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I have a PDF File titled - "TEK_XREF_TUNNEL_DIODES", also have a PDF file - "TEK-MADE INTEGRATED CIRCUIT CATALOG" If you would like them, I will upload to files directory.
David

Hi all,

I thought it might be useful to share my updated conclusion. My fix tamed the problem somewhat, but not enough to make it fully usable, so I replaced it with a compatible tube, which was a 154-0731-00 from a 465. This solved the problem: the display is now perfect, pin-sharp, constrasty and, more importantly, it remains so over time.

Besides, I found what seems to be the explanation in a document available on Tekwiki, discussing the Tektronix CRT reject codes:



More specifically, code R324 (page 5) entitled "Spurious mesh emission" is described as causing "a glowing spot or area which persists after the beam is removed" - well, well!. This is caused by "MgO particles not properly covered by aluminum [on the surface of the scan expansion mesh]". And, "It also appears if the aluminum is not conductive because of oxidation", which, I suppose, might explain why some tube develop this problem after several years, as aluminum deteriorates. So in conclusion, the tube is basically dead when it starts glowing, and there is no other cure than replacing it.

I hope this can be useful to those experiencing the same problem.

Raymond ACK on all,

I forgot about " show quoted text" to see interleaved response.

I referenced Jim W avalanche and Tek TD pulsers only as possible alternatives to Leo Bodnar, the gold standard

The PG506 is reasonable on fast but nowhere near as good the Leo B. I never used the avalanche JW.

I tried old Tek TD pulser adapter, but tweaky, high level input required.

Am lucky to have two of the old versions of the Leo Bodnar, handy to compare two plugins or channels.


Jon

The following items have been added to the Files area of the [email protected] group.

* /070-6860-00.Tektronix.2465B-Operators.Manual.pdf ( /g/TekScopes/files/070-6860-00.Tektronix.2465B-Operators.Manual.pdf )

*By:* vk2bea <vk2bea@...>

*Description:*
070-68860-00 2465B / 2455B / 2445B Oscilloscope - Operators manual (high quality scan with navigation links)

Sorry for delay and thanks!

I should probably mention that the schematics are NOT 100% accurate. What has been published is a scan of the last pre-production drawings. A final production set was never completed because there was never the intent to publish the finalized schematics in the manual. Most of the errors on the schematics are typos in captioning or incompleteness. For example, on several of the drawings there were added hand written information intended to be included in the next revision, Where there is a single line connecting two or more components but signifying a bus, an added slash with a number indication the number of conductors has been added. Other errors are obvious typos, +15VAC or -5VAC for example which are on the Front Panel schematics should be +15VDC and -5VDC respectively. To my knowledge there are no AC voltages present within the instrument other than the "line trigger" signal from the Auxiliary Power Board <A07>. I am not aware of any incorrect IC designations nor module interconnect errors.

Best regards,

Ferrous

It seems to me there was a pressure device for forcing cleaner around the shafts. It screwed onto the mounting and pushed cleaner in around the bearing. Have not seen one for years.
If these are the Allen-Bradley/Ohmite type pots you can pry off the back coverings and use Deoxit faderLube on them. Takes some care. The little tabs on the covers can be bent back into place to hold them. These are very good pots but, because they can't be easily cleaned, often develop bad spots or get noisy. I have even heard of drilling holes in the caps but would worry about particles getting into the pot.

--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998

Firstly, thanks for all the helpful, and generous, responses.

I decided to dribble Deoxit ‘down’ the spindle entry and it appears that it may well have got to the track and adjustment is very much improved. I hadn’t expected this to work.

Too early to confirm success but I’ll give it (a) some more and (b) some more time and retry tomorrow.

Hey Ferrous,

This is amazing, it's sure to extend the life of some of those TDS420/460
scopes that otherwise would have been landfill - thanks!

