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Hi John,

I've recently joined and have been lurking wondering the same thing. I'm part way through restoring a 535A, a 547 and have recently completed a 503. It is definitely a labor of love on these things, but I'm hoping after completely recapping and retubing them, I have a couple old scopes that run like the factory said they should.

Best regards,

Jason

Hi John,

I still have a 564 storage scope on the bench, it's smaller then a 547, etc and there's lots of plug-ins including sampling units! I guess I cornered the market on mint 3L10 SA units too. But I also use a 7000 series on the other bench and use a 465B portable. I like working on the older units, easier to fix then 7000.

I guess I'll always have a 560 series at homes since it was the first good scope I got for home in the 1970's! lol!

Pete

I had to keep looking and Q1478 is also shorted. Did the shorted tantalum take out both Q1474 and Q1478? Man, that happened since I started working on it.

I had to order Q1478 so, I'm done for a few days,

Thanks,
Glen

The .01uF 6kV disk capacitor arrived yesterday and this evening I soldered it in between T1320 and the NTE539 voltage tripler. I powered up the scope and Bingo! There is a trace bright and crisp.

Reed thank you so much for your guidance trouble shooting this problem with me. Now for the fun part, put the attenuator board back in and seeing what else might be wrong with this scope.

Ripley

Sent from Mail for Windows 10

From: SuddenLink
Sent: Thursday, March 21, 2019 11:08 PM
To: [email protected]
Subject: Re: [TekScopes] 475 with no Display and no HV

A little late now but a good tip th

Sent from Mail for Windows 10

From: Glenn Little
Sent: Thursday, March 21, 2019 9:02 PM
To: [email protected]
Subject: Re: [TekScopes] 475 with no Display and no HV

Ensure that the silicon sealer does NOT cure with acetic acid.
Use silicone sealer that cures with alcohol.
If it smells like vinegar do not use it on electronics.

Glenn


On 3/21/2019 7:05 PM, SuddenLink wrote:

Good to know. Right now I need to locate a .01uF cap with 5kv or better voltage rating. All that I have in stock only go up to 1kv. I am at the Radio Museum tomorrow. Will see what we have there.

Ripley

The words are mine but this iPad does what it will with them.

On Mar 21, 2019, at 6:13 PM, Reed Dickinson <reed714@...> wrote:

Hi Ripley:

If your scope does not fire up when you have the .01uF cap between the transformer and the NTE539 tripler then the tripler may be blown as your last note implied you tried the tripler without the cap. The cap was present inside the original tripler but you could not see it as the original tripler was potted in Hysol. Try the .01uF cap, the tripler just possibly might still be good.

Reed

On 3/21/2019 4:37 AM, SuddenLink wrote:
Hello Reed,

Ahhh. A .01uF capacitor is the secret. The NTE539 sure doesn’t work with a direct connection to the HV transformer’s secondary. I will give it a try and report back.

Ripley

The words are mine but this iPad does what it will with them.

On Mar 21, 2019, at 12:50 AM, Reed Dickinson <reed714@...> wrote:

Hi Ripley:

You are correct, do not connect to the focus lead, a blob of silicon seal should work. You need to splice the cable going from the tripler to the socket. Slide a piece of shrink wrap tubing over a piece of thick wall plastic tubing over the wires to be spliced, make sure that you have a good lapping solder joint. After the joint cools look closely and be sure there are no sharp pieces of wire showing then generously coat the entire joint with silicon sealer and slide the large piece of tubing over the joint then slide the shrink tubing over the plastic tubing and heat the shrink tubing to seal it. If it is loose use two small tie wraps. Mount the mew tripler where the old tripler was by drilling two holes and install screws. Next connect the transformer output to the IN terminal using a .01uF, 5KV or 10KV cap. The cap must be used to make it work. Connect up and fire it up. Good luck!


Reed

On 3/17/2019 5:28 PM, SuddenLink wrote:
Hi Reed,

I received the NTE539 a few days ago and pulled out the existing HV trippler these evening. It is going to be a tight fit but it looks I can squeeze the new trippler in it’s place. The question is, what do I do with the Focus tab on the NTE539. I am thinking that it gets clipped off and covered with a glob of silicon seal.

I am going to hold off until I hear back from you.

