Date   
Re: New member intro, and a request....- list of cover sizes?

Dave Seiter
 

I recently discovered that a blue tray i've been using for parts is actually a cover.  No numbers have been molded into it.  Does a cross reference exist anywhere that lists cover sizes and applications?
-Dave

On Monday, July 15, 2019, 04:15:44 AM PDT, Brian Cockburn <brian.cockburn.1959@...> wrote:

Hi,

  I too am interested in a cover as my 2245A came without one.  However as I got the 'scope at a bargain price (I think) I'm on the lookout for an inexpensive cover.  Which is to say on that's not 20% of what I paid for the scope.

  My point of posting is really to ask if 3D printing would be a viable and relatively inexpensive way forward?  Or is this too an expensive option.  I have already had a bit of a poke about in the places suggested for 3D print files for feet and knobs and didn't find any covers.

  As a neophyte to 3D printing it would seem that a cover is a classic case for a parametric design with width, height, depth, and corner radius being all the parameters that would be needed for a generic replacement cover.

  Cheers, Brian.

Re: Possibly dumb question regarding a 5111

Albert Otten
 

I can confirm this, Håkan. For some reason I experimented with a 7704A, one plate disconnected, no signal on the other plate. After a sudden change in Position the dot follows but it takes some time before the dot settles at the new position. Apparently the voltage (charge) at the open plate creeps slowly to a new equilibrium. That equilibrium also shifts slowly when Intensity is changed.
(Speculation: When Intensity is turned down the disconnected plate catches less electrons I think and becomes more positive. Then Dave's 5111 trace drifting to the bottom indicates that the lower plate is disconnected.)

Albert

On Mon, Jul 15, 2019 at 12:49 PM, zenith5106 wrote:


On Mon, Jul 15, 2019 at 06:30 AM, Dave Seiter wrote:


One bit of odd behavior that might be related:  whenever a trace is at the
top of it's travel (center screen), and the intensity gets turned down to
below normal viewing levels, the trace will start to move down the screen as
the intensity fades out, eventually going off the bottom edge of the
screen. 
Never seen that behavior on a Tek scope before.
I've seen similar behavior when one of the connections to the vertical
deflection plates (V amp output) has become open.
So that would be the first thing I'd check. In your case it would be pins 11
and 12 in the CRT socket.
This could also explain why you can't get the trace above center.

/Håkan

Re: T922 Power Supply Problem

Mlynch001
 

On Mon, Jul 15, 2019 at 10:04 AM, @DC912 wrote:


Thank you both gentlemen. There are two small 125v 1.5A pc board mounted fuses
on the power supply board that do not appear on the circuit diagram in the
copy of the service manual that I have. I had initially dismissed them,
wrongfully presuming they were in the 100v volt supply. After studying the
board, I realized they were in the secondary of the 8v supply, and that they
were open. I tacked in new fuses with an ammeter connected in order to carry
out a test, and everything is now working (replacing the electrolytics must
have corrected the cause of the failure of the fuses). Thanks for all of your
help. Dave.
Dave,

Don't you just love it when you find a problem and fix it! Glad you were successful. PS, if you need any parts for the 922 or similar scopes, I have a working 922 parts scope which I might be able to pull parts from.

--
Michael Lynch
Dardanelle, AR

Re: T922 Power Supply Problem

@DC912
 

Thank you both gentlemen. There are two small 125v 1.5A pc board mounted fuses on the power supply board that do not appear on the circuit diagram in the copy of the service manual that I have. I had initially dismissed them, wrongfully presuming they were in the 100v volt supply. After studying the board, I realized they were in the secondary of the 8v supply, and that they were open. I tacked in new fuses with an ammeter connected in order to carry out a test, and everything is now working (replacing the electrolytics must have corrected the cause of the failure of the fuses). Thanks for all of your help. Dave.

Re: Old Tektronix Books

Dave Daniel
 

bookfinder.com is a good resource for finding used books. Results from bookfinder.com include books listed on ABEbooks, Alibris, Amazon and others.