Siggi

On Fri, Jan 17, 2025 at 1:36?PM Ferrous Steinka via groups.io
<ferrous.steinka@...> wrote:

Although not 100% accurate schematics for the TDS400 series have been
posted to the files section of this group as well as TekWiki. They were
scanned from "C" and "D" size engineering drawings and then converted
mostly to "A" legal size. These were late pre-production drawings and did
not contain the power supply (not Tek made). I did not have access to
final engineering drawings. No manual was ever published by Tektronix for
the TDS400 series which contained schematics or parts layout drawings or
pictures. Being the first all digital oscilloscope which relied
extensively on microprocessor control, it was new territory. The next
series, TDS500, had manuals which were similar to past Tek manuals complete
with schematics, theory of operation, and pictures.

I have no background in manual writing or compiling, just a technical
background working at Tektronix for about 30 years. I was able to obtain
the drawings from one of the engineers who designed the TDS series, now
passed on. I tried to post on TekWiki but was not savvy enough to figure
out the posting process.

I had sent a couple of the trigger related schematics to Tim Wright who
was having triggering issues with his TDS420 in hopes it would help him
find his problem. I then posted all my jpg files to the cloud and informed
Tim that they were available for him to use. Kurt Rosenfeld at TekWiki has
also been informed of the existence of the schematics.

Both Tim and Kurt have assembled my jpg images into a single pdf file. I
thank them both for doing something that I had been unable to do which
resulted in my work to be available to those who may need it. The TekWiki
availability is here:
- or:


The schematics are available in the Group files section here:

/g/TekScopes/files/Tektronix%20TDS420_460%20Schematics.pdf

Best regards,

Ferrous Steinka

I have 2 potential solutions. The first is to simply swap the 2 pots since they are both 10k.
It is unlikely that the bad spots are the same in the 2 pots.

The second is for me to send you 2 pots from my unit which I've converted to all solid state operation. The 2 pots are probably still there (I'll have to open the unit to check) or they are in my junk box. Let me know if you want to pursue this and we can work out an arrangement (as long as shipping is to the US). The eBay prices are way above my range.

Amazing!!
Now what is missed is more schematics for the 500/600/700 series ? but
maybe more importantly it would amazing to find the service software they
use to find the problems. Basically what you would execute if you follow
the board level troubleshooting guide (for example for the tds520). My
knowledge is that there was a software that downloaded coded onto the scope
that would test different part of the system using either the GPU. Or the
console adapter board.
These software, at my knowledge, is lost on time and space.

Also schematics for 700 series scope would be amazing! Another thing would
be the source code of the boot room and software, but I would be already
happy with the service software ?


Il ven 17 gen 2025, 19:36 Ferrous Steinka via groups.io <ferrous.steinka=
[email protected]> ha scritto:

Although not 100% accurate schematics for the TDS400 series have been
posted to the files section of this group as well as TekWiki. They were
scanned from "C" and "D" size engineering drawings and then converted
mostly to "A" legal size. These were late pre-production drawings and did
not contain the power supply (not Tek made). I did not have access to
final engineering drawings. No manual was ever published by Tektronix for
the TDS400 series which contained schematics or parts layout drawings or
pictures. Being the first all digital oscilloscope which relied
extensively on microprocessor control, it was new territory. The next
series, TDS500, had manuals which were similar to past Tek manuals complete
with schematics, theory of operation, and pictures.

I have no background in manual writing or compiling, just a technical
background working at Tektronix for about 30 years. I was able to obtain
the drawings from one of the engineers who designed the TDS series, now
passed on. I tried to post on TekWiki but was not savvy enough to figure
out the posting process.

I had sent a couple of the trigger related schematics to Tim Wright who
was having triggering issues with his TDS420 in hopes it would help him
find his problem. I then posted all my jpg files to the cloud and informed
Tim that they were available for him to use. Kurt Rosenfeld at TekWiki has
also been informed of the existence of the schematics.

Both Tim and Kurt have assembled my jpg images into a single pdf file. I
thank them both for doing something that I had been unable to do which
resulted in my work to be available to those who may need it. The TekWiki
availability is here:
- or:


The schematics are available in the Group files section here:

/g/TekScopes/files/Tektronix%20TDS420_460%20Schematics.pdf

Best regards,

Ferrous Steinka

Would it work to place a parallel resistor to effectively move the defective part?

Thanks
Barry - N4BUQ

Jon,
Do you mean that you couldn't see the following?
Sometimes in the web interface you have to hit the button "Show Quoted Text'.

