Date   

Re: Obsolete Motorola IC

Dewey Wyatt
 

4 star electronics show 175 in stock.

On Tue, Oct 13, 2020, 7:39 AM <tenareze32@gmail.com> wrote:

Wow so fast, thanks a lot, I will now do some signal checking on the pins.
Simon






Re: Obsolete Motorola IC

Simon
 

Wow so fast, thanks a lot, I will now do some signal checking on the pins.
Simon


Re: Obsolete Motorola IC

Bruce Griffiths
 

On 14 October 2020 at 00:00 tenareze32@gmail.com wrote:


I have a faulty frequency counter (not Tektronix) which has some obsolete Motorola ICs. There is one that I suspect : MC1217L, a 14 pin DIL which I think is a Motorola ECL device, but I cannot find any data on it. They are still available, but at a price and I am not not keen to shot gun it without knowing what it is supposed to do. Does anyone have any information on this IC?. TIA.
Simon





Obsolete Motorola IC

Simon
 

I have a faulty frequency counter (not Tektronix) which has some obsolete Motorola ICs. There is one that I suspect : MC1217L, a 14 pin DIL which I think is a Motorola ECL device, but I cannot find any data on it. They are still available, but at a price and I am not not keen to shot gun it without knowing what it is supposed to do. Does anyone have any information on this IC?. TIA.
Simon


Re: Is my Tek 468 beyond repair?

John
 

With further investigation I have concluded that TIME cursors look like they are measuring pretty spot on. With a 1kHz signal it, in fact, measures 1.056mS which is correct. At 10MHz the measurement was 0.097μS which is just shy of 0.1μS which is also about right. The issue with the VOLTS measurement when there are two traces present is still a problem.

Storage does run into Nyquist at about 15MHz though and the display then becomes inaccurate. Storage captures simple waveforms but seems not to be able to cope very well with complex forms such as AM modulation even at 100kHz. I guess given the relatively small memory buffer by today's standards this is perhaps not surprising.


Re: Tektronix 2465A noise on readout

tek_547
 

Good find Gregor!
I was following this topic for a few days because HV problems are always interesting.
Congrats and thanx for the detailed explanations with pictures, René


Re: Repairing a 577 that is pretty far gone.

Eric
 

Turns out there was a fault in the 177 that was causing the issue. I will need to look at this 177 very closely. the 577 it seems is ok.

On 10/12/2020 6:38 PM, Eric via groups.io wrote:
I was able to acquire a spare op-amp from a unit that has yet to be repaired but I have some replacements on the way. I am at step 15 of the calibration document. And when I hit the invert switch my spot is off by about .8 divisions. The service manual says I should be off by about 0.1. The + -> AC -> - transition is correct and it is correct inverted but switching between inverted and normal display cause a shift +0.8.




Re: Tektronix 2465A noise on readout

Siggi
 

Congratulations!

On Mon, Oct 12, 2020 at 4:52 PM Gregor via groups.io <gregor_ruf=
yahoo.com@groups.io> wrote:

I fixed it! Now it's working fine.
And of course, I'll tell you how.
After the last test, I was pretty confident that the problem lies in the
HV power supply. So I continued searching for the error there. After
carefully probing around in the HV supply, I found that the focus voltage
(measured on C1813) had a big ripple on it. Here is the image of the
voltage on C1813: https://groups.io/g/TekScopes/photo/254966/1
Then I desoldered C1813 and checked it, and I found that it was definitely
broken.
Image of desoldered C1813: https://groups.io/g/TekScopes/photo/254966/2
I replaced it as you can see in the following picture:
https://groups.io/g/TekScopes/photo/254966/4
And look at the next picture: https://groups.io/g/TekScopes/photo/254966/3

Now it has a perfectly sharp trace and readouts without any noise! I am
super happy now :). So finally I can enjoy my 2465A.
Its always a great feeling getting something to work again.
And of course, thanks for all of your suggestions and support! I
appreciate it very much :)

-Gregor






Re: Lost Ch 1 on my 465 scope

toby@...
 