Personally, I don’t buy books from Amazon’s listings because the descriptions of the books listed there are rary accurate.

DaveD

Sent from a small flat thingy

On Jul 15, 2019, at 08:21, Roy Morgan <k1lky68@...> wrote:


On May 23, 2019, at 12:31 PM, treasurer@... wrote:

Someone in my copy of Typical Scope Circuitry ( Third printing October 1966 revision - forth printing 1968 ) has neatly indicated the scope models on the schematics. Figure 12-20 is marked 531 CRT circuit which agrees with the manual. Figure 12-16 is 531A & 545A. 11-3 is marked 531A. Figure 11-8 is 531A & 545A. 11-12 is 531A & 545A. I didn't verify the A scope versions. The spine of the book has the squared CRT in the logo whilst the front page has the round CRT in logo. When did they begin using the new logo?
Bruce
Bruce, Thanks for posting this information. I’ll include it in my copy of the book.

I just did a bookseller search (amazon and ABE Books) and find only two or three copies available, one at $12.50 and two at about $40.00. I guess is is an uncommon book. I was lucky to get mine for about $10 just after the discussion here started.\

I now have an extra copy of the book, and plan to offer it on the list, but I am not sure what price to ask!

Roy


Roy Morgan
K1LKY since 1958
k1lky68@...






Re: New member intro, and a request....

Mlynch001
 

On Mon, Jul 15, 2019 at 06:15 AM, Brian Cockburn wrote:


Hi,

I too am interested in a cover as my 2245A came without one. However as I
got the 'scope at a bargain price (I think) I'm on the lookout for an
inexpensive cover. Which is to say on that's not 20% of what I paid for the
scope.

My point of posting is really to ask if 3D printing would be a viable and
relatively inexpensive way forward? Or is this too an expensive option. I
have already had a bit of a poke about in the places suggested for 3D print
files for feet and knobs and didn't find any covers.

As a neophyte to 3D printing it would seem that a cover is a classic case
for a parametric design with width, height, depth, and corner radius being all
the parameters that would be needed for a generic replacement cover.

Cheers, Brian.
Such a cover could be printed, however, It would require a large format 3D Printer (which most do not have) to print as one piece or the model could be broken down into two or three pieces, printed on a smaller machine, then glued together to form the complete cover. This might not be an issue for some and the seams could be somewhat hidden. Keep in mind that 3D printing does not deliver exceptional surface finish on these less expensive machines, so don;t expect the resulting print to be anything like an injection molded part.

--
Michael Lynch
Dardanelle, AR

Re: New member intro, and a request....

 

Welcome WA6ILQ,
Plan to finally get around to doing my Tech and Gen HAM exams.
Always gazed at adverts for Tek scopes etc. in Radio Electronics mags from the late 70s & 80s. Could never buy one until some second hand 2465 & 2465A units a few years ago. Plus I also have a couple TM503s and about 9 plugins targeting calibration of those scopes.

Sadly, I don't use those fine analog scopes atm, as my lab space is so congested I need the compact (Rigol 300Mhz) digital units. My biggest Bandwidth scope is a 3Ghz Tek TDS694C in good cal.
Haven't done up new project write ups lately either as I had major surgery near Christmas last year with a 2 week to brain death encephalitis scenario driven by a 'silent' stage 2 cancer tumour.

Well, I'm still here to be an active part of the group. BTW, the neurologist found my cognitive brain healing (measured & documented by EEGs and MRis) has exceeded normal expectations....probably due to the technical work we all do, so I have documented evidence that our work/hobbies keep brain synapses and axions strong.

Welcome Again...
https://hackaday.io/projects/hacker/10957

Re: Lonely 555

TekTom
 

Yessir! I can't seem to find you in the directory...maybe another cup of coffee and I'll find you there, else I would have responded PM.

Thanks

Tom

2467B rear feet repros and other parts?

radioconnection@...
 

