Date   

2236 trace fades at higher sweep speeds

Oliver Viitamaki
 

Issue: The 'scope has good intensity at long sweep times, but when I switch it to fastersweeps, the trace fades away.

Troubleshooting so far:
I purchased the 2236 on ebay, as having no trace, so I have no long history with this scope.
When it arrived, I was able to get a trace, on both channels. So far, I have replaced the
Power Supply capacitors, focus resistors, the LVPS voltages and ripple is within spec.
I do not have a high voltage probe, so I can't measure the HV power supply. The Grid Bias
has been adjusted as per the manual.
The trace is nice (focused) and bright at lower sweep speeds (0.2 ms), and slowly fades
as the sweep speed is increased. The beam stays focused, as it fades. Without an input signal the trace can be still seen at the highest
sweep speed (0.05us). With an input signal, the trace can no longer be seen when sweep speeds are 2us, or faster.
I'm looking for suggestions on where to troubleshoot further.
Is this a Z axis problem, or a tube problem?
I have searched the forum, and can find similar problems, but not one very close to this one.


Tektronix 1140A-- any interest?

Brad Thompson <bradthompsonaa1ip@...>
 

Hello--

I have a Tek "1140A Load Current Shunt Fixture", part no.
067-0764-00, which isn't documented but appears to be an
assortment of load resistors (some defective), switches and fuseholders.

If no one finds this of interest or value, I plan to use it to house a vacuum-tube curve
tracer project...
(http://www.dos4ever.com/uTracer3/uTracer3_pag0.html)

However, I'd feel remorseful if I dismantled this instrument only to learn
that someone in the group needed this item to complete a system or
a collection.

Please advise-- I'm a couple of weeks away from starting my project.

Thanks, and 73--

Brad AA1IP
or augment a collection.


Power Supply Extender Cables

JJ
 

Be careful when using the multi-wire flat rainbow color ribbon jumper cables with connectors already installed that you can buy on eBay for a few dollars to extend the 7000 power supply cables. I used them to extend the cables on my 7904 after hanging the power supply out the back end of the mainframe. I found 4 tantalum caps that were shorted on the rectifier board. After replacing the caps, things were working fine until about 5 minutes after power on when all hell would break loose in the low voltage regulator board power supplies and the trace would tear and go off screen. The cables worked well until I encountered the thermal problem - the low voltage regulator board's 54V power supply would have its ripple increase to about 6V after awhile, and all the other supplies would follow suit. TP1625 on the rectifier board would go from 40V to 125V. It should be adjusted to and stay at 40VDC (no plugins, etc) according to the Tek Power Supply spec.

I thought I had a thermal issue with another component but it turned out that the ribbon jumper that I used to extend one of the low voltage regulator cables (the cable that connects to the main board) was heating up to over 175 F according to my infra-red thermometer. After freezing the connector, the voltage went back down to 40VDC. Took me awhile to find it.
The Tektronix ribbon cables fit very tightly on the pins and the wire gauge is heavier - maybe 22ga or 24ga - whereby the eBay jumpers were 28ga and the connectors didn't fit anywhere as tightly on the pins - thus a high resistance connection.

I hope this helps someone.

John Justin


Re: tektronix 475 help ic part

Roger Evans
 

It's the 'sweep logic' IC that controls A, B sweep, trigger and hold off. They turn up quite regularly on eBay, typically $20 or so plus postage to Europe. They are used in several of the 7000 timebases, eg 7B50A, 7B80, 7B85 and others, so you might be lucky and find a scrap timebase plugin but even scrap units seem to fetch quite high prices.

Regards,

Roger


Re: tektronix 475 help ic part

Jim Olson <v_12eng@...>
 

Roberto I do not have my 475 book right now so need to know what is and which board it is on? I have a 475 disassembled for parts most likely I have it.

Jim O

On January 22, 2019 at 10:07 AM Roberto <iw5bsf@alice.it mailto:iw5bsf@alice.it > wrote:


I'm looking for how and failed ic part number 155004901 sweep ,
qservice he has no one
Roberto



Re: Unknown 545A plugin

C Smith
 

Not sure what u have, but I had a few of these clones bk in the day, and they were pretty much exactly like the text Tek CA plugin.
http://w140.com/tekwiki/wiki/Lavoie_LA-265-CA.
The other link shows, I think a very old Lavoie CA clone.
The ones I had were exactly like the tek plug-in, Spec's, manuals were about the same.
Wish I still Had! :-(


c smith
ka3bnn


tektronix 475 help ic part

Roberto
 

I'm looking for how and failed ic part number 155004901 sweep ,
qservice he has no one
Roberto


Re: Unknown 545A plugin

Bob Albert
 

I would guess LaVoie (sp?), who made Tek 500 series clones.
Bob

On Tuesday, January 22, 2019, 9:29:25 AM PST, iMac via Groups.Io <luispla=mac.com@groups.io> wrote:

Hi
The sticker looks pretty close.Probably is a Lavoie.
Thanks.


