Date   

Re: are the 500 series scopes still usefull

Dave Seiter
 

My first scope was a 502.  It was fun to play with, but the bandwidth was so low!  I did use it to trouble shoot the Commodore PET and CBM computer I used to build from Commodore dumpster finds, but it was quite challenging.  Not the correct tool for the job.
-Dav

From: "Carl Hallberg n9ess@yahoo.com [TekScopes]" <TekScopes@yahoogroups.com>
To: TekScopes@yahoogroups.com
Sent: Tuesday, November 14, 2017 3:39 AM
Subject: Re: [TekScopes] are the 500 series scopes still usefull

  Hi Dave,
I had a 502. Bought it from work for $400 about 1967. Very sensitive input (100uV to 100KHz) and max B.W. of 1MHz on higher ranges. Limited use for me and ended up giving it away some years later. 502 had tubes for input and 502A was solid state input.
Carl
--------------------------------------------
On Sun, 11/12/17, Dave Seiter d.seiter@att.net [TekScopes] <TekScopes@yahoogroups.com> wrote:

Subject: Re: [TekScopes] are the 500 series scopes still usefull
To: "TekScopes@yahoogroups.com" <TekScopes@yahoogroups.com>
Date: Sunday, November 12, 2017, 9:30 PM

As were the 502 and 503.

-Dave



From: "Carl Hallberg n9ess@yahoo.com [TekScopes]"
<TekScopes@yahoogroups.com>

To: TekScopes@yahoogroups.com

Sent: Sunday, November 12, 2017 4:41 AM

Subject: Re: [TekScopes] are the 500 series scopes still
usefull


  Hi Bob,

The 547 is a single beam scope. It can be dual trace, 4
trace, etc, depending on plug-in. 555, 556 were dual beam.

Carl



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

On Fri, 11/10/17, Bob Albert bob91343@yahoo.com [TekScopes]
<TekScopes@yahoogroups.com> wrote:

Subject: Re: [TekScopes] are the 500 series scopes still
usefull

To: TekScopes@yahoogroups.com

Date: Friday, November 10, 2017, 11:06 AM



The 530 series went to 15 MHz and the 540 series to 30 or
33

MHz.  The 580 to 80 MHz.  Plus, sampling units were

available to go a lot higher.  The high gain
differential

plug in and the calibrated offset plugin were really
nice,

and today's units don't have that.  My favorite
was

the 547 dual beam.