The rear black feet are missing on my 2467B. Does anyone make and sell reproductions?
Used ones seem to be very scarce.

Also looking for a used rear cover (the part that the feet attach to).
The one on my scope is cracked. Anyone have a parts unit?

Re: 2245A mains filtering

Chuck Harris
 

Although the allowable range of capacitors for a line
filter are quite large, not all X and Y class filter caps
are used in the line filters. They are quite often used
as snubber capacitors in switching circuitry... where their
value is somewhat critical to efficient operation.

There should be absolutely no problem getting exact matches
for the X and Y capacitors in a Tek scope. Go to DigiKey,
or Mouser. Use film type rather than paper type. Your biggest
issue will be size. You may have to bend the leads on the
newer smaller capacitors to fit the holes in the circuit board...
Or, alternatively, you can specify higher voltage rating
capacitors, as they will be more likely to be the exact physical
dimensions.

Why are you singling out the X and Y caps? In the spectrum of
part failures, they are more reliable, and less important to the
function of the scope, than any electrolytic capacitor. I have
never had one that I *HAD* to replace because it failed... I have
had many that I replaced because of cracked epoxy coatings, and
because customers insisted I do so...

Corcom is a very good filter company. I have never had
one of their products fail electrically. I have seen a few
that were ripped out of the panel, but I don't think that was
a fault of manufacture... it looked deliberate.

Schafner, on the other hand....

It is also rare for any power line filter module to fail if it
is run from US 120V power... But quite common if it is run from
EU 240V power, especially if the utility runs to the high side
of tolerance, like the UK.

-Chuck Harris

Brian Cockburn wrote:

Hi,

I'm looking at replacing the three Y class and two X class capacitors in the PSU of my (new to me) 2245A as a very first step to keeping it in tip-top condition. How critical are the values of these capacitors? The Y class are 1.5nF (1500pF) and the X class are 150nF (0.15uF). I'm guessing that '22', '33', and '47' would be OK replacements for '15' if these are what's available at a reasonable price and (low enough) quantity.

Secondly, the mains inlet filter. I've read that there can be problems with these things. My unit has a Corcom filter (250 VAC, 3A, 50-60Hz). It has 8734 on it which seems likely for the date of manufacture given the filter is original to the 'scope. Do I need to worry about the age of the filter and fit a new one or are these units built to last?

Thanks, Brian.



Re: Old Tektronix Books

Roy Morgan
 

On May 23, 2019, at 12:31 PM, treasurer@... wrote:

Someone in my copy of Typical Scope Circuitry ( Third printing October 1966 revision - forth printing 1968 ) has neatly indicated the scope models on the schematics. Figure 12-20 is marked 531 CRT circuit which agrees with the manual. Figure 12-16 is 531A & 545A. 11-3 is marked 531A. Figure 11-8 is 531A & 545A. 11-12 is 531A & 545A. I didn't verify the A scope versions. The spine of the book has the squared CRT in the logo whilst the front page has the round CRT in logo. When did they begin using the new logo?
Bruce
Bruce, Thanks for posting this information. I’ll include it in my copy of the book.

I just did a bookseller search (amazon and ABE Books) and find only two or three copies available, one at $12.50 and two at about $40.00. I guess is is an uncommon book. I was lucky to get mine for about $10 just after the discussion here started.\

I now have an extra copy of the book, and plan to offer it on the list, but I am not sure what price to ask!

Roy


Roy Morgan
K1LKY since 1958
k1lky68@...

2245A mains filtering

Brian Cockburn
 

Hi,

I'm looking at replacing the three Y class and two X class capacitors in the PSU of my (new to me) 2245A as a very first step to keeping it in tip-top condition. How critical are the values of these capacitors? The Y class are 1.5nF (1500pF) and the X class are 150nF (0.15uF). I'm guessing that '22', '33', and '47' would be OK replacements for '15' if these are what's available at a reasonable price and (low enough) quantity.

