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Guessing a DAC dropped a binary bit, likely D3 or D4 in the successive approximation custom chip output.

These are crazy expensive for what they are — even second hand and out of calibration.

As far as I can guess the CT-6 current probe is just a moulded miniature toroid with 10 turns of thin wire attached to an SMA terminated 50R coax.
Does anybody have an insight what ferrite material is used in these?

I am thinking a Coilcraft or Mini-ciruits impedance matching transformer or a core from an ethernet pulse transformer. Two inches of 32 gauge magnet wire. SMA pig tail. A drop of epoxy.

Would this work?

Leo

On Mar 1, 2025, at 18:00 , Adam R. Maxwell via groups.io <amaxwell@...> wrote:

The garbage cleared off the display at some point, but after multiple power cycles, it will occasionally show a dot that can be repositioned vertically, so I assume CRT is good.

The garbage is back. Some idiot had bent a pin while plugging one of the storage boards back in. Photo here; there is a dot moving very slowly across the horizontal line, and the line can be moved up and down with a pot on the front panel.

/g/TekScopes/photo/301031/3891788?p=Name%2C%2C%2C20%2C1%2C0%2C0

The processor board "ROM 17" LED stays on after powerup, which might be a clue but I can't find a description of it in the manual.

Labeled ROM 17 on the board, but DS1044 on the board diagram, and that LED is referred to as "ROM 8" in the manual:

"Step 1. At power-up, the microcomputer vectors to the self-test in the ROM at the top of address space U2028 on the Memory board. The microcomputer first verifies the checksum of U2028. If the routine for this step runs, but doesn't obtain the correct checksum for the ROM, the routine halts and blinks the ROM 8 LED, DS1044."

DS1044 is steady, not blinking, so I'm still confused.

thanks,
Adam

James,

You should know to fan cool the CCD IC on the bottom when out of the case. These run hot. Use a good compound to help with heat transfer from the IC to the heatsink, like MX-4 compound. This statement about external cooling and compound may be redundant not knowing what you have done. Failure of the CCD IC will cause problems.

I have a 2440 and fully recapped it using high temp, low ESR and long life types. The battery was replaced with an axial type that is double the mA/hr of the original. Once working, recalibrating was easy. I wonder if you need more recapping and battery to see if it helps. The 22mfd axial types in a photo you posted, I used ULD 47mfd because I had them. The lack of a true ground may be a problem.

Mark

I picked up a 492 recently, shown with a trace in the listing photos, so figured it would be at least partially working. Unfortunately, when it arrived the CRT was broken (thanks to not-so-great packing and FedEx abuse). The seller sent me a replacement CRT, and after install it showed a bunch of garbage lines on the screen. The garbage cleared off the display at some point, but after multiple power cycles, it will occasionally show a dot that can be repositioned vertically, so I assume CRT is good.

DC voltages check OK, but I haven't checked ripple.

Various front panel buttons light up, but they are all unresponsive.

The processor board "ROM 17" LED stays on after powerup, which might be a clue but I can't find a description of it in the manual.

Setting S1033 switch 7 off to run a self test, the "OK" LED blinks 14 times. There are five unpopulated locations on the memory board A54 (U1017, U1023, U1028, U2012, U2017), and no GPIB board, so if I understand correctly it should only blink 13 times. This seems bad.

The manual says "look for a possible problem on the chip-select line or on the MSB (bit 7) data line." Can anyone suggest how I would do that?

thanks,
Adam

One other thing which might be related is that the chassis (and therefore GND points) are at 65v DC in relation to the mains Earth potential.

Here in Brazil there is not really an Earth system used, and the mains here is 127VAC.

Anyway...

Hi everyone.

Hoping that someone might have encountered this before.

So after the 492 repair, I picked up a nice, clean 2430A which was dead.