Bob


#yiv1987515682 #yiv1987515682 -- #yiv1987515682ygrp-mkp {border:1px solid #d8d8d8;font-family:Arial;margin:10px 0;padding:0 10px;}#yiv1987515682 #yiv1987515682ygrp-mkp hr {border:1px solid #d8d8d8;}#yiv1987515682 #yiv1987515682ygrp-mkp #yiv1987515682hd {color:#628c2a;font-size:85%;font-weight:700;line-height:122%;margin:10px 0;}#yiv1987515682 #yiv1987515682ygrp-mkp #yiv1987515682ads {margin-bottom:10px;}#yiv1987515682 #yiv1987515682ygrp-mkp .yiv1987515682ad {padding:0 0;}#yiv1987515682 #yiv1987515682ygrp-mkp .yiv1987515682ad p {margin:0;}#yiv1987515682 #yiv1987515682ygrp-mkp .yiv1987515682ad a {color:#0000ff;text-decoration:none;}#yiv1987515682 #yiv1987515682ygrp-sponsor #yiv1987515682ygrp-lc {font-family:Arial;}#yiv1987515682 #yiv1987515682ygrp-sponsor #yiv1987515682ygrp-lc #yiv1987515682hd {margin:10px 0px;font-weight:700;font-size:78%;line-height:122%;}#yiv1987515682 #yiv1987515682ygrp-sponsor #yiv1987515682ygrp-lc .yiv1987515682ad {margin-bottom:10px;padding:0 0;}#yiv1987515682 #yiv1987515682actions {font-family:Verdana;font-size:11px;padding:10px 0;}#yiv1987515682 #yiv1987515682activity {background-color:#e0ecee;float:left;font-family:Verdana;font-size:10px;padding:10px;}#yiv1987515682 #yiv1987515682activity span {font-weight:700;}#yiv1987515682 #yiv1987515682activity span:first-child {text-transform:uppercase;}#yiv1987515682 #yiv1987515682activity span a {color:#5085b6;text-decoration:none;}#yiv1987515682 #yiv1987515682activity span span {color:#ff7900;}#yiv1987515682 #yiv1987515682activity span .yiv1987515682underline {text-decoration:underline;}#yiv1987515682 .yiv1987515682attach {clear:both;display:table;font-family:Arial;font-size:12px;padding:10px 0;width:400px;}#yiv1987515682 .yiv1987515682attach div a {text-decoration:none;}#yiv1987515682 .yiv1987515682attach img {border:none;padding-right:5px;}#yiv1987515682 .yiv1987515682attach label {display:block;margin-bottom:5px;}#yiv1987515682 .yiv1987515682attach label a {text-decoration:none;}#yiv1987515682 blockquote {margin:0 0 0 4px;}#yiv1987515682 .yiv1987515682bold {font-family:Arial;font-size:13px;font-weight:700;}#yiv1987515682 .yiv1987515682bold a {text-decoration:none;}#yiv1987515682 dd.yiv1987515682last p a {font-family:Verdana;font-weight:700;}#yiv1987515682 dd.yiv1987515682last p span {margin-right:10px;font-family:Verdana;font-weight:700;}#yiv1987515682 dd.yiv1987515682last p span.yiv1987515682yshortcuts {margin-right:0;}#yiv1987515682 div.yiv1987515682attach-table div div a {text-decoration:none;}#yiv1987515682 div.yiv1987515682attach-table {width:400px;}#yiv1987515682 div.yiv1987515682file-title a, #yiv1987515682 div.yiv1987515682file-title a:active, #yiv1987515682 div.yiv1987515682file-title a:hover, #yiv1987515682 div.yiv1987515682file-title a:visited {text-decoration:none;}#yiv1987515682 div.yiv1987515682photo-title a, #yiv1987515682 div.yiv1987515682photo-title a:active, #yiv1987515682 div.yiv1987515682photo-title a:hover, #yiv1987515682 div.yiv1987515682photo-title a:visited {text-decoration:none;}#yiv1987515682 div#yiv1987515682ygrp-mlmsg #yiv1987515682ygrp-msg p a span.yiv1987515682yshortcuts {font-family:Verdana;font-size:10px;font-weight:normal;}#yiv1987515682 .yiv1987515682green {color:#628c2a;}#yiv1987515682 .yiv1987515682MsoNormal {margin:0 0 0 0;}#yiv1987515682 o {font-size:0;}#yiv1987515682 #yiv1987515682photos div {float:left;width:72px;}#yiv1987515682 #yiv1987515682photos div div {border:1px solid #666666;min-height:62px;overflow:hidden;width:62px;}#yiv1987515682 #yiv1987515682photos div label {color:#666666;font-size:10px;overflow:hidden;text-align:center;white-space:nowrap;width:64px;}#yiv1987515682 #yiv1987515682reco-category {font-size:77%;}#yiv1987515682 #yiv1987515682reco-desc {font-size:77%;}#yiv1987515682 .yiv1987515682replbq {margin:4px;}#yiv1987515682 #yiv1987515682ygrp-actbar div a:first-child {margin-right:2px;padding-right:5px;}#yiv1987515682 #yiv1987515682ygrp-mlmsg {font-size:13px;font-family:Arial, helvetica, clean, sans-serif;}#yiv1987515682 #yiv1987515682ygrp-mlmsg table {font-size:inherit;font:100%;}#yiv1987515682 #yiv1987515682ygrp-mlmsg select, #yiv1987515682 input, #yiv1987515682 textarea {font:99% Arial, Helvetica, clean, sans-serif;}#yiv1987515682 #yiv1987515682ygrp-mlmsg pre, #yiv1987515682 code {font:115% monospace;}#yiv1987515682 #yiv1987515682ygrp-mlmsg * {line-height:1.22em;}#yiv1987515682 #yiv1987515682ygrp-mlmsg #yiv1987515682logo {padding-bottom:10px;}#yiv1987515682 #yiv1987515682ygrp-msg p a {font-family:Verdana;}#yiv1987515682 #yiv1987515682ygrp-msg p#yiv1987515682attach-count span {color:#1E66AE;font-weight:700;}#yiv1987515682 #yiv1987515682ygrp-reco #yiv1987515682reco-head {color:#ff7900;font-weight:700;}#yiv1987515682 #yiv1987515682ygrp-reco {margin-bottom:20px;padding:0px;}#yiv1987515682 #yiv1987515682ygrp-sponsor #yiv1987515682ov li a {font-size:130%;text-decoration:none;}#yiv1987515682 #yiv1987515682ygrp-sponsor #yiv1987515682ov li {font-size:77%;list-style-type:square;padding:6px 0;}#yiv1987515682 #yiv1987515682ygrp-sponsor #yiv1987515682ov ul {margin:0;padding:0 0 0 8px;}#yiv1987515682 #yiv1987515682ygrp-text {font-family:Georgia;}#yiv1987515682 #yiv1987515682ygrp-text p {margin:0 0 1em 0;}#yiv1987515682 #yiv1987515682ygrp-text tt {font-size:120%;}#yiv1987515682 #yiv1987515682ygrp-vital ul li:last-child {border-right:none !important;}#yiv1987515682



