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That should work. You can experiment with different cores easily and see how they measure up. Ed

I plan to build 25 more demo boards for the museum in the next couple of weeks, and will post here when they are available again.

-Thomas

Since the last run of 25 sold out, I suspect they will plan to make some more of them. Being an all volunteer organization, it might not happen as quickly as some might like.

I bought mine some years ago at the VintageTEK museum since I live in the area.

Tom

The sine wave is a sawtooth on the screen. The modulation is in the Z axis. These two make it sound like ripple in the power supply. I have worked on these and found most of the 1mfd axial tantalums as decoupling on the boards to be high in ESR. I replaced them with radial film types. In a few spots, I put in 22mfd tantalum to boost the decoupling. I had these in stock and used them. The main filter cans and decoupling from the regulators could be going bad. At the age of this, condensers going bad is likely. The cans are a pain to get out and reinstall. Restuffing is not hard, for me. Since the flicker stops at slower sweep speeds, dirty contacts are possible. Some resistors, mostly the carbon ones, are too small in wattage. It is possible some have gone high in resistance. Heather-cathode leakage in any of the Nuvistors?

Mark

Hello I recently picked up a 453. When triggered on a sine wave it seems to flicker. Interestingly it will stop flickering when i reduce the time to a certain point. Wondering if someone can point me in the right direction. Attached is a video of the 453 flickering.

I just went to the ebay link, and it still shows "out of stock" and no way to order it...

I would like to get one of these boards, or at least the programmed Atmel chip or a source code listing for it to duplicate.

Hi Mark.

I've only been running the scope out of the case long enough for the display to be shown but I do have some good thermal paste so I'll take your advice on that one, although who knows what this scope has been through before?

The reason that I mentioned the +/- 65vdc on the chassis is that it occurred to me that perhaps something had shorted to ground? I reasoned that considering all the LV rails are present, then it likely wouldn't be in the PSU and turned my attention to the HV board, but no shorts were obvious there. I wary of connecting another scope in this condition so I'll probably just create an Earth path by connecting into the Neutral line.

Regarding the battery, it seems this is the model which used two Dallas NVSRAM's.


Shortly after starting the thread, I came across a section in the manual for troubleshooting the display, which I plan to check out today. Let's see?



James

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