Including the Rifas, the power supply board had 10 completely failed caps and a couple or three toasted resistors, which once replaced gave the scope life once more.
/g/TekScopes/photo/301027/3891759?p=Taken%2C%2C%2C50%2C1%2C0%2C0
All the LV rails are present, although uncalibrated. I've have a look over the boards for obvious damage and tested many caps and semi-conductors for shorts, as well as reseated the socketed IC's and cleaned the contacts on the hybrids. So far no difference.

The issue is, that once the scope is turned on, the scale illumination lights up and the scope clicks through the start-up,
/g/TekScopes/photo/301027/3891763?p=Taken%2C%2C%2C50%2C1%2C0%2C0
however nothing appears on the display, until there's a beep, and then the screen glows off to the right hand side.
/g/TekScopes/photo/301027/3891765?p=Taken%2C%2C%2C50%2C1%2C0%2C0
No control button or knob makes any difference whatsoever.

If I remove jumper J100,
/g/TekScopes/photo/301027/3891766?p=Taken%2C%2C%2C50%2C1%2C0%2C0
then the scope no longer beeps and it just displays a bright dot in the centre of the screen.
/g/TekScopes/photo/301027/3891764?p=Taken%2C%2C%2C50%2C1%2C0%2C0


I'm slowly working my way through the manual but if anyone can give a heads-up as to where the problem might be found, then that would be much appreciated.

The manual states that the beep occurs when there is a short in the unregulated section of the power supply, yet I have checked all the PSU test points, IC's and caps and nothing there is obviously shorted.

Yup, I wanted to check out my 2465 X-Y mode operation before I bought one, and now it's too late. :( Anyway, I verified that it should work with the 2465 - IF you enable X-Y mode properly. And that required some research here because CH 1 seemed to always move diagonally for me. The solution, as found in another message here, is to select (enable) ONLY CH 2. Then CH 1 will only move horizontally (X direction). Hope they will offer more of those demo boards in the future.

25 Sold, now out of stock one day later.

Looks like it has more features than the one I bought some years ago.

Tom

HI and thanks for all the links and great advice.
I will archive the information as when I went to look at the instrument is was seriously corroded by the leaky capacitors and I decided it was not for me.
However I will now renew my search armed with your collective knowledge :-)
Thanks once again
Dave

Tim’s original post is from 13 years ago, back on the Yahoo group list. I wonder if he is even still subscribed to the new groups.io list.

I found several sellers of reproduction feet on eBay. I bought some Tek 454 feet from eBay seller cats2pdx. He lists Tek 465 feet as well:

I, too, am interested in buying a set for my 465.
Arne

Hi Tim,

so how much are you looking for a set?

Thanks

James

Hi,

I'm in Toronto Canada but would probably pay a reasonable price plus shipping from anywhere, if someone has a spare or parted out intact plastic bezel for a Tektronix 606 XY.

One of mine took a hard knock at some point and got smashed in a corner...

Thanks,
--Toby

Ooh nice, been waiting a long time.
Too bad ebay are charging 3000yen shipping to Japan for a 5000yen item...

I'll have to keep dreaming...


Jared

On Fri, Feb 28, 2025 at 01:06 PM, <saturn.v2000@...> wrote:

Ozan:

The green indicator flicker I mention is very subtle.

This flicker seems to go away when trigger mode is set to "auto", regardless
of position of trigger level control
and with no signal input.

===
Mike,
In that case it is normal and expected. When trigger mode is "Auto Level" with no input signal trigger range is set to peak to peak amplitude of input noise and triggers randomly.
Ozan

Ozan:

The green indicator flicker I mention is very subtle.

This flicker seems to go away when trigger mode is set to "auto", regardless of position of trigger level control
and with no signal input.

Just thinking out loud:
Create a SW app that processes a design file (i.e. Autocad, maybe a monochrome BMP ??) into a format that is fed to the ATMega (via a UART port, or USB).
Then anyone could create new displayable images.

Pete

Thanks George, I'll make a note of that.

- Mike, de W9MAS (USA)

Demo boards that display the Tektronix logo and other images on your analog
scopes in XY mode are once again available from the museum!



-Thomas