Date   
Which probe is better suited for TDS 460A?

Ravi Moghe
 

Hi,


I have a question. I am looking at buying Probes for my TDS 460a. From my research on internet, it seems that P6138 could be that probe with 400 MHz frequency bandwidth.


But, I also saw P6137 with the almost same specifications. There are, at times, I have seen large price differences between P6138 and P6137. SO, I want to know whether P6137 and P6138 are interchangeable and whether P6137 will work equaly well with TDS 460A.


With Warm Regards,


Ravi

Re: 7S14 with not working CH2

Eino Väänänen
 

If the intensity is adjusted less enough the "noise" can not be seen:


https://www.flickr.com/photos/149607134@N07/33746966073/in/dateposted-public/ https://www.flickr.com/photos/149607134@N07/33746966073/in/dateposted-public/


The other problem is that the amplitude on CH1 should be 100 mV and on CH2 over 200 mV. So they are about 25% too small.


Eino

Re: TR502 A120 Assembly Required.... transistor update

Ed Breya
 

Before going through all kinds of hotplate stuff, I'd recommend just trying soldering it. The biggest factor is that it's now removed from the case. If the substrate is small, it will heat up anyway, as if it were on a hotplate - depending on the iron power, of course. You could also try helping it out thermally - tape it to a sheet of cardboard, which will insulate it somewhat, and conveniently hold it. The tape has to hold up for a while even when hot, so use something like masking or fiberglass - not plastic or electrical tape. If the heating is still insufficient, then look into preheating options.

Ed

Re: TR502 A120 Assembly Required.... transistor update

 

One nice trick for making IR temperature measurements on aluminum is to place a piece of kapton tape on the surface and measure that. Kapton is very black in the IR band, very close to 1 emissivity factor.

----- Original Message -----
From: Chuck Harris cfharris@... [TekScopes]
To: TekScopes@...
Sent: Tuesday, May 09, 2017 12:24 PM
Subject: Re: [TekScopes] Re: TR502 A120 Assembly Required.... transistor update

IR thermometers don't work well on aluminum. Their
effectiveness depends on the IR emissivity of the
material being measured, and on the size of the
measurement cone at the measurement distance.

Re: TR502 A120 Assembly Required.... transistor update

Craig Sawyers <c.sawyers@...>
 

Another way would be to buy just about any laboratory hotplate from ebay. They typically have a
solid, flat, aluminum hot surface, and reasonable temperature control.
You want the hotplate to be hot enough to give your soldering equipment some thermal gain over
room temperature, but not hot enough to damage components, or melt solder. Even a relatively
small amount of added heat helps. It is a lot easier to melt solder starting from 100C than from
20C.

-Chuck Harris
That is all solid advice, particularly given the thermal conductivity of Alumina. It has such a high
thermal conductivity it is used as a transistor to heatsink interface when there is a high voltage
between the package and heatsink https://www.aavid.com/product-group/interface/insulators .

Craig

Re: TR502 A120 Assembly Required.... transistor update

Tom Gardner
 

On 09/05/17 17:24, Chuck Harris cfharris@... [TekScopes] wrote:

If the hotplate can burn paper it is more than hot
enough for the task. You should put a thick piece
of aluminum on top to distribute the heat evenly.
I don't know whether it applies to this case, but when
reflowing single-sided SMD PCBs I use:
- saucepan on a gas hob
- a few mm thick layer of sand in the saucepan
- the PCB+components
- a glass lid on the saucepan.

The rationale behind the sand is:
- to spread the heat and prevent hotspots,
- to provide a thermal buffer so that the temperature
rises slowly and controllably.

The rationale behind the glass lid is to trap heat so that
not all heating is from underneath, and so that I can see
when the solder paste flows. Unfortunately I also take
the lid off every 30s or so, to monitor the PCB's temperature
with an IR thermometer :)

Re: TR502 A120 Assembly Required.... transistor update

Chuck Harris
 

If the hotplate can burn paper it is more than hot
enough for the task. You should put a thick piece
of aluminum on top to distribute the heat evenly.

