开云体育

Funny how upgrade usually means downgrade and yes my system does not flow as well as it did.
This page came up at the top where I could not see a place to respond.
Going back from a message on the bottom winds up at the top instead of where I was, what next?
--
Jeffeelcr

Hi Jon,

The 2712 has been in dedicated power supply ripple QC duty. It is fed by a jig with 0.1 uF caps blocking the 14 V supply DC, so it only sees any RF on the SMPS supply rails. It is possible that one of the supplies being checked had a bad output filter and very high ripple, but I do not remember one.

Well, if that first mixer is burnt out I wonder if the CR256B or CA130 diodes have failed? I did a search through the archive for 2712 issues and did not find any other reports where the fault was found. I guess I'll have to pull the can and do some measuring.

Cheers!
Howie

I have never paid that much for a computer. You can buy a new computer, but
I typically buy recent, used business computers for under$100 and get
several years of life out of them.
I prefer a used business grade, to a new, consumer grade system which isn't
likely to survive as long as its installed OS. Keep the old computer, with
the old software if it will still do the job.
I have working computers back to Win 95. and several older Commodore
computers to run old software, or to convert files

On Sat, May 11, 2024 at 2:28?PM Greg Muir via groups.io <big_sky_explorer=
[email protected]> wrote:

I use an old XP machine for email so as not to clutter up my main
machine. But now I can no longer send replies via the groups.io page.
When sending the message it no longer goes through and I only receive a
“{"DraftID":26752611}” reply. But replying through the digest I receive
via my email (use Yahoo for these types of sites) sending messages is
successful.

Somewhat unrelated to this there is the “Your Browser is No Longer
Supported” that occasionally pops up when bringing up a webpage. This XP
computer is using the last version of the FireFox browser that can be used
under this system. The computer has some issues trying to support other
later browser variants. So one has to look at an upgrade to a later OS.
But this computer also has a multitude of older software that will not work
with later operating systems unless upgraded.

Solution?

1. Buy new computer with recent operating system: ~$1000.00
2. Purchase new software to work on new operating system: ~$2800.00

Nearly 4 thousand dollars expenditure just to look at a single website? I
think not.

Problem here is that the people who design websites simply let those who
have older systems fall through the cracks. The young puppy programmers
are not willing to learn legacy systems. That serves as a good reflection
on how companies nowadays distribute their respect for customers. Not
everybody is on the bleeding edge of technology for many reasons.

It’s interesting to note that some actual vary good and professional
organizations have coded their websites to honor older browsers when they
send out probes to see what the client has. These are people who really
care for their website visitors. I have also experienced some companies
who will offer a XP patch for their upgraded software if requested.

Fundamentally things are working well with this older machine except for
the occasional “surprises” like the one that has now occurred with
groups.io.

I realize that there are many people out there who enjoy a brisk encounter
doing “scientific experiments” to accommodate website changes but I simply
don’t have the luxury of a lot of time to do so. When something works well
I simply stick with it. And I’m not about to jump through a dozen hoops
just to satisfy a variant introduced by just one website. I do understand
the aspects of technical progress but it has been my impression to have
companies concentrate on “neat, new & nifty” advances purely for
profit/stockholder motives is one of the issues doing damage to many people
out there from a user and cost standpoint.

Greg

Howard, was the input ever overloaded, the mixer is easy to burn out, and the symptoms are low sensitivity eg -24 db down.

Did the issue develop after measurement of a TX , PA or generator capability over 10 DVM?

Jon

Hi Jaap,
I'm back on the 2712 diagnosis...

I tested all the relays in the RF Attenuator block...and they were good, but upon reassembly the issue still exists: it does indeed show input, but the level is some 24 dB down, frequency dependent. I had thought the Calibrator signal was proper, but the unit fails just about all the Amplitude Normalizations, so the problem likely exists with the calibration signal as well. Since the RF Attenuator relays are OK, the issue must be afterwards, in the 1st Converter, LO or some other block I do not have test equipment to check, I only have a 350 MHz scope...

Barring any further ideas from the group, is there anyone in the US Southeast who repairs these older Tek gear?

