Date   

Re: Trace thickness and edge variation by probe

 

Hi David,
You should have saved that for April 1st. I had no idea you could still buy
antenna wax.

I assumed that now that the world's whale populations were threatened the
only ones that could get it were the Japanese. :)

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...]
Sent: Saturday, February 11, 2017 3:53 PM
To: TekScopes@...
Subject: Re: [TekScopes] Trace thickness and edge variation by probe

I guess nobody is going to buy my story now about rubbing the probe cables
down with antenna wax for less fuzzy traces.

The 475 bandwidth limit switch is the same as the trigger view control; pull
it out to activate the 20 or 100 MHz bandwidth limit.

On Sat, 11 Feb 2017 15:25:36 -0800, you wrote:

Simple: the frequency response of the P6106A is 250MHz which is much
greater than the no-name probe. In addition, the rolloff of the P6106A
will wider and more uniform than the no-name probe. The result of all
of this is that the 200MHz bandwidth of the 475 is capable of showing
more HF noise with the P6106A probe. Tek often puts a bandwidth limit
switch (such as BW FULL /
20MHZ) on their vertical amplifiers so you can reduce the HF noise on
your measurements. It doesn't appear that your 475 has this feature.

Either way the Tek P6106A probe is a much better probe than the
no-name. Do yourself a favor and look for another P6106A probe for the
other channel. It is quite common to need two matched channels on a
scope. Conversely, if the channels aren't matched you will often get
puzzling results.

Dennis Tillman W7PF

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Posted by: David <@DWH>
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Yahoo Groups Links


clean contacts on a 475A

James Graham
 

HiI'm new and I just bought a 475A that looks like it was stored for a long time. The volts/div and time/div act like they are dirty. I have tried 99% alcohol in a spray bottle on the volts/div and it helped some but they still act noisy. I don't see how I can get to the time/div switch without taking the board on the right off. I know that Tektronix recommends alcohol but does anyone know if any of the commercial contact cleaners are OK to use.Thank You


Help me in Repairing a 492P Spec An ?

jukebox netspace <jukebox@...>
 

Hello All,
I’m new to the group, from Australia.

I worked with a large TelCo for many years, in the repair, maintenance and calibration of fixed & field test equipment.
We used Tektronix, HP, W&G , some Siemens test gear.
I’m now retired.

I have an old 492P at home, which has a problem…

* the front panel lights up, but NONE of the lit buttons are responsive, there is a single slow traceline
at the lower edge of the screen (30 seconds, maybe), then a flicker every few seconds after that… no vertical deflection, no text on screen.
** Sometimes (rarely) on power-up, I get an erratic display with vertical lines like noise on a CRO… also no text.

I’m figuring something is not starting..maybe the uP that runs the front panel?

All voltages look ok at the test points over near the CRT and on the fuses in corner of power supply..

Can some-one point me in the right direction, please…. I do have some schematic pdfs.

Cheers, Dennis



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


Re: Trace thickness and edge variation by probe

 

I guess nobody is going to buy my story now about rubbing the probe
cables down with antenna wax for less fuzzy traces.

The 475 bandwidth limit switch is the same as the trigger view
control; pull it out to activate the 20 or 100 MHz bandwidth limit.

On Sat, 11 Feb 2017 15:25:36 -0800, you wrote:

Simple: the frequency response of the P6106A is 250MHz which is much greater
than the no-name probe. In addition, the rolloff of the P6106A will wider
and more uniform than the no-name probe. The result of all of this is that
the 200MHz bandwidth of the 475 is capable of showing more HF noise with the
P6106A probe. Tek often puts a bandwidth limit switch (such as BW FULL /
20MHZ) on their vertical amplifiers so you can reduce the HF noise on your
measurements. It doesn't appear that your 475 has this feature.

Either way the Tek P6106A probe is a much better probe than the no-name. Do
yourself a favor and look for another P6106A probe for the other channel. It
is quite common to need two matched channels on a scope. Conversely, if the
channels aren't matched you will often get puzzling results.

Dennis Tillman W7PF


Re: Vintage HP Signal Generator Acquired

 

On Sat, 11 Feb 2017 15:10:29 -0800, you wrote:

"It is so smooth now that I occasionally turn the knob even when it is
turned off."

Brad Salai

That happens here sometimes too, on a nice piece of gear that I am fond of,
good to know I am not the only one.

