I can say that the Hantek model is useful for me and is excellent for low frequency troubleshooting. When I want to trace HF frequencies through a transceiver I always fall back on my Tek scopes. I repaired a 1948 Philco AM/FM shortwave receiver. It was a dream with the Chinese scope. I even calibrated the dial by looking at the LO frequency on this scope. I suspect I would have to spend a lot more money on a Chinese scope that would out perform my 465. The Tek scope and the Hantek both have a useful place on my workbench.

Randy,
Please read my entire mail and then respond appropriately.
Dennis Tillman W7PF

I recently "inherited" two 2215 Tek scopes both dead... Both have cover screws missing....
Unit #1: Someone ripped the anode lead off the CRT! Is there any way way to reattached the anode lead to the CRT? It also has an inverter issue which I can handle.
Unit #2: Bright wide traces across the screen. Intensity controls the traces from bright to very bright. Vert/Horz amps and sweep functions seem to be operating correctly. The start of the trace "dot" can be focused correctly. Grid bias has little to no effect on the trace brightness. Looking for ideas on this one.
Thanks in advance.
Scott
AB4SL

On Tue, Nov 13, 2018 at 07:31 PM, Chuck Harris wrote:

I had a consulting contract years ago to help a
Swedish company with a problem they had in converting
from European 240V to the USA 120V. The engineer that
did the conversion didn't understand the ratings of the
molex connector.

He saw the 17A rating, and saw the 15A drawn by the heater,
and said, "Looks good, ship it!"

And, then the problems began. In the US, the connectors
burned up after the third or fourth cycle of the instrument.

The customers were not amused, and even less amused was
the guy that relocated his family to the US to become the
president of the USA division... My customer.

What happened?

Well, molex rates their connector at 17A with the following
stipulations:

1) 25C ambient temperature.
2) 12 inches of #14ga stranded wire on each side of the
connector with everything suspended in free air.
3) only one pin set per connector shell.

Does that sound like what you are doing? If so, you will
be fine.

It didn't sound like the Swedish company's 4 circuits in a
shell, with 3 inches of wire between connectors, and placed
next to a 700W heater... OOPS!

-Chuck Harris

Harvey White wrote:

On Wed, 14 Nov 2018 07:33:38 +1000, you wrote:

...

On the current ratings, from what I understand, the current rating is
good, but goes down with the number of insertions.

I completed the overhaul including the installation of Molex connectors for the transformer leads. I posted before and after pictures here: /g/TekScopes/album?id=79113

Overall, it went well. A little crowded now inside with the addition of the Molex connectors.

I still have other issues with the 577 I need to track down - traces look OK for diodes but don't line up for transistors; as other have stated "the out and back I-V curves do not lie on top of each other". I saw other posts on that topic and will pursue this next. And the storage option doesn't work either (it's a D1).

Thank you,
Wolfgang

Thanks a lot everybody. It seems just for my 2465B it's not a very useful part...
But the link from Dale Chayes was very interesting i didn’t find it. Thanks
Rolf

I to would like this link if available.