Thank you.

Ripley

Sent from Mail for Windows 10

From: Reed Dickinson
Sent: Tuesday, March 5, 2019 3:11 PM
To: [email protected]
Subject: Re: [TekScopes] 475 with no Display and no HV

Hi:
See answers in red below.

--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"

OK, I have made progress. I found a bad 18 ohm resistor near Q1496. It wasn't open but measured in the kilo-ohms. One of my component checkers thought it was a cap due to the varying resistance. I didn't have an 18 ohm but I stuck in a 22 and now have 111v on the 110 rail. This resistor was not in the documentation. My pcb looks slightly different than anything I have found online (in this area) of the board.

So, excited to make progress, I rechecked all of the voltages. Everything looked good except the -15 was down to just noise. I found a shorted 10uf tantalum cap. I pulled it and still no -15 volts. Turned off power, searched schematic and pulled/checked Q1474 it was bad. So, now I replaced Q1474 (2N2222A) and the 10uf tantalum (I used a 10uf 50v radial electrolytic). I now have voltage but instead of -15 I'm coming in at -21.5.

I think I'll call it a day. If you have thoughts on the high -15, please let me know.

Many thanks,
Glen

This is a used book...? Just sayin'

Phil

Dang, held on to my copy too long !!

Richard S.

On Thu, Mar 28, 2019 at 4:21 PM Dennis Tillman W7PF <dennis@...>
wrote:

Hi John,

Stan Griffiths of Aloha OR is THE definitive collector of Tek tube scopes.
By now he has upwards of 1,000 in his ham shack, storage containers, and
other out buildings on his property. Stan was one of the two founders of
the VintageTEK Museum and he loaned some of his collection to the museum
for its first 5 years or so.

Stan wrote a book which you may not be familiar with on Tek's early (tube)
scopes. It is called "Oscilloscopes: Collecting and Restoring a Classic";
ISBN-13: 9780963307156; Publisher: Stanley A. Griffiths; Publication date:
01/28/1992; Pages: 372; Product dimensions: 6.50(w) x 1.50(h) x 9.50(d).

After years of being out of print (and copies going for over $100 each) it
appears he has started printing again because you can get a copy from
Barnes and Noble for $6.39 according to this web page on their site:



I know that Stan was pretty pissed for many years that used book dealers
were demanding more than $100 each for copies of his book so it sounds like
he has finally done something about it and republished it.

Dennis Tillman W7PF

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of
John Williams
Sent: Wednesday, March 27, 2019 6:08 PM
To: [email protected]
Subject: [TekScopes] I wonder if there is much interest in vacuum tube
oscilloscopes such as the 500 series

Hi folks. I have been observing the topics of interest here for a few
weeks, and I am not seeing much on older scopes ie before the 7000
series. I am just wondering if this is a temporary trend or is it too
late. Has all interest in the restoration and repair of these old
“boat anchors” gone somewhere else, or has it died altogether? I am
still working on several projects bringing new life to the ‘50s and
‘60s units. I hope I am not the last of a dying breed. Regards, John

--
Dennis Tillman W7PF
TekScopes Moderator

If anyone is interested, I live 4 blocks from Vetco and I know the owner very well so it may be possible to get these scopes at a great price. I can pick them up and get the packed for shipment for you. If interested contact me OFF LIST at dennis at ridesoft dot com.

Dennis Tillman W7PF

Hi John,
The 7904A and the 7934 are both outstanding scopes for different reasons.
The 7934 is quite rare because it was introduced 3 years before Tek ended
the 7K product line. SO it is highly unlikely you will ever get another
chance to buy one. The 7904A is more common so I think Craig summed up it
perfectly when he said:

If ...the 7934... was available to buy, I'd buy it in a heartbeat. And

then look

for a 7904A.

It goes without saying that I have a 7934, a 7104, a 7844, a 7854, 3 7603s,
a 576, a 577 and a bunch of others as well. If Craig is almost certifiable I
hate to think what that makes me.