Thanks for the help,
Howard Hoyt

?ann lau., 11. maí 2024 kl. 13:26 skrifa?i david via groups.io <davide_us=
[email protected]>:

Now that I think about removing the front panel, it comes off without
removing the knobs. I had to remove the knobs to replace the BNC connector.
Are the relay contacts hard to get at in the attenuator? I don't want to
damage the attenuator.

Once you get the attenuator out, it’s easy to get into it. You do need to
desolder the connection to the preeamp, though. Be careful with the lion
foot contacts, though.

Stand Down. I found enough to proceed.

I use an old XP machine for email so as not to clutter up my main machine. But now I can no longer send replies via the groups.io page. When sending the message it no longer goes through and I only receive a “{"DraftID":26752611}” reply. But replying through the digest I receive via my email (use Yahoo for these types of sites) sending messages is successful.

Somewhat unrelated to this there is the “Your Browser is No Longer Supported” that occasionally pops up when bringing up a webpage. This XP computer is using the last version of the FireFox browser that can be used under this system. The computer has some issues trying to support other later browser variants. So one has to look at an upgrade to a later OS. But this computer also has a multitude of older software that will not work with later operating systems unless upgraded.

Solution?

1. Buy new computer with recent operating system: ~$1000.00
2. Purchase new software to work on new operating system: ~$2800.00

Nearly 4 thousand dollars expenditure just to look at a single website? I think not.

Problem here is that the people who design websites simply let those who have older systems fall through the cracks. The young puppy programmers are not willing to learn legacy systems. That serves as a good reflection on how companies nowadays distribute their respect for customers. Not everybody is on the bleeding edge of technology for many reasons.

It’s interesting to note that some actual vary good and professional organizations have coded their websites to honor older browsers when they send out probes to see what the client has. These are people who really care for their website visitors. I have also experienced some companies who will offer a XP patch for their upgraded software if requested.

Fundamentally things are working well with this older machine except for the occasional “surprises” like the one that has now occurred with groups.io.

I realize that there are many people out there who enjoy a brisk encounter doing “scientific experiments” to accommodate website changes but I simply don’t have the luxury of a lot of time to do so. When something works well I simply stick with it. And I’m not about to jump through a dozen hoops just to satisfy a variant introduced by just one website. I do understand the aspects of technical progress but it has been my impression to have companies concentrate on “neat, new & nifty” advances purely for profit/stockholder motives is one of the issues doing damage to many people out there from a user and cost standpoint.

Greg

Now that I think about removing the front panel, it comes off without removing the knobs. I had to remove the knobs to replace the BNC connector. Are the relay contacts hard to get at in the attenuator? I don't want to damage the attenuator.
David

So, the relay contacts are in the attenuator? I really don't want to remove the front panel if I can avoid it. Knobs are prone to breakage when removing them. But at least I'm sure that the relay contacts are the problem. If it continues to be an issue, I will have to open it up. I'm wondering if warming the knobs with a heat gun will allow me to remove them without breaking them. When I had to replace a BNC connector on my first 2465, I broke one Knob during removal. Previous owners probably never used 50ohm DC input enough to keep relay contacts clean.
David

I got channel 2 to 50ohm by repeatedly switching between 1Meg and 50ohm, after several hundred times, but it is still intermittent. Believe the relay contacts are the issue. Where is that relay located?
David

Hey David,

The 50 ohm terminator is on the ceramic hybrid in the attenuator. It might
have been burned by applying too much power, but it's also possible that
you have an oxidized relay contact. There is overload protection for the
terminator, so it would have had to be a pretty gross overload to burn it.
These attenuators are fairly serviceable, I took some photos of mine from
my 2430: /g/TekScopes/album?id=12814. Here's the ceramic
substrate: /g/TekScopes/photo/12814/163755. I believe the
50Ohm resistor is the big black film on the top left - you can see that
it's been laser trimmed by the cuts on both sides of the film.

