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Hey there Hachiroku,

nice to meet you, welcome to the group :).

On Mon, Mar 17, 2025 at 9:46?AM chester.jamie.jammy via groups.io
<chester.jamie.jammy@...> wrote:

Hi, my name's Hachiroku.
1.36V and -1.25V Ref tested OK according to this post:
/g/TekScopes/message/13732

I guess one other thing to check is whether J504 is in the correct
position, it should be jumpered between pins 1-2. If it's jumpered between
pins 2-3, it's possible that the DACs reference is bad, which would be good
as that's a well known, repairable fault that can lead to the symptoms you
see.

Here are the voltage measurements (reference to ground) at the DAC pins.
DAC Pin 14=0.151V
DAC Pin 15 =0.147V
More voltages:
Voltage drop across R2013 (10K)= 8.82V
Voltage drop across R2016(10K)= 1.02V
Voltage drop across R2011 (4.75K)= 0.639V
Voltage drop across R2014 (221K)= 7.97V
Voltage drop across R2015 (82.5K)= 8.18V

These all look reasonable.

It's a shame that I've decided to give it up as l observed different
Serial Numbers on different parts of the scope.

I don't think parts or PCBs were serial matched on these scopes, nor
generally in Tek instruments.

l assumed parts may have been replaced/repaired before by someone else.

Seeing how the NVRAM was missing, you know that someone was in there before
you, and without knowing the story it's hard to say whether the scope might
have e.g. been a parts donor. Usually it's reasonable to assume there's
going to be a single fault to fix, but with an instrument that's been a
parts donor, that may not be the case.
That being said, this might be as simple as some other fault on the A5
board or e.g. U950.
There might be some easy diagnostic steps you could try to see if you can
narrow this down, like do the HORIZ/VERT POS controls work and so on.

Have a nice day Siggi and thanks for helping.

No worries. I find it highly rewarding to get these old beauties working,
and every instrument I've repaired has been a learning experience for me.
If ever you decide to circle back to this, you might enjoy reading this
document: .

Have a nice one,
Siggi

I need plastic cover box #342-0592-00 for Tektronix 2236 which is on the multmeter board. Does anybody have one to sell.

Ryan, I sent you an e-mail directly, check junk if you don't see it.
Someone in this group was kind enough to send me an unbuilt Dennis Tillman PCB. I bought the majority of the parts from digikey/mouser and started building it, and then ended up finding a 570 so never finished it. I can pass it on to someone else in the group now, but would like to recover the cost of the DigiKey order (I have to add it up but I think it was around $70)

There is a revised Service Manual that shows the trimmer on the HV Board. That manual is labeled "REV B May 1980" on the first page of the Table of Contents. So this was a Tektronix factory modification that probably allowed the HV Board to be tuned for different versions of the CRTs.

Hi, my name's Hachiroku.
1.36V and -1.25V Ref tested OK according to this post: /g/TekScopes/message/13732

Here are the voltage measurements (reference to ground) at the DAC pins.
DAC Pin 14=0.151V
DAC Pin 15 =0.147V
More voltages:
Voltage drop across R2013 (10K)= 8.82V
Voltage drop across R2016(10K)= 1.02V
Voltage drop across R2011 (4.75K)= 0.639V
Voltage drop across R2014 (221K)= 7.97V
Voltage drop across R2015 (82.5K)= 8.18V

It's a shame that I've decided to give it up as l observed different Serial Numbers on different parts of the scope. l assumed parts may have been replaced/repaired before by someone else.
Have a nice day Siggi and thanks for helping.

ebay says I got the last one. Whew!

Jim

On Mon, Mar 17, 2025 at 03:07 AM, rivet_head wrote:

What is the title / Tek # of that document?

It's on page 2 in the Modified Products section of the RM15 microfiche set.
Only a brief description and no schematics or detailed description.

/H?kan

On Sun, Mar 16, 2025 at 6:35?PM Giuseppe Marullo[iw2jww] via groups.io
<giuseppe@...> wrote:

> From the back panel it looks like you have option 09 (CTT) at least.
It seems so. No probe and really I don't know how to use it, which could
it be the advantage over a logic analyzer?

