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Barry,

How do you want me to get you payment?

Mark

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Hey Jason,

From the photos you posted, I can see that:
1. The scope is triggering on the 850Mhz signal, meaning the trigger hybrid
sees it.
2. The signal is *probably* internally generated, as
/g/TekScopes/photo/302469/3916792 shows GND coupling with
the oscillation visible.

From here, in your shoes, I'd do some organized diagnosis, so if you
measure the below and report back, we can perhaps help you try and suss
what's going on.

1. What is the DC resistance of the attenuator in DC coupling?
This should be 1MOhm within 1% or so, but because of potential leakage
currents, you have to measure this both ways (DMM positive on GND then
center contact) and average. Or you can report both measurements.
You have to measure this across multiple V/DIV settings, as the attenuator
may be working right at some, but not all settings. There are two 10X
attenuator stages, so the total attenuation can be 1X, 10X or 100X, and I
think it's probably best to measure all three combos.

2. What is the DC resistance of the attenuator in AC coupling?
This should be infinite, but you can measure it at any one V/DIV setting.

3. What is the DC resistance of the attenuator in 50Ohm coupling?
This should be 50Ohm within 1% or so, you can measure this once at any
V/DIV setting.

These are all important because of the way GND coupling is implemented
(faked) on these scopes, and so these measurements only allow us to
validate whether the attenuator is working OKish.

You also probably want to pop the case off and measure the voltages on
A1J119, because if your power supplies are bad, there really is no point in
speculating about anything else until those are fixed.

My $0.02 is that your CH2 preamp is oscillating for some reason, but that's
just a guess at this point.

Good luck,
Siggi

On Wed, May 14, 2025 at 4:50?PM Jason B via groups.io <sydbowen=
[email protected]> wrote:

Okay I'll try this. I couldn't upload the vid showing me switching through
everything. Idk if any of these pics will help anyone see anything though.
/g/TekScopes/album?id=302469

I have put the Windows source code out on GitHub under the MIT license for public use. It should be fairly easy for some skilled in the art of Linux to get it running on their OS of choice. It's just a simple C program. The ugly part was trying to determine the COM port name that Windows assigns to the CurveBug. Other than that it's a matter of triggering the device to spit out a trace and then to draw the resulting graph. It uses double buffering to draw the graph off screen then swap it onto the screen in a single operation. This link will get you going if you want the challenge.

Okay I'll try this. I couldn't upload the vid showing me switching through everything. Idk if any of these pics will help anyone see anything though. /g/TekScopes/album?id=302469

Barry- those look great!!!!
搁别苍é别

They are pretty rare, particularly ones that fit a 2465x that has the DVM
option. $110 is probably as inexpensive as you will find. That's slightly
more than what I paid many years ago for my cover (but I do have the DVM
option and so expected to pay a bit more). In my mind, it's kind of like
buying the proper 'scope probes for various applications/purposes for use
with a 'scope. And a rigid front panel cover is pretty important if you are
going to transport or ship the 'scope (for calibration, for instance).

There used to be a member of either the TekScopes or TekScopes2 forums who
occasionally would sell 2465x covers.

While not as protective but just as good for keeping dust off of a 'scope,
large clear plastic bags are a temporary alternative. I have collected a
few of those over the years for use on my 7xxx and 5xx scopes.

DaveD
KC0WJN


On Wed, May 14, 2025 at 14:25 KL7AM via groups.io <w7apm=
[email protected]> wrote:

Ebay, Sphere
One on Ebay but not willing to pay a third of what I paid for the scope

----- Original Message -----
From: "Dave Daniel via groups.io" <kc0wjn@...>
To: "TekScopes" <[email protected]>
Sent: Wednesday, May 14, 2025 10:11:43 AM
Subject: Re: [TekScopes] Want Front Cover 2465b

Where have you looked?

DaveD

On 5/14/2025 1:45 PM, KL7AM via groups.io wrote:

Looking for the above

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Ebay, Sphere
One on Ebay but not willing to pay a third of what I paid for the scope

Where have you looked?

DaveD

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Looking for the above

Mark,

I have knobs and skirts if you need.

Barry

I got knobs and Skirts for the SC502, SC503, and SC504s.

The skirts came out perfect!

See Photos /g/TekScopes/album?id=302038

Barry

The following photos have been uploaded to the SC503 and SC504 Volts/Div and Time/Div Knob Shaft ( /g/TekScopes/album?id=302038 ) photo album of the [email protected] group.

