开云体育

The parametric measurements use the trigger hybrid extensively,
and their performance is directly related to how well that hybrid
performs. Some are better than others.

-Chuck Harris

joe@... wrote:

After successfully calibrating my 2465B, it reports "All tests passed"

on start up. The question marks are all gone! My issue is with the
parametric measurement of frequency. When I attempt to measure the
frequency of a sine wave at frequencies higher than 10 MHz, the scope
reports the frequency as 35.62 kHz. Any test frequency above 10 MHz gets
the exact same report, 35.62 kHz. Below 10 MHz, it reports various
incorrect values (i.e. a 4.89 MHz signal is reported as 6.35 MHz). At
about 500 kHz and lower frequencies, the scope reports the correct
frequency. I have replaced the PAL at U975 - no change. Any suggestions?

After successfully calibrating my 2465B, it reports "All tests passed" on start up. The question marks are all gone! My issue is with the parametric measurement of frequency. When I attempt to measure the frequency of a sine wave at frequencies higher than 10 MHz, the scope reports the frequency as 35.62 kHz. Any test frequency above 10 MHz gets the exact same report, 35.62 kHz. Below 10 MHz, it reports various incorrect values (i.e. a 4.89 MHz signal is reported as 6.35 MHz). At about 500 kHz and lower frequencies, the scope reports the correct frequency. I have replaced the PAL at U975 - no change. Any suggestions?

All,

While I was searching eBay for a transistor adaptor for my 576, I came across a parts 577 in good condition with both the adaptor and an original safety cover for a low price... and ended up snagging it, too.

It was advertised as not powering up - and on closer inspection, the power cable's strain relief is loose, and there's no fuse present. I can obviously fix both, but I'm wary of powering it up given that perhaps there's a reason the fuse is absent (although I'm comfortable checking rail voltages with suitable precautions once it's up). Any advice? Would a variac help?

Thanks,

Neil

All,

While I was searching eBay for a transistor adaptor for my 576, I came
across a parts 577 in good condition with both the adaptor and an
original safety cover for a low price... and ended up snagging it, too.

It was advertised as not powering up - and on closer inspection, the
power cable's strain relief is loose, and there's no fuse present. I
can obviously fix both, but I'm wary of powering it up given that
perhaps there's a reason the fuse is absent (although I'm comfortable
checking rail voltages with suitable precautions once it's up). Any
advice? Would a variac help?

Thanks,

Neil

On Apr 4, 2019, at 06:22, David C. Partridge <david.partridge@...> wrote:

No, those are the older ones the ones I'm looking for look like this:

<>

Dave

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of
Colin Herbert via Groups.Io
Sent: 04 April 2019 13:13
To: [email protected]
Subject: Re: [TekScopes] Wanted: Earth leads with croc-clip for P6139A

Would these do?


eads-w
ith-Alligator-Clip-Tektronix-HP/222659358233?ssPageName=STRK%3AMEBIDX%
3AIT&_
trksid=p2060353.m1438.l2649

They have a length of 7 inches (17.5 cm). I bought some a while ago
and they are fine, if possibly not genuine Tek. He also has the "witches hat"
grabbers for P6139, etc. probes. Be careful, though, as while he will
offer combined postage, eBay doesn't seem to go along with that. It
took me some time to get combined postage when I bought three items
from him. Of course, this might have improved, now.

Colin.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of David C.
Partridge
Sent: 04 April 2019 12:03
To: TekScopes
Subject: [TekScopes] Wanted: Earth leads with croc-clip for P6139A

I'm looking for the earth leads with crocodile clip to fit the P6139A
and similar probes.

I have the ones that connect to mini-grabbers, but lack the croc-clip
versions.

Does anyone have these available?

Cheers, David

On Sat, Apr 27, 2019 at 05:59 AM, Raymond Domp Frank wrote:

If you want to do measurements on high-frequency signals or signals with
high-frequency content, always consider using Lo-Z probes like 1:1 50 Ohm,
1:10 500 Ohm or even 1:100 5 kOhm probes. These have relatively constant
impedance and many can be made at home. Search for that on the Internet.

You may want to look for an old-fashioned Lo-Z probe like a P6056 (500 Ohm) or P6057 (5000 Ohm). Even with their standard BNC connection, they work well with your more modern digital 'scope and can be bought for little money.

Raymond

Good luck,

the RIFA caps are worth replacing, especially if you're in 240V land. Make
sure you replace them with properly specified X or Y class capacitors, as
required. You can find plenty of info about what that means on the
interwebs, but I wouldn't buy those from any but reputable sources.

Those old scopes are a work of art, and the service manuals are an
education - you're in for a treat :).

Good luck,
Siggi

On Fri, Apr 26, 2019 at 12:34 PM Tony Fleming <czecht@...> wrote:

Thank you very much for comprehensive email, that is pointing me to the
right direction!
It seems to me that the Beam Switch is sticking for sure and could cause
most of my problems.
I'll try to update the videos as soon as I make some progress.
Should I also replace some of the square caps that are something like
0.006xx nF? Many people do this ASAP, since these caps are not a good
quality - despite most of the parts are very good quality.
Where should I buy the caps and other parts, if I'll need them?
I'm sure, China and eBay should not be on my list for caps - right?
Anyway, Have a great day and I'll post videos so you can see what I did

and

the results that happen.
Have a great day and weekend!
Tony

On Fri, Apr 26, 2019 at 9:05 AM Siggi <siggi@...> wrote:

Hey Tony,

welcome to the group. I watched the videos you posted in another thread
detailing your 2465 CTS troubles <
>.
Here's my advice for how to proceed:

1. Get a service manual for your scope. You can download one from

here <

>, or if you're not satisfied with

the

scan quality you can buy a very good quality scan from Artek

Manuals <

>.
2. Get familiar with the controls of your scope. Alan Wolke has a

bunch

of tutorial-like videos on coupling and trigger setup and such,

there's

a
list of his YouTube videos here <
>.
3. Read this document <
>

on

how to troubleshoot oscilloscopes.

Now looking through your videos, I think you one problem for sure, and
possibly one more.

1. Your beam finder button sticks or glitches.
2. Something else, possibly more than one other problem.

It's very hard to reason about what the CRT is displaying while the

beam

finder is bad, but it's easy to fix. You can probably get by with

isopropyl

alcohol - just squirt some into the switch and work it several times.

If

that doesn't do it, get yourself some kind of contact cleaner (Deoxit

D5

is

what I use), and clean the switch with that.

What makes me think that you may have a second problem is the fact that

the

readout would sometimes shrink only in the horizontal, but it's

possible

that this is simply due to a high-resistance beam finder switch, so fix
that first.

Once the beam finder switch is good, it's possible to move forward to
diagnose whatever else is wrong, if anything. A key question I found

myself

asking while watching your videos was whether the intermittent

shrinking

affects only the readout, or whether it also affects the traces.
Unfortunately I didn't see the shrinkage occur while traces and readout
were both displayed.

Note that for the traces to be displayed, your triggering controls have

to

be set up right. If you set the trigger to AUTO & CH1, then set the CH1
coupling switch to GND coupling, you should be able to display all

traces

reliably.

Siggi

On Fri, Apr 26, 2019 at 1:12 AM Tony Fleming <czecht@...> wrote:

I have the same oscilloscope. It is also listed under (at least that

is

what I found today) as Tektronix 2465CTS (or 2465 CTS) .
Mine has some problems, sometimes I loose the text on top and bottom

of

the display and also the FIND BEAM gets stuck, so I don't know

exactly

where to find the solution.
Anyway, I hope your scope is working.

Tony Fleming