Re: Calibrate the time base, or horizontal amplifier?


Here is how I did the calibration without time mark generator.

Using a 5B10B time base and a 5A14N vertical module in slot #1.

The +30V has a very small tolerance, which I used to calibrate the scope calibrator output. So I set the +30V until I had exactly 400mV on the calibrator, and the 30V was still within calibration. 400mV measured with an Agilent 34401A. Then I set the -30V to exactly the same level. So +30 and -30 are nicely balanced.

Make the calibration signal visible with 4 divisions vertical.

The sensitivity at the backplane is 50mV/cm. I soldered two wires on the PCB of the 5A14N, which lead to pins 7A and 7B. I hooked those up to the Agilent 34401A. Connect the calibrator to the vertical module input, and use the "Cal" potmeter to adjust the backplane signal to exactly 200mV. So 4 divisions on the screen. Do not touch this potmeter setting. Any deviation is now caused by the vertical amp. Adjust the vertical gain for 4 divisions.

The next step is a bit strange, but the manual sais so too.

Swap the time base module and the vertical amp.
This rotates what you see on the CRT by 90°. The vertical amp output which has a known 200mV still, is now in the time base slot (#3). This 200mV drives the horizontal amp. Adjust it for 4 divisions.

So now the vertical and horizontal amp are cablibrated.

Put back the time base and the vertical amp in the normal slots, and make the calibration signal visible. Any error is now caused by the time base being too slow or too fast. The calibration signal is not 50% duty cycle nicely. So I used a digital controlled oscillor and set it for 10kHz square wave. Now adjust the timebase to 10kHz is displayed correct.

That's it. A bit unconventional, and I hope there is no mistake in the system, but it worked very good.

Re: TDS-540B Repair?

Jim Ford

Another issue is space.  Sure, I'd love to have multiple parts mules for every piece of gear I own, but where the hell would I put it all?  Property values are so high here in Southern California that most of us don't have much of it.  OTOH, a new LCD replacement for a CRT would take up zero extra space.             Jim Ford  Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: Roy Thistle <> Date: 7/12/21 2:48 PM (GMT-08:00) To: Subject: Re: [TekScopes] TDS-540B Repair? On Mon, Jul 12, 2021 at 02:33 PM, Stephen Hanselman wrote:>> These are great mods>Yes, but pricey... they're called "NewScope LCD kit" For the price, I'd rather get "Another Scope Kit"... and take the parts from that mule.But if money is no object... go for it.They have kits for HP scopes too.-- Roy Thistle

Re: RSA 3408 A Real time spectrum analyser

Roy Thistle

On Sun, Jul 11, 2021 at 09:36 PM, nj902 wrote:

You should also capture an image of the hard drive
One really should. (One won't realise how germane that recommendation is until Win 2000 begins working its evil.)
Roy Thistle

Re: TDS-540B Repair?

Roy Thistle

On Mon, Jul 12, 2021 at 02:33 PM, Stephen Hanselman wrote:

These are great mods
Yes, but pricey... they're called "NewScope LCD kit"
For the price, I'd rather get "Another Scope Kit"... and take the parts from that mule.
But if money is no object... go for it.
They have kits for HP scopes too.
Roy Thistle

Re: TDS-540B Repair?

Stephen Hanselman Is the company I use. I’ve done just over a dozen all worked great.

My only issue was the first TDS-540C I did, I think (yup I forgot) that the instructions told me to leave the old glass off. Looked a bit tacky so when I did my personal one I modified the support frame, cutting and placing padding) so I could leave the glare cutting glass in place. Looks better and works fine..

If you happen to have a 8566 the mod gets you a slightly bigger screen but you have to exchange the bezel Assembly. A little extra on this one, the old astigmatism control now switch’s the display through 4 color formats.

These are great mods can’t say enough good things!


Stephen Hanselman
Datagate Systems, LLC

On Jul 12, 2021, at 07:42, Christopher Maness <> wrote:

Thanks, I did not know such a thing existed. Linky?

Chris KQ6UP

On Mon, Jul 12, 2021 at 7:23 AM Stephen Hanselman <> wrote:

Buy the LCD replacement soooo much easier.


Stephen Hanselman
Datagate Systems, LLC
On Jul 12, 2021, at 05:13, Christopher Maness <> wrote:
The CRT went intermittent with brightness and vertical spread last week. I put it in my car hopping that a friend of mine would take a look at it. He did not want to bother, so it rode around in my car in the heat. The hot bumpy car ride seems to have fixed it at least temporarily, so it could be something simple like card contacts a little dirty. It also took an ESD hit on channel 1. The channel still works, but is no longer high impedance. Was wondering if there is a good tech in the SoCal area. If not, I am willing to box it up and send it to one based on recommendations.