Raymond

I have an early 130 here (brown case) - those look to me like regular RV4 style 2w 10k pots which can be had on eBay for around $10 NOS. Such as RV4LAYSA103A. I do notice one of them says "S-taper" on them, but not sure how critical that is in this application? Good luck!

I don't disagree that it will be difficult but so far I've got a pretty high success rate from posting want ads on other rare items (I found a guy with 4 570 curve tracers, bought one, managed to get my hands on two Hewlett Packard Barney Oliver amplifiers, etc). So worth a shot.

I would be willing to buy an entire 570 / 575 with the tube if needed. I have an early S/N 570 with the one piece case, so would be willing to pay a decent amount for a later S/N 570 if it has the P11 phosphor tube and is within 12 hours drive of Rochester, NY

You are going to have an extremely hard time finding a P11 T52 CRT.

I bought three 532’s from eBay recently, and they all have P2 CRT’s, which now reside in three of my 575’s. Only one 532 was in restorable shape, so it now has one of the P31 CRT’s. The only source of extra CRT’s for the 570/575 are going to be 532’s, and those are hard to find.

You’ll have to use a P11 535 CRT and modify it, unless you get extremely lucky and find a 532 with P11.

Is it possible to drill a small hole in the case +- 1/8” and give it a small shot of Deoxid?

If that works and you feel so inclined, you can put a small amount of wax or some other sealer to close the hole.
Tom N5AMA

On Sat, 18 Jan 2025 at 10:33, Jean-Paul via groups.io <jonpaul=
[email protected]> wrote:

Ray, Bonjour

No idea about the divider, the output must drive a 50 ohm load, at leas 1
V

Easier with discrete parts. No freq divider needed.

Usually a 1-10 MHz rate.

many fast pulser designs on EEVBLOG, see " show me your fast square wave
", as well as Jim Williams as mentioned.

As I'm sure you know, for scope risetime you need a step, not an avalanche
generator pulse. If a pulse is shorter than the scope's risetime then a
100ps 1V pulse will look exactly the same as a 1ns 100mV pulse.

If you need 1V into 50ohms, then consider homebrewing 3*(74lvc1g14+143ohms)
in parallel. That will drive 2.5V into 50ohms with <300ps risetime. You
need to be very careful of layout and decoupling.

I ought to respin mine; I think I could reduce the ~6% overshoot.

For lower voltages, either reduce the Vcc and accept the increased
risetime, or use a "GHz" RF attenuator.

Be aware that even short lengths of coax will attenuate higher frequencies;
if possible "mount" the step generator on the scope's input.

If using a coax cable for a conventional scope input (1Mohm//15pF), be
aware that the 15pF will cause the standard problems with mis-terminated
transmission lines. The problems can be reduced by having an inline pad
mounted on the scope's (BNC) input. Even 3dB is useful, but 6dB is better
(and a 2.5V step would still be >1V).

Yea I've spent quite a bit of time researching it at TekWiki and other places over the past year. They definitely exist - I've seen at least two, and were documented in the manuals. You could get them in P7 as well, though I've never seen one of those. Here's a link to a vid of one in operation with P11:

The 575 page on TekWiki even has a link to a document to replace the tube with the P11 phosphor - looks like they have you change a 100K pot to a 250k:

I believe the only other tube that can be made to work in a 575 is the 535A CRT (T64P/T533/T5330) - but it's not a perfect swap and requires a modification. It looks like some people aren't happy with it only having 8cm vertical deflection as well: /g/TekScopes/topic/535a_crt_in_a_575_clever/33170927

I've been keeping an eye out for those, too.

Having does the necessary restoration on my T130L-C, I am now running through the calibrations.

I have an issue with the 0-3 and 0-10pF calibrations. The controls, R100 and R99 respectively., have the 'range' but it's clear that the points at which they were set have become 'burnt in' for want of a better description. At those very points where it is almost correct the control loses its authority and idle goes full scale.

A spot of cleaner I figured. But no...

On inspection, they both seem, uniquely amongst the rest of the pots, to be wax-sealed or similar. I'm assuming in pursuit of stability, but sadly now working against that at 50+ years on!

Anyone come across this issue, and therefore recommended resolution? Before I extricate then and attempt to clean.