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


Re: New member and owner of a dead 2225

 

I have run across at least 4 different files but I think they all
originate from a single scan.

On 14 Nov 2017 01:13:50 +0000, you wrote:

I have the 1982 version I think and one from a website that is no longer there called Tek-cross-ref-free. It has a sig in the pdf of www.aa4df.com http://www.aa4df.com which is available for someone to purchase but no longer online. I can't post either because they are way past the limit on upload sizes. Transistors and IC's are in both..

Mitch
N4MF


Re: New member and owner of a Ten 465

 

On 14 Nov 2017 16:25:00 +0000, you wrote:

...

I only have a problem with phasing. When I try to test the x-y mode with the same signal on both channels, I don’t have a diagonal line, but an elliptic diagonal figure.

I have to check that more out, because Now it looks like there is few degrees phase difference between the 2 channels.

When I see the both channels on my screen not in x-y mode, they seem in phase, but that is probably because the way I trigger. I don’t know, I haven’t seen this problem in a scope before. But never have had a more then 40 year olol scope that probably hasn’t had any calibration in 20 years or so.
Triggering has no meaning in X-Y mode except in that the trigger
source and trigger coupling affect the X input.

The vertical delay line and to a lesser extent low horizontal
bandwidth limits X-Y bandwidth at low phase differences. For the 465,
I think this is 50 kHz up to 3 degrees of phase difference. Some
oscilloscopes but not the 465 series or portable oscilloscopes in
general have a phase correction option which increases this to 1 MHz
or more.


Re: New member and owner of a Ten 465

Albert Otten
 

Hello Peter,

The manual (for S/N B250000-up) specifies the X-Y phase angle typically less than 3 degrees up to 50 kHz. That would be very well visible, ellipse opening (hor. or vert.) I think about 10 % of total width or height.
The signal path for the X deflection passes the horizontal amplifier. If you compare phases of CH1 and CH2 in ordinary mode then both use the same vertical amplifier. In many or most Tek 'scopes the (external) horizontal BW is very low compared to the vertical BW. For some types there is an Option for smaller X-Y phase difference.

Albert


Re: New member and owner of a dead 2225

 

On Tue, 14 Nov 2017 07:29:01 -0800, you wrote:

...

In studying the schematic of the 2225 power supply, we see that it has
at least twice as many parts as the more common 22xx family which
includes the 2235, etc. Maybe this explains why it is fairly rare to
hear about 2225 power supply problems?
tom jobe...
It is just a very different design with much less stress on the
individual parts. The price for this is having to include a large 60
Hz power transformer. The 2225 series has also not aged quite as
much.


Re: New member and owner of a dead 2225

 

On 14 Nov 2017 13:44:55 +0000, you wrote:

After a marathon session at distributor's web sites, I found a number of perfect fit replacement caps but still missing a few.

