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Finally I decided to take care of the baby, before is too late:

TEK2465B
S/N: B017389
Hours: 10045
Pwer On/Off: 1783
AFAIK never recalibrated, no sticker applied

Apparently I have at leasr OPTION 5 installed, I have the same panel:


I dumped the CAL values using a video (actually two, I discovered I made some errors, with light "0", "B" and "8" seems similar, so I took another one (still to be triple checked).

Now I would like to know which are my options:

1) could I apply the solution that writes the values after burning a special eprom/eeprom with cal data in it? Keep the same/replace SRAM after replacing the battery? I see there is a utility (24xxAB-writecal-1.1) that would allow me to put CAL data and have it be written in the SRAM. Is this one fit for the purpose:

GQ PRG113 GQ4X4 + ADP054 + EPROM ERASER



2) would it be possible to use the FRAM+DIP adapter solution and get rid of the battery altogether? It is not clear to me if this could be used on the low serial scopes also. Same goes for the programmer mentioned before.

In addition:
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?

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

Thanks in advance.

--
Giuseppe Marullo
IW2JWW - JN45RQ

Jon,

I have 2 SC504. Both of these units have this exact mod. I found some documentation that stated that a later crt required a circuit mod.

Thanks, still putting the pieces together.

Barry

The power supply on a 2465 has 2 four pin connectors to power optional Lemo jacks on the rear panel of the 2465. No new power supply needed, just a jack, board connector, hole and some wire.

Hi, I have VmtWin-release032201.zip and some more. Try this:

My VM700T backup battery did run out, and I don't have security key to activate unit anymore. I tried to ask key from Tektronix, but they can't generate those anymore. I'm looking working serial number + activation code (not sure if it's possible to change serial on unit and then activate it again).



Ramppa / OH2LIY

Thanks, I'll look at that. Andy.

Hello Jose,

the one you are mentioning is not right schematic for TDS784A power supply.

Here you can find proper diagram: (PS).pdf

Power supply in TDS784A is the same as in TDS544A (above link) and several other TDS models.


Vladimir



Dne 16.03.2025 v 6:16 Jose Luu via groups.io napsal(a):

OK, found one good enough: page 5-141

I'm assuming a similar setup like the later 492 for the following comments...
The issue seems to be one of accuracy. It won't lock in time when high accuracy is demanded by the cpu.
If like the 492 scheme, there are 4 oscillators used in 2nd if, a 2200 fixed from 100 MHz ref, a 16 to 20MHz, a 2182 and 719Mz which is used only for the middle bands.

It's like noise is getting into one of the oscillators, likely the 2182, or 18 hz or the error amp. After the cal, if no joy, check the 2182 error signal is clean. The later 27xx units may have the surface mount caps that fail and or leak. Checking inside rf shields is a good idea as some circuits have a dedicated 5v regulator under shields. I bet it's similar to the older design 492b etc.

Good Morning All:
Got a 784A where the PSU is bad (this model: )
one of the capacitors has leaked and may be exploded to the point where the fiber glass weaving of the PCB is swollen and exposed.
It may be the +5V @22A supply.
Since these are large PCB traces, not to many are destroyed, I may attempt to repair the area, having the schematic would help.

Thanks
闯辞蝉é

I think you should probably review what was done with the EHT transformer replacement. My guess is its running unregulated and the output is way too high. That would cause reduced horizontal and vertical deflection and probably the lack of intensity control.

The bus,wire is,perhaps an indicator of a mod,perhaps b y previous repair attempt.

Suggest you Remove the Trim pot see the,original PCB.

Jon

GM all -

Someone from the list has responded to my plea for assistance and I have a couple of the required connectors on the way.

Cheers,
Bill

GM Clark -

Buying a 1101A would definitely be more practical but building stuff is fun. It is, after all, why i have all this gear in the first place. If I fail, the 1101A is the fallback option (and, yes, probably cheaper in the long run).

Cheers,
Bill

Does anyone have a copy of the “REV B” manual? If so, does the HV board show a trimmer?

Many thanks!