Chris Maness

Re: TDS-540B Repair?

Tam Hanna

I cannot praise Jay Walling enough for the work he did on our Danaher TDS754D. The unit has survived a move from Bratislava to Budapest and still works like a champ.

With best regards

Enjoy electronics? Join 19k7 other followers by visiting the Crazy Electronics Lab at

Re: What do you do when you get a call from AUSTRALIA



I am glad you are OK.

Have some fun. Get yourself a new to you Tektronix instrument like a DSA or RTSA and occupy your mind with learning new things!

Re: What do you do when you get a call from AUSTRALIA



so I am very glad to hear from Dennis today. I think I was not the only one who was more than a little concerned primarily as we all have heard about that heat wave and other hazardous conditions in the western US right now.
And I am very glad once again knowing this community consists of people who care!

Regards, Joe

Re: RSA 3408 A Real time spectrum analyser


You will love it. A great learning tool. I didn't realize how much they weigh until I got one. The new Tek USB real time analyzers just weigh a few pounds but these are very substantial at 20 kg / 44 lbs

Re: Dennis Tillman

Richard R. Pope

Hello all,
I know but you have to be able to afford it. Social Security doesn't go very far!
GOD Bless and Thanks,

On 7/12/2021 5:43 AM, cheater cheater wrote:
Yeah, a fall detector is definitely something you should buy if you're
concerned. It doesn't cost so much and it's definitely comforting and

On Mon, Jul 12, 2021 at 10:06 AM Tom Gardner <> wrote:
On 12/07/21 02:53, Richard R. Pope wrote:
I am up there in years and my body no longer works correctly. I could easily
fall and hurt myself and not be able to call for help!
That's a common problem. Over here there are services where you have button on
your wrist or around your neck, and a box connected to the phone line. If you
press the button it calls a service centre and someone comes to help. My mother
had one for years, and it was a great comfort to ME :)

There are also many other devices available, e.g. those which sense movement in
the building (to verify you are up and about) and accelerometers that detect falls.

Re: What do you do when you get a call from AUSTRALIA



when I began with Tektronix some years ago, one of the 1st names I've read was yours. I did't know TekScopes at that time.

Some thoughts:
Wouldn't it be good to...
- have one, two or three more moderators to divide work?
- find people who can help with TekScopes specific computer problems?
- talk with real friends face to face in private?
- sort SCRs or label boxes sometimes?
- not forget that many people want to help?

All the best

Re: Looking for an T5611-25 CRT (or -7 or -2)

Ulf Kylenfall

At the Onsala Space Observatory, we had a LINC8 too. I operated it in ~1975/1976
as it was in used for processing data from the 25M telescope on 4 GHz.
I recognized the upside-down R561. Remember loading the tapes and also
the procedure to manually starting the boot-loader. Bottom left beside
all the data switches, there was a knob "Chime". Turning it on, the processing
could be "heard". If the system hang, the character of the sound would change.

The LINC 8 was salvaged from being scrapped and is on display at
the observatory today.

Ulf Kylenfall SM6GXV
SR Research Engr (Retired)
ex Onsala Space Observatory

Re: Looking for an T5611-25 CRT (or -7 or -2)


We had a PDP-12 in our lab years ago. We got it when another department was
discarding it and we adopted it. Ours had a different color scheme from the
LINC-8 systems, but it was the same machine. Ours had a A-D converter in
the rack above the scope - the same modified Tek scope that is in yours. We
played “Spacewar” on it (we did use it for some lab data acquistion work).
It had a pair of DECtape drives.

The engineer I shared the lab with left a couple of years before I did.
When I left, I left that PDP-12 behind along with Tek 585 and 547 (the one
scope I wish I had taken with me) scopes. I did take the 556 but it sat on
my bench at home unused. I sold it off at a hamfest (should have kept that
one, too). The PDP-12, a PDP-8 system (DF-32 disk, two DECtape drives, 8K
memory, high-speed paper tape reader and punch, plus the ubiquitous ASR-33
Teletype), and the Tek scopes were all offered to me. Since I didn’t take
it, it all went into storage in an area of the building that was slated for
then future development. When I visited a few years later, what had been
“shell” space had been fully developed. All that stuff got scrapped.

As I recall, that modified Tek scope in the PDP-12 had a separate
edge-lighted graticule. The plug-ins were the same in each plug-in bay and
were basically amplifiers to run the scope in XY mode.