Secondly, the mains inlet filter. I've read that there can be problems with these things. My unit has a Corcom filter (250 VAC, 3A, 50-60Hz). It has 8734 on it which seems likely for the date of manufacture given the filter is original to the 'scope. Do I need to worry about the age of the filter and fit a new one or are these units built to last?

Thanks, Brian.

Re: New member intro, and a request....

Brian Cockburn
 

Hi,

I too am interested in a cover as my 2245A came without one. However as I got the 'scope at a bargain price (I think) I'm on the lookout for an inexpensive cover. Which is to say on that's not 20% of what I paid for the scope.

My point of posting is really to ask if 3D printing would be a viable and relatively inexpensive way forward? Or is this too an expensive option. I have already had a bit of a poke about in the places suggested for 3D print files for feet and knobs and didn't find any covers.

As a neophyte to 3D printing it would seem that a cover is a classic case for a parametric design with width, height, depth, and corner radius being all the parameters that would be needed for a generic replacement cover.

Cheers, Brian.

Re: Possibly dumb question regarding a 5111

 

On Mon, Jul 15, 2019 at 06:30 AM, Dave Seiter wrote:


One bit of odd behavior that might be related:  whenever a trace is at the top of it's travel (center screen), and the intensity gets turned down to
below normal viewing levels, the trace will start to move down the screen as the intensity fades out, eventually going off the bottom edge of the screen. 
Never seen that behavior on a Tek scope before.
I've seen similar behavior when one of the connections to the vertical deflection plates (V amp output) has become open.
So that would be the first thing I'd check. In your case it would be pins 11 and 12 in the CRT socket.
This could also explain why you can't get the trace above center.

/Håkan

Re: DP501 Digital Prescaler

J Mcvein
 

Well, I have a DC509/5009 counter and a DP501 prescaler set. 
There is a backplane connection to enable the counter to recognize
the extender.  While there may be the capability of a DC503 touse a prescaler, the triggering/threshold on said counter is crap.The device is said to work marginally with a DC504.
I do have a manual for DC501, it was from Qservice Greece.  The setupdoes work quite well, and the upshot might be that the DP501 is a
one trick pony.
JimMc

On Sunday, July 14, 2019, 3:48:11 PM PDT, walter shawlee <@walter2> wrote:

I have one of these (and in mint condition, probably because nobody ever used it), and have not been able to find a manual anywhere, so it's hard to answer this burning question:

Why on EARTH does it divide by 16?  how is this good for anybody in practice?  every other prescaler on earth (including the ones in other Tek counters) provides effective divide by 10 results so the data is instantly usable, but this item does not.  Is there some mystical way it fixes that by a rear panel connection I can't see (thanks to no manual)?

I have tested it, and YES, it does in fact divide by 16, and mine worked up the 1.6Ghz with no trouble.
what I can't figure out is why it works this way with other Tek counters, like my DC503, which has a GHz indicator, but makes no special use of the DP501.  I feel like there is an answer out there, I am just not sure where it is hiding in all the Tek docs. Are there some magical backplane connections that make this work correctly? I would really like to know, the catalog listing is totally unhelpful, and seems to imply this has a solution, but doesn't say how.

any help appreciated,
walter (walter2 -at- sphere.bc.ca)
sphere research corp.

