Date   

TDS 420 Oscilloscope

Bill
 

How reliable is the TDS 420 oscilloscope? Saw a video about it and thought it would be a nice upgrade from my 453. Looks to be easily service but have no knowledge about the reliability or availibility of the ICs if needed at some time.
Thanks,
Bill


TDS420 Oscilloscope

Bill
 

How reliable is the TDS 420. I've been thinking about buying ever since I saw a video about it. Looks to be easily serviced and would be handy in the shop. The only scope I have now is a 453 which I use quite a bit. Would like to upgrade from it.
Thanks,
Bill


Off topic - Electronics Book Club from the 70s and 80s

Richard in Edenton NC
 

Hi, I have been a ham radio operator since 1976 when I was a teenager. I do have a Tektronix scope and a 492 spectrum analyzer and a bunch of other electronic test equipment but it has been years since I was a component level bench tech. I am hoping some on here might have a catalog from the former Electronics Book Club that advertised in electronics magazines back in the 70s and 80s. My goal is to find names of older pubs and order them and give me something to do that I used to enjoy. I have a few of Harold Kinleys books, some by John Link and some decent oscilloscope books. I am wanting to get back to basics on theory and troubleshooting. Thanks everyone.

73 Richard W4MCD


Re: New 2465 Seimens brushless motor

victor.silva
 

Ok, I'll try both Zinc dissolved in some HCl and Zinc Chloride soldering paste and report back here on the results.

--Victor


Re: Any Tektronix magnetic shield for a CRT? A strange problem...

Roy Thistle
 

On Thu, Mar 26, 2020 at 08:27 PM, Ed Breya wrote:


The shielding effectiveness does degrade from deformation, but doesn't go to
zero. I wouldn't worry too much about minor dents and dings.
Hi:
I do recall that working mu-metal alloy, alters its crystal structure and so decreases its permeability (but by how much?... don't recall). I'm guessing cutting it with shears would substantially decrease it near the cut line. When they fabricate structures, like shields, they sometimes anneal the object in an oven to reform the crystal structure, and get back the rated permeability. Something to keep in mind, if you are retrofitting a CRT with a repurposed shield, and you have to cut or reshape it.
Best regards and wishes.
Roy


Re: TM500/TM5000 extender v0.8

Ke-Fong Lin
 

Hi everyone,

As for the sharp back corners, I'll fix that for v1.0, that's easy!

Regarding the high current consumption, this is about the plug-in modules themselves. The PCB extender is purely passive, except for the TM5000 "power ok" circuitry that I've not yet populated for my testing. It has no led in particular.
The FG501 (2MHz function generator) that I tested, eats up around 200mA on each of the +/- 26VDC rails, for a total of around 10W. Well within specification, but I expected a "simple" function generator to use much less.

Regarding the wiring, I'm using 22AWG 1551 "premium" from Alpha Wire, these are PVC and even "mil-spec". I have some 24AWG at hand but only in white, so I used 22AWG all along.
This is completely overkill, as they have a 1000V at 3A rating. Probably because of that, the PVC insulation is thick and stiff (silicon should be "softer" than PVC).
Perhaps, if I've used 24AWG or 26AWG, things would have been more convenient.

As for connectors, 56p connectors are both tough and easy to find. They're the same as jamma standard so aliexpress is full of them, but solder eyelets.
Right angled PCB mount connectors are available at manufacturers, but Mouser or Farnell don't have them in stock. Whereas they have the solder eyelet ones.
For probing, this can be done on the eyelets.

All in all, this is certainly not the perfect, but should do the job for some hobby repair/calibration of TM500/TM5000 plug-ins.

Best regards,


Re: Tektronix 2440 no channel 2 trace

Szabolcs Szigeti
 

Hi,

First see what the extended diagnostics says.
Then the usual suspects:
Power supply voltages and ripple.
Remove the hybrids from their socket, clean the contacts a reseat then.
If that does not help, then you can swap the hybrids between the channels.

Szabolcs

<andystewart211@...> ezt írta (időpont: 2020. márc. 27., Pén 18:20):

Channel 1 trace is fine but no channel 2 trace only noise . The cursers
move fine but the noise stays at the bottom of the screen . Any repair tips
would be helpful.




Re: One more quick question about CRTs

 

Bruce and David, thank you for your answers.

Yes, to turn power on when the tubes have their right impedance instead of being open circuit avoids weird voltages, I realize that this is the main reason instead of cathode damage. It's true that an oscilloscope CRT has a very low beam current (otherwise the HV supplies would be much larger) and the energy of the bright image comes from the accelerating voltage.