What is glaring is the absence of axial cap selection. It looks like these are disappearing fast. Not that I blame the manufacturers - I hate bending leads and would rather use SMDs any day. I was wrong about the axial caps' value - 15 uF, not 10. I wasn't able to find anything at mouser or digikey that matched except for some tant caps that were like $100. Since I need 7 of those, that ain't happening. These aren't in the power supply section so I don't HAVE to replace them. What are people doing in this situation? accepting worse tolerance? Significantly higher voltage (like 100+ for 10V caps), if that's even available?
Unless they are used for timing like in a soft start circuit, the
values are not critical. Larger values are better up to a point.

For local bulk decoupling capacitors, values are usually selected
based on ESR at high frequency so a lower value solid tantalum
capacitor can replace a larger value aluminum electrolytic capacitor
with a ratio of about 2 to 4.

There is a wonderful selection of SMD caps with tight tolerances for well less than a buck. I could imagine making a tiny little carrier board that would convert the SMD to the right pitch and size to replace an axial cap. Anything wrong with that idea?
It is much easier to use radial lead parts by insulating and bending
one lead around the capacitor body.


Re: New member and owner of a dead 2225

 

On 14 Nov 2017 10:11:05 +0000, you wrote:

On higher voltage caps, it's it the case the higher V often means higher ESR?
With higher voltage ratings up to about 100 volts, dissipation factor
and ESR drop and ripple current rating increases. Ripple current
rating depends on ESR and surface area for dissipating heat. There is
a jump at about 160 volts and higher where the dissipation factor and
ESR increase because the electrolyte is different (at least I think it
is due to a different electrolyte) to support higher voltage
operation.

I am planning on pulling all the switcher electrolytic caps out and am hoping to find what went bad to help with the general diagnosis. Right now, my bet is on either C915 or C971. Hopefully the series regulator and inverter are ok as I don't have a scope to debug my scope with...
It might just be a case of Q913 failing for whatever reason including
CR912 shorting, R920 failing open or high, base drive being
insufficient, or contamination through the package. But I would still
change the aluminum electrolytic capacitors in the power supply except
maybe for C900 if it and the bridge rectifier diodes CR901 through
CR904 test good. If diode shorted and then failed open, it might
have damaged C900 without it being apparent.

Another thing which could have caused failure of Q913 is a low input
voltage. With low input voltage, the duty cycle to maintain the
output voltage is higher so Q913 conducts longer and runs hotter.


New member and owner of a Ten 465

hendrickx.peter@...
 

Hello, my name is Peter Hendrickx. I’m a European who lives in Canada. I have worked for 22 years in cable TV for testing and repairing measurement equipment and amplifiers.
I’m licensed ham radio amateur too.
I recently bought a cheap Tek 465 on ebay with condition for parts or not working. But it was described as Trace for channel 1 and no trace for channel 2. When it arrived, the scope was like described. After take out and plugin again the transistors in vertical amp CH2, I had traces for both channels. On channel 1 , there was a problem with the level (the level displayed was 2.5 times to high). After take out and plugin the transistors for the vertical amp in Ch1, the problem was solved. Then I aligned the potters for step attenuator balance, so there is only a 0.2 Div varriation when I change Volt/Div switch from both channels between min and max.
I aligned the both voltage traces at the same voltage out on the display on a 1000 Hz frequency.
I have tested the bandwith till 20 MHz, and the output voltage seems fine. I cannot test to a higher frequency, because I don’t have a good source where I know the amplitude on a higher frequency.
I have cleaned the contacts from the attenuator with isopropyl alcohol and a small painting brush.
I calibrated the time base on 50 ns.
The power supply seems fine, gives out all the right voltages with a ripple of a few millivolts. On.y on the 110V, I have between 10 and 20 mv ripple. The high voltage, I’m not able to test.
The screen is bright and the traces are sharp focussed.
The triggering seems to work fine.
I only have a problem with phasing. When I try to test the x-y mode with the same signal on both channels, I don’t have a diagonal line, but an elliptic diagonal figure.
I have to check that more out, because Now it looks like there is few degrees phase difference between the 2 channels.
When I see the both channels on my screen not in x-y mode, they seem in phase, but that is probably because the way I trigger. I don’t know, I haven’t seen this problem in a scope before. But never have had a more then 40 year olol scope that probably hasn’t had any calibration in 20 years or so.
I will try to calibrate the complete scope as far I can with the equipment I have.