Re: Unknown 545A plugin

iMac
 

Hi
The sticker looks pretty close.Probably is a Lavoie.
Thanks.


Re: Unknown 545A plugin

Daniel Koller
 

Is this one of the Lavoie "clones"?  Others here might know exactly, but look on the wiki here:http://w140.com/tekwiki/images/d/dd/Lavoie_la-545-54b_2.jpg

You might send a photo to Kurt at the wiki page if there is not one up there already.
  Dan

On Tuesday, January 22, 2019, 12:10:38 PM EST, iMac via Groups.Io <luispla=mac.com@groups.io> wrote:

HI
Some time ago I bought a Tek 545A.Some days ago I start inspectig it before refurbishment and notated this strange plugin : PREAMP LA-545-54CA.
TekWiki has no info about it.Any ideas of the manufacturer?

There is a folder in the photos section.

Best regards from Spain.


Unknown 545A plugin

iMac
 

HI
Some time ago I bought a Tek 545A.Some days ago I start inspectig it before refurbishment and notated this strange plugin : PREAMP LA-545-54CA.
TekWiki has no info about it.Any ideas of the manufacturer?

There is a folder in the photos section.

Best regards from Spain.


Tektronix 2336YA Elapsed Time Indicator

Kevin Kolb
 

Where is the ETI on the 2336YA? I've looked in the operator and service manual but don't see it mentioned.

Thanks,
Kevin


Re: 2467B Trace flicker

 

In a previous post you described noise on the DIA signal and high frequency noise on the DI signal.  You have to quiet that noise before any other intensity measurements can be meaningful.  If DIA in noise free you can check the Z-axis by putting a test scope on The Z-Axis outputs (test points 65 and 66 in the service manual).  The Display sequencer and a few other parts CAN give you screen flicker but they don't put noise on DIA and they usually present other problems too.  So, if DIA is quiet, and test points 65 and 66 show proper waveforms with little noise in their amplitude, try other sweep speeds and see if the flicker "walks" across the screen.  
Step 1:  Obtain clean, noise free DIA signal.

On ‎Monday‎, ‎January‎ ‎21‎, ‎2019‎ ‎09‎:‎53‎:‎36‎ ‎AM‎ ‎CST, thespin@gmail.com <thespin@gmail.com> wrote:

Is there a good way to trace whether it's the z-axis hybrid, the display sequencer, or the front panel DAC subsystem?

On Fri, Jan 18, 2019 at 12:02 PM, victor.silva wrote:


Issues like you describe are usually related to a display sequencer (U650).
In my opinion I believe this is selected part.  I see many 2465Bs with the
display sequencer chip with a green thick magic marker line on it.
2445Bs do not normally have that mark on them.

--Victor


Re: 2467B Trace flicker

thespin@...
 

Is there a good way to trace whether it's the z-axis hybrid, the display sequencer, or the front panel DAC subsystem?

On Fri, Jan 18, 2019 at 12:02 PM, victor.silva wrote:


Issues like you describe are usually related to a display sequencer (U650).
In my opinion I believe this is selected part. I see many 2465Bs with the
display sequencer chip with a green thick magic marker line on it.
2445Bs do not normally have that mark on them.

--Victor


Re: 7104 -7854 SMPS Dummy Load Construction Article

Robert Calk Jr.
 

Looks nice! Thanks Dennis.


Re: UNC Taps

Jim Olson <v_12eng@...>
 

You can also remove broken taps and or steel screws and bolts from aluminum using nitric acid. It will dissolve the steel and leave the alum bright and shiny. Just use a glass tube over the hole to pour the acid down.

Jim O

On January 20, 2019 at 6:22 PM n4buq <n4buq@knology.net mailto:n4buq@knology.net > wrote:


I did not know alum would etch steel that way. Perhaps useful for more than just taps.