David, you proved me 180 deg. wrong thinking that low CRT filament would degrade it. .Good, I will stop worrying about having changed my Tektronix scope to the highest line voltage setting (lower filament voltages)

Ernesto


Re: Any Tektronix magnetic shield for a CRT? A strange problem...

 

Ernesto,
I can second Carsten's recommendation of the magnetic viewing film. It is really amazing stuff.
https://www.ebay.com/sch/i.html?_nkw=magnetic+field+viewing+film

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Carsten Bormann
Sent: Friday, March 27, 2020 6:08 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Any Tektronix magnetic shield for a CRT? A strange problem...

<snip>
Or, if you don’t want to clean up after that:
https://www.ebay.com/sch/i.html?_nkw=magnetic+field+viewing+film

Grüße, Carsten




--
Dennis Tillman W7PF
TekScopes Moderator


Tektronix 2440 no channel 2 trace

andystewart211@...
 

Channel 1 trace is fine but no channel 2 trace only noise . The cursers move fine but the noise stays at the bottom of the screen . Any repair tips would be helpful.


Re: Any Tektronix magnetic shield for a CRT? A strange problem...

David Kuhn
 

" I never leave home without my mu-metal hat and my copper bracelets"

5G buddy, you need that mu metal hat more than ever. Not alien, but
government mind control for the one World Order that is currently being put
in to place.

You got any extra of that special metal? I could use some to make my rebel
hat.

Dave

On Thu, Mar 26, 2020 at 7:40 PM Dennis Tillman W7PF <@Dennis_Tillman_W7pF>
wrote:

Hi Ernesto,
I would think it will be nearly impossible to find a mu-metal shield that
is the right size for a cheap CRT you bought 50 years ago.
Instead why not try thinking outside the box or at least approach the
problem in reverse.
For instance look for a CRT that has a mu-metal shield already attached to
it that will fit into the space you have. The 154-0667-00/-01/-02 CRT used
in the 1502 TDR is quite nice. It is rectangular 3"x 2 1/2" and it has an 8
x 10 internal graticule. It is 10" long so it will fit in your scope. You
also get an interesting challenge which is to see how much you have learned
since you figured out a clever way to shield the scope you repaired 50
years ago. You should be capable of figuring how to install a much more
modern tube now.

I once asked the TekScopes members if they had any suggestions for
experiments I could do with mu-metal since I saved some of the shields from
older Tek Scopes and I didn't want to throw it out if there was a use for
it. I even went onto the web pages of companies that made mu-metal to see
if they had any clever things that could only be done with it.
The subject of my post was Fun with Mu-Metal (Message #37701 · 04/12/09).
There were 2 interesting replies and 8 that were not so interesting. The
best one was "Use it to make one of those caps that those worried about
alien mind control wear."
I already did that long ago. I never leave home without my mu-metal hat
and my copper bracelets. Unfortunately the hat didn't help with the other
voices in my head - could they be electrostatic voices? Maybe I could stop
them if I put the hat in one of those pink electrostatic bags when I'm not
using it.

This company has a little video showing how they shape and machine
mu-metal.
http://www.mumetal.com
They list a few examples of what mu-metal is being used for today. Aside
from the MRI machines I don't think the other two applications they mention
use much if it:
* When the Smithsonian Astrophysical Observatory scientists set up an
experiment to test Einstein's Theory of Relativity, they specified MuShield
to protect the atomic clock used to explore the structure of space and time.
* High Technology companies using SQUID (Superconducting Quantum Interface
Device) technology call MuShield to eliminate all interference from the
Earth's Magnetic Field so that ultrasensitive R & D experiments will result
in accurate findings.
* As MRI (Magnetic Resonance Imaging) technoglogy continues to evolve,
leaders within the medical industry continue to trust and call upon
MuShield to be the designer and supplier of critical mumetal magnetic
shields

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
Ernesto
Sent: Thursday, March 26, 2020 2:36 PM
To: TekScopes@groups.io
Subject: [TekScopes] Any Tektronix magnetic shield for a CRT? A strange
problem...

Has anyone a recommendation for a mumetal Tektronix shield that could fit
an old CRT of 4 inch face plate, 2 inch neck and 13 inch length?

And... why hasn't Tektronix ever built a round face 4" CRT? It jumped
from 3" to 5".....darn!

I experienced a strange problem with a small oscilloscope that I built 50
years ago and I am recalibrating now, and which has this odd 4" round
non-flat CRT (the only cheap one I could find at that time, poor kid! )
At that time, I wrapped a metal sheet around the tube neck to magnetically
shield it. I have no idea what metal this was. This "shield" was held
with some old string, and to make it look more pretty I removed the string
and replaced it with tape.