I’m looking forward to participate this group and helping as far as I can.


Greetings,

Peter


Re: New member and owner of a dead 2225

 

Just go up to 15uF, or 18uF, or maybe even 20uF. Odds are that the old part
was -10%,+100%, so an 18uF part would likely be spot on, and 20uF would not
harm any.

These are after all just decoupling caps.

Dave

-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com]
Sent: 14 November 2017 13:45
To: TekScopes@yahoogroups.com
Subject: [TekScopes] Re: New member and owner of a dead 2225

After a marathon session at distributor's web sites, I found a number of
perfect fit replacement caps but still missing a few.

What is glaring is the absence of axial cap selection. It looks like these
are disappearing fast. Not that I blame the manufacturers - I hate bending
leads and would rather use SMDs any day. I was wrong about the axial caps'
value - 15 uF, not 10. I wasn't able to find anything at mouser or digikey
that matched except for some tant caps that were like $100. Since I need 7
of those, that ain't happening. These aren't in the power supply section so
I don't HAVE to replace them. What are people doing in this situation?
accepting worse tolerance? Significantly higher voltage (like 100+ for 10V
caps), if that's even available?


There is a wonderful selection of SMD caps with tight tolerances for well
less than a buck. I could imagine making a tiny little carrier board that
would convert the SMD to the right pitch and size to replace an axial cap.
Anything wrong with that idea?


Phil






------------------------------------
Posted by: phillip.lyne.barrett@gmail.com
------------------------------------


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

Yahoo Groups Links


Re: New member and owner of a dead 2225

Tom Jobe <tomjobe@...>
 

Another question. There are at least 9 10 uF axial electrolytics in
various places. I should replace them as well? I'm not wild about removing the attenuator/timebase board, though it's probably easier than it looks.

Hi Phil,
Sorry for not being clearer about my suggestion of replacing the 10 uF and up aluminum electrolytic caps, my comments are only about the repairing of the power supply, and not about any other sections of your oscilloscope.
The leads on those 'snap' caps bend easily, maybe spread them to fit and plan on not having the cap sit down on the board tightly? Maybe use two pair of pliers so the joint between the leads and the capacitor body are not disturbed?
In studying the schematic of the 2225 power supply, we see that it has at least twice as many parts as the more common 22xx family which includes the 2235, etc. Maybe this explains why it is fairly rare to hear about 2225 power supply problems?
tom jobe...


Re: Engine Analyzer Plug-In Modification

Albert Otten
 

Sure this does show on the outside. Just compare the photo in "Engine Analysis Measurements" (Measurement Concepts Series) with an ordinary 2B67.
For example, the text mentions a Rotational Function Generator position of the (modified) Time/Div switch.

Albert


---In TekScopes@yahoogroups.com, <grbosworth@...> wrote :

Does anyone know the specific modification that was done to the 2B67 horizontal sweep plug-in to make it work with the Engine Analyzer that Tektronix offered back in the 1960's and 1970's? Physically, does it show on the outside of the plug-in?


Re: New member and owner of a dead 2225

phillip.lyne.barrett
 

After a marathon session at distributor's web sites, I found a number of perfect fit replacement caps but still missing a few.

What is glaring is the absence of axial cap selection. It looks like these are disappearing fast. Not that I blame the manufacturers - I hate bending leads and would rather use SMDs any day. I was wrong about the axial caps' value - 15 uF, not 10. I wasn't able to find anything at mouser or digikey that matched except for some tant caps that were like $100. Since I need 7 of those, that ain't happening. These aren't in the power supply section so I don't HAVE to replace them. What are people doing in this situation? accepting worse tolerance? Significantly higher voltage (like 100+ for 10V caps), if that's even available?


There is a wonderful selection of SMD caps with tight tolerances for well less than a buck. I could imagine making a tiny little carrier board that would convert the SMD to the right pitch and size to replace an axial cap. Anything wrong with that idea?


Phil


Re: DIY TD Pulser

Eino Väänänen
 

I have also Tektronix 067-0513-00 with broken original tunnel diode. I have installed tunnel diode 1N3718 to GR-874 connector. Rise time is now 800 ps.