Possibly dumb question regarding a 5111

Dave Seiter
 

Last week a buddy of mine gave me a 5111 to look into (he got it cheap, didn't know if it worked, has never used a scope before, but wants to learn when he gets time.  I traded a working Dumont R1062 for it).  
It was really grimy inside, but I got a trace right away, and the storage worked, but obviously had a few issues.  Once, I smelled something burning at one point, and got a small plume of smoke out of the HV section before I was able to shut it off.  Strangely enough, I couldn't find the source of the smoke, even after I cleaned the entire scope up.  
The question is this (and this is the first split screen storage scope I've played with):  The storage is obviously split into upper and lower halves of the screen.  Do the vertical amps do the same thing?  The reason I ask is that both vertical amps only work on the lower half of the screen.  The two pdf manuals I have don't really address vertical centering at all in the usage sections, so I doubt it's the case, but the 4 5xxx V amps I have all behave the same way- the center of vertical adjustment is in the center of the lower half of the screen, and the trace will never adjust more than 1/10 of a division above the center line.
I've adjusted all the power supplies, and the voltage measurements throughout the vertical deflection system, while not being spot on, are near enough that they're "ok".  The scope is an earlier version (the LV board doesn't have the row of fuses), and I've found circuit differences from both of the pdfs I've been using  (and I hate debugging using pdfs!!!)
One bit of odd behavior that might be related:  whenever a trace is at the top of it's travel (center screen), and the intensity gets turned down to below normal viewing levels, the trace will start to move down the screen as the intensity fades out, eventually going off the bottom edge of the screen.  Never seen that behavior on a Tek scope before.  
Is it possible that the storage system is actually limiting trace movement in some way?  Just thought of that.  Not sure how that would work, but I'm not all that familiar with storage scopes either, only having one that works correctly (T912).

-Dave

Re: Lonely 555

fiftythreebuick
 

Hi Tom-

I might be able to help.... OK to contact you via email?

Thanks much!

Tom

Re: New member intro, and a request....

Dave Seiter
 

Welcome!  My first real scope was a Tek 502; I started repairing it when I joined years ago, but never completed the repair- too many better scopes to play with.  One of these days...
-Dave

On Sunday, July 14, 2019, 10:49:14 AM PDT, M M <wa6ilq@...> wrote:

Just joined as I inherited a Tek 485 in operational condition.  I'm looking for a cover, Tek part number 200-1251-00.

My first exposure to Tek equipment was in high school, we had several model 502? (It's been 40+ years).  Then to
NASA / JPL where we had hundreds of various models....  Always loved Tek gear.

Mike Morris WA6ILQ
wa6ilq //at// arrl //dot// net

Re: DP501 Digital Prescaler

 

On Mon, Jul 15, 2019 at 01:17 AM, Raymond Domp Frank wrote:


even changing the time base frequency "in prescaled mode only" by an
equivalent factor. Ugly but it would work...
The DP501 specs on Tekwiki state that "In the Prescaler mode, the DP501 divides the input signal by 16 and causes the associated counter's display to be multiplied by 16", which definitely points to my suggested solution. A simple logic signal across from the prescaler to the counter would take care of this switching-in of a divide-by-16 counter into the time base chain. I can't imagine the User Manual and/or Service Manual *not* mentioning this.

Raymond

Re: DP501 digital prescaler

Dave Casey
 

Yes, the DP501 is designed to work with specific TM500 counters and uses a
backplane signal to tell the counter that the input has been divided. The
counter also can enable/disable the prescaler (even over GPIB in the case
of the DC5009). See the DC5009 manual for more info about the signals
involved.

Dave Casey

On Sun, Jul 14, 2019 at 5:45 PM walter shawlee <@walter2> wrote:

I have one of these (an din mind condition, probably because nobody ever
used it), and have not been able to find a manual anywhere, so it's hard to
answer this burning question:

why on EARTH does it divide by 16? how is this good for anybody in
practice? every other prescaler on earth (including the ones in other Tek
counters) provides effective divide by 10 results so the data is instantly
usable, but this item does not. Is there some mystical way it fixes that
by a rear panel connection I can't see (thanks to no manual)?

I have tested it, and YES, it does in fact divide by 16, and mine worked
up the 1.6Ghz with no trouble.
what I can't figure out is why it works this way with other Tek counters,
like my DC503, which has a GHz indicator, but makes no special use of the
DP501. I feel like there is an answer out there, I am just not sure where
it is hiding in all the Tek docs. Are there some magical backplane
connections that make this work correctly? I would really like to know.

any help appreciated,
walter (walter2 -at- sphere.bc.ca)
sphere research corp.