Dennis Tillman W7PF

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of
Craig Sawyers
Sent: Wednesday, March 27, 2019 8:30 PM
To: [email protected]
Subject: Re: [TekScopes] Advice sought on 7934 vs 7904A mainframe

I have an opportunity to buy a 7934 mainframe. I would have

preferred

a 7904A but the 7934 has come up. I am not all that impressed with
storage tube scopes but ignoring the storage function how do the
2 mainframes compare? They are both 500 MHz units so the question
becomes are there any real or effective differences in their
performance? Are there any weak spots in either of these two
mainframes? On the surface ignoring the storage capability of the

7934 it and the 7904A look fairly similar. Can I get some feedback on
these two units from the group.

The 7934 is somewhat rare (much rarer than the 7834), and is a fine
storage scope. Like all Tek's "multimode" storage scopes, bistable is
useless (ridiculously low contrast), but in variable persistence and
fast variable persistence it has astonishing performance.

The other main difference is that driving a storage scope is an
acquired art; it is quite easy to damage the storage meshes,
particularly where the readout is. If you get the chance to try before
you buy, check that out.

Also the 7934, and the 7834 before it, has a relatively low
acceleration voltage (8kV) as compared with 21kV on the 7904A. That
makes the 7934 trace appear somewhat dim as compared with any non-
storage scope, like the 7904A. The 7934 uses a much lower acceleration
voltage because it is optimised for storage.

But if you want to store a single shot (or even repetitive waveform)
for photography or visual inspection, that is the way to go. And it is
very impressive to see a single shot with a sub-nanosecond rise
stored.

If it was available to buy, I'd buy it in a heartbeat. And then look
for a 7904A.

I suppose it goes without saying that I have a 7834 and 7934, and 7904
and 7904A. But then again I'm almost certifiable.

Craig

--
Dennis Tillman W7PF
TekScopes Moderator

Hi John,

Stan Griffiths of Aloha OR is THE definitive collector of Tek tube scopes. By now he has upwards of 1,000 in his ham shack, storage containers, and other out buildings on his property. Stan was one of the two founders of the VintageTEK Museum and he loaned some of his collection to the museum for its first 5 years or so.

Stan wrote a book which you may not be familiar with on Tek's early (tube) scopes. It is called "Oscilloscopes: Collecting and Restoring a Classic"; ISBN-13: 9780963307156; Publisher: Stanley A. Griffiths; Publication date: 01/28/1992; Pages: 372; Product dimensions: 6.50(w) x 1.50(h) x 9.50(d).

After years of being out of print (and copies going for over $100 each) it appears he has started printing again because you can get a copy from Barnes and Noble for $6.39 according to this web page on their site:


I know that Stan was pretty pissed for many years that used book dealers were demanding more than $100 each for copies of his book so it sounds like he has finally done something about it and republished it.

Dennis Tillman W7PF

Glen,
The ripple looks ok. The manual I am using is the 108MB file on the 475 page at w140.com/tekwiki.

If you locate schematic <12> power supply, the previous schematic shows power distribution including a decoupled 110V and 104V to the horizontal amplifier. A couple of pages before that you will find a parts list 7-17 showing C1267 at square 7F and the board layout with the parts marked out. It is part of the board with the power regulators.

A difficulty with the 475 construction is that it is not easy to remove power from parts of the scope to narrow down the problem. If something is drawing too much current it will probably be hot but at 110V you don't want to touch everything in sight.

Good luck,

Roger

PS I am in the UK so the time difference is a drawback in these exchanges.

Hi John,

The resistor string is pretty evident. It is about
10, 10M SMD resistor all in series, sitting off by
themselves. You can see it when you pull the cover
off the HV. Clear plastic cover comes to mind.

The last 2710 I worked on with focus issues had a bad
solder joint to one of the resistors I fluxed the
heck out of the board, resoldered, and I haven't heard
any complaints since.

-Chuck Harris

john@... wrote:

On 2019-03-28 3:28 PM, Dave Seiter wrote:

I wouldn't worry too much about death, as long as you take reasonable precautions.? I've been hit many times by both line voltage and HV, but I try not to make it a habit!

But since that unpleasant topic was raised, I really worry a lot about
the succession plans for some of the magnificent collections described
in here.

It's a lot of work for an executor to find new homes for vintage
equipment so thorough preparations should be made in advance.

If anyone has helpful advice on this, please add to thread.

