Date   

Re: O.T. Digital scopes versus Tek analogue.

Sean Turner
 

Jeff,

An instrument called a "source measure unit" is what is typically sold these days as an instrument for curve tracing (and other purposes). Keithley (which is a Tektronix/Danaher subsidiary now) offers them, and they are ruinously expensive for the hobbyist (at least new). They have computer interfaces and programmability. I don't think any of the big T&M manufacturers offer a curve tracer any more. Since everything is either tiny surface mount or an ASIC or an FPGA nowadays, there's no demand. Logic analyzers are headed the same way. I think Keysight is the only company that offers a true benchtop logic analyzer anymore. Tek discontinued the TLA series and directs you to buy a mixed signal scope instead.

Sean

On Mon, Mar 1, 2021 at 01:55 PM, Jeff Dutky wrote:


Okay, I'm not disagreeing with you (I'm kind of interested in a good X-Y mode
too), but, for curve tracing, aren't there any good, modern, purely digital
(as in all data collected by a DAC and then displayed on a simple raster
display) curve tracers?


Re: 547 HV Transformer: Bill Schell rewind failed

fiftythreebuick
 

Hi Dave-

I'm sorry to hear that you're having trouble with that HV XFMR....

I did a lot of testing and evaluation for Bill Schell over the years and I don't remember him every testing a transformer with any epoxy in it at all. He and I both felt that we oughta get as far away from that as possible. He first wound them without sealing them and I have never had one of those fail. Then when he started treating them with beeswax and a vacuum chamber, it seemed like he had found quite a good process. So far, I have never had one of his fail, of any description.

Just saw your later post and I'm glad that yours is improving! A friend of mine has restored an original xfmr by putting it in a vacuum chamber and keeping it in a deep vacuum for a while. Don't remember how long he left it in there.

I hope yours comes out alright. It really does seem like the moisture is the major factor.

Tom


7854 Source Code for version 1.02, 1982 release now on Kurt's TekWiki

Clark Foley
 

Kurt Rosenfeld has posted the entire line printer listing (454 pages) of the 1982 source code version 1.02 for the 7854. It's an early release but it reveals some interesting things.


Re: 2235 AN/USM-488 power supply low voltages

Ozan
 

Voltages as follows


+5.2=4.3
+8.6=7.4
-8.6=-7.3
+30=+25.8
+100=+87.8
All the voltages are about 86-88% of their target value. Especially -8.6V is the reference for all other supplies so if it is off by some percentage all others will be off by about the same percentage. "Power Supply and CRT DISPLAY" adjustment section (page 5-4) of the manual gives the steps for R938 trim which should fix -8.6V and all other supplies if there is no other fault.

Ozan


Re: 547 HV Transformer: Bill Schell rewind failed

Eric
 

Chuck,

Are you in need of bees wax? I might be able to get some in bulk. I happen
to know a couple of bee keepers. I would also like to learn more about the
transformer winder when the time is right.

Eric

On Thu, Mar 4, 2021, 7:45 PM Chuck Harris <cfharris@erols.com> wrote:

Hi Bernd,

All indications are that my new machine is going to
do an even better job than the best I could do with
the old manual machine.

As an example, I was able to get 2/3 of the way to a
full wind without using the rosin/alcohol mixture that
I developed to enhance the wire's friction...

Using the rosin/alcohol, I am there already.

And, I will be using beeswax.

I'm glad to hear the prototype is still soldiering
on. Soon, I may be able to get you the winds I promised
oh so long ago...

-Chuck Harris

widgethunter via groups.io wrote:
My memory certainly hasn't improved with age.Not much else seems to
have, either...But, the beeswax thing I'd be willing to put money on - fwiw.
Incidentally, I still have not installed the 2nd wax xfrmr you made for
me, but the 1st prototype continues to perform flawlessly.Bernd



-----Original Message-----
From: Chuck Harris <cfharris@erols.com>
To: TekScopes@groups.io
Sent: Thu, Mar 4, 2021 4:05 pm
Subject: Re: [TekScopes] 547 HV Transformer: Bill Schell rewind failed

Hi Bernd,

I guess the biggest indicator of a scatter wind would be
the presence of a spool. The universal wind doesn't require
any additional support.

In addition to talking to you, I talked to Deane Kidd, and
Deane talked about Bill using beeswax, like tektronix did in
the earlier transformers.

But, like you, it has been a looong time, and I don't think
our memories are getting any better.

-Chuck Harris

widgethunter via groups.io wrote:
Hi Chuck;Assumed scatter because of the larger size of Schell
rewinds.It has been a looong time, but I think I'd remember if he'd said
anything about epoxy...B



-----Original Message-----
From: Chuck Harris <cfharris@erols.com>
To: TekScopes@groups.io
Sent: Wed, Mar 3, 2021 9:57 am
Subject: Re: [TekScopes] 547 HV Transformer: Bill Schell rewind failed

Hi Bernd,

There have been several discussions about Bill's transformers of
late, and there is a picture on the group, that looks very much
like epoxy varnish, or some other non wax compound.