Eino


Re: are the 500 series scopes still usefull

Carl Hallberg
 

Hi Dave,
I had a 502. Bought it from work for $400 about 1967. Very sensitive input (100uV to 100KHz) and max B.W. of 1MHz on higher ranges. Limited use for me and ended up giving it away some years later. 502 had tubes for input and 502A was solid state input.
Carl
--------------------------------------------

On Sun, 11/12/17, Dave Seiter d.seiter@att.net [TekScopes] <TekScopes@yahoogroups.com> wrote:

Subject: Re: [TekScopes] are the 500 series scopes still usefull
To: "TekScopes@yahoogroups.com" <TekScopes@yahoogroups.com>
Date: Sunday, November 12, 2017, 9:30 PM

As were the 502 and 503.

-Dave



From: "Carl Hallberg n9ess@yahoo.com [TekScopes]"
<TekScopes@yahoogroups.com>

To: TekScopes@yahoogroups.com

Sent: Sunday, November 12, 2017 4:41 AM

Subject: Re: [TekScopes] are the 500 series scopes still
usefull


  Hi Bob,

The 547 is a single beam scope. It can be dual trace, 4
trace, etc, depending on plug-in. 555, 556 were dual beam.

Carl



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

On Fri, 11/10/17, Bob Albert bob91343@yahoo.com [TekScopes]
<TekScopes@yahoogroups.com> wrote:

Subject: Re: [TekScopes] are the 500 series scopes still
usefull

To: TekScopes@yahoogroups.com

Date: Friday, November 10, 2017, 11:06 AM



The 530 series went to 15 MHz and the 540 series to 30 or
33

MHz.  The 580 to 80 MHz.  Plus, sampling units were

available to go a lot higher.  The high gain
differential

plug in and the calibrated offset plugin were really
nice,

and today's units don't have that.  My favorite
was

the 547 dual beam.

Bob


Re: New member and owner of a dead 2225

phillip.lyne.barrett
 

Thanks. I went through Mouser looking for the caps. 300 mil pitch doesn't seem to exist anymore. Will try Digi. On higher voltage caps, it's it the case the higher V often means higher ESR?

I am planning on pulling all the switcher electrolytic caps out and am hoping to find what went bad to help with the general diagnosis. Right now, my bet is on either C915 or C971. Hopefully the series regulator and inverter are ok as I don't have a scope to debug my scope with...


As to Dave, it's not his Aussie accent and turn of phrase, rather his high pitched voice and geeky mannerisms that bug my Wife. It sometimes gets a bit wearing to me too. Plus it can be hard to figure out if he thinks something is good or bad. I went to school with a bunch of Aussies - great group of friends.


Re: New member and owner of a dead 2225

 

On 14 Nov 2017 07:18:45 +0000, you wrote:

I've seen those videos. Dave's tear down is really good though my wife makes me wear headphones for any of his videos - she's a non-fan. I kind of get her point...
Crikey! Dave's Australian speech makes for entertaining listening but
I can understand how it would get old after a while. The same thing
happens to me if I binge watch Doctor Who episodes.

After following the circuits on the schematic, I think the 38V/67.5V feeds are probably OK because there doesn't seem to be anything particularly sensitive there. Two 100n 50V ceramics are worth looking at, one on the X-Axis Amp and one in the vertical output amp. Everything else feeds though resistors. Though the lowest is 330 so bears looking at a bit more.
Damage to the vertical CRT amplifier transistors is possible.
Depending on the bias conditions which are not real clear with the
power supply malfunctioning, the 2N3866s could have a specified
maximum breakdown voltage between Vceo of 30 volts and Vcbo of 55
volts. Luckily they should be easy to replace if damaged.

I am surprised that the switching preregulator did not include an SCR
crowbar circuit to protect against a shorted switching transistor but
maybe Tektronix determined that it was not necessary.

On the caps, I've found what look like decent replacements - reasonably low ESR, same or better tolerance and all are 105C. However, not a single lead pitch matches. I can make them fit by bending the leads in an L to make them fit the original pitch. I assume that there is no issue with that. So, not worried except for C900 - the big 2200 uF 80V on the mains input board. The only matches are snap-in caps with fat, stiff, stubby leads and the wrong terminal pitch. (10mm vs a measured 12mm on the one that's there now). I guess I can make a little adapter but it will be a bit ugly. If I was industrious, I'd 3D print a foot for it to keep it from moving around - though it will probably be hot glued instead.
Usually capacitors with the correct lead pitch can be found. Higher
voltage parts can be selected if necessary and this may even be
desirable for improved reliability and operating life.