John
The planetary reduced frequency dial on my FG502 gained that allure
after I refurbished it. I like the ergonomics of the huge selector
control on the 7D13 multimeter also.


Re: Luck with an SC501

 

In their catalogs, Tektronix mentions combining the MR501 with the
RG501 (ramp generator) to make an oscilloscope.

On Sat, 11 Feb 2017 15:10:48 -0800, you wrote:

Hi Szabolcs,

The SC501 is a remarkably useful and clever scope given the space
constraints the engineer had to deal with who did the design. The only other
scope I am aware of that is as useful and about as compact is a little
Non-Linear Systems MS-215 which was also battery powered.

My impression is you have to watch out for the HV Oscillator transformer. It
goes bad in these scopes more often than anything else. I don't know why.
The only practical way to fix it is to get a transformer from a pats unit
when this happens.

Also very useful, and just as clever, is the MR501 Monitor. Instead of an X
axis timebase it has a X axis amplifier. The rest is the same.


Re: Trace thickness and edge variation by probe

 

Simple: the frequency response of the P6106A is 250MHz which is much greater
than the no-name probe. In addition, the rolloff of the P6106A will wider
and more uniform than the no-name probe. The result of all of this is that
the 200MHz bandwidth of the 475 is capable of showing more HF noise with the
P6106A probe. Tek often puts a bandwidth limit switch (such as BW FULL /
20MHZ) on their vertical amplifiers so you can reduce the HF noise on your
measurements. It doesn't appear that your 475 has this feature.

Either way the Tek P6106A probe is a much better probe than the no-name. Do
yourself a favor and look for another P6106A probe for the other channel. It
is quite common to need two matched channels on a scope. Conversely, if the
channels aren't matched you will often get puzzling results.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...]
Sent: Saturday, February 11, 2017 2:54 PM
To: TekScopes@...
Subject: [TekScopes] Trace thickness and edge variation by probe

On my Tektronix 475 scope I notice that when I change probes the thickness
and the edge of the trace change. See an example of two different types of
probes at each channel:

https://beta.groups.yahoo.com/neo/groups/TekScopes/photos/albums/868321764/l
ightbox/439640810?orderBy=ordinal&amp;sortOrder=asc&amp;photoFilter=ALL#zax/
439640810
The top one is a no name 100 MHz probe and the bottom one is Tektronix
P6106A probe. Both are at 10X attenuation. Note that the trace of P6106A is
thicker and the edge is less defined.
Does anybody has an explanation?








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Posted by: pesho_dage@...
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Yahoo Groups Links


Re: Luck with an SC501

 

Hi Szabolcs,

The SC501 is a remarkably useful and clever scope given the space
constraints the engineer had to deal with who did the design. The only other
scope I am aware of that is as useful and about as compact is a little
Non-Linear Systems MS-215 which was also battery powered.

My impression is you have to watch out for the HV Oscillator transformer. It
goes bad in these scopes more often than anything else. I don't know why.
The only practical way to fix it is to get a transformer from a pats unit
when this happens.

Also very useful, and just as clever, is the MR501 Monitor. Instead of an X
axis timebase it has a X axis amplifier. The rest is the same.

-----Original Message-----
Sent: Saturday, February 11, 2017 1:13 PM
Subject: [TekScopes] Luck with an SC501

Hi,

Recently I put an offer on eBay on an SC501, which was advertised as
faulty. The seller wrote that it had problem with the HV circuit, and thus
no trace.
Well, it has just arrived, in excellent shape. Turns out that the seller
probably just turned it on, saw no trace, assumed it's a HV problem and sold
it as not working. When in fact it was in normal trigger mode. As soon as
pulled the knob to auto trigger, I got a trace. Further testing showed that
it is fully working and in spec. I'm really happy.
Moral is, when selling stuff, be sure you know how it works, otherwise
people will buy it cheap.

I have to say, this is a cute little scope.
Szabolcs
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Posted by: szigszabolcs@...
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Re: Vintage HP Signal Generator Acquired

ykochcal
 

"It is so smooth now that I occasionally turn the knob even when it is
turned off."

Brad Salai

That happens here sometimes too, on a nice piece of gear that I am fond of,
good to know I am not the only one.

