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Hello guys! I got an oscilloscope from ebay. When I turned it on for the first time, I received a clear image with the inscription - Replace the battery -. Great, I thought, bought a battery and replaced it. But now it doesn't start at all, the blurry image is impossible to read. (perhaps again about replacing the battery?). Maybe there will be thoughts on the direction of troubleshooting?
The ripple of the power supply has been verified and the supply voltages are correct.
Photo
/g/TekScopes/album?id=262436

Hi Joe,

Michael and Chuck are right - there is no such thing as a retrace on the (analogue) CRT curve tracers. A retrace is something you have to adresse when you display a raster.

The HV in these units (as well as in scopes) is generated with a flyback transformer circuit, but that has no connection to the horizontal deflection circuits.

cheers
Martin

When I looked it up, I decided that yes, he was right on target, but don't most people have odd hobbies?? Everyone I know who's actually interesting has at least one.
My name is Dave, and I too am an Anorak

?I'm an anorak too! We're all anoraks!


Dave Anorak Wise

________________________________
From: [email protected] <[email protected]> on behalf of Dave Seiter via groups.io <d.seiter@...>
Sent: Tuesday, March 30, 2021 6:10 PM
To: [email protected]
Subject: Re: [TekScopes] Odd 453A on ebay UK

I tried also... Apparently, I'm an "anorak". Confused; I politely asked why he was calling me a parka. It went downhill from there. He's an angry individual.
-Dave
On Tuesday, March 30, 2021, 02:53:34 PM PDT, Mlynch001 <mlynch002@...> wrote:

The sad thing is, the seller seems unwilling to even consider that he could be wrong. I have run into such people on E-Bay, (and elsewhere). I just move on or sometimes watch the show from the sidelines.

--
Michael Lynch
Dardanelle, AR

I tried also...? ?Apparently, I'm an "anorak".? Confused; I politely asked why he was calling me a parka.? It went downhill from there.? He's an angry individual.
-Dave

On, I think all, of the tektronix curve tracers,
the forward trace, and the backward trace are equivalent
as there is no z-axis control, save for the intensity control.

So, unless you are planning to add a whole bunch of twidgety
circuitry that senses when the sine wave hump that traces the
horizontal trace reaches its peak, and blanks as it returns to
its minimum, I would suggest that you live with it.

The degree of looping that you are seeing can be increased by
stray capacitance, and by thermal effects in the transistor that
cause it to warm on the forward trace, and being warm, retrace
a different path on the retrace. The knowledge it presents is
also useful. You should be able to calculate all sorts of thermal
effects from the width of the loop.

Enjoy! It is a good curve tracer.

-Chuck Harris


On Tue, 30 Mar 2021 13:41:57 -0700 "Joe"
<The-Lohrbach-Family@...> wrote:

Hello,

Today I let the unit running for an hour at regular mains voltage and
did comparison tests on a pair of BC 238 C transistors. What can I
say? I am deeply impressed by the bright, sharp and stable display.
That is great! Nevertheless I registered a minor problem that has to
be solved: The flyback traces of the beam are "visible, too bright".

@ John: Yes I forgot to mention these sticky fan bearings. Well, a
little "Ballistol" oil did the job quickly. @Jeff: Thanks, your
explanation must be right. That tells us the Tek designers did a very
good job. I know a lot of other instruments where several components
are tied to higher voltage levels and not any provision is done to
prevent shorting or so.

BTW: All of my BC 238 C transistors produced very similar curve
families, so they seem to have close tolerances. I think I will try
some older OC 26 now and see what happens. Joe

The sad thing is, the seller seems unwilling to even consider that he could be wrong. I have run into such people on E-Bay, (and elsewhere). I just move on or sometimes watch the show from the sidelines.

--
Michael Lynch
Dardanelle, AR

If my memory is serving me correctly, the 575, like the 576 curve tracer does not “blank” the fly back retrace, so there is always a slight retrace visible.