Another way would be to buy just about any laboratory
hotplate from ebay. They typically have a solid,
flat, aluminum hot surface, and reasonable temperature
control.

Or, you could buy an IR underboard heater meant for
SMT work... I wouldn't recommend the hot air variety.

I use a laboratory hotplate/stirrer to do small SMT
reflow jobs. It controls very precisely, has a flat
aluminum top, and looks nice.

IR thermometers don't work well on aluminum. Their
effectiveness depends on the IR emissivity of the
material being measured, and on the size of the
measurement cone at the measurement distance.

You want the hotplate to be hot enough to give your
soldering equipment some thermal gain over room
temperature, but not hot enough to damage components,
or melt solder. Even a relatively small amount of
added heat helps. It is a lot easier to melt solder
starting from 100C than from 20C.

-Chuck Harris

NIgel Pritchard nigel-pritchard@... [TekScopes] wrote:

Hmm, did think about this. I've just found a quite cheap single cooking hotplate
on Amazon that supposedly has "full-range" temperature control. No idea what they
think full range is but maybe someone has some experience of using such devices?
They are rated at 1500 watts but that's not very intuitive about the actual
temperature that will appear on the plate.

Obviously I need to ensure that the whole substrate temperature can't rise above
about 200degC so that the other component's soldered pads don't suffer.

I've got an infra-red thermometer that reads up to 365degC so I can keep a check
on it.

Nigel

Re: 575 curve tracer on UK eBay

Craig Sawyers <c.sawyers@...>
 

Here is a link to
photos of one of my restored 575 tracers.
Cheers,
Steve Ripper
That is a really nice job! But where did you get the handles?

Cheers

Craig

Re: 575 curve tracer on UK eBay

ykochcal
 

Real nice restoration.

Can you tell us more about the handles and what restoration you may have
done?

I have a number of 500's, none of my handles look close to yours.

John

P.S. this link worked better for me no password requested.
<https://goo.gl/photos/gZD7ZNp8pmAecZMN8>

-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...]
Sent: Tuesday, May 09, 2017 5:07 AM
To: TekScopes@...
Subject: [TekScopes] Re: 575 curve tracer on UK eBay

I love my 575. Have a couple in storage in case I ever need a spare. One of
my hobbies is the restoration of vintage TEK scopes (if it doesn't have
tube's I am not interested). Would like to get a 570 but prices here in the
USA are very high. Don't see for them for less than $4,000. Here is a link
to photos of one of my restored 575 tracers.

https://goo.gl/photos/gZD7ZNp8pmAecZMN8
https://goo.gl/photos/gZD7ZNp8pmAecZMN8





Cheers,
Steve Ripper








------------------------------------
Posted by: steveripper@...
------------------------------------


------------------------------------

Yahoo Groups Links

Re: Type 503 Oscilloscope Issues

ykochcal
 

Yes that good point I had missed.

It is true that some meters may not, but some meters may.

So it would be help full if you let us know what type of meter you have to
check things with.

Also if you have access to a scope
the type of scope and probe(s) you have access to would be helpful to know.

And if you have any probes for the 503 what kind?

John

-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...]
Sent: Tuesday, May 09, 2017 1:37 AM
To: TekScopes@...
Subject: Re: [TekScopes] Re: Type 503 Oscilloscope Issues

Evan, note that a simple DMM or analog voltmeter might not respond properly
to an AC ripple component of several kHz (the oscillator frequency).
IIRC you would have had another scope available last weekend to perform
waveform measurements?
Albert


---In TekScopes@..., <polara413@...> wrote :

Measuring the AC voltage to GND on the -100V bus will be a good first
check. It should be very low as has been previously mentioned.
--

Dave Casey










------------------------------------
Posted by: aodiversen@...
------------------------------------


------------------------------------

Yahoo Groups Links

Re: 468 DSO problem

 

On 09 May 2017 12:36:06 +0000, you wrote:

My 468 DSO, which I am slowly going through the calibration procedure with, is showing a problem or two.