John


Trace thickness and edge variation by probe

Peter
 

On my Tektronix 475 scope I notice that when I change probes the thickness and the edge of the trace change. See an example of two different types of probes at each channel:
https://beta.groups.yahoo.com/neo/groups/TekScopes/photos/albums/868321764/lightbox/439640810?orderBy=ordinal&amp;sortOrder=asc&amp;photoFilter=ALL#zax/439640810 https://beta.groups.yahoo.com/neo/groups/TekScopes/photos/albums/868321764/lightbox/439640810?orderBy=ordinal&amp;sortOrder=asc&amp;photoFilter=ALL#zax/439640810

The top one is a no name 100 MHz probe and the bottom one is Tektronix P6106A probe. Both are at 10X attenuation. Note that the trace of P6106A is thicker and the edge is less defined.
Does anybody has an explanation?


Re: Tektronix 475 brightness variation

Peter
 

Indeed I meant that with faster sweep speed the screen becomes dimmer.

David, if I press 10x magnification the screen becomes dimmer, but I would not say it is 10 times dimmer. Still I can see the trace. I assume that if it was 10 times dimmer I wouldn't see it.
The important thing for me is that you confirm that the issue is normal.
Thank you all!


545H photos

kngtron
 

I added a album of the Tektronix 545H photos , thanks for your help


Re: Vintage HP Signal Generator Acquired

Craig Thibodeaux
 

I will be following this, I picked up 3 of these, in the lot of 'stuff' left over from Phillips exit from TN.

The first one I brought up slowly, and it is as solid as it weight. Nothing changed. The only thing I did was put the nut back on the rear of the binding post, as the ring terminal was just floating on it. I haven't cal'ed one yet, the manual is avail online, so I intend to do that.


There is a quick check of output voltage in the manual, easy to do.


You could bring it up slowly on a variac to reform the caps, or smoke em easier.


I plan on keeping one and was thinking of restoring the other two.


Re: Tektronix 475 brightness variation

David Berlind
 

Wow. This greenhorn is learning and foldering so much from well-explained
posts like these. That makes perfect sense and I can't wait to get back to
my scope just to see this principle in action first hand.

One day, I hope to answer a question.


Luck with an SC501

Szabolcs Szigeti
 

Hi,


Recently I put an offer on eBay on an SC501, which was advertised as faulty. The seller wrote that it had problem with the HV circuit, and thus no trace.
Well, it has just arrived, in excellent shape. Turns out that the seller probably just turned it on, saw no trace, assumed it's a HV problem and sold it as not working. When in fact it was in normal trigger mode. As soon as pulled the knob to auto trigger, I got a trace. Further testing showed that it is fully working and in spec. I'm really happy.
Moral is, when selling stuff, be sure you know how it works, otherwise people will buy it cheap.


I have to say, this is a cute little scope.


Szabolcs


Re: Gain calibration of a 468 scope

Colin Herbert
 

Continuing..

I have now got to the point of trying to adjust the Low-Frequency
Compensation. I believe that I have a little too much overshoot. The manual
states that on the Vertical Output Board there are five pre-sets which
affect the compensation at 1, 10 and 100KHz. That is all very well, but
there is also a requirement set the 486 vertical mode to CH1 & CH2 alternate
and disconnect P686 from J686 on the interface board. This J686 is the "Vert
Alt Sync". Now, either a 1KHz square-wave from a low-frequency generator (an
SG502?), or the fast-rise negative output from the PG506 is connected to
J686 with a BNC-to-Peltola adaptor. I don't understand why this is
considered to be necessary or what it is actually doing.

Neither the 464 nor the 465 scopes use this protocol, but the 465B does. Is
it really necessary, or could one simply leave P686/J686 connected and just
adjust the pre-set on the Vertical Output Board?

Any help and information appreciated. I am learning a lot fiddling with this
beast.

Colin.


Re: Vintage HP Signal Generator Acquired

Dave Casey
 

Well it's also a business decision. Ashley was refurbishing these for
resale and didn't want them coming back for silly reasons. If you're
maintaining your own, you only cost yourself if you replace the bad ones
and others fail shortly thereafter.