--
Michael Lynch
Dardanelle, AR

I wonder if it's possible to report him to ebay (selling items that are not as described)...
On the other hand, they are unlikely to care since all they are interested in is their hefty commission.

from craigsList 03/30/21.
Tektronix Oscilloscope 533 - $20 Location- Orange County, California. pickup only.
"Vintage Oscilloscope from the 1960s. This was my dad’s when he was an engineer for the defense industry. I believe it works it powered up last time we plugged it in but that was many years ago. What you see is what you get no cords or cables included.
It’s a very heavy duty unit and has a great vintage patina.
Cheap - Come and get it!"
There are 3 pictures - I looks very restorable.

I have no affiliation but contacted Gabe (the seller) at the CL ad; he has no other electronics available, will be moving soon, wants to find it a good home for this vintage lab scope. I am posting the info here with seller's permission. CL ref. number is 7295941086 and a CL link below. Contact Gabe direct through CraigsList or me OFFLIST if you need help.






All fir now,
Ben

Hello,

Today I let the unit running for an hour at regular mains voltage and did comparison tests on a pair of BC 238 C transistors. What can I say? I am deeply impressed by the bright, sharp and stable display. That is great! Nevertheless I registered a minor problem that has to be solved: The flyback traces of the beam are "visible, too bright".

@ John: Yes I forgot to mention these sticky fan bearings. Well, a little "Ballistol" oil did the job quickly.
@Jeff: Thanks, your explanation must be right. That tells us the Tek designers did a very good job. I know a lot of other instruments where several components are tied to higher voltage levels and not any provision is done to prevent shorting or so.

BTW: All of my BC 238 C transistors produced very similar curve families, so they seem to have close tolerances. I think I will try some older OC 26 now and see what happens.
Joe

Welcome John!

You should begin at the beginning: open her up and do a visual inspection, you'd be surprised what will jump out at you, even if you're a novice (I assume that you are not actually a novice to electronics, based on the call sign, but even a novice to scopes can still spot some signs of trouble). Next, clean the insides as needed using a static safe brush or compressed air. Finally power it up and have a look at the power rails (as Siggi suggested).

Take pictures. Take notes. People here will be more than willing to assist you with further diagnosis and repair.

You might want to have a look at this document:

Also, download this service manual from TekWiki:

The TekWiki is a source for a great deal of information, both general and specific, about Tek scopes and other instruments. Here is the "reference material" page:
and here is the main page:

Finally, some of the 2400-series scopes can be damaged if they are run for more than a few minutes with the case off. Some of the hybrids really need the forced air cooling, so if you are running it with the case off (to check the power supply rails, for instance) you should direct a fan to be blowing air over the main board with all the heat sinks. I'm not sure that the 2430 is one of the ones that can be damaged that way, but better safe than sorry.

-- Jeff Dutky

I've added a photo of the left interface board of my 7S12 so you can compare.

From the sound of the previous attempts to inform the seller, I doubt that anyone will be successful with any "correction". This is the "Thing that won't go away".

--
Michael Lynch
Dardanelle, AR

Well, it's now listed for (minimum) third time.
Desciption states it's a "dual beam" scope, so I do hope someone can politely correct him on this: don't want it sold and then rejected as "not as described" , do we?
john

Joe:
congratulations, and I hope you enjoy using this wonderful piece of test equipment. I had a very simlar experience with a 575 which I bought "blind" on an auction site a couple of years ago (not Ebay). I've managed to retain the HV electrolytics, but changed all the black jobbies. On my unit, there were quite a few tired valves/tubes: in particular the triodes used as HT regulators. Oh, and the fan bearings were sticky with old green oil, so the fan would not run until things got hot. It took some effort to completely clean the oilite bearings.
John

On Tue, Mar 30, 2021 at 10:02 AM John Morris <k7rld@...> wrote:

Scopes are not my expertise so if anyone has an idea where to start
looking, I'd sure appreciate some guidance.

You'd generally start by looking at the power supplies which may simply
need recapping by now.

Grin!? The 7704A probably isn't recommended, but I've had one on that cart for years.? Just last week I was thinking that my 465 would make more sense on it (and be safer!)

Hi Dave, I didn't realise that. But then I've never worked with 7000 series kit. I don't think it would take my 547:)

Also works for 7704As, well strapped down, of course!