As for the larger taps etching faster, I'd guess it's due to the larger surface area.

Thanks,
Barry - N4BUQ

----- Original Message -----

> > From: "Ovidiu Popa [Business]" <ovidiu.popa@rogers.com mailto:ovidiu.popa@rogers.com >
To: TekScopes@groups.io mailto:TekScopes@groups.io
Sent: Sunday, January 20, 2019 4:20:22 PM
Subject: Re: [TekScopes] UNC Taps

In such cases I just etch away the broken tap in a supra-saturated hot
solution of alum. May have to "cook" the aluminum part overnight, but the
result is perfect. For large aluminum parts, I just use a double turkey
aluminum pan, dip the part in the alum solution (broken tap side down),
place it on the barbecue, when it's close to boiling add more alum until
saturating the solution, and leave it overnight (make sure the temperature
is high, but below the boiling point).



I've etched taps from 2-56 to 3/8-24. Interesting enough, small taps take
longer time to etch away.



Won't work for broken taps in steel, of course.



O.



>Then one day I had a hardened set screw

>sieze and break in a nonreplaceable machined aluminum component (a

>heat block put together without anti-sieze). If it was a regular screw

>I could have drilled it out but trying to get that one out is like

>trying to drill through a rock in a lump of butter. After many bad

>words I pulled the disintegrator out and got it set up. It's a bit of

>a pain and it gets messy, but it took about 10 minutes to remove the

>screw and clean up the hole.



>


Re: UNC Taps

n4buq
 

I did not know alum would etch steel that way. Perhaps useful for more than just taps.

As for the larger taps etching faster, I'd guess it's due to the larger surface area.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Ovidiu Popa [Business]" <ovidiu.popa@rogers.com>
To: TekScopes@groups.io
Sent: Sunday, January 20, 2019 4:20:22 PM
Subject: Re: [TekScopes] UNC Taps

In such cases I just etch away the broken tap in a supra-saturated hot
solution of alum. May have to "cook" the aluminum part overnight, but the
result is perfect. For large aluminum parts, I just use a double turkey
aluminum pan, dip the part in the alum solution (broken tap side down),
place it on the barbecue, when it's close to boiling add more alum until
saturating the solution, and leave it overnight (make sure the temperature
is high, but below the boiling point).



I've etched taps from 2-56 to 3/8-24. Interesting enough, small taps take
longer time to etch away.



Won't work for broken taps in steel, of course.



O.



Then one day I had a hardened set screw
sieze and break in a nonreplaceable machined aluminum component (a
heat block put together without anti-sieze). If it was a regular screw
I could have drilled it out but trying to get that one out is like
trying to drill through a rock in a lump of butter. After many bad
words I pulled the disintegrator out and got it set up. It's a bit of
a pain and it gets messy, but it took about 10 minutes to remove the
screw and clean up the hole.




Re: Tek Probe Cables free to a good home

 

After a few other members were able to identify which probes my cables were for I was concerned that I didn't find any references to these cable part numbers when I searched for them so I decided to make another attempt myself.

The first time I tried (before sending my original post) I found nothing at all. Now that I am doing this a second time more determined to duplicate the results from Emil and Jack I still found extremely little information and some of it seems to contradict what they found.

For instance, a new (to me) site called SMC Electronics (http://www.smcelectronics.com) reports these two part numbers are for the same P6131 probe

175-3217-00:
Tektronix part numbers: 175-3217-00/206-0214-00/ 206-0289-00/134-0044-00.
Tektronix P6131 Attenuator/Cable Assembly

175-8011-00:
Tektronix part numbers: 010-6131-00/131-1799-03/ 200-2547-03/175-8011-00.
Tektronix P6131 Attenuator BNC Readout

BUT when I refer to the P6131 Instruction Manual on TekWiki (070-5514-03) it says that the cable should be 174-0972-00. This isn't a 175-8011-00.

The TekWiki Instruction Sheet for the P6122 (070-5512-00) says the correct cable is 174-0069-00 which is not 175-3217-00. Fortunately I found the P6122 Instruction Manual (070-4431-00) which does list all the cables used on this probe. They are (in chronological order): 175-3217-00, 175-9411-00, 174-0069-00, 174-0967-00. Apparently Tek has been changing the part number for this cable quite often. This explains some, but not all, of the confusing numbers I am finding.