* IMG_2585.JPG ( /g/TekScopes/photofromactivity?id=3916678 )
* IMG_2587.JPG ( /g/TekScopes/photofromactivity?id=3916679 )
* IMG_2583.JPG ( /g/TekScopes/photofromactivity?id=3916680 )

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

On Tue, May 13, 2025 at 11:00?AM Jason B via groups.io <sydbowen=
[email protected]> wrote:

Also I noted that on the waveform in question on the 2465, when I move the
?T markers across the waveform it distorts the waveform as I move across
the center of the screen, and the waveform disappears as I use the vertical
position control to move the trace towards the upper readout values. Does
that ring any bells to anyone here? Keep in mind also this is a 2465 with
the DMM/TV/CTT options if it's possible those options could be doing
something screwy.

From your description it's hard to say what's going on. If you've done any
of the testing suggested above, that might help you narrow down the
problem. If you report the results here, then others might help you
interpret them.
If you haven't read this document before, now might be a good time:
. Even though the
2400-series is digitally controlled, the guts are all analog goodness, so
the advice in the document applies directly.

Photos in this forum go into the photos section:
/g/TekScopes/photos, ideally in a new album with a
descriptive name. It generally helps if you then share the link to the new
album in your post, as that reduces friction for others to look at them.

Andy:

Would be very interested to see what you learn. The crt replacement scenario is a bit draconian. A workaround would be preferred.

Gordon

On 13 May 2025, at 18:52, Gerdy via groups.io <gerdy_maelbrancke@...> wrote:

Then I wanted to try a Cold Start but the entire menu with COLD START, CCD SIDE, CCD ADJ, CAL PATH, FORCE DAC is 'Disabled - See manual’.

There’s a calibration jumper J156 that needs to be removed to enable that menu.

Make sure to run a fan on the hybrids if you run the unit with the case off.

Next step taken on my beloved TEK 2432A:
I replaced the Li battery by a new one, also replaced the bad X2 caps in the PS, and replaced 2 elcos in the PS that measured NOK (once removed these measured OK but I replaced them anyway), all the other elcos in the PS look & measure fine, probably because this scope has only 4400 operating hours.
No CHKSUM NVRAM fail any more, a nice PASS.

But I still have 3 FAIL messages:
7000 (CCD),
8000 (PA),
9000 (TRIGS).

FAIL details:
7200 CCD-GAIN -> 7210...40 fail,
8220 PA-POS GAIN CH2 & 8410...50 PA-GAIN & 8510...50 PA-INV GAIN fail,
9210 TRIGS-GAIN A TRIG & 9220 TRIGS-GAIN B TRIG fail,

Although it showed PASS at startup, from the test results menu I tested the RAM chips one by one, all PASS. Can I conclude that the battery backed up SRAM chips are OK now or do I need to replace these 2 chips?

From the menu I erased the memory, no effect.

Scope is UNCALD, so I tried to calibrate:
SELF CAL: does not pass, shows me the 3 same FAIL messages (7000 / 8000 / 9000) as above.
EXT CAL: I can only do the REPET test which passes, the other ones are locked ('All selections except REPET are locked, see service manual').

Then I wanted to try a Cold Start but the entire menu with COLD START, CCD SIDE, CCD ADJ, CAL PATH, FORCE DAC is 'Disabled - See manual'.

CH1 works pretty OK up to about 10KHz sinewave, correct voltage level, above 10KHz there is a lot of aliasing.
CH2 shows a sinewave that is much too low in voltage.
Trigger seems to work on CH1.

I'm now really getting stuck, calling out for help, any suggestions pls.?

Okay, so I played with the scope a little using my 2445 and the 2465s channel 2 out. I still haven't completely gone about the check of the preamp settings on the 2465. So with the 2465 set at 2 mV and the 10x'd 850 MHz waveform displayed on the 2465 with no probe connected I noticed a couple things. One is that the waveform does not show on the 2445 other than a fuzzy trace with a "check" in the left hand side of the trace like this -^√----- (sorry best I can do without pics), but the 2445 WILL display a calibrator trace if I connect a probe to the 2465 and connect it to calibration lug. Also I noted that on the waveform in question on the 2465, when I move the ?T markers across the waveform it distorts the waveform as I move across the center of the screen, and the waveform disappears as I use the vertical position control to move the trace towards the upper readout values. Does that ring any bells to anyone here? Keep in mind also this is a 2465 with the DMM/TV/CTT options if it's possible those options could be doing something screwy.

Is section 11 of service manual what you have in mind:


Ozan

Hi Gary,

I'm trying to do the same calibration and get the same error.
Did you find a solution?

Kind regards,

Daan