Seeing the photos of the LINC-8 brought back memories of using those front
panel switches to key in the RIM loader so we could load the BIN loader
from the ASR-33 (slow and noisy). On the PDP-8, we still had to enter the
BIN loader, but could then load the RIM loader from the high speed reader.
If we were not doing a cold start, we could also start up from the DF32
disk or DECtape. I did use the Tek scopes for troubleshooting - usually the
Teletype and trying to look at the various timing signals in it or the
current loop interface when it wasn’t working right.

On Sun, Jul 11, 2021 at 23:02 Bob Rosenbloom <> wrote:

I know this is a long shot, but I'm looking for an T5611-25 CRT for use in
restoring an DEC LINC-8 minicomputer.
It used a modified Tektronix 561B oscilloscope, with DEC plug-ins, and the
P25 phosphor CRT with no graticule.
The one in the LINZ has a badly burned face. A P7 or even P2 phosphor
would also work though would look
different than the original. So basically any slow phosphor and no

Some cell phone photos of the LINC and scope are on my web site here:

Re: What do you do when you get a call from AUSTRALIA


Glad you are ok Dennis. Your 1st post displayed a great sense of humor concerning all this - much respect.

my 2 cent response to a great list:
- It's completely off-topic
# yes, but the humanity frequently displayed in this forum is not.
- It objectifies Dennis and his experiences
- Contents of posts may spread uncontrollably
# What? BTW: my cat... more later :-)
- With Dennis being our moderator, how/when can/should he moderate and cut the off-topic thread, should he decide in favor of that?
# Very insightful!
- The familiar lack of distinction between being depressed and (clinical) depression, common with laymen and non-patients, already popped up. These are *very* different things. From what Dennis told us, it's extremely likely that the latter applies to him. Again, I recommend - without any authority to enforce - to not touch this.
# Agree. See objectified comment above.

One note if I may: (from personal experience without making this about me) While knowing one is not alone is very helpful, there is the potential for well meaning concern becoming a burden, requiring response at a time when response is difficult. And there is the privacy issue that might be difficult to fathom unless you have been the object of inquiry, though I bet many here get that, having been around long enough to have their own stories.

Re: Looking for an T5611-25 CRT (or -7 or -2)

Bob Rosenbloom

Thanks for all of the options, gives me a lot more part numbers to search for. It turns out my CRT is marked T5032-25 on the glass and T5611-25 on a label so I guess it could use either one.

Glass or ceramic is fine, I just need the slow phosphor and no graticule.

It's interesting that none of the part numbers show the P25 phosphor that's actually used in the scope I have. May have been a special order by DEC. A P7 would be the next best choice. I did buy a ceramic P2 phosphor CRT with graticule off of eBay just to have something to play with until I can find the more correct no graticule one.



Re: What do you do when you get a call from AUSTRALIA

Harvey White

It can be helpful to mix long term complex projects with some short term things where you can point at an immediate (or close) success.  Sometimes you get tired of working on the same thing for month after month.


On 7/12/2021 11:05 AM, Jeff Dutky wrote:
I would like to second Ananda's suggestion of "puttering" as a treatment, if not a cure, for depression. Just as it is helpful to have several tasks (in a hobby, or at work) that engage different "gears" of the intellect, so that when you have exhausted one mode of thinking you can rest while exercising another (for me, at work, it's the difference between hard analytic problems, like writing a new program, or analyzing existing program code, and writing a set of data for test cases, which is voluminous and detailed, but does not require the same kind of intense concentration that reading and understanding program code does).

When I'm depressed I find it hard, if not impossible, to concentrate on analytical tasks, but I can do more "menial" tasks, like sorting through piles of things. One of my own therapy activities, since I joined TekScopes, was to buy a pack of 50 cardboard stock boxes, and whenever I'm feeling overwhelmed with things (literal things, as is piles of loose stuff) I pull out a couple of stock boxes and start filling them with items that go together in some category. Then I label the filled box with the category name. It combats the depression both by giving me something to focus on, and by reducing the clutter in my office: the palpable progress gives me some kind of dopamine hit, or something.

This is just a bit of "self medication" that I've learned over the course of decades. I wonder if this is something that is recognized in therapy circles.

-- Jeff Dutky

Re: TDS-540B Repair?

Harvey White

The display is a standard magnetically deflected monitor.

There are some tricks if you have some shaky hands, and that's to do what artists do, which is a palm or wrist rest while working.


On 7/12/2021 11:29 AM, Jeff Dutky wrote:
The fact that heat and vibration "cured" the CRT issues suggests a bad solder joint or connector contact, so that should be eminently repairable. You might even be able to fix it merely by careful disassembly and reassembly with cleaning of all contacts with IPA. The dead high impedance on channel 1 may be a bit more work, but I expect it's down to replacement of a now shorted component early in the input channel. I see from the TekWiki that the TDS540 is all SMD construction, so it's not easy work for people with failing eyesight and shaking hands.