I initially thought that checking all of the calibration would point out the first observed problem. When in "storage mode", the triggering is less than perfect, in that the first cycle of any waveform doesn't get displayed properly or consistently, so the front or the display is bad. If I choose to display "pre-trigger" the display doesn't respond to show more cycles.
Is it the triggering which is the problem or the recording or display
of the first part of the waveform or the part of the waveform before
the trigger which is the problem?

If the last part of the waveform is stable, then the trigger is
working fine.

I have now got to the point where I am checking the voltages on the storage power-supply. Most of the test-points are showing voltages which are within the acceptable range (isn't TP148, the +12V, a pain to access?). The one that isn't correct is TP315 (+5V). The +5V is ok, but the noise is far too much. If I use "AC HF REJ" triggering on the test scope (my 7623A with a 7A18 and 7B53A), I can see a wave-form that looks like it should be from the manual, but there is a lot of noise on the signal. Since this is a supply for the storage circuits, could this be the cause of the poor triggering in "store" modes?
How much is "far too much"? +5 volt logic can tolerate 10s to 100s of
millivolts of noise. Quantitative measurements are important.

What is the exact average value? It is worse to be on the low side
than the high side of the nominal value when powering logic.

The peak-to-peak value of noise is what counts and it is normally
measured with a 20MHz bandwidth which is why the 7A26 is preferred to
the 7A18 for these measurements; the faster vertical amplifier has a
20MHz bandwidth function. This is difficult to measure on a
non-storage oscilloscope but your 7623A in storage mode should be
great; I use my 2232 DSO for this but my 7834 would also work.

There is a complication when making these measurements using an
oscilloscope involving the probes.

The ground loop between the measurement point and the oscilloscope can
make the noise measurement greater than it really is. This can be
checked by first connecting the probes tip to the same point as the
ground lead; ideally the result should be nothing but in practice,
some noise will be present. Also run your hand along the probe cable
to see if the noise level changes.

If a long ground lead is used, it can pick up magnetic flux leakage
like that which would come from a poorly shielded switching power
supply inductor or transformer. Keep the lead close to the probe body
to help with this.

Looking at the circuit diagram (schematic) of the A19 time base power supply board, TP315 is on the junction of C162 (390uF, 15VDC electrolytic), VR258 (5.6V, 0.4W Zener diode and Q157 (200V, 8.0A transistor - for a +5V supply?). Could any of these be causing the noise? I am inclined to think that C162 must have failed, otherwise I would have thought that it would eliminate this noise, but where is it coming from in the first place? Perhaps another component has failed and the noise generated has killed C162?
Any ideas? It looks like a right fiddly job to get access to the back of the A19 time-base power supply board, but I suppose if I have to....
Colin.
This would have been easier to find if you had included "schematic
21".

C162 is the prime suspect for excessive noise on the +5 volt digital
supply. C175 is also important and once access is gained, I would
change all of the aluminum electrolytic capacitors on the board.

VR258 is part of the over voltage protection circuit with SCR Q157 and
has nothing to do with voltage regulation. If the regulator fails
shorting the input to the output, then the SCR fires blowing fuses
F4007 and F4009.

The regulator circuit built around U570 and U566B is one of my
favorites. The 7905 (79052 normally used to produce -5.2 volts for
ECL?) is operating as a protected pass element for a standard
operational amplifier regulator allowing a precision tracking output.

Re: TR502 A120 Assembly Required.... transistor update

Ed Breya
 

Well, one thing for sure is the soldering will be easier than when it was still mounted - now it won't have the heatsinking into the case, so the whole substrate piece will tend to warm up fast with heat applied. How big is this section? I'm guessing maybe one square inch or so.

Ed

Re: 575 curve tracer on UK eBay

Merchison Burke
 

Thanks Chuck.

On 2017-May-09 1:11 AM, Chuck Harris cfharris@... [TekScopes] wrote:
It's really pretty easy, set up the curve tracer for
any DC sweep, such as you would do to test a diode, and
put the current up pretty high.

For a good low impedance battery, you should see something
that looks a lot like a zener diode knee. No current drawn
until you get to the battery voltage, and then the current
will go sky high.

