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From: "n4buq" <n4buq@...>
To: "tekscopes" <[email protected]>
Sent: Saturday, May 7, 2022 3:15:52 PM
Subject: CRT in 7514 Stuck

Following the instructions in the manual, I cannot get the CRT in my 7514 to
budge. I have removed the CRT from my 7704A which is physically very similar
and when I loosened the clamp spring screws in that scope, the CRT slid right
out. Not so much for this scope.

If I push on the front of the CRT, I can see that it moves ever so slightly
towards the back of the housing but that's about all the movement I can get out
of it.

I know this has an extra cable that supports the storage function and I have
that loose as well as the anode connector.

Anyone know what might be holding it so tightly and how to properly get it
loose?

Thanks,
Barry - N4BUQ

I have what seems a simple question, but I am sure is not so much. Backgrounder: I am just an electronics hobbyist who has never worked in technology or electronics as a career. Was trained in electronics maintenance and repair in the late 1970's through the military, but never used what I learned to any great extent since then. Most of my efforts in the last 30+ years have been focused on antique radios and vacuum tube test equipment, the majority of the test gear being service grade and pre-WWII.

Over the last 10-12 years, I become enamored with Tektronix and HP equipment, and have collected a sizeable number of cast-off oscilloscopes, signal generators and counters from the aforementioned companies, all being produced from the late 1950's to 1970. As I have delved ever deeper into the more modern lab-grade test equipment, I have found that I am becoming limited in my restoration efforts due to bandwidth. My two bench 'scopes are a 564B Mod121N, and a 561A. I also have my recently acquired 549 Serial #101, and a 545B. The 545B suffers from HV transformer disease, and is currently in a rather long queue awaiting repair. The 549 is special due to it being the first production unit, therefore I am loathe to use it except to just maintain it in an operational state. It appears to have a good CRT, but has some minor issues and needs calibration.

Given the above, I am therefore limited to at most 30 MHz, but in practical terms, just 10 MHz. From what I know, I have three options: I can purchase a more modern 'scope that can get me to 100 Mhz. or higher, go with sampling, or do without. The last option is not really feasible, as I am running into issues with the calibration of some of the instruments in my collection. I have just done a restoration on a Type 114 Pulse Generator. Do not need it, but find it an interesting piece of equipment. While I can perform most of the calibration procedure, I cannot check the risetime as my equipment isn't capable of going into the the nanosecond region.

I am not keen on getting a newer 'scope. At this juncture, I wish to limit my endeavors to "hollow state" devices, or hybrids with transistors and tubes. While I used 465 and similar oscilloscopes in the Navy, the idea of poking around inside them I find rather daunting.

That leaves sampling. This is an area I am almost totally unfamiliar with, but find fascinating. Over the years, I have collected a Type 3S76 and a 3T77A. Both units are literally pristine in appearance, but inoperable. I have also acquired a 3S2 and a 3T2. These units, while repairable, are in a sad state. Both are absolutely filthy, and the 3T2 has been dropped savagely. While the 3T2 is not bent or twisted, a good number of the transistors are MIA and even a couple of the transistor sockets are broken. The PCB's appear OK, not being cracked, broken or have jacked up traces, but even some of the passive components are damaged.

It has always been my intention of going into sampling, and eventually getting the above mentioned plugins working. The 3S76 and 3T77A have already been thoroughly cleaned, inspected for obvious issues, and lubricated. I have also checked the tubes and transistors and have found none obviously bad. It is just a matter of diagnosing whatever is wrong with either one, or both of them.

My questions are whether I can adequately engage the higher frequencies with the old systems I do have, or whether I should just bite the bullet and go with more modern equipment. I have very little interest in SMD, IC's, digital devices, etc. Just wanting greater bandwidth. What are the cons of sampling?

Thank you all for your input, it is much appreciated.

Dave

Re: Hacking a digital camera

Removing the IR filter won't make much of a difference. The objects have
to be *very* hot in order to have any appreciable IR emission at
wavelengths short enough for a silicon-based camera. With a bandgap of
1.2eV or so, you aren't going to see anything with greater than 1um
wavelengths. Think of how hot something has to be to glow red, and back
off a little. If you have parts that hot, you won't need a camera to
tell you that!

--Cheers
Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070


On 5/6/2022 18:13, James55 wrote:

Hi fellas, thanks for the input, it all helps.

@ Harvey;

Nicely outlined. You've helped clarify a few things which weren't so

clear. The feeding a 50% duty cycle signal shall have to wait. My intention
right now is to nail the technique in finding shorts by analyzing the
millivolts

One more question, would be, "how might one find out if the tester has

a high impedance?" There is no mention in the manual.

@ Aldue;

Yes, an infrared camera is definitely on the horizon, in fact, I do

have one back in Europe.

Has anyone ever tried hacking a 'normal' digital camera by removing

the IR filter lens to see if the components glow when hot? That might be my
best option here.

@ Ed Breya;

I'm currently in Rio, so obviously have access to lots of LIA's...

What color were you thinking?

No... apologies for being silly, but don't have access to a Lock-in

Analyzer, tbh I have never heard of one. That said, I do appreciate the
input and shall look further into them. My goal is ultimately to fault-find
as quickly as possible, regardless of which technique or apparatus is used.

I'm still a hobbyist so still accumulating tools and testers. The

reason for asking about the millivolt method in particular was that
following a prior thread, it became very clear that it was something quite
basic which was missing from my repair 'armory'.

Like Jim Ford however, I am intrigued as to recommended makes and

models.

Appreciations to you all.

James

Hi fellas, thanks for the input, it all helps.

@ Harvey;

Nicely outlined. You've helped clarify a few things which weren't so clear. The feeding a 50% duty cycle signal shall have to wait. My intention right now is to nail the technique in finding shorts by analyzing the millivolts

One more question, would be, "how might one find out if the tester has a high impedance?" There is no mention in the manual.

@ Aldue;

Yes, an infrared camera is definitely on the horizon, in fact, I do have one back in Europe.

Has anyone ever tried hacking a 'normal' digital camera by removing the IR filter lens to see if the components glow when hot? That might be my best option here.


@ Ed Breya;

I'm currently in Rio, so obviously have access to lots of LIA's... What color were you thinking?

No... apologies for being silly, but don't have access to a Lock-in Analyzer, tbh I have never heard of one. That said, I do appreciate the input and shall look further into them. My goal is ultimately to fault-find as quickly as possible, regardless of which technique or apparatus is used.
I'm still a hobbyist so still accumulating tools and testers. The reason for asking about the millivolt method in particular was that following a prior thread, it became very clear that it was something quite basic which was missing from my repair 'armory'.
Like Jim Ford however, I am intrigued as to recommended makes and models.

Appreciations to you all.

James