However, it is most definitely not scatter wound. It is a nice
looking, self supporting, universal wind.

Bill didn't use an outer tape covering on this transformer. The
naked winding is right there for you to see.

-Chuck Harris














2235 AN/USM-488 power supply low voltages

richardallred@...
 

I bought this scope earlier this summer as new old stock, never powered on. Due to covid illness I never opened it until a week ago. The scope powered on ,but the trace only covered about 2/3s of the screen and was jumping all over.

After it was warming up only got worse, I decided to check the voltages on the power supply and all were low.

So I did a full recap (caps are still old even though the scope has zero hours) and also replaced the following:

VR 901
Q935
Q946, 947
Q9070
R888,889,890,891,892
R900
and the ac filter
all 3 rifa x class caps


Same problem still exist

Voltages as follows


+5.2=4.3
+8.6=7.4
-8.6=-7.3
+30=+25.8
+100=+87.8

resistance to ground;

+5.2=188oms
+8.6=129.8 ohms
-8.6=81 oms
+30=552 ohms
+100=16k ohms


also the trigger led blinks when the scope is on. I have been reading all the power supply post here and frankly, I'm stumped

This is my first attempt a troubleshooting a switch mode power supply. any and all suggestions would be greatly appreciated

Thanks in advance
R A


Re: Replacing Variable Vertical Attenuator Shaft

stevenhorii
 

Dick,

I parted out some 7000-series plug-ins that were not repairable. I believe
I have some of those G-10 rods. They connect to pots via a coupler with two
set screws. If that rod is what you need, let me look at what I have and
I’d be glad to send you one. If they are longer than 7”, it would be simple
to cut it to length.

You can contact me off list if you wish or reply here. My e-mail is:
sonodocsch at gmail dot com.

Steve Horii

On Thu, Mar 4, 2021 at 20:47 Dick <w1ksz@outlook.com> wrote:

The shaft is a piece of G-10 rod that's about 7" long. It goes
from the Front panel to a bushing buried in the Vertical Amplifier.

I thought I would ask before I butcher the job.

I am located in Vail, Arizona. About 20m SSE of Tucson.

73, Dick, W1KSZ
________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Waltzingbear
<alan@waltzingbear.com>
Sent: Thursday, March 4, 2021 10:57 AM
To: TekScopes@groups.io <TekScopes@groups.io>
Subject: Re: [TekScopes] Replacing Variable Vertical Attenuator Shaft

I bet that is an AB mod pot, in which case you can repair the pot with a
new shaft part. What is the length of the shaft?

oh, and what part of the world are you located in.

Cheers
Alan











Re: Replacing Variable Vertical Attenuator Shaft

Dick
 

The shaft is a piece of G-10 rod that's about 7" long. It goes
from the Front panel to a bushing buried in the Vertical Amplifier.

I thought I would ask before I butcher the job.

I am located in Vail, Arizona. About 20m SSE of Tucson.

73, Dick, W1KSZ
________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Waltzingbear <alan@waltzingbear.com>
Sent: Thursday, March 4, 2021 10:57 AM
To: TekScopes@groups.io <TekScopes@groups.io>
Subject: Re: [TekScopes] Replacing Variable Vertical Attenuator Shaft

I bet that is an AB mod pot, in which case you can repair the pot with a new shaft part. What is the length of the shaft?

oh, and what part of the world are you located in.

Cheers
Alan


Tek 492BP how to save via GPIB to a PC

 

I have an 492BP, and a GPIB to USB National Instruments. Can I use the HP 7470A plotter program to save screens?
I tried and I get error borad GPIB0 not found.


Re: 547 HV Transformer: Bill Schell rewind failed

Chuck Harris <cfharris@...>
 

Hi Bernd,

All indications are that my new machine is going to
do an even better job than the best I could do with
the old manual machine.

As an example, I was able to get 2/3 of the way to a
full wind without using the rosin/alcohol mixture that
I developed to enhance the wire's friction...

Using the rosin/alcohol, I am there already.

And, I will be using beeswax.

I'm glad to hear the prototype is still soldiering
on. Soon, I may be able to get you the winds I promised
oh so long ago...