The shape of the knee, and the slope of the curve above the
knee are indicators of the charging current ability.

If you use AC, and a charged battery, the curve will show
the charging impedance and the discharging impedance.

OBTW, the slope of the curve above the knee is an amalgam of
the load resistor you have selected, and the impedance of the
battery.... Z=V/I.

Try it, you will like it!

-Chuck Harris

Merchison Burke merchison@... [TekScopes] wrote:
Hello Tom,

Is there an article on-line which describes the method of testing Ni-Cad
batteries as you mentioned?

Thank you


On 2017-May-08 5:52 PM, ae5i@... [TekScopes] wrote:
Craig, you are so right! A 575 is one of the most useful instruments I have. For hand-selecting transistors/diodes/etc, there's nothing like it. For sorting, testing, matching so many components.

It's also a good tool for assessing the condition of NiCad batteries. By sweeping the battery and looking at the curve, you can see an indication of the source impedance of the battery which is a guide to its overall condition. Deane Kidd taught me that trick.

Definitely the sort of instrument that you'd want to have a backup unit for.... :-) Just too handy to be without it when you need it!

Tom

Re: TR502 A120 Assembly Required.... transistor update

NigelP
 

Hmm, did think about this. I've just found a quite cheap single cooking hotplate on Amazon that supposedly has "full-range" temperature control. No idea what they think full range is but maybe someone has some experience of using such devices? They are rated at 1500 watts but that's not very intuitive about the actual temperature that will appear on the plate.

Obviously I need to ensure that the whole substrate temperature can't rise above about 200degC so that the other component's soldered pads don't suffer.

I've got an infra-red thermometer that reads up to 365degC so I can keep a check on it.

Nigel

Re: Tek Blue paint source?

Cliff Carrie
 

You may not have to look that far. Most big box home improvement stores carry Krylon aerosols. I found Bahama Sea at my local store along with many other colors.


Regards, Cliff Carrie
________________________________
From: TekScopes@... <TekScopes@...> on behalf of Jan Bottorff jcbottorff@... [TekScopes] <TekScopes@...>
Sent: Tuesday, May 9, 2017 4:14:14 AM
To: TekScopes@...
Subject: Re: [TekScopes] Tek Blue paint source?



I see Krylon Bahama Sea spray paint is available on amazon https://www.amazon.com/Krylon-K09102000-COVERMAXX-Spray-Bahama/dp/B013LT52E0/ref=sr_1_1?ie=UTF8&qid=1494317136&sr=8-1&keywords=krylon+bahama+Sea

Jan

From: <TekScopes@...> on behalf of "Chris Elmquist chrise@... [TekScopes]" <TekScopes@...>
Reply-To: "TekScopes@..." <TekScopes@...>
Date: Sunday, May 7, 2017 at 7:39 PM
To: "TekScopes@..." <TekScopes@...>, "Gary Robert Bosworth @grbosworth [TekScopes]" <TekScopes@...>
Subject: Re: [TekScopes] Tek Blue paint source?



On May 3, 2017 9:49:15 PM CDT, "Gary Robert Bosworth @grbosworth [TekScopes]" <TekScopes@...> wrote:
Krylon "Bahama Sea" is very close. It cannot be used as touch-up, but
is
near perfect if sprayed on all over. It is called Colormaster gloss.
Sherwin-Williams orders it for me and does not charge for the service.
Each can is about $6.00.

On May 3, 2017 6:03 PM, "Chris Elmquist chrise@... [TekScopes]" <
TekScopes@...> wrote:



Wondering if there is still a source for Tek Blue spray paint?

I've tried to contact Stan Griffiths here,

http://www.reprise.com/ash/clients2/parts_shop/contact.html

but the email is bouncing. He used to be able to supply it in spray
cans, apparently having it mixed by the same Sherwin-Williams outfit
in
OR that Tek did.

I may have missed a discussion that Stan is no longer with us or no
longer in that business.

Any other sources or perhaps knowledge of the mixing codes so we can
get our own mixed locally?