--Toby

-Dave
On Thursday, March 28, 2019, 12:23:46 PM PDT, Brendan via Groups.Io <the_infinite_penguin@...> wrote:

On Wed, Mar 27, 2019 at 06:07 PM, John Williams wrote:

Hi folks. I have been observing the topics of interest here for a few weeks,
and I am not seeing much on older scopes ie before the 7000 series. I am just
wondering if this is a temporary trend or is it too late. Has all interest in
the restoration and repair of these old “boat anchors” gone somewhere
else, or has it died altogether? I am still working on several projects
bringing new life to the ‘50s and ‘60s units. I hope I am not the last of
a dying breed. Regards, John

I would love to have a tube scope to refurbish. There are a few things that stop me from buying every time one is available.? First thing is, I'm worried I wont be able to fix it due to limited parts and the such. The second is, my skill level is not super high and the voltages in those could prevent me from improving my skill level due to death. With the newer 4xx series and up most everything dangerous is covered with protection and covered in big red warning labels. After reading Jim Williams notes on vintage scopes I know I want one but I think I'm a few years out from actively looking.

Thanks for the input. I remember Tek storage scopes as rather dull display and blooming quite a bit when storing but that was back in the 60s. Ok I bought the 7934 with the following plugins 7A24, 7A26,7B92A and 7B80. The display pictures looked very good (no evidence of burn-in) and the price was definitely right so I took the punt on it. As a friend of mine said, "If the mainframe goes down just get another mainframe!" I can see where he is leading me to....

John Proctor
VK2DLP

I wouldn't worry too much about death, as long as you take reasonable precautions.? I've been hit many times by both line voltage and HV, but I try not to make it a habit!
-Dave

My reason for collecting scopes has nothing to do with providing my workbench with a working scope. For me, it's more similar to collecting classic cars, while driving a Prius.

On Wed, Mar 27, 2019 at 06:07 PM, John Williams wrote:

Hi folks. I have been observing the topics of interest here for a few weeks,
and I am not seeing much on older scopes ie before the 7000 series. I am just
wondering if this is a temporary trend or is it too late. Has all interest in
the restoration and repair of these old “boat anchors” gone somewhere
else, or has it died altogether? I am still working on several projects
bringing new life to the ‘50s and ‘60s units. I hope I am not the last of
a dying breed. Regards, John

I would love to have a tube scope to refurbish. There are a few things that stop me from buying every time one is available. First thing is, I'm worried I wont be able to fix it due to limited parts and the such. The second is, my skill level is not super high and the voltages in those could prevent me from improving my skill level due to death. With the newer 4xx series and up most everything dangerous is covered with protection and covered in big red warning labels. After reading Jim Williams notes on vintage scopes I know I want one but I think I'm a few years out from actively looking.

Yuck!? Nothing more annoying then getting a great piece of gear in the mail, only to open the box and be greeted by tobacco residue/odor!
-Dave
---------------------
?It was so bad that the tubes would actually stick to your hands!

I made an extension cable years ago from a trashed plugin and the socket from a scrapped out mainframe.? It's pretty basic, but gets the job done, at least at low frequencies.? If you can find the parts, it's easy to make.
-Dave

I have always had a soft spot in my heart for the 561/564 series, especially the later B versions with the solid state frame. somehow the look and operation of this unit with the nice rectangular CRT is supremely elegant.? I had one long ago, and manged to get another two years ago, took a few tries to get both good appearance and function.

I have a nice 561B? working now, along with an assortment of plug ins including the SA and tracking generator, still waiting to be restored. I like this series better than the much larger 53/545 style, as it is more compact, and nicer looking (in my mind), and 10Mhz bandwidth works for a lot of things.

all the best,
walter

PS: STUFF DAY is coming SOON, just two weeks away, on April 13th, hope to see you there.
I have lots of 56X compatible plug-ins if anybody needs some.


--
Walter Shawlee 2
Sphere Research Corp. 3394 Sunnyside Rd.
West Kelowna, BC, V1Z 2V4 CANADA
Phone: +1 (250-769-1834 -:-
+We're all in one boat, no matter how it looks to you. (WS2)
+All you need is love. (John Lennon)
+But, that doesn't mean other things don't come in handy. (WS2)
+Nature is trying very hard to make us succeed, but nature does not depend on us.
We are not the only experiment. (R. Buckminster Fuller)