On 2020-10-12 5:34 p.m., Tom Lee wrote:
...
The 465 uses matched pairs in a can for the input source follower +
bias. These were always somewhat rare, and they've only gotten
rarer/more expensive over time. It's good that you have a parts queen.
Hopefully that unit has good FETs, because I have a feeling that you'll
be needing them.
Not sure which type is in the 465, but Linear Systems does sell various
equivalent dual matched JFETs for types used in other Tek instruments
(specifically 603/604 XY's in my case) and they have been great to deal
with.

http://www.linearsystems.com/product.html

--Toby
(not affiliated, just customer)



Good luck!

--Tom


Re: Tektronix 2465A noise on readout

Dave Wise
 

Do I take it that C1813 was open-circuit?
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Gregor via groups.io <gregor_ruf=yahoo.com@groups.io>
Sent: Monday, October 12, 2020 1:52 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tektronix 2465A noise on readout

I fixed it! Now it's working fine.
And of course, I'll tell you how.
After the last test, I was pretty confident that the problem lies in the HV power supply. So I continued searching for the error there. After carefully probing around in the HV supply, I found that the focus voltage (measured on C1813) had a big ripple on it. Here is the image of the voltage on C1813: https://groups.io/g/TekScopes/photo/254966/1
Then I desoldered C1813 and checked it, and I found that it was definitely broken.
Image of desoldered C1813: https://groups.io/g/TekScopes/photo/254966/2
I replaced it as you can see in the following picture: https://groups.io/g/TekScopes/photo/254966/4
And look at the next picture: https://groups.io/g/TekScopes/photo/254966/3

Now it has a perfectly sharp trace and readouts without any noise! I am super happy now :). So finally I can enjoy my 2465A.
Its always a great feeling getting something to work again.
And of course, thanks for all of your suggestions and support! I appreciate it very much :)

-Gregor


Re: Repairing a 577 that is pretty far gone.

Eric
 

I was able to acquire a spare op-amp from a unit that has yet to be repaired but I have some replacements on the way. I am at step 15 of the calibration document. And when I hit the invert switch my spot is off by about .8 divisions. The service manual says I should be off by about 0.1. The + -> AC -> - transition is correct and it is correct inverted but switching between inverted and normal display cause a shift +0.8.


Re: Tektronix 2465A noise on readout

Tom Lee
 

Great job, Gregor! Persistence wins again. Glad you restored that nice scope!

-- Cheers,
Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 10/12/2020 13:52, Gregor via groups.io wrote:
I fixed it! Now it's working fine.
And of course, I'll tell you how.
After the last test, I was pretty confident that the problem lies in the HV power supply. So I continued searching for the error there. After carefully probing around in the HV supply, I found that the focus voltage (measured on C1813) had a big ripple on it. Here is the image of the voltage on C1813: https://groups.io/g/TekScopes/photo/254966/1
Then I desoldered C1813 and checked it, and I found that it was definitely broken.
Image of desoldered C1813: https://groups.io/g/TekScopes/photo/254966/2
I replaced it as you can see in the following picture: https://groups.io/g/TekScopes/photo/254966/4
And look at the next picture: https://groups.io/g/TekScopes/photo/254966/3

Now it has a perfectly sharp trace and readouts without any noise! I am super happy now :). So finally I can enjoy my 2465A.
Its always a great feeling getting something to work again.
And of course, thanks for all of your suggestions and support! I appreciate it very much :)

-Gregor




Re: Lost Ch 1 on my 465 scope

Tom Lee
 

I have seen several scopes with blown inputs, although I acquired them in the dead state, with no knowledge of how they were killed.

That said, I'm sure it's not a big surprise that the input FETs do not fare well during big input overloads (the drain-gate diode tends to bite it, as it's used as a voltage clamp). Open up the 465, take a look around for obvious damage, and trace signals as they progress from the input forward. Don't be surprised if signal is lost pretty quickly. I've never seen wholesale destruction of a channel, so you may be lucky and find that the damage is confined to a small handful of components.

The 465 uses matched pairs in a can for the input source follower + bias. These were always somewhat rare, and they've only gotten rarer/more expensive over time. It's good that you have a parts queen. Hopefully that unit has good FETs, because I have a feeling that you'll be needing them.

Good luck!

--Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 10/12/2020 14:05, Ray, W4BYG wrote:
I accidentally touched the ground clip on my 465 Ch 1 probe to a "hot " AC-DC radio chassis. (I have an isolation transformer. Thought it was connected). It blew channel 1 out, but channel 2 and the rest of the scope's operations seem to be OK. I haven't yet started to trouble shoot the problem but tend to think it will be a major deal trying to fix channel one.

Has anyone gone thru this kind of an issue yet that they can offer any insight as to what gets damaged in a situation like this?

I bought this cope new in the seventies and have been the only user of it for all these years.

I have a spare 465 that is not working, which might serve for parts or modules as needed.

Your assistance and insight will be appreciated.
Ray, W4BYG


Re: Tektronix 2465A noise on readout

Chuck Harris <cfharris@...>
 

Congratulations!!!

-Chuck Harris

Gregor via groups.io wrote:

I fixed it! Now it's working fine.
And of course, I'll tell you how.
After the last test, I was pretty confident that the problem lies in the HV power supply. So I continued searching for the error there. After carefully probing around in the HV supply, I found that the focus voltage (measured on C1813) had a big ripple on it. Here is the image of the voltage on C1813: https://groups.io/g/TekScopes/photo/254966/1
Then I desoldered C1813 and checked it, and I found that it was definitely broken.
Image of desoldered C1813: https://groups.io/g/TekScopes/photo/254966/2
I replaced it as you can see in the following picture: https://groups.io/g/TekScopes/photo/254966/4
And look at the next picture: https://groups.io/g/TekScopes/photo/254966/3

Now it has a perfectly sharp trace and readouts without any noise! I am super happy now :). So finally I can enjoy my 2465A.
Its always a great feeling getting something to work again.
And of course, thanks for all of your suggestions and support! I appreciate it very much :)

-Gregor


Lost Ch 1 on my 465 scope

Ray, W4BYG
 

I accidentally touched the ground clip on my 465 Ch 1 probe to a "hot " AC-DC radio chassis. (I have an isolation transformer. Thought it was connected). It blew channel 1 out, but channel 2 and the rest of the scope's operations seem to be OK. I haven't yet started to trouble shoot the problem but tend to think it will be a major deal trying to fix channel one.

Has anyone gone thru this kind of an issue yet that they can offer any insight as to what gets damaged in a situation like this?

I bought this cope new in the seventies and have been the only user of it for all these years.

I have a spare 465 that is not working, which might serve for parts or modules as needed.

Your assistance and insight will be appreciated.
Ray, W4BYG


--
This email has been checked for viruses by AVG.
https://www.avg.com


Re: Tektronix 2465A noise on readout

Gregor
 

I fixed it! Now it's working fine.
And of course, I'll tell you how.
After the last test, I was pretty confident that the problem lies in the HV power supply. So I continued searching for the error there. After carefully probing around in the HV supply, I found that the focus voltage (measured on C1813) had a big ripple on it. Here is the image of the voltage on C1813: https://groups.io/g/TekScopes/photo/254966/1
Then I desoldered C1813 and checked it, and I found that it was definitely broken.
Image of desoldered C1813: https://groups.io/g/TekScopes/photo/254966/2
I replaced it as you can see in the following picture: https://groups.io/g/TekScopes/photo/254966/4
And look at the next picture: https://groups.io/g/TekScopes/photo/254966/3

Now it has a perfectly sharp trace and readouts without any noise! I am super happy now :). So finally I can enjoy my 2465A.
Its always a great feeling getting something to work again.
And of course, thanks for all of your suggestions and support! I appreciate it very much :)

-Gregor


Re: Where was the 567/6R1 used?

Kurt Rosenfeld
 

Nice. The 567 is an impressive machine.


Re: Air filters for big 500 series scopes

stevenhorii
 

An easy to use and cut filter material is open cell foam. It is sold as
filter material and is usually about 1/4-inch thick. It is also easily
washable and inexpensive. The material is not designed to be a HEPA filter,
but it will certainly keep down the dust inside the scope. This material is
popular as a coarse (initial) filter for Shop Vac vacuums and by itself in
kitchen range hoods. I have used it on smaller electronics that have a
filter holder over the fan. For use in the larger Tek scopes like a 547,
you will need a piece of backing material like coarse metal screening or
the filter may get sucked into the fan.

Steve H.