-Chuck Harris

widgethunter via groups.io wrote:

My memory certainly hasn't improved with age.Not much else seems to have, either...But, the beeswax thing I'd be willing to put money on - fwiw.
Incidentally, I still have not installed the 2nd wax xfrmr you made for me, but the 1st prototype continues to perform flawlessly.Bernd



-----Original Message-----
From: Chuck Harris <cfharris@erols.com>
To: TekScopes@groups.io
Sent: Thu, Mar 4, 2021 4:05 pm
Subject: Re: [TekScopes] 547 HV Transformer: Bill Schell rewind failed

Hi Bernd,

I guess the biggest indicator of a scatter wind would be
the presence of a spool.  The universal wind doesn't require
any additional support.

In addition to talking to you, I talked to Deane Kidd, and
Deane talked about Bill using beeswax, like tektronix did in
the earlier transformers.

But, like you, it has been a looong time, and I don't think
our memories are getting any better.

-Chuck Harris

widgethunter via groups.io wrote:
Hi Chuck;Assumed scatter because of the larger size of Schell rewinds.It has been a looong time, but I think I'd remember if he'd said anything about epoxy...B



-----Original Message-----
From: Chuck Harris <cfharris@erols.com>
To: TekScopes@groups.io
Sent: Wed, Mar 3, 2021 9:57 am
Subject: Re: [TekScopes] 547 HV Transformer: Bill Schell rewind failed

Hi Bernd,

There have been several discussions about Bill's transformers of
late, and there is a picture on the group, that looks very much
like epoxy varnish, or some other non wax compound.

However, it is most definitely not scatter wound.  It is a nice
looking, self supporting, universal wind.

Bill didn't use an outer tape covering on this transformer.  The
naked winding is right there for you to see.

-Chuck Harris










Re: Replacing Variable Vertical Attenuator Shaft

Waltzingbear
 

I bet that is an AB mod pot, in which case you can repair the pot with a new shaft part. What is the length of the shaft?

oh, and what part of the world are you located in.

Cheers
Alan


Tektronix 2205-40 SGL SWP not working

Jay Czaja
 

Hello group. I have a 2205-40 that I use to repair tube amplifiers and other simple audio stuff. Everything works perfectly on the scope except for the SGL SWP trigger. I haven't yet opened up the scope to test if the momentary switch is faulty but was wondering if there was anything else besides the switch that could potentially go wrong with this part of the scope? Also, if the switch is indeed faulty does anyone know of a suitable replacement that will fit properly as I can not find the Tektronix part (260-2290-00)? Thanks.


Re: 547 HV Transformer: Bill Schell rewind failed

widgethunter
 

My memory certainly hasn't improved with age.Not much else seems to have, either...But, the beeswax thing I'd be willing to put money on - fwiw.
Incidentally, I still have not installed the 2nd wax xfrmr you made for me, but the 1st prototype continues to perform flawlessly.Bernd

-----Original Message-----
From: Chuck Harris <cfharris@erols.com>
To: TekScopes@groups.io
Sent: Thu, Mar 4, 2021 4:05 pm
Subject: Re: [TekScopes] 547 HV Transformer: Bill Schell rewind failed

Hi Bernd,

I guess the biggest indicator of a scatter wind would be
the presence of a spool.  The universal wind doesn't require
any additional support.

In addition to talking to you, I talked to Deane Kidd, and
Deane talked about Bill using beeswax, like tektronix did in
the earlier transformers.

But, like you, it has been a looong time, and I don't think
our memories are getting any better.

-Chuck Harris

widgethunter via groups.io wrote:
Hi Chuck;Assumed scatter because of the larger size of Schell rewinds.It has been a looong time, but I think I'd remember if he'd said anything about epoxy...B



-----Original Message-----
From: Chuck Harris <cfharris@erols.com>
To: TekScopes@groups.io
Sent: Wed, Mar 3, 2021 9:57 am
Subject: Re: [TekScopes] 547 HV Transformer: Bill Schell rewind failed

Hi Bernd,

There have been several discussions about Bill's transformers of
late, and there is a picture on the group, that looks very much
like epoxy varnish, or some other non wax compound.

However, it is most definitely not scatter wound.  It is a nice
looking, self supporting, universal wind.

Bill didn't use an outer tape covering on this transformer.  The
naked winding is right there for you to see.

-Chuck Harris


Re: 547 HV Transformer: Bill Schell rewind failed

Chuck Harris <cfharris@...>
 

Hi Bernd,

I guess the biggest indicator of a scatter wind would be
the presence of a spool. The universal wind doesn't require
any additional support.

In addition to talking to you, I talked to Deane Kidd, and
Deane talked about Bill using beeswax, like tektronix did in
the earlier transformers.

But, like you, it has been a looong time, and I don't think
our memories are getting any better.