Option 09 includes the 06 CTT option, plus it allows for using the word
recognizer probe.
The CTT option gives you a counter/timer integrated to the scope. It allows
counting frequency and measuring time intervals, as well as extending the
trigger capabilities a little bit.
This might be useful depending on what you're going to do with this scope.
My 2467 has the 09 option, and I have used its basic functions on occasion.

I may have Option 6 but front plate should have different layout, mine
seems just about OPTION 5 and maybe OPTION 9.

Option 9 includes option 6. IIRC you bring up the CTT menu with the A/B
TRIG/MENU button.

> I have a 2467, where in my opinion this isn't worth it because it only
> really gives you the ability to set up and read back measurement
Ouch, I was expecting it to have the ability to send a "screenshot" of
the waveforms too.

This is a purely analog scope, the only place the trace exists is on the
CRT.

Trying to fix a 5L4N SA - the sweep functions OK, except for single sweep,
but nothing else works. Is there a later version of the manual ? A
trouble-shooting guide ?
The TekWiki one is 'interim'. although it has the schematics and component
layout.
Don't really know where to start on this one.The 15V supplies are good at
the test points, but that's as far as I have got.

TIA
Tim P
-

"That would cause reduced horizontal and vertical deflection and probably the lack of intensity control." Could you explain why please Tom?

I've tested the regulator circuit which is working ok. However I have too high a voltage at the cathode IE -2200v instead of -1850v but too low a voltage on the intensity part of the circuit IE -1606v instead of -1950v which doesn't make sense as both have the same diode replacements - two R5000F's.

Will do some digging, Andy.

Yes I have a few. Did you see the box and write up made by Chuck A? These boards are not meant to interface with an outboard tube tester... they interface directly to a 576 / 577 (maybe all Tek curve tracers) and do not need a tube tester.

Dave

Update: I built another round of demo boards for the museum, and all but 7 have sold. More details about the demo boards (including the new eBay link for purchasing them) are found here:



-Thomas

I didn't know that. I just went through the schematics and some photos of the A2 board and found the connectors. It should be an easy upgrade. Thank you for the assist!

Bill

AH! thank you very much, sir.
What is the title / Tek # of that document?

On Tue, Mar 11, 2025 at 10:29 PM, rivet_head wrote:

I cant find a thing on MOD801C. Anyone hear of such a thing?

Here's the exact text on Mod 801C from an old document (microfiche):

"Trig, 2 vert & cal paralleled to rear, BNC; ext horiz,
sawtooth & gate out paralleled to rear, binding posts;
2 gound posts added."

/H?kan

Thanks Sigur?ur,

I have not done this, but IMHO if any of the 24X5|7A|B scopes allow this,
all of them do, as they all have the same processor and the same bus
timings.

I could just try to program a fram, if it won't work I could simply use the eeprom trick and keep the battery(sigh).

OTOH, I could just try to replace the battery and if everything goes well, maybe return on the matter in the next ten years...

From the back panel it looks like you have option 09 (CTT) at least.

It seems so. No probe and really I don't know how to use it, which could it be the advantage over a logic analyzer?

there is an options service manual, maybe it has the details?

I was not able to locate many explicit information, I was expecting for example indication of a different face plate for options that would add specific functions, like OPTION 5.

You could pull the case and have a look-see, though it's a bit of a

pickle

to pull out the options (I only have the CTT in my 2467).

I already pulled the case to check the P501 jumper's position, not keen to rip open the patient just to see if I have options I think I will never need.
Option 5 is for analog TV, right? Not needed by me.
Option 9 is for word recognition and logic trigger, no use for these either (I don't have the probe, and I have cheap logic analyzers for this up to 400MHz). Maybe I am missing something here.

I may have Option 6 but front plate should have different layout, mine seems just about OPTION 5 and maybe OPTION 9.
Nevertheless, this one:

Is listed as having option 6...but it has A/B TRIG instead of A/B Menu
At least this is what is shown in the OPTION 6/9 Operator's manual.
Looking for the manual to see which function I should check to confirm/dismiss.

I have a 2467, where in my opinion this isn't worth it because it only
really gives you the ability to set up and read back measurement

Ouch, I was expecting it to have the ability to send a "screenshot" of the waveforms too.

