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That doesn't make sense? Show the display with the calibrator as input. Set trigger to Auto.

Yup, a balun (CM choke) could be in the rather long section of the mechanical mounting structure between the small core and the cable connection. It would help with CMRR.

Joe, the board seems very simple to build. If the processor was programmed is there any reason we can't assemble it?
Pretty sure we have the skills and tools to succeed!

And it seems it would take a load off your staff and allow us to have some fun!

Paul
WB6GHK

Followed the SM instructions for 'No Display' but haven't made any real progress, other than getting a dot to appear on the screen (as opposed to merely glowing off-screen) by adjusting the R587 'Horizontal Offset' pot.

/g/TekScopes/photo/301027/3892267?p=Taken%2C%2C%2C50%2C1%2C0%2C0

In fact, once the unit is fully 'on', there appears a second dot, which is slightly fainter.

/g/TekScopes/photo/301027/3892268?p=Taken%2C%2C%2C50%2C1%2C0%2C0

Also verified that the HV -1.9kV is present.
All the LV rails are present, although there is a 61v rail somewhere which I haven't yet discovered where to test (nor where it comes from).

Due to the 'Beep' at start-up, I feel certain that something is shorted somewhere, but why the rails are not low in that case, is a mystery to me?

So the flicker only shows up at slower sweep speeds it goes away as I slow the time base down.

Hi all,
In addition to the obvious current transformer, there’s likely to be a balun, to make the probe less sensitive to electric (capacitive) coupling.
Thats’ probably in the longer tail, away from the hole where the wire goes through.

Cheers
David K

Check the CPU's reset line. It's driven by an optocoupler on the power
supply board, as I recall, and the resistor that drives the LED side of the
optocoupler can open up.

-- john KE5FX

Hello everyone,
First of all, I apologize for being absent from the forum for so long.
Some time ago, I ordered the capacitors and have already replaced them. However, I made a mistake: instead of buying 10?F 35V, I purchased 10?F 16V, a big error. Well, it's only two of them, so I will find a way to fix it.
Regarding the power supply, it seems to be fine, but it clicks, which suggests a short circuit. That’s why I checked the bottom board (acquisition board) and found that it is shorted, seemingly on the 5V and 15V lines.
I am thinking of injecting 1V at 100mA to locate the short, but I don’t know which pins correspond to these voltages on the connectors.
Additionally, the rear BNC Signal Output connector is also shorted, which might be a useful clue.
I don’t have the service manual for my TDS, otherwise, I would be able to track the issue better.
Once again, I apologize for being away for so long.
73!

If you go to our website and search for demo board, you find the description. eBay listings disappear when sold out.


Dave

Here is the link to the board description. It contains a link to a zip file that has some instructions, a Digikey BOM, schematic, and hex file. I assume the hex file is to load the ATMEGA328P. Unfortunately there is no information on the PCB.

Given the fact that these 25 boards were sold out rapidly I'd assume there is demand for the next 250 boards rather than the next 25! I hope I will be quick enough next time! Thanks to you volunteers who make the boards!
Joe

?ann sun., 2. mar. 2025 kl. 15:49 skrifa?i Larry McDavid via groups.io
<lmcdavid@...>:

Please point to where this demo board is described. What does it do? I
could not find it on the Tek museum website.When you say "Watch the
store," what store? Do you mean the Tek Museum eBay store? Please add a few
details.Larry McDavidSamsung Galaxy S10

Follow the white rabbit (from the first post):

Please point to where this demo board is described. What does it do? I could not find it on the Tek museum website.When you say? "Watch the store," what store? Do you mean the Tek Museum eBay store? Please add a few details.Larry McDavidSamsung Galaxy S10

We have inventory for another set of 25 and will begin building. Watch the store. We didn't expect this amount of demand and have a lot of shipping to tend to this week.

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.