The display appears to be a regular raster display, not a traditional electrostatic deflection CRT, so replacement with an LCD does seem like an excellent option.

-- Jeff Dutky

Re: the dreaded letter from the County Property Appraiser (somewhat OT reply)

Jim Strohm


IANAL but -- if you can sell those limited common elements without selling
the real property, then those elements are separate from the real property
and their value is zero for the purposes of this inquiry from the tax

If those limited common elements MUST transfer with the title of the real
property, then they have a taxable value. If you cannot legally generate
income from them, and if you don't receive tangible assets or value from
them, then they're worth ... a dollar.

I don't know where you are, but you should find out what other people in
your neighborhood have valued them at. For example, if you have a covered
parking space in Manhattan, it's easily worth $250 a month whether you use
it or not. Here in Austin TX, it's "pull (or push) your car into the back
yard, throw a tarp over it, and tell your neighbors to <scribbled-out word>
themselves." The value is the price of the tarp, plus the 100 square feet
of lawn you won't have to mow per car. For me, that's 16 cents per mowing
(4 vehicles on the lawn @100 sqft each). I guess the jet boat adds another
4 cents. This is at $50 to mow about 100,000 sqft of lawn on a
quarter-acre city lot.

Edging around them costs me more time than mowing, so my taxable value is

So basically you need to see what your situation is. Without other
guidance, you may want to ascribe some nominal value to those limited
common elements just to keep your assessor happy. Or -- burn a few dozen
hours of their time to make them clarify the request. Their loaded hourly
rate is at least a hundred bucks an hour, and those limited common elements
would have to be worth more than a hundred grand taxable value for them to
get their costs back after you're done with them.


Re: What do you do when you get a call from AUSTRALIA

Vince Vielhaber

Great hearing from you again Dennis!


On 07/12/2021 12:37 AM, Dennis Tillman W7pF wrote:
Yesterday was a really nice day.
The temperature was perfect, the sun was out.
I was on the deck of our little summer house working on my computer.
In front of me across an inlet of Puget Sound I can see snow covered Mt
Rainer 40 miles away.

Suddenly my cell phone rings.
Annoyed! I pick it up to look at the screen and it says in all capital
Underneath that seemingly giant word is a strangely formatted phone number.
That strange format could only belong to an international telephone number.

This is exactly what my brain said to me in the next 2 seconds between the
2nd and the 3rd ring.
"Holy Crap!"
"It's a mistake"
"I don't know anyone in Australia"
"It's a robo-call. It must be"
"Wait a minute, nobody makes robo-calls from Australia"
"The number format means it really might be coming from Australia"
"Why would anyone want to call me from Australia"
"It's a new trick by the robo-callers to get people to answer and listen to
their recordings"
"They must have mis-dialed"
"They accidentally sat on their phone and pressed a bunch of numbers at
"I don't know anyone in Australia" (that was the second time my brain said
this to me to make sure I got the point)

Then my brain shut up for a moment while it waited to see what I would do
I realized someone probably went to a lot of trouble to find me. So I

ARGH! It was someone from TekScopes who was very concerned that I was OK
because I disappeared about 4 weeks ago without a trace. We had a very long
talk about what was going on. I was in a depression and couldn't get out of
it. I was overwhelmed with all the things going on in my life - most of them
it seemed to me were going badly. I have suffered from depression almost my
entire life. Until I was in my late 40s I had no idea this was the case. By
then I spent several years in therapy with several different therapists and
eventually one Psychiatrist I was seeing worked out the right balance of
medications for me to take for the rest of my life to help me avoid falling
into another depression. Depression is a learned behavior and the real
danger about it is that the more it happens to you the easier it is to
become depressed. Once I am in one it is like a trap and I can't get out.

But the phone call and the conversation I had with the caller - he said his
name so fast I didn't have a chance to get it was wonderful. He understood
completely what I was going through. That call made it possible to spend
most of today catching up on my email and facing the world once again. I'm
still a little shaky (mentally) but I think (I hope) I will be on my feet
again (mentally) in a few days.

In the meantime I would like to thank Michael Dunn for covering for me. He
and I both agree I could use help with TekScopes because it beginning to
take up too much of my time (that was one of the things I was not able to
spend enough time on but I didn't know how to fix it).

Give me a few days to get caught up
Dennis Tillman W7pF
Thank you for your concern!!!
That really means a lot to me.
I'm happy to be back!!!
Who was it that called me all the way from Australia. I need to thank them

Michigan VHF Corporation -- nobucks dot net
K8ZW -

the assessors note

John Ferguson

Hi Gang,

Please ignore my missent query about property tax.


4061 - 4080 of 188196