Giuseppe Marullo
IW2JWW - JN45RQ

Riga caps replaced. Scope still apart.
The "Control Button Error" seems to be in the interlocked DMM push button assembly, specifically the last section of the "CH1V" switch. Ohmmeter checks show these contacts as unreliable, probably exacerbated by the buttons being read in a "time slot" along with other data on the 6802 data buss. I had a problem with similar switches in a Sencore "Z Meter", flushing with DeoxIT and exercising them solved that, hopefully it will also be the solution here.
HOWEVER, I was also able to secure a "new" Tek switch assembly (640-7434-00), so I would be able to replace the entire switch assembly. The problem would be in desoldering and removing the old one without destroying the board. Anyone have any "words of wisdom"? There are 40 switch pins to desolder.
Lastly, on the ReadOut ring. The scope now reads the ring correctly when grounded but not with a 10X ReadOut probe. From my research, a 10X probe should provide 11K pin-to-ground resistance to indicate 10X attenuation, which this probe does provide. I am assuming the 2236 complied with the "11K" standard, but I can find no verification of this. Anyone have a 2236 to check this?

@dc_rawding,
I've been looking for Dennis Tillman's boards with no luck, but the effort led me to this thread. At only ~15 months old, I have some hope that it's still relevant... I did check out the album you linked to. Looks promising. Do you have boards for sale?

Thanks!

Ryan

I have repaired and adjusted a 2756P and a 494P.

Apart from replacing all old capacitors as recommended by KE5FX
document I also checked all RF boards for "suspicuous" components.

One thing to look out for is that there are several resistors with very
high resistance. Old Allen-Bradley, 4.7, 10 MOhm, etc. that has aged far beyond
their rated tolerance. In my case > 50% (!). One is located on the span attenuator:
R1046 and that one was some 16 MOhms.

There are also low resistance Allen-Bradley types used in the decoupling networks.
They too had drifted and was replaced even though I cannot say that they were
faulty.

Before replacing these resistors, I was able to execute the internal calibration
procedure without any problem only to discover that the analyzer did not
lock the next time it was used in narrow band modes.

The batteries were dead on both analyzers and I replaced them with modern
types. On the 2756 with a larger capacity battery that was placed outside
the PCB (plenty of space in that instrument).

There are also electrolytic capacitors that should be checked and replaced
in the phase lock assembly modules.

After having replaced most axial and radial type electrolythic capacitors, a number of
A-B resistors and having re-run the calibration routine, the analyzers
became stable, not needing any further adjustments.

And a bit OT. I mentioned, before in another thread: The Air inlet holes
for the 2756P are IMO way to few/small. The small Buhler fan ran at full
speed and the air that came out from the PSU was very very hot.

After having drilled a lot more holes on the bottom side close to the
front, the fan now runs at lower speed. I have not noticed any drift or other
instabilities on the analyzer after that modification.

Ulf
SM6GXV

On Sun, Mar 16, 2025 at 11:39?AM Giuseppe Marullo[iw2jww] via groups.io
<giuseppe@...> wrote:

2) would it be possible to use the FRAM+DIP adapter solution and get rid
of the battery altogether?

I have not done this, but IMHO if any of the 24X5|7A|B scopes allow this,
all of them do, as they all have the same processor and the same bus
timings. IIRC the one concern is what happens when the power is dying,
which is where the original NVRAM module has well defined behavior. I've
never heard of NVRAM corruption with the FRAM conversion, though that
doesn't mean a lot :).

3) is there any way to know for sure which are the options installed? I

see these options (BU EXER F1, CT EXER 01, TV EXER something, maybe
CCT/WR OPTION 9?), but is there an official method to confirm?
this is the back panel:

Is that the connector for the P6407?

From the back panel it looks like you have option 09 (CTT) at least. I know
there is an options service manual, maybe it has the details?
You could pull the case and have a look-see, though it's a bit of a pickle
to pull out the options (I only have the CTT in my 2467).

4) Is there any way to retrofit a 2465B with a GPIB board? Is it worth it?

I have a 2467, where in my opinion this isn't worth it because it only
really gives you the ability to set up and read back measurement
settings. I guess with the -Bs you also have auto measurements, and so the
ability to read back measurement. Unless you have a whole lot of batch
measurements to do, that's not going to be worth it either.