Then I started to experience a weird problem. The brightness of the trace
was much lower at the start of the sweep. I broke my head analyzing the HV
supply, the unblanking circuit, etc. etc. Maybe a leakage in the HV
ceramic capacitors? Maybe the unblanking signal not uniform? I moved
things around, and then the sweep was normal at the beginning and vanished
at the end. Moving more things around, and then changing the horizontal
position the trace disappeared at the left of the tube and was perfectly
normal towards the right! The trace could always be adjusted for good
focus and astigmatism.

Until I realized that I had been rotating this in-house "shield"
cylinder. Fortunately....I found a position where the trace was back to
normal. It must be that the unknown metal is magnetized! Had it been like
this for 50 years?
I have no idea how the magnetization affected the CRT beam, if it hit
some internal electrodes while preserving good geometry, but I know little
about that CRT, not even its part number.

This is why I am looking for a CRT shield, if possible a Tektronix one,
that has not been banged around. If it is not available, I might try to
build one with some permalloy sheet, or forget about it and play with
something else.

Thank you for your help, and hopefully you never experience such CRT beam
problems (no attaching of big speakers to the side of your oscilloscope)

Ernesto





--
Dennis Tillman W7PF
TekScopes Moderator




Re: One more quick question about CRTs

David Kuhn
 

With an instrument, in my industry, that we use to work on, the KB6000, we
significantly INCREASED the life of the CRT by lowering the
filament voltage. We went from a filament transformer rated at 6.3 volts to
one rated at 5.2volt (I think, or maybe 5.0) and the tubes never failed on
on us again. If I fire one up today, it looks as good as it did 25 years
ago. Before with the higher filament voltage, we were lucky to get two
years from the tube, in 24hrs/day/365. It was rated for 6.3 volt
filament. Its possible if the original transformer was for 110vac that
running on 120vac cause a problem. All I know is that the new transformer
allowed the CRTs to last, virtually indefinitely, and the presentation was
better. They used Telefunkin tubes, if memory serves correctly.

On Fri, Mar 27, 2020 at 10:20 AM Ernesto <ebordon@...> wrote:

Hi,
Since I realize the vast expertise in the group, I want to ask a question
for which I didn't find an answer.
It is about the life of the metal oxide cathode in a CRT.
In vacuum tubes, insufficient electron emission due to insufficient heat
can shorten the life of the cathode, the tube.
This is why my 547 scope has a time delay before the higher voltages turn
on.
Is the CRT included in this precaution, or is it only for the regular
tubes?

Regards,
Ernesto




Re: TM500/TM5000 extender v0.8

KeepIt SimpleStupid
 

Wire typically comes in 2 strandings, one being more flexible than the other.
Silicone insulated wire is a possibility.  The jacket is bit more flexible.
Heat shrinking the edge connector wires is a possibility too, but the ability to probe safely sounds even better.


Re: Tek 222/224 Battery Replacement

garp66
 

hi Jeff,

Any chance you can include some *jumpers* so that this battery replacement PCB unit can also function in an AC/DC Tek 422 scope ?
(With or without a 3D printed plastic retrofit case ?)

thank you,
rick


Re: New 2465 Seimens brushless motor

Chuck Harris
 

One hates to be a forgone conclusion...

Perhaps using killed HCl, also known as
zinc chloride. killed HCl is what you get
when you dissolve as much zinc into HCl as
you can. It eliminates that nasty evaporation
problem that HCl has.

Zinc Chloride is the active ingredient in the
old soldering flux tins from the days of steel
chassis TV's. It was a mixture of Zinc Chloride
and petroleum jelly, with something to keep them
from separating out.

-Chuck Harris

victor.silva via Groups.Io wrote:

The seller has little experience with ebay and has no idea on how to setup multiple items shipping.
I was the one that bought 20 (at a discount) and initially the shipping was $320 for parcel post!

It took forever for him to revise the invoice with continuous hand holding all the way.

One note on these motors, not just from this seller, but I've seen this issue on all the NOS Seimens motors I've used;
The terminals do not solder well. I've tried fluxing, long heating, etc., the terminals just don't wet well.

The only solution I have found was to dip the terminal for 10 secs in 10% HCl. Then neutralize with baking soda solution and dry well.
After this the solder would wet very well.
I know Chuck Harris will caution against this, but I believe his concerns are that once you apply HCl to the motors, if any vapors or liquid
creep inside the motor it will be toast.
I would love to hear of any suggestions or if anyone has success soldering these without using HCl to clean the terminals.