On Mon, Oct 12, 2020 at 11:59 Grayson Evans <wa4gvm@gmail.com> wrote:

I am trying to figure out an air filter for my two 547's and a 556. I
found an air conditioner filter that is close in size, but when I used it,
I got too little air flow and the 547 overheated. Probably need to find
some material that can be cut to size.
Any ideas?
Thanks! Grayson






Re: Tektronix 2465A noise on readout

Gregor
 

Thanks for that suggestion! To check if the noise gets added on the way between the low voltage and high voltage power supply, I did the following Test.
I desoldered one side of L1974 (the side which goes to the -15V UNREG). Then I connected the minus of my lab power supply on the free pin of L1974. After that, I connected the plus of my lab power supply to the plus of C1972 (which has ground potential of the oscilloscope). The voltage of the lab power supply was set to 18V. With this setup, I turned on the oscilloscope and the lab power supply. As a result, the noise on the scope screen was still there.
Therefore I can conclude that the noise does not come from the -15V UNREG rail of the low voltage power supply or its way between LV and HV power supply.

-Gregor

On Mon, Oct 12, 2020 at 07:03 PM, Chuck Harris wrote:


If you look at the power distribution schematic <11>, you
will notice that the only place -15V unreg goes is to the
little test socket (J119) and through a 5 ohm resistor to
power the EHT circuit board.

There are not a lot of places for noise on the -15V unreg
supply to couple to any other circuit,... except for direct
radiation and through bad grounds.

Your changing the time base between your spike photo on
C1972, and this latest photo at the fuse makes comparison
difficult.

The collector being a pseudo sine wave is normal.

-Chuck Harris



Gregor via groups.io wrote:
I measured the ripple at the fuse, and it looks like this:
https://www.dropbox.com/s/csz4sp6pfv5na3k/IMG_0743.jpg?dl=0
I also tried if it's possible to synchronize the spikes of the noise in some
way with the noise on the traces (like in #172230). And the result is that
they are not synchronous.
And since the HV oscillator is perfectly synchronous with the noise on the
traces I think it must have something to do with the HV oscillator. John's
suggestion was to check the collector of Q1981 which gives me this:
https://www.dropbox.com/s/ixpkoemepg4txht/IMG_0739.jpg?dl=0
Could this be problematic? Compared with the picture in the service manual
it's a bit distorted and clipped.

-Gregor

On Mon, Oct 12, 2020 at 04:57 PM, Chuck Harris wrote:


Ok,

400mVp-p EHT supply ripple on the 15V unreg line seems excessive
to me, but I haven't measured it lately, and don't remember if that
is normal.

The filter for the EHT's current surges is a pi type filter.
C1972 and L1974 work together to make 2/3 of the filter,
where the other 1/3 is in the power supply.

Try measuring the ripple at the fuse, and it should be greatly
reduced...

The scope will be noisy if it is run without the EHT section
shield in place.

Just for grins, I would loosen and retorque the screws that hold
the EHT circuit board. If any of the grounds are bad, though the
circuit may still work, the filtering of its noise will be greatly
impared.

-Chuck Harris

Gregor via groups.io wrote:
I have some new findings! I jumped back to John's idea that it could be
caused by HV power supply. So I did the following test. I connected the CH1
input of the oscilloscope to 100uF filter capacitor (C1972) on the HV power
supply (I connected nothing to the other channels).
And here is the result:
https://www.dropbox.com/s/th61anj5sho2m98/IMG_0737.jpg?dl=0
As you can see the HV oscillator is perfectly synchronous with the noise
(I
should have done this test earlier).
So I know from my previous test, that C1972 isn't causing the problem
therefor I will dig deeper into the HV power supply. Any additional
suggestions?

-Gregor










Re: Help needed 7633 horizontal board wanted

Mark Litwack
 

Hi Randy,

I have a 7633 and the CRT is shot. It's very dim but otherwise everything works. It's been sitting around for years because I wanted the backplane and power supply for a project that I never got around to.

If you want to send me a pre-paid label for a USPS flat rate box, you are welcome to the horizontal board and any other board(s) or parts that will fit in the box.

If interested please email me directly and we can work out the details.

After Randy is done with first dibs, anyone else is also welcome to any 7633 parts they want. Please email me.

Thanks,

-mark

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