Dave Casey


On 2/11/2017 2:41 PM, David Holland david.w.holland@...
[TekScopes] wrote:

On Sat, Feb 11, 2017 at 2:47 PM, Ashley40@... [TekScopes]
<TekScopes@...> wrote:

Replace all of the caps. Frankly speaking, we never tested any of
them. If they were original ?, out they went.
I dunno that I disagree, but as soon as you mention wholesale
replacement, everyone comes out of the wood work to tell you you're
wrong, that HP & Tektronix used better than the average capacitor, and
they are likely still good, yada..yada..yada.. So I was trying to
head off that discussion. I think it has something to do with:
https://xkcd.com/386/ :-)

ESR'ing is what I do anymore. Most of the time they're bad anyways.
<shrug>

David



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


Re: Vintage HP Signal Generator Acquired

David Holland
 

On Sat, Feb 11, 2017 at 2:47 PM, Ashley40@... [TekScopes]
<TekScopes@...> wrote:

Replace all of the caps. Frankly speaking, we never tested any of them. If they were original ?, out they went.
I dunno that I disagree, but as soon as you mention wholesale
replacement, everyone comes out of the wood work to tell you you're
wrong, that HP & Tektronix used better than the average capacitor, and
they are likely still good, yada..yada..yada.. So I was trying to
head off that discussion. I think it has something to do with:
https://xkcd.com/386/ :-)

ESR'ing is what I do anymore. Most of the time they're bad anyways. <shrug>

David


Re: Vintage HP Signal Generator Acquired

Ashley40@...
 

"Specific Exercises"
At one time we overhauled these beasts and our "exercises " were pretty much like this:

Disassemble the bearings, gears, mechanical parts. Clean shafts ( polish with jewelers rouge after cleaning)
Re-lubricate ( we used Lubriplate)
( Note) It was not unusual to find the "pinch drive" mechanism "lost its pinch due to frozen gear/shaft/bearing issues"
Replace all of the caps. Frankly speaking, we never tested any of them. If they were original ?, out they went.
Replace the AC Cord Set ( I don't remember exactly, but I seem to recall we installed an IEC male connector)
It was, as I recollect, unusual to find "out of tolerance range resistors". HP made some pretty robust fixed attenuator resistors "back in the day"
These units clean up nicely, are very "boat-anchorish" and robust . Great addition to a test bench with room for them.

My $.02 worth
Kiss Electronics
Ms Ashley Hall
Owner
W7DUZ









Thank You
Kiss-Electronics
Ms Ashley Hall
183 N 5th Avenue
Cornelius, Oregon
97113


W7DUZ


www.kiss-electronics.com

-----Original Message-----
From: David Holland david.w.holland@... [TekScopes] <TekScopes@...>
To: TekScopes <TekScopes@...>
Sent: Sat, Feb 11, 2017 11:08 am
Subject: Re: [TekScopes] Vintage HP Signal Generator Acquired

No specific exercises on a 200CD, as I've never had one...

But they're tube based, and with just about anything that old, I'd ESR
out the electrolytics and see if they need replacement, and replace
any paper caps on general principles.
(Presuming you don't see signs of it having already been done.)

David


On Sat, Feb 11, 2017 at 11:42 AM, David Berlind david@...
[TekScopes] <TekScopes@...> wrote:
Here is a photo of my latest acquisition that I'll be looking to use in
combination with my Tek 2220. The previous owner thinks it works but I
haven't hooked it up yet and I've just left on a business trip.

https://goo.gl/photos/GWj97ERYEtLPR2S56

Suggested "exercises" and other general thoughts are welcome.




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Posted by: David Berlind <david@...>
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Posted by: David Holland <david.w.holland@...>
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Re: Tektronix 475 brightness variation

 

Between sweeps is a fixed minimum time where the sweep circuits have
to reset. I am not sure what that time is the 475 but say it is 2us
which is typical. Then at a sweep speed of 200ns/div, the entire
sweep takes about 2us but since the sweep is only active for 1/2 of
the time with the remaining time being spent blanked while the sweep
circuits reset, the brightness will be down to 1/2. At 100ns/div the
sweep is only active for 1/3rd of the time so the brightness is down
to 1/3rd. Etc. This all assumes that the sweep is free running in
automatic mode or that trigger events are occurring as fast as
possible.

There is a test you can do. When you activate the x10 horizontal
magnification, the brightness should becomes 1/10th.

Some oscilloscopes adjust the brightness with different sweep speeds
but I think the 475 only dims it at 0.1s/div and slower and in X-Y
mode.

On 11 Feb 2017 18:35:38 +0000, you wrote:

I noticed that when I change down the time base of my Tektronix 475 the screen brightness becomes dimmer.
Is that normal? Any similar observations by other owners of 475?
Best regards
Peter