Thanks,
--Victor




Re: One more quick question about CRTs

greenboxmaven
 

There are several reasons to delay the B+, they are mostly to protect high current tubes that are not yet at full emission from damage. The cathode current of a one gun CRT is usually a hundred microamps or so, unlikely to damage the cathode. Consider solid state TV receivers that applied full operating voltage to the pix tube the moment the set was turned on, and an image faded in over about a 15-20 second warmup, usually needing a minute or two to reach fullest brightness and resolution. Delaying the B+ in the scope will protect the voltage regulator circuits, prevent excessive voltage on the ciruitry because of there being no load, and avoiding wild voltage excursions, parasitic oscillations, and instability in directly coupled or multiple paralell tube amplifier circuits.

Bruce Gentry, KA2IVY

On 3/27/20 10:20 AM, Ernesto wrote:
Hi,
Since I realize the vast expertise in the group, I want to ask a question for which I didn't find an answer.
It is about the life of the metal oxide cathode in a CRT.
In vacuum tubes, insufficient electron emission due to insufficient heat can shorten the life of the cathode, the tube.
This is why my 547 scope has a time delay before the higher voltages turn on.
Is the CRT included in this precaution, or is it only for the regular tubes?

Regards,
Ernesto



Re: TM500/TM5000 extender v0.8

Oz-in-DFW
 

First, really excellent work.

I also have some suggestions and comments that are work exactly what you paying for them ;-)

Ribbon cable will be more convenient, but I'm not sure it's better or worse. the advantages I see are:
- neater and less likely to be tangled.
- easy to change when the wires work harden and break
- will likely connect all contacts - those contacts were doubled for a reason - usually lower connection resistance for power, but also reduced inductance,, etc.

Disadvantages:
- Much higher wire to wire capacitance, including to ground wires
- generally stiffer
- smaller gauge wire

You can reduce a lot of the disadvantages of ribbon cable by separating the wires once the IDC connectors are installed. If you stick with discrete wires I'd use connectors on both sides to make replacement easier and less likely (due to better wire strain and bend relief when compared to soldering.

Whether you go with ribbon or not, I strongly suggest a second PCB on the unit-under-test side. Right angle PCB mount connectors are still available from distribution and are a whole lot easier to solder that individual wires. I also suggest test points or posts on that side as well. I have a TM503 on the bench and I hate pulling the covers to poke at a plug in. This lets you get the unit out of the case, but not easily probe backplane signals.

I second the suggestion to round the corners of the board, or at least break the point with a 45 degree cut.

As to split pads, I have library parts that are normally open and normally closed (10mil shorting trace between the pads) I use them a lot.


Re: New 2465 Seimens brushless motor

Mlynch001
 

Paul,

Don't get me started on taxes. The government now gets their pound of flesh, regardless. All of this stems from the brick and mortar retailers lobbying for taxing online purchases and the ever growing LUST for $$$ of the typical government. Politicians win, both ways, more tax $$$ to spend and lots of money coming (under the table) from the aforementioned lobbyists

--
Michael Lynch
Dardanelle, AR


Re: New 2465 Seimens brushless motor

Paul Amaranth
 

Yes, AND you get taxed on shipping as well.

Still, the total price is not terrible so I grabbed a spare as well.

PaulA

On Fri, Mar 27, 2020 at 08:18:47AM -0700, Mlynch001 wrote:
On Fri, Mar 27, 2020 at 09:41 AM, <joeschm@...> wrote:


As has been mentioned, shipping is somewhat high.
Becoming the "norm" on E-bay, outrageous shipping charges on many items. This seller actually has his item priced cheap, for a new motor, and even with the shipping, it is a good price. At least I thought so, since I bought one to keep as a spare.

--
Michael Lynch
Dardanelle, AR
--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@... | Unix & Windows


Re: New 2465 Seimens brushless motor

victor.silva
 

The seller has little experience with ebay and has no idea on how to setup multiple items shipping.
I was the one that bought 20 (at a discount) and initially the shipping was $320 for parcel post!

It took forever for him to revise the invoice with continuous hand holding all the way.

One note on these motors, not just from this seller, but I've seen this issue on all the NOS Seimens motors I've used;
The terminals do not solder well. I've tried fluxing, long heating, etc., the terminals just don't wet well.

The only solution I have found was to dip the terminal for 10 secs in 10% HCl. Then neutralize with baking soda solution and dry well.
After this the solder would wet very well.
I know Chuck Harris will caution against this, but I believe his concerns are that once you apply HCl to the motors, if any vapors or liquid
creep inside the motor it will be toast.
I would love to hear of any suggestions or if anyone has success soldering these without using HCl to clean the terminals.

Thanks,
--Victor