The big bulk input capacitor is one of the aluminum electrolytics
which is likely to last the longest so maybe leaving it in place would
be best unless testing shows that it has failed. The reason for this
is that it was originally selected based on capacitance instead of ESR
or ripple current rating which will be more than enough and it is the
last one which impacts operating life.

Another question. There are at least 9 10 uF axial electrolytics in various places. I should replace them as well? I'm not wild about removing the attenuator/timebase board, though it's probably easier than it looks.
They will not have caused the failure but replacing them may lead to
better performance and perhaps less noise in the displayed trace. On
the other hand, replacing parts unnecessarily risks causing damage.

Once I get my ESR meter (due this Friday), I'll hopefully find a smoking gun.
Unfortunately an ESR meter will consider a shorted capacitor good.
They are useful and convenient for in-circuit measurements but not
always easy to interpret.

Soon your 2225 will be operating with peak efficiency and Bob's your
uncle!

You should hear some of the San Dimas slang I picked up when I worked
there which was not featured in the Bill and Ted movies.


Re: A fool and his money ...OR ... moneywell spent

 

On 13 Nov 2017 18:11:41 +0000, you wrote:

I got the Agilent probes and they seem to be performing well with the Tek 2465 CTS but I really can't check the upper part of the bandwidth. I looked at getting a Tektronix 067-0681-01 (Calibration fixture / tunnel diode pulser) and was quite shocked on the availability and cost - more than I paid for the scope, shipping, and three of the four probes. Guess I'll be on the lookout for one of these. Not going to pay $250 that some folks want for these.
Oh, and I forgot to mention that this is not something I would worry a
great deal about. Even without adjustment, the Agilent probes will be
close and you are unlikely to be measuring any signals with high
impedance passive probes that will reveal a problem because of the
relatively high probe loading at 300 MHz and higher.


Re: DIY TD Pulser

Craig Sawyers <c.sawyers@...>
 

Alternatively, the UKP50 pulser we discussed a month or two back that does <40ps.

http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295&zenid=e90df0d242b960a20cbff2cb95ed16f3

The calibration data that came with mine was ~31ps. Although technically there are some aberrations
probably as a result of the BNC connector, they would possibly only be visible if pushing the limits
of an S4 or S6 sampling head. For a 7104 the rise is exceptionally clean and verifies a system rise
time of 350ps with 7A29's.

Unless the idea is to try and make a Tek TD pulser as a technical challenge. Which is absolutely fine
of course - I totally understand that!

Craig

-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com]
Sent: 14 November 2017 04:19
To: TekScopes@yahoogroups.com
Subject: Re: [TekScopes] Re: DIY TD Pulser

Pardon, two of the 067-0513-00 pulse generators that David
mentioned wanting to see the inside of.

Which can be arranged, as I have two of them.

-Chuck Harris

Jeff Davis n0dyjeff@hotmail.com [TekScopes] wrote:
Not sure what exactly you have two of... ??


I've posted some test results from two samples of the build I did following the notes from Sergey
Kubushyn. The test was conducted over the noon hour on an 8 GHz digital Tektronix scope at work -
didn't catch the exact model number.

I posted captures of the rise time photos under "DIY TD Pulser" in the Photos section. Got 159 pS
on
the first build. Was a little more careful with the output construction on the second and got down
to
119 pS with it.


Jeff


________________________________
From: TekScopes@yahoogroups.com <TekScopes@yahoogroups.com> on behalf of Chuck Harris
cfharris@erols.com [TekScopes] <TekScopes@yahoogroups.com>
Sent: Monday, November 13, 2017 6:46 PM
To: TekScopes@yahoogroups.com
Subject: Re: [TekScopes] Re: DIY TD Pulser



I have two of them. One has a bad TD, the other works, but
is easily 10 times slower than the spec's say it should be.

I had heard that when tektronix made them they had no real
way of measuring the pulse risetime, so they guessed.