Siggi

On Sat, May 11, 2024 at 12:19?PM david via groups.io <davide_us=
[email protected]> wrote:

Hey guys, I bought another 2465 for parts, only 100 bucks. Have two 2465's
already but couldn't stop myself from buying it. Channel Two 50 ohm DC
Input is not working correctly. Can hear relay click, LED lights up, but
input remains at 1Meg ohm. Can anyone save me some time and point me in the
right direction? Where is the 50 ohm load located? I put new electrolytics
in power supply, and new power switch. All voltage's good, scope is working
fine except for the Channel Two 50 ohm dc input. If I use a 50 ohm
termination on the bnc cable Time markers are correct.
David

Hey guys, I bought another 2465 for parts, only 100 bucks. Have two 2465's already but couldn't stop myself from buying it. Channel Two 50 ohm DC Input is not working correctly. Can hear relay click, LED lights up, but input remains at 1Meg ohm. Can anyone save me some time and point me in the right direction? Where is the 50 ohm load located? I put new electrolytics in power supply, and new power switch. All voltage's good, scope is working fine except for the Channel Two 50 ohm dc input. If I use a 50 ohm termination on the bnc cable Time markers are correct.
David

Hi Beros,
Very useful idea and excellent work!
Renaud

NE2H for one, it's a high brightness one, then any green neon will work for the other.? You could, of course, simply use two of the same lamp and just label them.

This same kind of circuit, with different resistors, would work with LEDS, but I'm not sure about the current, since neons can light with less current, IIRC.

Harvey

great stuff, thanks Harvey. any idea what sort of neon lamps to get?
are there standard model numbers?

On Fri, May 10, 2024 at 5:05?PM Harvey White via groups.io
<madyn@...> wrote:

Photo in the photo album, look under neons.

Harvey


On 5/10/2024 10:30 AM, cheater cheater wrote:

Harvey I'll need a drawing of that, can you take a photo and post it
to the list? Or if that doesn't work, to imgur? Thanks

On Thu, May 9, 2024 at 6:10?AM Harvey White via groups.io
<madyn@...> wrote:

If you're looking for direction, you'll need two of them

I'd be tempted to use a resistor and neon with a one KV diode in series
with the neon. The neon will limit the maximum voltage to about 100
volts or so.

so: resistor connected to a neon with a series diode, connecting both
across each other, and the diodes reversed.

Might be a good idea.

Harvey


On 5/8/2024 11:00 PM, stevenhorii wrote:

Could you use a small (NE-2) neon bulb for this? I recall holding the lead
of one and shuffling across a carpet. I got the bulb to flash.

Steve H.

On Wed, May 8, 2024 at 21:03 Ed Breya via groups.io <edbreya=
[email protected]> wrote:

The LEDs would protect each other from reverse breakdown. They should be
stout enough to take the forward hit and flash. If not, you can put some C
across them or R in series to soften things up (which would also stretch
the pulse for better visibility). Try it and see.

What's really needed to assess part durability is a power rating and an
energy rating. You won't find energy rating for LEDs, so have to
experiment. If you study the HBM you'll have an idea of the energy
available from your own spark. Unfortunately, I don't think there's a spec
for SCM, but you can be sure it would be quite a bit more C, and nearly
zero R. Good luck.

Ed

I don't really have an answer for you, but I'll caution that it seems
to me superglue (cyanoacrylate) and clear acrylic almost always hazes
the plastic.....

On Fri, May 10, 2024 at 8:22?PM Benjamin Badrakh via groups.io
<benbadr2009@...> wrote:

The clear part of the volt/div knob has broken in two. This a part of my Tek 2230. I'm just wondering what is the best method for repair. Epoxy? Cyanocrylate? Tape? Plastic welding? Acetone?

Thanks

Benjamin

The clear part of the volt/div knob has broken in two. This a part of my Tek 2230. I'm just wondering what is the best method for repair. Epoxy? Cyanocrylate? Tape? Plastic welding? Acetone?

Thanks

Benjamin

No big issues using my iPhone SE nor with my Firefox browser on Ubuntu/Linux.

Lately it doesn’t correctly indicate read or unread posts but that doesn’t bother me.

My few and infrequent replies seem to be unmolested but they always seem less important after I read my own posting.

no issues using thunderbird 68.12.1 on linux mint xfce machine. ( did not like the changes after TB 68) handling 9 email accounts.
搁别苍é别