开云体育

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

All I can find online is the Operations manual for the LA-501. I have both early and late versions needing a look at, and schematics would be most helpful. Going to be a bit of work since they are loaded with those awful TI sockets.

On 5/9/24 19:05, Ed Breya via groups.io wrote:

I'd like to hear if anyone else is having these kind of troubles

Not a bit. Using thunderbird email reader.

You can just use the 475A manual. Isolate the DM44 from the 475A and troubleshoot the 475A.

Then reconnect the DM44 and troubleshoot that with the DM44 manual. The manuals are separate.
Think of the DM44 and 475A as two different instruments.

Looking for the Tek 475A Service Manual and the DM44 Service Manual.
I assume there never was a combined 475A/DM44 Service Manual?
Thanks!

Photo in the photo album, look under neons.

Harvey

Maybe colorizing the envelope with two different gels, or just colored
sharpies, could help. or put a divider right in the middle so light
doesn't bleed, and put the whole thing in a larger box where one half
is red and one half is blue (and they're divided by the said divider)

What voltage can a neon bulb withstand?

Are there compact neon bulbs that are still very long (say an inch+
while being very thin)?

On Fri, May 10, 2024 at 4:36?PM Steve Hendrix via groups.io
<SteveHx@...> wrote:

On 2024-05-10 10:31 AM, cheater cheater wrote:

Steven great idea but how would I get this to be directional? I know
that the discharge happens by the pain alone, so the next step is to
figure out which way it's going.

With a neon bulb you can see which electrode glows to determine
polarity. I'd have to do some looking to determine which is which, but I
recall that only one electrode glows on a neon bulb driven by DC. Not
sure how long the flash would last and whether you could tell the
difference by eye, though.

Steve Hendrix

Hi all,
(Not sure if there are limits to the frequency a member can post "for sale" items here, but please let me know if I'm exceeding that.)

Please see: .

I'm not sure how to test these, so I'm selling them "as is." I have a few in reasonable physical condition - appropriate for the age - and a few with blemishes (cracked knobs, etc.). When making an offer, please mention what you're targeting to get for your offer. I can send pictures of the specific item you'd get at your request.

Thank you,
Radu.

On 2024-05-10 10:31 AM, cheater cheater wrote:

Steven great idea but how would I get this to be directional? I know
that the discharge happens by the pain alone, so the next step is to
figure out which way it's going.

With a neon bulb you can see which electrode glows to determine polarity. I'd have to do some looking to determine which is which, but I recall that only one electrode glows on a neon bulb driven by DC. Not sure how long the flash would last and whether you could tell the difference by eye, though.

Steve Hendrix

Steven great idea but how would I get this to be directional? I know
that the discharge happens by the pain alone, so the next step is to
figure out which way it's going.

On Thu, May 9, 2024 at 5:00?AM stevenhorii via groups.io
<sonodocsch@...> 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

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