The 1986 catalog on page 447 says the cable for the P6122 is 175-9411-00 for 1.5 meters, not 175-3217-00. It also says the cable for the P6131 is 175-9414-00 for 1.3 meters, not 175-8011-00.
Both of those numbers sound like Tek came up with newer replacement cables for these two probes and as of 1986 the numbers were correct. It looks like they were changed since then to 174-xxxx-xx numbers.

The TekWiki P6006 Instruction manual (010-0127-00 changed to 070-0381-00) lists the cable as 175-0281-00 for the 12ft BNC version of the probe. At least everyone agrees on this one.

I trust Emil and Jack's results. Part of the problem seems to be Tek making a lot of changes to their part numbers.

Dennis Tillman W7PF

-----Original Message-----
From: Jack Wills
Sent: Saturday, January 19, 2019 10:43 PM

Based on a little Googling:

175-8011-00 P6131
175-3217-00 P6122
175-1205-00 P6061
175-0281-00 P6006
Jack Wills
-------- Forwarded Message --------
Date: Sun, 20 Jan 2019 02:47:13 +0200
From: Emil <driller2old@yahoo.com>

Hi Dennis,
Greetings from Romania.
This is what i was able to find:
175-8011-00 1.3 m 39 Ohm P6131
175-3217-00 1.5 m 39 Ohm P6122
175-1205-00 ?????
175-0281-00 P6006


On Sat, Jan 19, 2019 at 6:25 PM Dennis Tillman W7PF
<dennis@ridesoft.com>
wrote:

Hi Dave,

I looked in the detailed index of the 175-xxxx-xx section of my 1988
edition of the Common Parts Design Catalog 6: Wire, Insulation, and
Power Supplies.

None of them were listed!
What are the odds of that happening?

At least two of them are recent numbers so I would think they can't
be obsolete.
They are definitely Probe cables so I thought for sure they would be
there.

Dennis Tillman W7PF


--
Dennis Tillman W7PF
TekScopes Moderator


Re: UNC Taps

Ovidiu Popa [Business]
 

In such cases I just etch away the broken tap in a supra-saturated hot
solution of alum. May have to "cook" the aluminum part overnight, but the
result is perfect. For large aluminum parts, I just use a double turkey
aluminum pan, dip the part in the alum solution (broken tap side down),
place it on the barbecue, when it's close to boiling add more alum until
saturating the solution, and leave it overnight (make sure the temperature
is high, but below the boiling point).



I've etched taps from 2-56 to 3/8-24. Interesting enough, small taps take
longer time to etch away.



Won't work for broken taps in steel, of course.



O.

Then one day I had a hardened set screw
sieze and break in a nonreplaceable machined aluminum component (a
heat block put together without anti-sieze). If it was a regular screw
I could have drilled it out but trying to get that one out is like
trying to drill through a rock in a lump of butter. After many bad
words I pulled the disintegrator out and got it set up. It's a bit of
a pain and it gets messy, but it took about 10 minutes to remove the
screw and clean up the hole.


Re: Basic Rule of all mailing Lists

Jim Ford
 

Yep, that's about the way it works! ;)
Jim Ford 


Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: Dennis Tillman W7PF <dennis@ridesoft.com> Date: 1/20/19 1:14 PM (GMT-08:00) To: TekScopes@groups.io Subject: [TekScopes] Basic Rule of all mailing Lists
Hi John,
Well done!
This is going up on my wall as a great reference.
All mailing list moderators should have a copy of this.
Dennis Tillman W7PF

-----Original Message-----
From: John Parkins G8KVP
Sent: Sunday, January 20, 2019 12:33 AM
Subject: Re: [TekScopes] UNC Taps

Hello,

Unfortunately  it  seems  to  be  a  rule  in  mailing  lists that the
following happens:

1. a slightly OT post is made.
2. as they all do they generate lots of responses.
3. they generate even more OT comments and go off at tangents.
4. someone asks that the members bring it under control.
5.  that  generates  even  more  post  in support of the OT (slightly)
post.
6.  the,  "if  you  don't  like  it you can always use the delete key"
comment is made.
7. the comments slowly die down, over the next few weeks.
8. the moderator will ask that the topic be put to bed.

This  is  how a question about where to purchase UNC taps can have 500
responses but only 5 or 6 which answer the original question.

This is how mailing list work and it will always be so, it's the law!
--
Best regards,
  John                            mailto:john@g8kvp.com



--
Dennis Tillman W7PF
TekScopes Moderator

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