Anybody know how close the 2755 is to the earlier 492b ... 494a series design?

Hey there,

Do you have a name we could call you by?

The most common problem by far with the 24X5B scopes is a bad DAC reference
due to electrolyte leakage from the SMD caps on the A5 board. The quick and
painless way to assess the state of the DAC reference is to measure the
1.36V and the -1.25V references on the A5 board. If those are not good,
then that needs fixing first. These scopes are all drive by wire, and the
DAC on the A5 board generates a whole host of analog voltages that control
sundry functions of the scope, including trace and OSD brightness.

Siggi

On Sat, Mar 15, 2025 at 9:02?AM jammythewinner via groups.io
<jammythewinner@...> wrote:

Hi everyone.
I recently got a 2465B scope and replaced all leaky/high ESR CAPs.
The Dallas NVRAM was missing so I hacked in a FRAM and the machine did
switch on; have to press A/B TRIG to proceed when the unit self tests
(presumably TEST 04 FAIL).
The first thing is that, I had to adjust the GRID BIAS before I could see
anything.
After adjusting, I noticed there're dots and weird characters on the
screen.
I've read somewhere else that this has something to do with the CAL data.
So I tried to do the CAL procedures. But I cannot finish beyond the first
step of CAL 08, the center dots dim with other dots as I adjust the GRID
BIAS.
The Intensity trim pot seems to do nothing. Readout Intensity is either on
or off.
The problem is very similar to this post on EEVBlog, and there's a video
in this post:


Feeding in 10MHz sine wave into all 4 channels and they looks good except
the flashing dots and weird characters.

Checked all voltages according to the 5-1 table, and traced down all lines
related to the DI, ROI to the U650.
Before R361 and R353, dramatic changes on voltage when turning the pots.
But checking the 22 and 23 pin of U650, changes were, however, in 100mV
range.
Removing the U950 chip restore the amplitude to reasonable levels.
But this also did nothing the the screen. Everything is still in place -
nothing disappeared, nothing changed - weird characters, dots, signals
remain the same.

Test signals 22, 23, 65, 66 shown in the SM are way out on amplitude.
Feeding 3Hz 5Vpp signals into the Ext, Z-axis in did absolutely nothing to
the screen.

I don't have another U950 on hand to test but the U950 seems to be the
culprit?

The following photos have been updated in the SC504 Trace Problem ( /g/TekScopes/album?id=300558 ) photo album of the [email protected] group.

* IMG_2541.jpeg ( /g/TekScopes/photofromactivity?id=3896193 )

*By:* Barry Breaux <groupsio@...>



---

Barry Breaux <groupsio@...> updated the photo album SC504 ( /g/TekScopes/album?id=300558 ) : SC504 photos

I'd like to build Dennis' design also. I do have one of his PCBs. His paper
lists the Eico 665 and 667 as vacuum tube testers that have been tested to
work. I found it odd that the 666 is *not* listed in his paper at all, even
in the "Should Work Just Fine" list.

I would be interested to know if anyone has successfully built the VTCT
using an Eico 666.

DaveD
KC0WJN


On Sat, Mar 15, 2025 at 09:01 ryanhart via groups.io <ryanhart=
[email protected]> wrote:

This is quite an old thread, and I'm unable to find the original, which is
even older.

I'd love to buy one of Dennis's boards. Is anyone selling them? I've read
his Oct. 2019, v1.04 paper on the tube tester-to-curve tracer adapter. It
sounds fascinating.

I have an Eico 666 that I think I could use for this. I have a Tek 577 on
the way that's described as being in perfect working order. It'll need a
once-over, but assuming the seller is an honest Joe, my hopes are high. I
certainly can use the 577 for other things as well, but matching tubes is
very high on my list of things I'd like to do with it.

Any info on where this project stands is much appreciated! Thanks in
advance for any info.

Ryan

Serials starting with a 1 are IIRC from the Guernsey plant

Here is a photo of the HV board showing the trimmer.

/g/TekScopes/photo/300558/3883505?p=Created%2C%2C%2C20%2C2%2C0%2C0

Regards,

Barry