Thanks and 73,

Chris NJCF
--
Chris Elmquist



[Non-text portions of this message have been removed]
Gary,

This was a great recommendation. I happened to find a can of Bahama Sea while at the local farm store today. $3.50. Promptly cleaned the top of the TM-504 I am refurbing and sprayed it in the backyard. It looks great! It's just a tiny bit more green than the original blue on the rest of the box but it is definitely close enough for government work (as we say in government). So, I am happy with this easy solution.

Thanks again for the suggestion,

Chris
--
Chris Elmquist



[Non-text portions of this message have been removed]





[Non-text portions of this message have been removed]

Re: TR502 A120 Assembly Required.... transistor update

Chuck Harris
 

In general the answer to soldering difficulty
is to place the substrate on a hot plate, and
preheat it to 100 to 200C before you touch it
with a soldering iron.

-Chuck Harris

'Craig Sawyers' c.sawyers@... [TekScopes] wrote:

It never ceases to amaze me what an incredible resource of knowledge we have within this
community :)...... like the other thread on "sooty cable".... Radon decay and..... a "Geiger
counter"
group!

Now I've got to arrange a small work-jig to hold the tiny module stationary while I work on it.

Nigel G8AYM
I'm reading this thread with great interest! You might still have problems soldering, because
alumina has a high thermal conductivity. At 35W/mK it is 140 times more conductive than FR4 circuit
board material, and only 6 times less conductive than aluminium.

Good luck

Craig

468 DSO problem

Colin Herbert
 

Hi,
My 468 DSO, which I am slowly going through the calibration procedure with, is showing a problem or two.
I initially thought that checking all of the calibration would point out the first observed problem. When in "storage mode", the triggering is less than perfect, in that the first cycle of any waveform doesn't get displayed properly or consistently, so the front or the display is bad. If I choose to display "pre-trigger" the display doesn't respond to show more cycles.
I have now got to the point where I am checking the voltages on the storage power-supply. Most of the test-points are showing voltages which are within the acceptable range (isn't TP148, the +12V, a pain to access?). The one that isn't correct is TP315 (+5V). The +5V is ok, but the noise is far too much. If I use "AC HF REJ" triggering on the test scope (my 7623A with a 7A18 and 7B53A), I can see a wave-form that looks like it should be from the manual, but there is a lot of noise on the signal. Since this is a supply for the storage circuits, could this be the cause of the poor triggering in "store" modes?
Looking at the circuit diagram (schematic) of the A19 time base power supply board, TP315 is on the junction of C162 (390uF, 15VDC electrolytic), VR258 (5.6V, 0.4W Zener diode and Q157 (200V, 8.0A transistor - for a +5V supply?). Could any of these be causing the noise? I am inclined to think that C162 must have failed, otherwise I would have thought that it would eliminate this noise, but where is it coming from in the first place? Perhaps another component has failed and the noise generated has killed C162?
Any ideas? It looks like a right fiddly job to get access to the back of the A19 time-base power supply board, but I suppose if I have to....
Colin.

Re: 575 curve tracer on UK eBay

smrippe
 

Re: 575 curve tracer on UK eBay

smrippe
 

I love my 575. Have a couple in storage in case I ever need a spare. One of my hobbies is the restoration of vintage TEK scopes (if it doesn't have tube's I am not interested). Would like to get a 570 but prices here in the USA are very high. Don't see for them for less than $4,000. Here is a link to photos of one of my restored 575 tracers.

https://goo.gl/photos/gZD7ZNp8pmAecZMN8 https://goo.gl/photos/gZD7ZNp8pmAecZMN8





Cheers,
Steve Ripper

Re: 7S14 with not working CH2

Eino Väänänen
 

I have now changed the batteries to silver oxyde watch batteries 1,55V SR48. There is no remarkable change on the signals. The "noise" is stlill there. Here is a picture when there is no signal on both channels. There is signal on external trigger input connector. Noise is about +75 mV on channel 1 and about -25 mV on channel 2.


https://www.flickr.com/photos/149607134@N07/34551230285/in/dateposted-public/ https://www.flickr.com/photos/149607134@N07/34551230285/in/dateposted-public/


Any suggestions what toi do next?


Eino