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Hi Dave,

You can unlock the options via GPIB. They are locked in EEPROM. See

for example. You need 2F option.

Regarding VGA,
Yes, somebody did it.

Regarding NuColor,
Is more simple, do it via VGA. NuColor uses a specific signals with
different frequencies.

Regards,
Peter

вт, 11 мар. 2025?г. в 11:54, Dave B via groups.io <davebullockmbe=
[email protected]>:

You might try asking in the Test Equipment section of the eevblog forums <>

Go to the photos section </g/TekScopes/photos> and create a folder called (e.g.) TU-50, and upload your pix there.

David

Hey everyone, I was pointed in the direction of this group from the Tektronix subreddit.

Like the title says I don't have a formal background in EE or repairs, just some modest restorations of tape machines and other audio equipment. Apologies if I say something glaringly incorrect lol

So basically, I frequent a lot of e-waste recycling type places here in the Bay Area and today I spotted this vintage Tektronix unit next to the dumpster at one of these spots. I asked the cashier if I could take it instead, which apparently required a small transaction for their records. So $5 later I'm driving home with a TU-50 in the back seat

Now what I was expecting was that the internals would already have been more or less parted out already and that I'd reuse the chassis for a project, but when I took a look inside I was floored. The entire 70+ tube complement, original selenium rectifiers, coils, ect were untouched. The only thing missing seemingly was the accessory that plugs into the sine wave gen section, a single knob in square wave section that I replaced in the meantime, and also the cage that's supposed to hold up the fan has an issue I haven't looked at. I'm by no means set up or experienced enough to test complicated tube equipment like this so I can't report on that front unfortunately.

From what I've gathered, this was a low production one-stop shop for calibrating oscilloscopes that was only used internally by Tektronix during production in the 60s-70s? This one's no. 248

I really don't have the heart to tear down a well preserved piece of tech history like this. I mean even among the other pre-IC Tek equipment I've opened up, the point-to-point layout and construction is just artful. The row of 50 tubes upside down in the frequency division(?) section kept bringing to mind a flock of bats hanging from the ceiling of a cave or something similar

So then, what's the deal with these units? Are they well known among Tek fanatics? Are they still relevant for current day technicians who restore vintage scopes? Are there many collectors interested in test equipment like this that never had a public production run? I wouldn't even know where to start in terms of price, as there's seemingly no record of one being listed on ebay. Would it be better to hold on to for when I inevitably make the descent into building a proper amateur bench setup?

Very curious to hear from y'all, thanks!


Also, is there a good way to attach photos? My first post came back saying no attachments

Hi Teksperts,
Is it possible to identify which options are locked within a Tektronix TDS640A from the serial number?
I understand that many options are present but 'locked' from access on lower spec models and are unlockable with a hardware/software 'hack'? I am particularly interested in the FFT math function...
I am aware that there is often an extra 'sticker' on the rear of the instrument declaring enabled options like (1F floppy drive) etc but is there a database that explains what hidden options are available?
Secondly:-
Does anyone know if the VGA output displays in colour even if the oscilloscope is shipped with a monochrome screen (and if VGA colour), can the screen be substituted for a colour LCD like the "CRT and shutter" swap previously described in this forum?
Thanks
Dave

Thank you all that responded, I have now contacted VintageTek Museum to inquire. QService where not listing these particular parts

Thanks and kind regards,
Daniel

The Novasensor product line is still around. Jim Williams's AN61 () includes several application circuits that might help you think about what could be in the probe.

--
George

While looking for some manuals I found the bitsavers.computerhistory.org site.

It has some very high quality manuals including TEK ones.

Regards,
Brian

Thanks. The ebay listing is for the pressure transducer part of the probe set I have. Definitely labeled as Tektronix gear. The probe assembly has a Lemo power cable and a P6137 style BNC connector and body. Maybe it was a custom probe for internal use or a particular customer. Just trying to figure out if I can use the probe amplifier for anything interesting but I'd definitely need to find a schematic first.

Bill

Hi David, and thanks for the suggestion.

That could well be the case.

It seems that I need to figure out which part of the PSU board supplies the horizontal control circuit?

Whatever is causing this, is 100% located on that board, and nowhere else.

So far, on this original PSU board, I've changed two of the four Rifas, three resistors (which were all burned out), eight of the electrolytics, five LM358's (which had heated to the point of losing their graphics), three 1N4007 rectifiers, tested all the remaining caps for high ESR and probed across almost all of the remaining components looking for a short, but to no avail.

It's almost like the component only fails when a voltage is applied or it's put under load.

Unless someone has a better idea, I'm considering powering-up the two PSU boards side-by-side and taking readings at every point from the AC in, until the various DC outs, as surely that would reveal where the 'issue' lies?



Onwards and upwards.

James

Thank you, Jared, for the gesture. I really appreciate it. 73!

A glow off to the right might suggest that the left horizontal plate signal was disconnected ...

Further testing..

Swapping the known good PSU and top boards into the original 2430A reveals that the display problem is indeed created by the original PSU.

The original scope starts up and has a perfect display, as well as various diagnostic FAIL's, but we can take it that the HV board is functioning.


Now to figure out what is going wrong in the power supply..

James

Shall keep this short, however...

swapping the PSU from the 'original' (no display) scope into the working 2430A, brings back the 'BEEP' and the glow off of the right hand side of the CRT (no display).

It is surely fair to assume that the root of the problem lays on the PSU board?


James

Ok - thank you. I'll try it as soon as I got my 3034C

These schematics are for the TDS540, but the power pins will be the same:





Jared

Thanks for the reply...

After having spent some time going through the CPU/CTM schematics I am inclined to agree with you, it's more probably a mechanical connection problem somewhere. The un-read CH1 probe sense ring is easy to check.
The D0-D7 bus lines on the 6802 are MUXed to many places, not only reading the push buttons but also the ROMs running the firmware. Given that, I suspect an active component failure on a data bus line would kill the entire CTM firmware function including the scrolling "Control Button Error" message. Hopefully it's not some small timing problem in one of the multiplexers...

It won't be the first (or probably last) time I will have reseated connections in my older gear. It's the price we pay to keep legacy equipment operating.
I just need to be particularly careful with the CTM/DMM button extension and Time position knob removal (if necessary). Don't want to break any plastic parts...

See

It has an alternative part number

(Not my auction just a Google result)
Sent via mobile annoyance thingy, please pardon any typos.

On Sat, Mar 8, 2025, 9:09?PM ed breya via groups.io <eb=
[email protected]> wrote:

If your probes don't seem to be Tek or related to engine analyzers, then
also look at HP's foray into laser interferometer systems, which had some
transducers for barometric pressure, temperature, and other physical stuff,
to compensate for effects on the laser optics. HP also had some other
pressure transducer stuff related to HPLC and GC in their analytical
equipment lines, up to around 6,000 PSIG.

Ed

If your probes don't seem to be Tek or related to engine analyzers, then also look at HP's foray into laser interferometer systems, which had some transducers for barometric pressure, temperature, and other physical stuff, to compensate for effects on the laser optics. HP also had some other pressure transducer stuff related to HPLC and GC in their analytical equipment lines, up to around 6,000 PSIG.

Ed

Here's the rest.



Ed