-Chuck Harris

David davidwhess@gmail.com [TekScopes] wrote:
Why can't you use the random sampling capability on the 7T11? Then at
least no delay line should be required. A power divider might still
be desirable to separate the sampling kickout from the trigger.

Tektronix had a slightly more complex tunnel diode pulse generator
which generated a pretrigger:

<http://w140.com/tekwiki/wiki/067-0513-00>

It would be interesting to see the inside to see how it was
constructed.

------------------------------------
Posted by: Chuck Harris <cfharris@erols.com>
------------------------------------


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

Yahoo Groups Links



Re: New member and owner of a dead 2225

phillip.lyne.barrett
 

Thanks, David, Tom, Tom and Glen.

I've seen those videos. Dave's tear down is really good though my wife makes me wear headphones for any of his videos - she's a non-fan. I kind of get her point...

After following the circuits on the schematic, I think the 38V/67.5V feeds are probably OK because there doesn't seem to be anything particularly sensitive there. Two 100n 50V ceramics are worth looking at, one on the X-Axis Amp and one in the vertical output amp. Everything else feeds though resistors. Though the lowest is 330 so bears looking at a bit more.


It looks like Q912 is not blown, at least a resistance check across the collector and base sees a cap charging up - probably C909 though the 2.2K resistor on the base. Not sure how to determine if either TL594 is dead. I've got the datasheet but haven't looked yet. Will probably order a few just in case, they're cheap.


On the caps, I've found what look like decent replacements - reasonably low ESR, same or better tolerance and all are 105C. However, not a single lead pitch matches. I can make them fit by bending the leads in an L to make them fit the original pitch. I assume that there is no issue with that. So, not worried except for C900 - the big 2200 uF 80V on the mains input board. The only matches are snap-in caps with fat, stiff, stubby leads and the wrong terminal pitch. (10mm vs a measured 12mm on the one that's there now). I guess I can make a little adapter but it will be a bit ugly. If I was industrious, I'd 3D print a foot for it to keep it from moving around - though it will probably be hot glued instead.


Another question. There are at least 9 10 uF axial electrolytics in various places. I should replace them as well? I'm not wild about removing the attenuator/timebase board, though it's probably easier than it looks.


Once I get my ESR meter (due this Friday), I'll hopefully find a smoking gun.


Anyway, again, thanks for all the help. I really do appreciate all your efforts.


Phil


Re: DIY TD Pulser

Chuck Harris <cfharris@...>
 

Pardon, two of the 067-0513-00 pulse generators that David
mentioned wanting to see the inside of.

Which can be arranged, as I have two of them.

-Chuck Harris

Jeff Davis n0dyjeff@hotmail.com [TekScopes] wrote:

Not sure what exactly you have two of... 😊


I've posted some test results from two samples of the build I did following the notes from Sergey Kubushyn. The test was conducted over the noon hour on an 8 GHz digital Tektronix scope at work - didn't catch the exact model number.

I posted captures of the rise time photos under "DIY TD Pulser" in the Photos section. Got 159 pS on the first build. Was a little more careful with the output construction on the second and got down to 119 pS with it.


Jeff


________________________________
From: TekScopes@yahoogroups.com <TekScopes@yahoogroups.com> on behalf of Chuck Harris cfharris@erols.com [TekScopes] <TekScopes@yahoogroups.com>
Sent: Monday, November 13, 2017 6:46 PM
To: TekScopes@yahoogroups.com
Subject: Re: [TekScopes] Re: DIY TD Pulser



I have two of them. One has a bad TD, the other works, but
is easily 10 times slower than the spec's say it should be.

I had heard that when tektronix made them they had no real
way of measuring the pulse risetime, so they guessed.

-Chuck Harris

David davidwhess@gmail.com [TekScopes] wrote:
Why can't you use the random sampling capability on the 7T11? Then at
least no delay line should be required. A power divider might still
be desirable to separate the sampling kickout from the trigger.

Tektronix had a slightly more complex tunnel diode pulse generator
which generated a pretrigger:

<http://w140.com/tekwiki/wiki/067-0513-00>

It would be interesting to see the inside to see how it was
constructed.

40381 - 40400 of 182169