-Chuck Harris

widgethunter via groups.io wrote:

Hi Chuck;Assumed scatter because of the larger size of Schell rewinds.It has been a looong time, but I think I'd remember if he'd said anything about epoxy...B



-----Original Message-----
From: Chuck Harris <cfharris@erols.com>
To: TekScopes@groups.io
Sent: Wed, Mar 3, 2021 9:57 am
Subject: Re: [TekScopes] 547 HV Transformer: Bill Schell rewind failed

Hi Bernd,

There have been several discussions about Bill's transformers of
late, and there is a picture on the group, that looks very much
like epoxy varnish, or some other non wax compound.

However, it is most definitely not scatter wound.  It is a nice
looking, self supporting, universal wind.

Bill didn't use an outer tape covering on this transformer.  The
naked winding is right there for you to see.

-Chuck Harris


Re: 547 HV Transformer: Bill Schell rewind failed

Roy Thistle
 

Roger:
If's beeswax (It could be paraffin wax, or a silicone wax, or some other wax type potting...or not even wax)
If it's beeswax... and you want to verify... put a tiny scraping of it in a spoon, and hold it in the steam of a boiling kettle... it will soon melt.
Also, beeswax has a pleasant fragrance.
--
Roy Thistle


Re: 7104 readout issue

Steven Bender
 

Sean,

A friend of mine found a burned resistor and bad TO-5 metal can transistor on the Readout Board in a military version of the 7603. The R was 3.9k, the TO-5 can something like a 2n2905 or 2n3440 with an OEM number. Maybe examine / check for those parts, if that transistor loses beta over time, it may overheat the R, then self destruct causing a loss of display.

Steven


Re: Tek 2782

Steven Bender
 

Hi Steve,

I can think of a few possibilities... maybe the tilting caused something to short, blowing a fuse or some circuitry. Maybe a board became disconnected. Maybe a PS line got pulled from its connection. Maybe a board became warped and hit ground, damaging surge blew out a circuit or fuse. Maybe the socket on the CRT lost connection to its pins... pull anything and clean contacts gently, look for item in contact with the case or ground, check fuses, test PS capacitors, try again!

Steven


Re: [Tek 485] No intensity control

Ozan
 

I see ~42mV at collector of Q1548, no dot on screen in XY Mode.
Base of Q1544 is at ~1V, HFE measured with a TC1 tester : 214
Look OK.

CR1539 is ok : ~.6V and 0L
Looks OK.

R1536 measured in circuit gives : 300kohm and 100kohm (when inverting the test
leads of DMM).
This is a very large resistor, you won't be able to get a good read without removing a leg. I recommend checking C1537 first, see below.

I just noticed C1537 is an electrolytic cap although its value is small. It could have developed a small leakage. If you remove it do you see any difference?
Ozan


Re: 547 HV Transformer: Bill Schell rewind failed

widgethunter
 

Hi Chuck;Assumed scatter because of the larger size of Schell rewinds.It has been a looong time, but I think I'd remember if he'd said anything about epoxy...B

-----Original Message-----
From: Chuck Harris <cfharris@erols.com>
To: TekScopes@groups.io
Sent: Wed, Mar 3, 2021 9:57 am
Subject: Re: [TekScopes] 547 HV Transformer: Bill Schell rewind failed

Hi Bernd,

There have been several discussions about Bill's transformers of
late, and there is a picture on the group, that looks very much
like epoxy varnish, or some other non wax compound.

However, it is most definitely not scatter wound.  It is a nice
looking, self supporting, universal wind.

Bill didn't use an outer tape covering on this transformer.  The
naked winding is right there for you to see.

-Chuck Harris

widgethunter via groups.io wrote:
Talked to Bill Schell a couple of decades ago about taking over and buying his setup from him.Instead, I ended up contributing what I had learned to Chuck Harris' efforts.My recollection is that Bill did NOT use epoxy, but potted in straight beeswax.Chuck and I discussed this at length, considering beeswax vs paraffin.Chuck tested 10 mixtures and found best dimensional stability with a mixture of both.
I suspect incomplete impregnation or less than ideal coil pack resulting from his scatter winding method.Never heard of a Schell rewind failing until now.Bernie Schroder
 
 


Re: Replacing Variable Vertical Attenuator Shaft

Dick
 

Might help if I mentioned the Model Number !!!
Sorry about that ...

It's a 485.

Thanks, Dick, W1KSZ
________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Dick <w1ksz@outlook.com>
Sent: Thursday, March 4, 2021 9:24 AM
To: TekScopes@groups.io <TekScopes@groups.io>
Subject: [TekScopes] Replacing Variable Vertical Attenuator Shaft

I broke one of the 1/8" shafts that goes from the Front Panel
to the Variable Attenuator Pot in one of the Vertical Amplifiers.

I removed the Outer Case and the cover on the Vertical Attenuator
and came to a grinding halt.

How does one get to that Pot so I can replace the shaft ?

Thanks for the help,

Dick, W1KSZ

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